National Library of Energy BETA

Sample records for rbob-brent crack spread

  1. 3:2:1 Crack Spread

    Gasoline and Diesel Fuel Update (EIA)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of Natural GasAdjustments (Billion Cubic Feet) Wyoming Dry NaturalPrices1 Table 1.10 CoolingNotes &* j o n5 1:2:1 Crack

  2. Hydrocarbon cracking

    SciTech Connect (OSTI)

    McCoy, R.D.

    1980-12-02

    A cracking reactor is controlled in response to the proportion of heavy aromatic constituents in a feedstock to be cracked.

  3. Shadows and Cracks

    E-Print Network [OSTI]

    Dowson, Mark

    The VIRGIN program will interpret pictures of crack and shadow free scenes by labelling them according to the Clowes/Huffman formalism. This paper indicates methods of extending the program to include cracks and shadows ...

  4. Crack coalescence in granite

    E-Print Network [OSTI]

    Miller, James Thomas, Ph. D. Massachusetts Institute of Technology

    2008-01-01

    This thesis experimentally investigates crack coalescence in prismatic Barre Granite specimens with two pre-cut, open flaws under uniaxial compression. Using a high-speed video system, crack initiation, propagation, and ...

  5. The relationship between crack-tip strain and subcritical cracking...

    Office of Scientific and Technical Information (OSTI)

    crack-tip strain and subcritical cracking thresholds for steels in high-pressure hydrogen gas. Citation Details In-Document Search Title: The relationship between crack-tip...

  6. strawberry-spread

    E-Print Network [OSTI]

    Date: 17 May 93 02:15:00 EDT From: KEVWIL@delphi.com ---------- Recipe via Meal-Master (tm) v7.04 Title: FRESH STRAWBERRY SPREAD Categories: ...

  7. Catalytic cracking process

    SciTech Connect (OSTI)

    Lokhandwala, Kaaeid A.; Baker, Richard W.

    2001-01-01

    Processes and apparatus for providing improved catalytic cracking, specifically improved recovery of olefins, LPG or hydrogen from catalytic crackers. The improvement is achieved by passing part of the wet gas stream across membranes selective in favor of light hydrocarbons over hydrogen.

  8. Hybrid spread spectrum radio system

    DOE Patents [OSTI]

    Smith, Stephen F. (London, TN) [London, TN; Dress, William B. (Camas, WA) [Camas, WA

    2010-02-09

    Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.

  9. Rifts in Spreading Wax Layers

    E-Print Network [OSTI]

    Rolf Ragnarsson; J. Lewis Ford; Christian D. Santangelo; Eberhard Bodenschatz

    1995-10-19

    We report experimental results on the rift formation between two freezing wax plates. The plates were pulled apart with constant velocity, while floating on the melt, in a way akin to the tectonic plates of the earth's crust. At slow spreading rates, a rift, initially perpendicular to the spreading direction, was found to be stable, while above a critical spreading rate a "spiky" rift with fracture zones almost parallel to the spreading direction developed. At yet higher spreading rates a second transition from the spiky rift to a zig-zag pattern occurred. In this regime the rift can be characterized by a single angle which was found to be dependent on the spreading rate. We show that the oblique spreading angles agree with a simple geometrical model. The coarsening of the zig-zag pattern over time and the three-dimensional structure of the solidified crust are also discussed.

  10. Stress corrosion crack growth in porous sandstones. 

    E-Print Network [OSTI]

    Ojala, Ira O

    Stress corrosion crack growth occurs when the chemical weakening of strained crack tip bonds facilitates crack propagation. I have examined the effect of chemical processes on the growth of a creack population by carrying out triaxial compression...

  11. Peridynamic model for fatigue cracking.

    SciTech Connect (OSTI)

    Silling, Stewart A.; Abe Askari

    2014-10-01

    The peridynamic theory is an extension of traditional solid mechanics in which the field equations can be applied on discontinuities, such as growing cracks. This paper proposes a bond damage model within peridynamics to treat the nucleation and growth of cracks due to cyclic loading. Bond damage occurs according to the evolution of a variable called the %22remaining life%22 of each bond that changes over time according to the cyclic strain in the bond. It is shown that the model reproduces the main features of S-N data for typical materials and also reproduces the Paris law for fatigue crack growth. Extensions of the model account for the effects of loading spectrum, fatigue limit, and variable load ratio. A three-dimensional example illustrates the nucleation and growth of a helical fatigue crack in the torsion of an aluminum alloy rod.

  12. Nonlinear structural crack growth monitoring

    DOE Patents [OSTI]

    Welch, Donald E. (Oak Ridge, TN); Hively, Lee M. (Philadelphia, TN); Holdaway, Ray F. (Clinton, TN)

    2002-01-01

    A method and apparatus are provided for the detection, through nonlinear manipulation of data, of an indicator of imminent failure due to crack growth in structural elements. The method is a process of determining energy consumption due to crack growth and correlating the energy consumption with physical phenomena indicative of a failure event. The apparatus includes sensors for sensing physical data factors, processors or the like for computing a relationship between the physical data factors and phenomena indicative of the failure event, and apparatus for providing notification of the characteristics and extent of such phenomena.

  13. Cracking in reinforced concrete bent caps 

    E-Print Network [OSTI]

    Young, Bradley S.

    2000-01-01

    cracking in order to improve durability and reduce maintenance costs of bent caps throughout the lifetime of the structure. Excessive cracking in RC bent caps can be controlled through improved design detailing for both flexure and shear. For flexure...

  14. Using a Bull Call Spread 

    E-Print Network [OSTI]

    Bevers, Stan; Amosson, Stephen H.; Waller, Mark L.; Dhuyvetter, Kevin C.

    2008-10-07

    The Bull Call Spread can be used to hedge against or to benefit from a rising market. The user buys a call option at a particular strike price and sells a call option at a higher strike price. Margin requirements, advantages and disadvantages...

  15. The influence of cracks in rotating shafts

    E-Print Network [OSTI]

    Sinou, Jean-Jacques

    2008-01-01

    In this paper, the influence of transverse cracks in a rotating shaft is analysed. The paper addresses the two distinct issues of the changes in modal properties and the influence of crack breathing on dynamic response during operation. Moreover, the evolution of the orbit of a cracked rotor near half of the first resonance frequency is investigated. The results provide a possible basis for an on-line monitoring system. In order to conduct this study, the dynamic response of a rotor with a breathing crack is evaluated by using the alternate frequency/time domain approach. It is shown that this method evaluates the nonlinear behaviour of the rotor system rapidly and efficiently by modelling the breathing crack with a truncated Fourier series. The dynamic response obtained by applying this method is compared with that evaluated through numerical integration. The resulting orbit during transient operation is presented and some distinguishing features of a cracked rotor are examined.

  16. The influence of cracks in rotating shafts

    E-Print Network [OSTI]

    Jean-Jacques Sinou; A. W. Lees

    2008-01-19

    In this paper, the influence of transverse cracks in a rotating shaft is analysed. The paper addresses the two distinct issues of the changes in modal properties and the influence of crack breathing on dynamic response during operation. Moreover, the evolution of the orbit of a cracked rotor near half of the first resonance frequency is investigated. The results provide a possible basis for an on-line monitoring system. In order to conduct this study, the dynamic response of a rotor with a breathing crack is evaluated by using the alternate frequency/time domain approach. It is shown that this method evaluates the nonlinear behaviour of the rotor system rapidly and efficiently by modelling the breathing crack with a truncated Fourier series. The dynamic response obtained by applying this method is compared with that evaluated through numerical integration. The resulting orbit during transient operation is presented and some distinguishing features of a cracked rotor are examined.

  17. Hybrid spread spectrum radio system

    DOE Patents [OSTI]

    Smith, Stephen F. (London, TN); Dress, William B. (Camas, WA)

    2010-02-02

    Systems and methods are described for hybrid spread spectrum radio systems. A method includes modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control an amplification circuit that provides a gain to the signal. Another method includes: modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control a fast hopping frequency synthesizer; and fast frequency hopping the signal with the fast hopping frequency synthesizer, wherein multiple frequency hops occur within a single data-bit time.

  18. Using a Bear Put Spread 

    E-Print Network [OSTI]

    Bevers, Stan; Amosson, Stephen H.; Waller, Mark L.; Dhuyvetter, Kevin C.

    2008-10-07

    spread. In this example, assume the current Chicago Board of Trade December Corn contract is trad- ing at $6.00 per bushel. The associated December put option premiums are listed in Table 1. The producer begins the strategy by buying a put op- tion... near the money, in this case a $6.00 put op- tion for $0.90 per bushel ($4,500 per 5,000-bushel contract). At the same time, he also writes (sells) a put option with a strike price below the put option. In our example, he writes a $5.00 put option...

  19. Characterization of geothermal reservoir crack patterns using...

    Open Energy Info (EERE)

    with form History Characterization of geothermal reservoir crack patterns using shear-wave splitting Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal...

  20. On Macroscopic and MicroscopicAnalyses for Crack Initiationand Crack Growth Toughness in DuctileAlloys

    E-Print Network [OSTI]

    Ritchie, Robert

    On Macroscopic and MicroscopicAnalyses for Crack Initiationand Crack Growth Toughness in Ductile microvoid coalescence, expressions are shown for the fracture toughness of materials in terms and the nondimensionalized crack initiation fracture toughness Ji~ is described and shown to yield a good fit to experimental

  1. Characterization of Fatigue Cracking and Healing of Asphalt Mixtures 

    E-Print Network [OSTI]

    Luo, Xue

    2012-07-16

    Fatigue cracking is one of the most common distresses of asphalt pavements, whereas healing is a counter process to cracking which alleviates cracking damage and extends fatigue life of asphalt pavements. Most of existing ...

  2. SAW correlator spread spectrum receiver

    DOE Patents [OSTI]

    Brocato, Robert W

    2014-04-01

    A surface acoustic wave (SAW) correlator spread-spectrum (SS) receiver is disclosed which utilizes a first demodulation stage with a chip length n and a second demodulation stage with a chip length m to decode a transmitted SS signal having a code length l=n.times.m which can be very long (e.g. up to 2000 chips or more). The first demodulation stage utilizes a pair of SAW correlators which demodulate the SS signal to generate an appropriate code sequence at an intermediate frequency which can then be fed into the second demodulation stage which can be formed from another SAW correlator, or by a digital correlator. A compound SAW correlator comprising two input transducers and a single output transducer is also disclosed which can be used to form the SAW correlator SS receiver, or for use in processing long code length signals.

  3. Investigation of Cracked Lithium Hydride Reactor Vessels

    SciTech Connect (OSTI)

    bird, e.l.; mustaleski, t.m.

    1999-06-01

    Visual examination of lithium hydride reactor vessels revealed cracks that were adjacent to welds, most of which were circumferentially located in the bottom portion of the vessels. Sections were cut from the vessels containing these cracks and examined by use of the metallograph, scanning electron microscope, and microprobe to determine the cause of cracking. Most of the cracks originated on the outer surface just outside the weld fusion line in the base material and propagated along grain boundaries. Crack depths of those examined sections ranged from {approximately}300 to 500 {micro}m. Other cracks were reported to have reached a maximum depth of 1/8 in. The primary cause of cracking was the creation of high tensile stresses associated with the differences in the coefficients of thermal expansion between the filler metal and the base metal during operation of the vessel in a thermally cyclic environment. This failure mechanism could be described as creep-type fatigue, whereby crack propagation may have been aided by the presence of brittle chromium carbides along the grain boundaries, which indicates a slightly sensitized microstructure.

  4. Constraint effects observed in crack initiation stretch

    SciTech Connect (OSTI)

    Lambert, D.M.; Ernst, H.A.

    1995-12-31

    The current paper characterizes constraint in fracture: J-modified resistance (Jr) curves were developed for two tough structural materials, 6061-T651 (aluminum) and IN718-STA1 (nickel-base superalloy). A wide variety of configurations was tested to consider load configurations from bending to tension including three specimen types (compact tension, center-crack tension, and single-edge notched tension), and a range of ligament lengths and thicknesses, as well as side-grooved and smooth-sided ligaments. The Jr curves exhibited an inflection point after some crack extension, and the data were excluded beyond the inflection. Qualified Jr curves for the two materials showed similar behavior, but R-curves were identical for equal ligament length-to-thickness ratio (RL), for the aluminum alloy, with increasing slope for increasing RL, while for the nickel, the resistance curves aligned for equal ligament thickness, B, and the slope increased for decreasing B. Displacements at the original crack tip (CToD) were recorded throughout the test for several specimens. CToD-versus-crack extension curves were developed, and data were excluded beyond the inflection point (as with the Jr curves). The data collapsed into two distinct curves, thought to represent the surface, plane stress effect and the central, plane strain effect. This was observed for both materials. A technique called profiling is presented for the aluminum alloy only, where the crack face displacements are recorded at the final point of the test as a function of the position throughout the crack cavity, along with an effort to extract the observations in a usable form. Displacements were consistent throughout the cross-section at and behind the original crack tip. In the region where the crack grew, this displacement was developed by a combination of stretch and crack growth. The stretch required to initiate crack extension was a function of the depth beneath the surface into the cross-section.

  5. Cracked-fuel mechanics. [PWR; BWR

    SciTech Connect (OSTI)

    Williford, R.E.; Lanning, D.D.

    1982-01-01

    This paper presents a modelling concept and a set of measurable parameters that have been shown to improve the prediction of the mechanical behavior of cracked fuel/cladding systems without added computational expense. The transition from classical annular gap/cylindrical pellet models to modified bulk properties and further to local behavior for cracked fuel systems is discussed. The results of laboratory experiments to verify these modelling parameters are shown. Data are also presented from laboratory experiments on unirradiated and irradiated rods which show that fuel rod mechanical response depends on fuel fragment size. The impact of these data on cracked fuel behavior and failure modelling is also discussed.

  6. Fatigue Enhancement of Undersized, Drilled Crack-Stop Holes

    E-Print Network [OSTI]

    Crain, Joshua Sakumura

    2010-04-20

    A common technique used to prevent the propagation of cracks in bridge girders is drilling crack-stop holes at the crack tips. By doing so, stress concentrations at the tip of the cracks are reduced and fatigue life of the ...

  7. Effect of Desiccation Cracks on Earth Embankments 

    E-Print Network [OSTI]

    Khandelwal, Siddharth

    2012-07-11

    Levees are earth structures used for flood protection. Due to their easy availability and low permeability, clays are the most common material used for the construction of levees. Clays are susceptible to desiccation cracks ...

  8. Contstraint effects of shallow cracks in structures containing fillet weld toe cracks 

    E-Print Network [OSTI]

    Neligon, Melinda T

    1995-01-01

    for structures containing a/W--O.l and a/W--O.5 fillet weld toe cracks. The Anderson-Dodds scaling model is applied to quantify the effects of finite size on J contour integral values for structures containing a/W=O.l and a/W=0.5 fillet weld toe cracks loaded...

  9. Characterization of cracking restraint at sawcut joints using the German Cracking Frame 

    E-Print Network [OSTI]

    Vepakomma, Shilpa

    2002-01-01

    shrinkage and creep. Early age creep and shrinkage also appear to be key factors of stress and cracking. Experiments were run to provide insight on the effect of shrinkage and creep on crack developments. The results were useful in evaluating the behavior...

  10. Discontinuous surface cracks during stress corrosion cracking of stainless steel single crystal

    E-Print Network [OSTI]

    Volinsky, Alex A.

    becomes equal to the fracture toughness, KIC, the crack will open and prop- agate. Stroh showed a crack [18]. Therefore, the fracture of most FCC metals is ductile. The chemical environment changes KIC and Protection Center, Key Laboratory for Environmental Fracture (MOE), University of Science and Technology

  11. MATERIAL POINT METHOD CALCULATIONS WITH EXPLICIT CRACKS, FRACTURE PARAMETERS, AND CRACK

    E-Print Network [OSTI]

    Nairn, John A.

    MATERIAL POINT METHOD CALCULATIONS WITH EXPLICIT CRACKS, FRACTURE PARAMETERS, AND CRACK PROPAGATION." This new method has several advantages for numerical work on fracture. Compared to finite element analysis works well for calculating key fracture parameters such as J integral, stress intensity factors

  12. TRANSPORT THROUGH CRACKED CONCRETE: LITERATURE REVIEW

    SciTech Connect (OSTI)

    Langton, C.

    2012-05-11

    Concrete containment structures and cement-based fills and waste forms are used at the Savannah River Site to enhance the performance of shallow land disposal systems designed for containment of low-level radioactive waste. Understanding and measuring transport through cracked concrete is important for describing the initial condition of radioactive waste containment structures at the Savannah River Site (SRS) and for predicting performance of these structures over time. This report transmits the results of a literature review on transport through cracked concrete which was performed by Professor Jason Weiss, Purdue University per SRR0000678 (RFP-RQ00001029-WY). This review complements the NRC-sponsored literature review and assessment of factors relevant to performance of grouted systems for radioactive waste disposal. This review was performed by The Center for Nuclear Waste Regulatory Analyses, San Antonio, TX, and The University of Aberdeen, Aberdeen Scotland and was focused on tank closure. The objective of the literature review on transport through cracked concrete was to identify information in the open literature which can be applied to SRS transport models for cementitious containment structures, fills, and waste forms. In addition, the literature review was intended to: (1) Provide a framework for describing and classifying cracks in containment structures and cementitious materials used in radioactive waste disposal, (2) Document the state of knowledge and research related to transport through cracks in concrete for various exposure conditions, (3) Provide information or methodology for answering several specific questions related to cracking and transport in concrete, and (4) Provide information that can be used to design experiments on transport through cracked samples and actual structures.

  13. Damage spreading and coupling in Markov chains

    E-Print Network [OSTI]

    Etienne P. Bernard; Cédric Chanal; Werner Krauth

    2011-06-23

    In this paper, we relate the coupling of Markov chains, at the basis of perfect sampling methods, with damage spreading, which captures the chaotic nature of stochastic dynamics. For two-dimensional spin glasses and hard spheres we point out that the obstacle to the application of perfect-sampling schemes is posed by damage spreading rather than by the survey problem of the entire configuration space. We find dynamical damage-spreading transitions deeply inside the paramagnetic and liquid phases, and show that critical values of the transition temperatures and densities depend on the coupling scheme. We discuss our findings in the light of a classic proof that for arbitrary Monte Carlo algorithms damage spreading can be avoided through non-Markovian coupling schemes.

  14. A new theory for interface spreading 

    E-Print Network [OSTI]

    Puthran, Hansraj Nagappa

    1994-01-01

    A new theory for interface spreading during sedimentation of monodisperse suspensions of spheres has been developed. Employing no adjustable parameters, it compares well with new data obtained using magnetic resonance imaging.

  15. Modeling of LNG Pool Spreading and Vaporization 

    E-Print Network [OSTI]

    Basha, Omar 1988-

    2012-11-20

    In this work, a source term model for estimating the rate of spreading and vaporization of LNG on land and sea is introduced. The model takes into account the composition changes of the boiling mixture, the varying thermodynamic properties due...

  16. Spreading of oil spilled under ice

    SciTech Connect (OSTI)

    Yapa, P.D.; Chowdhury, T. )

    1990-12-01

    A new set of equations is presented to describe the process of oil spreading under ice in clam waters. These equations consider the gravity (buoyancy)-inertia phase, the gravity (buoyancy)-viscous phase, and the termination of spreading during the buoyancy-surface-tension phase. The derivation considers both the constant discharge mode and the constant volume mode. Therefore, a complete description of the spreading phenomena from the time of initial spill to the termination of spreading is presented. Laboratory experiments were conducted using both real ice covers in a cold room and artificial ice covers. The experiments included different ice-cover roughnesses from smooth to rough, oils of different viscosities, and a variety of discharge conditions. The experimental data show close agreement with the theory. These equations can be used during cleanup or environmental impact assessment to estimate the area of an oil slick with respect to time.

  17. STRESS CORROSION CRACKING IN TEAR DROP SPECIMENS

    SciTech Connect (OSTI)

    Lam, P; Philip Zapp, P; Jonathan Duffey, J; Kerry Dunn, K

    2009-05-01

    Laboratory tests were conducted to investigate the stress corrosion cracking (SCC) of 304L stainless steel used to construct the containment vessels for the storage of plutonium-bearing materials. The tear drop corrosion specimens each with an autogenous weld in the center were placed in contact with moist plutonium oxide and chloride salt mixtures. Cracking was found in two of the specimens in the heat affected zone (HAZ) at the apex area. Finite element analysis was performed to simulate the specimen fabrication for determining the internal stress which caused SCC to occur. It was found that the tensile stress at the crack initiation site was about 30% lower than the highest stress which had been shifted to the shoulders of the specimen due to the specimen fabrication process. This finding appears to indicate that the SCC initiation took place in favor of the possibly weaker weld/base metal interface at a sufficiently high level of background stress. The base material, even subject to a higher tensile stress, was not cracked. The relieving of tensile stress due to SCC initiation and growth in the HAZ and the weld might have foreclosed the potential for cracking at the specimen shoulders where higher stress was found.

  18. Crack detection using pulsed eddy current stimulated thermography

    SciTech Connect (OSTI)

    Kostson, E.; Weekes, B.; Almond, D. P. [RCNDE, Department of Mechanical Engineering, University of Bath (United Kingdom); Wilson, J.; Tian, G. Y. [School of Electrical, Electronic and Computer Engineering, Newcastle University (United Kingdom)

    2011-06-23

    This contribution presents results from studies investigating factors that influence the detection of surface breaking cracks using pulsed eddy current thermography. The influences of the current strength and crack orientation in both ferromagnetic and non-ferromagnetic metals have been investigated. It has been found that crack detection is far more sensitive to crack orientation in non-ferromagnetic metals than in ferromagnetic metals. The effects of crack size on detectability are presented for a large number of steel, nickel alloy and titanium samples. Results of studies comparing crack images obtained prior and after coating a nickel alloy sample with a thermal barrier coating are presented.

  19. Crack detection using resonant ultrasound spectroscopy

    DOE Patents [OSTI]

    Migliori, Albert (Santa Fe, NM); Bell, Thomas M. (Santa Fe, NM); Rhodes, George W. (Albuquerque, NM)

    1994-01-01

    Method and apparatus are provided for detecting crack-like flaws in components. A plurality of exciting frequencies are generated and applied to a component in a dry condition to obtain a first ultrasonic spectrum of the component. The component is then wet with a selected liquid to penetrate any crack-like flaws in the component. The plurality of exciting frequencies are again applied to the component and a second ultrasonic spectrum of the component is obtained. The wet and dry ultrasonic spectra are then analyzed to determine the second harmonic components in each of the ultrasonic resonance spectra and the second harmonic components are compared to ascertain the presence of crack-like flaws in the component.

  20. Crack detection using resonant ultrasound spectroscopy

    DOE Patents [OSTI]

    Migliori, A.; Bell, T.M.; Rhodes, G.W.

    1994-10-04

    Method and apparatus are provided for detecting crack-like flaws in components. A plurality of exciting frequencies are generated and applied to a component in a dry condition to obtain a first ultrasonic spectrum of the component. The component is then wet with a selected liquid to penetrate any crack-like flaws in the component. The plurality of exciting frequencies are again applied to the component and a second ultrasonic spectrum of the component is obtained. The wet and dry ultrasonic spectra are then analyzed to determine the second harmonic components in each of the ultrasonic resonance spectra and the second harmonic components are compared to ascertain the presence of crack-like flaws in the component. 5 figs.

  1. Fracture of surface cracks loaded in bending

    SciTech Connect (OSTI)

    Chao, Y.J.; Reuter, W.G.

    1997-12-31

    Theoretical background of the constraint effect in brittle fracture of solids is reviewed. Fracture test data from D6-aC, a high strength steel, using three-point-bend (SE(B)) specimens and surface cracked plate (SC(B)) specimens under bending are presented. It is shown that the SE(B) data has an elevated fracture toughness for increasing a/W, i.e., a crack geometry with a larger T/K corresponds to a higher K{sub c} which is consistent with the theoretical prediction. The fundamental fracture properties, i.e., the critical strain and the critical distance, determined from the SE(B) test data are then applied to the interpretation and prediction of the SC(B) test data. Reasonable agreement is achieved for the crack growth initiation site and the load.

  2. Environmentally assisted cracking of LWR materials.

    SciTech Connect (OSTI)

    Chopra, O. K.; Chung, H. M.; Kassner, T. F.; Park, J. H.; Shack, W. J.; Zhang, J.; Brust, F. W.; Dong, P.

    1997-12-05

    The effect of dissolved oxygen level on fatigue life of austenitic stainless steels is discussed and the results of a detailed study of the effect of the environment on the growth of cracks during fatigue initiation are presented. Initial test results are given for specimens irradiated in the Halden reactor. Impurities introduced by shielded metal arc welding that may affect susceptibility to stress corrosion cracking are described. Results of calculations of residual stresses in core shroud weldments are summarized. Crack growth rates of high-nickel alloys under cyclic loading with R ratios from 0.2-0.95 in water that contains a wide range of dissolved oxygen and hydrogen concentrations at 289 and 320 C are summarized.

  3. Reflective cracking of shear keys in multi-beam bridges 

    E-Print Network [OSTI]

    Sharpe, Graeme Peter

    2009-06-02

    strength to resist cracking from vehicular loads, but uneven temperature changes and shrinkage strains cause high tensile stresses in the shear key regions and lead to reflective cracking. The analyses showed the highest stresses were often times near...

  4. Environmentally assisted cracking in light water reactors

    SciTech Connect (OSTI)

    Chopra, O.K.; Chung, H.M.; Gruber, E.E. [and others

    1996-07-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from April 1995 to December 1995. Topics that have been investigated include fatigue of carbon and low-alloy steel used in reactor piping and pressure vessels, EAC of Alloy 600 and 690, and irradiation-assisted stress corrosion cracking (IASCC) of Type 304 SS. Fatigue tests were conducted on ferritic steels in water that contained various concentrations of dissolved oxygen (DO) to determine whether a slow strain rate applied during different portions of a tensile-loading cycle are equally effective in decreasing fatigue life. Crack-growth-rate tests were conducted on compact-tension specimens from several heats of Alloys 600 and 690 in simulated LWR environments. Effects of fluoride-ion contamination on susceptibility to intergranular cracking of high- and commercial- purity Type 304 SS specimens from control-tensile tests at 288 degrees Centigrade. Microchemical changes in the specimens were studied by Auger electron spectroscopy and scanning electron microscopy to determine whether trace impurity elements may contribute to IASCC of these materials.

  5. Strip edge cracking simulation in cold rolling

    SciTech Connect (OSTI)

    Hubert, C.; Dubar, L.; Dubar, M.; Dubois, A.

    2011-01-17

    This research work focuses on a specific defect which occurs during cold rolling of steel strips: edge-serration. Investigations on the industrial processes have led to the conclusion that this defect is the result of the edge-trimming and cold rolling sequences. The aim of this research work is to analyze the effect of the cutting process and the cold rolling on cracks occurrence, especially on strip edges.This study is performed using an experimental testing stand called Upsetting Rolling Test (URT). It allows to reproduce cold rolling contact parameters such as forward slip, reduction ratio and friction coefficients. Specimens sampled near trimmed industrial strip edges are deformed using the URT stand. Two sets of specimens with different stress states, obtained by annealing, are submitted to two reduction passes with extreme forward slips.Scanning electron microscopy observations added to 3D optical surface profiler topographies show that on one hand, forward slip has a major effect on cracks opening. On the other hand, cracks opening decreases according to high roll strip speed gradient. Concerning the heat-treated specimens, no crack appeared after all reduction passes, showing a large influence of the cutting process and consequently of the local stress state in the vicinity of the burnish and fracture regions.

  6. SCATTERING BY CRACKS BENEATH FLUIDSOLID INTERFACES

    E-Print Network [OSTI]

    Craster, Richard

    , and accurately determine the position of, cracks. The non­destructive testing of a solid to detect such flaws as the fluid coupling tends to zero is non­uniform, that is, the Rayleigh wave is not related to the Sch

  7. Digital radiographic systems detect boiler tube cracks

    SciTech Connect (OSTI)

    Walker, S. [EPRI, Charlotte, NC (United States)

    2008-06-15

    Boiler water wall leaks have been a major cause of steam plant forced outages. But conventional nondestructive evaluation techniques have a poor track record of detecting corrosion fatigue cracking on the inside surface of the cold side of waterwall tubing. EPRI is performing field trials of a prototype direct-digital radiographic system that promises to be a game changer. 8 figs.

  8. Stress corrosion cracking and crack tip characterization of Alloy X-750 in light water reactor environments

    E-Print Network [OSTI]

    Gibbs, Jonathan Paul

    2011-01-01

    Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288°C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

  9. Stress Corrosion Cracking and Crack Tip Characterization of Alloy X-750 in Light Water Reactor Environments

    E-Print Network [OSTI]

    Gibbs, Jonathan Paul

    Stress corrosion cracking (SCC) susceptibility of Inconel Alloy X-750 in the HTH condition has been evaluated in high purity water at 93 and 288°C under Boiling Water Reactor Normal Water Chemistry (NWC) and Hydrogen Water ...

  10. Application of the cracked pipe element to creep crack growth prediction

    SciTech Connect (OSTI)

    Brochard, J.; Charras, T.

    1997-04-01

    The modification of a computer code for leak before break analysis is very briefly described. The CASTEM2000 code was developed for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading. The modification extends the capabilities of the cracked pipe element to the determination of fracture parameters under creep conditions (C*, {phi}c and {Delta}c). The model has the advantage of evaluating significant secondary effects, such as those from thermal loading.

  11. The Central Basin Spreading Center in the Philippine Sea: Structure of an extinct spreading center and implications

    E-Print Network [OSTI]

    Okino, Kyoko

    The Central Basin Spreading Center in the Philippine Sea: Structure of an extinct spreading center of the West Philippine Basin (WPB), display along-axis variations of spreading style. We have described, seafloor morphology, extinct spreading center, Philippine Sea Citation: Okino, K., and K. Fujioka

  12. Soil cracking modelling using the mesh-free SPH method

    E-Print Network [OSTI]

    Bui, H H; Kodikara, J; Sanchez, M

    2015-01-01

    The presence of desiccation cracks in soils can significantly alter their mechanical and hydrological properties. In many circumstances, desiccation cracking in soils can cause significant damage to earthen or soil supported structures. For example, desiccation cracks can act as the preference path way for water flow, which can facilitate seepage flow causing internal erosion inside earth structures. Desiccation cracks can also trigger slope failures and landslides. Therefore, developing a computational procedure to predict desiccation cracking behaviour in soils is vital for dealing with key issues relevant to a range of applications in geotechnical and geo-environment engineering. In this paper, the smoothed particle hydrodynamics (SPH) method will be extended for the first time to simulate shrinkage-induced soil cracking. The main objective of this work is to examine the performance of the proposed numerical approach in simulating the strong discontinuity in material behaviour and to learn about the crack ...

  13. Process for magnetic beneficiating petroleum cracking catalyst

    DOE Patents [OSTI]

    Doctor, R.D.

    1993-10-05

    A process is described for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded. 1 figures.

  14. Circumferential cracking of steam generator tubes

    SciTech Connect (OSTI)

    Karwoski, K.J.

    1997-04-01

    On April 28, 1995, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 95-03, {open_quote}Circumferential Cracking of Steam Generator Tubes.{close_quote} GL 95-03 was issued to obtain information needed to verify licensee compliance with existing regulatory requirements regarding the integrity of steam generator tubes in domestic pressurized-water reactors (PWRs). This report briefly describes the design and function of domestic steam generators and summarizes the staff`s assessment of the responses to GL 95-03. The report concludes with several observations related to steam generator operating experience. This report is intended to be representative of significant operating experience pertaining to circumferential cracking of steam generator tubes from April 1995 through December 1996. Operating experience prior to April 1995 is discussed throughout the report, as necessary, for completeness.

  15. Process for magnetic beneficiating petroleum cracking catalyst

    DOE Patents [OSTI]

    Doctor, Richard D. (Lisle, IL)

    1993-01-01

    A process for beneficiating a particulate zeolite petroleum cracking catalyst having metal values in excess of 1000 ppm nickel equivalents. The particulate catalyst is passed through a magnetic field in the range of from about 2 Tesla to about 5 Tesla generated by a superconducting quadrupole open-gradient magnetic system for a time sufficient to effect separation of said catalyst into a plurality of zones having different nickel equivalent concentrations. A first zone has nickel equivalents of about 6,000 ppm and greater, a second zone has nickel equivalents in the range of from about 2000 ppm to about 6000 ppm, and a third zone has nickel equivalents of about 2000 ppm and less. The zones of catalyst are separated and the second zone material is recycled to a fluidized bed of zeolite petroleum cracking catalyst. The low nickel equivalent zone is treated while the high nickel equivalent zone is discarded.

  16. Dynamical Event during Slow Crack Propagation

    SciTech Connect (OSTI)

    Ma {sup o}loy, Knut Jorgen; Schmittbuhl, Jean

    2001-09-03

    We address the role of material heterogeneities on the propagation of a slow rupture at laboratory scale. With a high speed camera, we follow an in-plane crack front during its propagation through a transparent heterogeneous Plexiglas block. We obtain two major results. First, the slip along the interface is strongly correlated over scales much larger than the asperity sizes. Second, the dynamics is scale dependent. Locally, mechanical instabilities are triggered during asperity depinning and propagate along the front. The intermittent behavior at the asperity scale is in contrast with the large scale smooth creeping evolution of the average crack position. The dynamics is described on the basis of a Family-Vicsek scaling.

  17. Structures for dense, crack free thin films

    DOE Patents [OSTI]

    Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

    2011-03-08

    The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

  18. An investigation of crack-tip stress field criteria of predicting cleavage-crack initiation

    SciTech Connect (OSTI)

    Keeney-Walker, J.; Bass, B.R.; Landes, J.D. (Oak Ridge National Lab., TN (United States))

    1991-09-01

    Cleavage-crack initiation in large-scale wide-plate (WP) specimens could not be accurately predicted from small, compact (CT) specimens by using a linear-elastic fracture-mechanics, K{sub Ic}, methodology. In the wide-plate tests conducted by the Heavy-Section Steel Technology Program at Oak Ridge National Laboratory, crack initiation has consistently occurred at stress-intensity (K{sub I}) values ranging from two to four times those predicted by the CT specimens. Studies were initiated to develop crack-tip stress field criteria incorporating effects of geometry, size, and constraint that will lead to improved predictions of cleavage initiation in WP specimens from CT specimens. The work centers around nonlinear two-and three-dimensional finite-element analyses of the crack-tip stress fields in these geometries. Analyses were conducted on CT and WP specimens for which cleavage initiation fracture had been measured in laboratory tests. The local crack-tip field generated for these specimens were then used in the evaluation of fracture correlation parameters to augment the K{sub I} parameter for predicting cleavage initiation. Parameters of hydrostatic constraint and of maximum principal stress, measured volumetrically, are included in these evaluations. The results suggest that the cleavage initiation process can be correlated with the local crack-tip fields via a maximum principal stress criterion based on achieving a critical area within a critical stress contour. This criterion has been successfully applied to correlate cleavage initiation in 2T-CT and WP specimen geometries. 23 refs., 16 figs., 5 tabs.

  19. Application of the cracked pipe element to creep crack growth prediction

    SciTech Connect (OSTI)

    Brochard, J.; Charras, T. [C.E.A.-C.E.-Saclay DRN/DMT, Gif Sur Yvette (France); Ghoudi, M. [C.E.A.-C.E.-Saclay, Gif Sur Yvette (France)

    1997-04-01

    Modifications to a computer code for ductile fracture assessment of piping systems with postulated circumferential through-wall cracks under static or dynamic loading are very briefly described. The modifications extend the capabilities of the CASTEM2000 code to the determination of fracture parameters under creep conditions. The main advantage of the approach is that thermal loads can be evaluated as secondary stresses. The code is applicable to piping systems for which crack propagation predictions differ significantly depending on whether thermal stresses are considered as primary or secondary stresses.

  20. Multicarrier orthogonal spread-spectrum (MOSS) data communications

    DOE Patents [OSTI]

    Smith, Stephen F. (London, TN); Dress, William B. (Camas, WA)

    2008-01-01

    Systems and methods are described for multicarrier orthogonal spread-spectrum (MOSS) data communication. A method includes individually spread-spectrum modulating at least two of a set of orthogonal frequency division multiplexed carriers, wherein the resulting individually spread-spectrum modulated at least two of a set of orthogonal frequency division multiplexed carriers are substantially mutually orthogonal with respect to both frequency division multiplexing and spread-spectrum modulation.

  1. COMPARING SIMULATION METHODS FOR FIRE SPREADING ACROSS A FUEL BED

    E-Print Network [OSTI]

    Wainer, Gabriel

    choice to solve the problem. Diffusion processes (oil spills, fire spread, insect infestation, etcCOMPARING SIMULATION METHODS FOR FIRE SPREADING ACROSS A FUEL BED Alexandre Muzy Computer Modeling computer simulation of a semi-physical fire spread model. Forest fire is a com- plex phenomenon, which

  2. Spreading of energy in the Ding-Dong model

    SciTech Connect (OSTI)

    Roy, S.; Pikovsky, A.

    2012-06-15

    We study the properties of energy spreading in a lattice of elastically colliding harmonic oscillators (Ding-Dong model). We demonstrate that in the regular lattice the spreading from a localized initial state is mediated by compactons and chaotic breathers. In a disordered lattice, the compactons do not exist, and the spreading eventually stops, resulting in a finite configuration with a few chaotic spots.

  3. Effect of CTE on Fatigue Cracking of Stainless Steel Vessels

    SciTech Connect (OSTI)

    Bird, E. L.; Mustaleski, T. M.

    2002-01-31

    Visual examination of lithium hydride reactor vessels revealed cracks that were adjacent to welds. Most cracks were parallel to the weld in the bottom portion of the vessel. Sections were cut out of the vessel containing these cracks and examined using the metallograph, scanning electron microscope, and microprobe to determine the cause of cracking. most of the cracks originated on the outer surface just outside the weld fusion line in the heat affected zone and propagated along grain boundaries. Crack depth of those sections examined ranged from about 300 to 500 {micro}m. Other cracks were reported to have reached a maximum depth of 0.32-cm (0.125-inch). The primary cause of cracking was the creation of high tensile stresses associated with the CTE differences between the filler metal and the base metal during operation of the vessel in a thermally cyclic environment. This failure mechanism could be described as creep-type fatigue whereby crack propagation might have been aided by the presence of brittle chromium carbides along the grain boundaries, which is indicative of a slightly sensitized microstructure.

  4. Hot Rolling Scrap Reduction through Edge Cracking and Surface...

    Broader source: Energy.gov (indexed) [DOE]

    Our Approach use a precompetitive material to develop new modeling technology (AA-7050) account for the anisotropic behavior during crack growth. validate model to...

  5. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, R.B.

    1994-08-16

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct. 11 figs.

  6. Increasing jet entrainment, mixing and spreading

    DOE Patents [OSTI]

    Farrington, Robert B. (Wheatridge, CO)

    1994-01-01

    A free jet of air is disturbed at a frequency that substantially matches natural turbulences in the free jet to increase the entrainment, mixing, and spreading of air by the free jet, for example in a room or other enclosure. The disturbances are created by pulsing the flow of air that creates the free jet at the desired frequency. Such pulsing of the flow of air can be accomplished by sequentially occluding and opening a duct that confines and directs the flow of air, such as by rotating a disk on an axis transverse to the flow of air in the duct.

  7. Shrinkage - cracking characteristics of structural lightweight concrete 

    E-Print Network [OSTI]

    McKeen, Robert Gordon

    1969-01-01

    restraint of the material, such as reinforcement and external fri. ction 28 (h) chemical admixtures employed (i) unit water content 2. 4 ~fk' f. C 2. 4. 1 General The cracking of concrete has been a subject of interest to desi. gners for many years... were made on two six by t. )elve in. c; linders from each batch of concrete for purposes of control. . The pecimens were moist cured 14 days prior to testing. Testing was performed in accordance with ASTM C39-64. The data were taken to provid...

  8. Wavepacket of the Universe and its spreading

    E-Print Network [OSTI]

    Marek Czachor; Andrzej Posiewnik

    2015-10-16

    Wavepackets in quantum mechanics spread and the Universe in cosmology expands. We discuss a formalism where the two effects can be unified. The basic assumption is that the Universe is determined by a unitarily evolving wavepacket defined on space-time. Space-time is static but the Universe is dynamic. Spreading analogous to expansion known from observational cosmology is obtained if one regards time evolution as a discrete process with probabilities of jumps determined by a variational principle employing Kolmogorov-Nagumo-R\\'enyi averages. The choice of the R\\'enyi calculus implies that the form of the Universe involves an implicit fractal structure. The formalism automatically leads to two types of "time" parameters: $\\tau$, with dimension of $x^0$, and dimensionless $\\varepsilon=\\ln \\epsilon_\\tau$, related to the form of diffeomorphism that defines the dynamics. There is no preferred time foliation, but effectively the dynamics leads to asymptotic concentration of the Universe on spacelike surfaces that propagate in space-time. The analysis is performed explicitly in $1+1$ dimensions, but the unitary evolution operator is brought to a form that makes generalizations to other dimensions and other fields quite natural.

  9. Oil spreading in surface waters with an ice cover

    SciTech Connect (OSTI)

    Yapa, P.D.; Weerasuriya, S.A.; Belaskas, D.P.; Chowdhury, T.

    1993-02-01

    A study of oil spreading in surface waters in the presence of a floating ice cover is presented. The ice can be solid or fragmented. Both axi-symmetrical and uni-directional spreading are studied. The report describes the analytical and numerical model development, the experimental set-up, results from the laboratory experiments, and their comparison with the derived theory and the numerical simulation. To analyze the spreading of oil under solid ice, new equations are derived. These equations consider gravity (buoyancy) - inertia phase, gravity (buoyancy) - viscous phase, and the termination of spreading during the buoyancy - surface tension phase. The derivation considers both the constant discharge mode and the constant volume mode. Therefore, a complete description of the spreading phenomena from the time of initial spill to termination of spreading is presented. The emphasis of the study is on the dominant spreading mechanism for oil under ice, which is the buoyancy-viscous phase.

  10. Experimental Determination of Crack Driving Forces in Integrated Structures

    E-Print Network [OSTI]

    Suo, Zhigang

    8/2/2004 1 Experimental Determination of Crack Driving Forces in Integrated Structures Jun He in a structure, the crack driving force G is the reduction of the elastic energy in the structure, associated. In practice, however, such a calculation is prohibitively difficult for integrated structures of complex

  11. Crack patterns in thin lms Z. Cedric Xiaa

    E-Print Network [OSTI]

    Hutchinson, John W.

    Crack patterns in thin ®lms Z. Cedric Xiaa , John W. Hutchinsonb, * a Ford Research Laboratory elastic ®lms. Speci®c examples are presented for ®lms subject to equi-biaxial residual tensile stress Elsevier Science Ltd. All rights reserved. Keywords: Crack propagation; Thin ®lms; Integral equations 1

  12. Fracture mechanics analysis of slow crack growth in polyethylene 

    E-Print Network [OSTI]

    Self, Robert Alan

    1997-01-01

    Slow crack growth in polyethylene is often the limiting factor in long-term service of plastic pipe or other structural applications. A new test method and analysis method was developed to study slow crack growth in polyethylene. Two high density...

  13. WATER PERMEABILITY OF CRACKED CEMENTITIOUS MICHAEL LEPECH & VICTOR C. LI

    E-Print Network [OSTI]

    Lepech, Michael D.

    of ECC material exhibits a water permeability close to that of uncracked concrete when strained up to 1 structures. With compressive strengths twice that of normal concrete and a low water permeability coefficient is the permeability of concrete structures in the cracked state. Regardless of the reason for cracking, whether

  14. CRACKING OF PRESTRESSED CONCRETE CONTAINMENTS DUE TO INTERNAL PRESSURE

    E-Print Network [OSTI]

    applied to a 1/14 scale test structure. Observed values agreed well with predicted values. #12;Mac of a containment vessel (wall segment tests) reported in this paper and Ref. 4 and 5, and a test of a 1/14 size reached, all cracks observed in the tests had formed. At greater strains certain existing cracks became

  15. The Simulation of Paint Cracking and Peeling Eric Paquette

    E-Print Network [OSTI]

    Montréal, Université de

    The Simulation of Paint Cracking and Peeling Eric Paquette D´ep. I.R.O., Universit´e de Montr of time results in cracking and peeling of layers such as paint. To include these ef- fects in computer of paint peeling. We present a new approach which computes such a simulation on surfaces. Our simulation

  16. Predicting crack growth in continuous-fiber composite materials

    SciTech Connect (OSTI)

    Cordes, J.A.; Yazici, R.

    1995-12-31

    Pre-notched composite lamina with unidirectional fibers were studied experimentally and using finite element analysis. Experiments were conducted on notched graphite/aluminum and glass/epoxy panels and the results were compared to a finite element method. Under remote tensile loading, cracks in the graphite/aluminum panels propagated perpendicular to the applied load without stable crack growth. In the glass/epoxy panels, crack propagation was initially stable and parallel to the fibers. A nonlinear damage zone method (DZM) was used to predict the crack growth directions, estimate damages, model stable and unstable crack growths, and predict the loads at failure. For both materials, the predicted loads at failure were within 20% of experimental loads.

  17. The ROSAT HRI Point Spread Function

    E-Print Network [OSTI]

    Peter Predehl; Almudena Prieto

    2001-09-28

    A sample of the brightest point-like sources observed with the ROSAT-HRI were analysed to asses on the intrinsic shape of the ROSAT-HRI Point Spread Function (PSF). Almost all of the HRI observations collected during the ROSAT lifetime are found to be artificially broadened by factors up two ~2 due to residual errors in the ROSAT aspect solution. After correction by departing pointing positions, the width of the core of the PSF is found to be less than 5 arcsec (half energy width, HEW). On the basis of these results, an improved analytical representation of the ROSAT-HRI PSF is provided. However, for most of the new observations the source countrate is too weak to allow reliable recovering pf the ROSAT-HRI resolution. Therefore, a series of examples (data, correction, and theoretical PSF) are given in order to help the ROSAT user in determining whether "his/her source" is extended or not.

  18. Fatigue cracking in materials with brittle surface coatings

    SciTech Connect (OSTI)

    Suresh, S.; Sugimura, Y.; Ogawa, T. (Brown Univ., Providence, RI (United States))

    1993-07-15

    Ceramic coatings enhance the resistance of metal alloys to wear, oxidation, thermal exposure, corrosion, erosion and delamination in a variety of structural, optical, electrical , electronic and bioengineering applications. Recent experimental work on steel-steel bimaterials has shown that the conditions for the growth or arrest of a fatigue crack, which approaches the interface between the two steels perpendicularly, are determined by whether the crack propagates to the interface from the weaker or the stronger material. Specifically, it is found that as the fatigue crack advances toward the interface from the weaker steel, the interaction of the crack-tip plastic zone with the interface results in the arrest of the crack. However, when the fatigue crack is propagated from the stronger to the weaker steel, crack growth occurs unimpeded through the interface. In this paper, the authors present additional experimental and mechanistic descriptions of fatigue crack growth normal to interfaces. They then apply the mechanisms underlying these experiments to the design of fatigue-resistant surface coatings for alloys. In particular, they demonstrate experimentally that a fatigue crack emanating from the brittle outercoating and advancing into the substrate can be arrested and/or deflected by proper choices of ductile interlayers. Experimental results of fatigue crack profiles and high-cycle fatigue lives are presented for two different coated materials: a steel coated with a Cr[sub 2]O[sub 3] layer and a steel coated with a Cr[sub 2]O[sub 3] outerlayer and a soft Ni-Al interlayer. The paper also includes a brief discussion of the application of proposed concepts to nitrided titanium alloys.

  19. ffe1098 FFE March 7, 2007 21:55 Crack tip displacements of microstructurally small cracks in 316L steel

    E-Print Network [OSTI]

    Cizelj, Leon

    -strain finite element crystal plasticity model. The model consists of 212 randomly shaped, sized and oriented plane. Keywords crack tip displacements; crystal plasticity; polycrystals; small cracks. NOMENCLATURE a) and sliding displacements (CTSD) for single crystal and polycrystal models, considering also different

  20. The effect of crack surface interaction on the stress intensity factor in Mode III crack growth in round shafts

    E-Print Network [OSTI]

    Vaziri, Ashkan

    in round shafts A. Vaziri 1 , H. Nayeb-Hashemi * Department of Mechanical, Industrial and Manufacturing March 2004; accepted 31 March 2004 Available online 6 July 2004 Abstract Turbine-generator shafts and propagate a circumferential crack in the shafts. Mode III crack growth in turbo-generator shafts often

  1. Mixed-mode, high-cycle fatigue-crack growth thresholds in II. Quantication of crack-tip shielding

    E-Print Network [OSTI]

    Ritchie, Robert

    -tip shielding J.P. Campbell, R.O. Ritchie * Department of Materials Science and Mineral Engineering, University 2000; accepted 11 May 2000 Abstract The role of crack-tip shielding in in¯uencing mixed-mode (mode I crack-tip shielding with respect to both the mode I and mode II applied loading, enabling an estimation

  2. Short and Large Crack, Mixed-Mode Fatigue-Crack Growth Thresholds in Ti-6Al-4V1

    E-Print Network [OSTI]

    Ritchie, Robert

    and control of failures due to high cycle fatigue (HCF) in turbine engine components is currently one, Dr. J. P. Campbell and Professor R. O. Ritchie2 Department of Materials Science and Engineering-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy, heat

  3. Cracking in liquid petroleum gas Horton spheres

    SciTech Connect (OSTI)

    Trivedi, D.K. Gupta, S.C.

    1997-07-01

    A gas processing plant on the western coast of India produces sweet gas after processing sour natural gas. Liquid petroleum gas (LPG) is recovered from the sweet gas. The LPG, containing a H{sub 2}S concentration of 10 ppm to 20 ppm, is stored in Horton spheres, each 17 m in diameter with a capacity of {minus}27 C to 55 C. Horton spheres for containing liquid petroleum gas (LPG) were fabricated on-site using prestressed plates of high-strength carbon steel (CS) SA 537 Class-1 with post-weld heat treatment. High-residual tensile stresses and hydrogen absorption from H{sub 2}S present in LPG could be the cause of cracking at weld and heat-affected zone interfaces at high hardness locations. Recommendations are given for inspection and use of lower-strength CS and improved welding procedures.

  4. Longitudinal bunch profile and electron beam energy spread

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ring Parameters Previous: Storage Ring Operation Modes Longitudinal bunch profile and electron beam energy spread Longitudinal bunch profile depends mainly on the single bunch...

  5. 01-07-1999 - Contamination Spread Outside of Radiation Control...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    9 - Contamination Spread Outside of Radiation Control Areas by Fruit Flies Document Number: NA Effective Date: 011999 File (public): PDF icon 01-07-1999red...

  6. HIV virus spread and evolution studied through computer modeling

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    HIV and evolution studied through computer modeling HIV virus spread and evolution studied through computer modeling This approach distinguishes between susceptible and infected...

  7. Multi-gigaelectronvolt, low-energy spread acceleration of positrons...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Multi-gigaelectronvolt, low-energy spread acceleration of positrons in a self-loaded plasma wakefield Citation Details In-Document Search Title:...

  8. The cracking and spalling of multilayered chromium coatings

    SciTech Connect (OSTI)

    Joergensen, O.; Horsewell, A.; Soerensen, B.F. [Risoe National Lab., Roskilde (Denmark). Materials Dept.] [Risoe National Lab., Roskilde (Denmark). Materials Dept.; Leisner, P. [Technical Univ. of Denmark, Lyngby (Denmark). Centre of Advanced Electroplating] [Technical Univ. of Denmark, Lyngby (Denmark). Centre of Advanced Electroplating

    1995-11-01

    Cracks in a chromium coating on a steel substrate which are caused by residual stresses developed during an electroplating process are examined. The chromium coating, formed as a multilayer by alternating electroplating utilizing direct current (DC) and periodic current reversal (PR), is in a state of biaxial tensile stress due to a volume contraction in the successive DC layers which occurs during deposition. A uniform biaxial misfit strain idealizes this layerwise contraction. The state of stress in the multilayer is model during laminate theory. Special emphasis is given to the influence of the substrate flexibility on the stress build-up. It is shown that the flexibility of the substrate produces an equal biaxial bending moment in the coating. At a critical coating thickness, the chromium multilayer cracks and spalls off the substrate. The radius of curvature of detached coating fragments provides a measure of the size of the bending moment and, indirectly, of the misfit strain. The observed fracture mechanism is qualitatively divided into cracks channeling in the coating and debonding cracks running in the interface between the coating and the substrate. Long crack asymptotic solutions for the two distinct crack types are presented. The fracture analyses of the multilayered chromium coating show the functional dependence of relative layer and substrate thicknesses and flexibility on the energy release rate for crack propagation.

  9. Reliability of steam generator tubes with axial cracks

    SciTech Connect (OSTI)

    Cizelj, L.; Mavko, B. [Jozef Stefan Inst., Ljubljana (Slovenia). Reactor Engineering Div.; Vencelj, P. [Univ. of Ljubljana (Slovenia). Faculty of Mathematics and Physics

    1996-11-01

    An approach for estimating the failure probability of tubes containing through-wall axial cracks has already been proposed by the authors. It is based on probabilistic fracture mechanics and accounts for scatter in tube geometry and material properties, scatter in residual and operational stresses responsible for crack propagation, and characteristics of nondestructive examination and plugging procedures (e.g., detection probability, sizing accuracy, human errors). Results of preliminary tests demonstrated wide applicability of this approach and triggered some improvements. The additions to the model are extensively discussed in this paper. Capabilities are demonstrated by results of analysis of steam generator no. 1 in Slovenian nuclear power plant located in Krsko after the 1992 inspection and plugging campaign. First, the number of cracked tubes and the crack length distribution were estimated using data obtained by the 100% motorized pancake coil inspection. The inspection and plugging activities were simulated in the second step to estimate the efficiency of maintenance in terms of single and multiple-tube rupture probabilities. They were calculated as a function of maximum allowable crack length. The importance of human errors and some limitations of present nondestructive examination techniques were identified. The traditional wall thickness and crack-length-based plugging criteria are compared. The crack-length-based criterion is shown to be more efficient and more safe, especially because of strong suppression effect on probability of multiple-tube rupture. The results are considered to be important for safety and maintenance of existing plants and for further research.

  10. Three-dimensional crack growth assessment by microtopographic examination

    SciTech Connect (OSTI)

    Lloyd, W.R.; Piascik, R.S.

    1995-12-31

    The initial stage of the stable tearing process in two 2.3 mm sheet 2024-T3 aluminum alloy M(T) specimens are analyzed using fracture surface microtopography reconstruction techniques. The local crack tip opening angles (CTOA) in the interior of the specimens are determined relative to both crack extension and through-thickness position. The microtopographic analysis of cracks grown in the L-T and T-L orientations reveal that interior CTOA is comparable to those measured on the surface using standard optical analysis methods. Similar to surface CTOA results, interior (mid-thickness) CTOA exhibit a transient behavior; CTOA transitions from high angles, at near crack initiation, to a lower steady-state value of 5 deg. and 4.2 deg. for L-T and T-L, respectively, at crack lengths greater than 1.5mm. Fracture surface topographic projection maps are used to study the evolution of crack front tunneling during the initial stage of the fracture process. Stable tearing initiates at mid-thickness followed by a crack front tunneling process to a depth of approximately 2mm. A brief discussion of the basis of the fracture process reconstruction method is provided and comments on the general utility of microtopographic fracture surface examination for general assessment of elastic-plastic and fully-plastic fracture processes are made.

  11. Fatigue crack growth behavior of Ti-1100 at elevated temperature

    SciTech Connect (OSTI)

    Maxwell, D.C.; Nicholas, T.

    1995-12-31

    Effects of temperature, frequency, and cycles with superimposed hold times are evaluated in Ti-1100 in order to study the complex creep-fatigue-environment interactions in this material. Crack growth rate tests conducted at cyclic loading frequency of 1.0 Hz show that raising the temperature from 593 to 650 C has only a slightly detrimental effect on crack growth rate, although these temperatures produce growth rates significantly higher than at room temperature. From constant {Delta}K tests, the effects of temperature at constant frequency show a minimum crack growth rate at 250 C. From the minimum crack growth rate at 250 C, the crack growth rate increases linearly with temperature. Increases in frequency at constant temperatures of 593 and 650 C produce a continuous decrease in growth rate in going from 0.001 to 1.0 Hz, although the behavior is primarily cycle dependent in this region. Tests at 1.0 Hz with superimposed hold times from 1 to 1,000 s are used to evaluate creep-fatigue-environment interactions. Hold times at maximum load are found to initially decrease and then increase the cyclic crack growth rate with increasing duration. This is attributed to crack-tip blunting during short hold times and environmental degradation at long hold times. Hold times at minimum load show no change in growth rates, indicating that there is no net environmental degradation to the bulk material beyond that experienced during the baseline 1 Hz cycling.

  12. Standard test method for creep-fatigue crack growth testing

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the determination of creep-fatigue crack growth properties of nominally homogeneous materials by use of pre-cracked compact type, C(T), test specimens subjected to uniaxial cyclic forces. It concerns fatigue cycling with sufficiently long loading/unloading rates or hold-times, or both, to cause creep deformation at the crack tip and the creep deformation be responsible for enhanced crack growth per loading cycle. It is intended as a guide for creep-fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. Therefore, this method requires testing of at least two specimens that yield overlapping crack growth rate data. The cyclic conditions responsible for creep-fatigue deformation and enhanced crack growth vary with material and with temperature for a given material. The effects of environment such as time-dependent oxidation in enhancing the crack growth ra...

  13. Stress-corrosion cracking of copper single crystals

    SciTech Connect (OSTI)

    Sieradzki, K.; Newman, R.C.; Sabatini, R.L.

    1984-10-01

    Constant extension rate tests have been carried out in a sodium nitrite solution. Crack velocities up to 30 nm per second were obtained at 30/sup 0/C. If dynamic straining is stopped, the cracks apparently stop growing within about 20 ..mu..m. The steps between adjacent flat facets are more energy-absorbing than in ..cap alpha..-brass, providing a possible explanation for the importance of dynamic strain. Simultaneous acoustic emission and electrochemical current transients suggest that cracking proceeds by discontinuous cleavage.

  14. Tearing of thin sheets: Cracks interacting through an elastic ridge

    E-Print Network [OSTI]

    Fabian Brau

    2014-12-17

    We study the interaction between two cracks propagating quasistatically during the tearing of a thin brittle sheet. We show that the cracks attract each other following a path described by a power law resulting from the competition between elastic and fracture energies. The power law exponent (8/11) is in close agreement with experiments. We also show that a second (asymptotic) regime, with an exponent of 9/8, emerges for small distances between the two crack tips due to the finite transverse curvature of the elastic ridge joining them.

  15. Forest Fire Spread and Suppression in DEVS Lewis Ntaimo1

    E-Print Network [OSTI]

    Forest Fire Spread and Suppression in DEVS Lewis Ntaimo1 , Bithika Khargharia2 , Bernard P. Zeigler2 , Maria J. Vasconcelos3 Abstract In this paper we discuss modeling and simulation of forest fire simulation-based predictions of forest fire spread and suppression in uniform and non-uniform environmental

  16. Spectral phase encoded time spread optical code division multiple

    E-Print Network [OSTI]

    Yoo, S. J. Ben

    -CDMA, efficient and compact W-CDMA chip develop- ment allowed rapid market-driven transition from the conventionalSpectral phase encoded time spread optical code division multiple access technology for next and summarize the progress of the spectral phase encoded time spreading (SPECTS) optical code division multiple

  17. PRICING AND HEDGING SPREAD OPTIONS RENE CARMONA AND VALDO DURRLEMAN

    E-Print Network [OSTI]

    Carmona, Rene

    a chance to venture in the poorly understood world of asset valuation and real options which are the objectPRICING AND HEDGING SPREAD OPTIONS REN´E CARMONA AND VALDO DURRLEMAN ABSTRACT. We survey the theoretical and the computational problems associated with the pricing of spread options. These options

  18. Implied and Local Correlations from Spread Options Rene Carmona

    E-Print Network [OSTI]

    Carmona, Rene

    cor- relation skew examplifies how inaccurate the constant correlation assumption in the multivariate a set of special parameters, and we propose a calibration procedure using option prices on individual. For example, the spark spread option is a spread between natural gas and electric power. The underlying is St

  19. APPLICATIONS Forest Fire Spread and Suppression in DEVS

    E-Print Network [OSTI]

    Ntaimo, Lewis

    APPLICATIONS Forest Fire Spread and Suppression in DEVS Lewis Ntaimo Department of Industrial. Speedway Tucson, AZ 85721 In this article, the authors discuss modeling and simulation of forest fire to obtain timely simulation-based predictions of forest fire spread and suppression in uniform

  20. White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel!

    E-Print Network [OSTI]

    Cambridge, University of

    ! quenched! and! untempered! steel! normally! used! in! the! manufacture! of! bearings.!The!varieties!of!cracks!studied!include!sparsely!distributed!martensite(lubricant!interactions,!or!hydrogen!trapping!can!be!studied!further.! ! Keywords:!bearing!steel,!indentation!cracks,!cracked!martensite,!grain(boundary!decohesion,! surface! 1! White(etching!matter!in!bearing!steel! Part1:!Controlled(cracking!of!52100!steel! ! W

  1. Modeling of crack initiation, propagation and coalescence in rocks

    E-Print Network [OSTI]

    Gonçalves da Silva, Bruno Miguel

    2009-01-01

    Natural or artificial fracturing of rock plays a very important role in geologic processes and for engineered structures in and on rock. Fracturing is associated with crack initiation, propagation and coalescence, which ...

  2. Crack coalescence in rock-like material under cycling loading

    E-Print Network [OSTI]

    Ko, Tae Young, 1973-

    2005-01-01

    A total of 170 tests (68 tests for monotonic loading, 102 tests for cyclic loading) have been performed to investigate crack initiation, propagation and coalescence. The specimens have two pre-existing flaws which are ...

  3. Analytical determination of critical crack size in solar cells

    SciTech Connect (OSTI)

    Chen, C.P.

    1988-05-01

    Although solar cells usually have chips and cracks, no material specifications concerning the allowable crack size on solar cells are available for quality assurance and engineering design usage. Any material specifications that the cell manufacturers use were developed for cosmetic reasons that have no technical basis. Therefore, the Applied Solar Energy Corporation (ASEC) has sponsored a continuing program for the fracture mechanics evaluation of GaAs. Fracture mechanics concepts were utilized to develop an analytical model that can predict the critical crack size of solar cells. This model indicates that the edge cracks of a solar cell are more critical than its surface cracks. In addition, the model suggests that the material specifications on the allowable crack size used for Si solar cells should not be applied to GaAs solar cells. The analytical model was applied to Si and GaAs solar cells, but it would also be applicable to the semiconductor wafers of other materials, such as a GaAs thin film on a Ge substrate, using appropriate input data.

  4. Roles of grain boundaries in cleavage cracking and thermal crack arrest experiments in iron-silicon alloy

    E-Print Network [OSTI]

    Qiao, Yu, 1972-

    2002-01-01

    High-angle grain boundaries in steel offer an important resistance to the propagation of cleavage cracks that affects the fracture toughness and can modulate the ductile-to-brittle transition temperature of fracture downward. ...

  5. Grain-by-grain study of the mechanisms of crack propagation during iodine stress corrosion cracking of Zircaloy-4

    SciTech Connect (OSTI)

    Haddad, R.E. [CNEA, Buenos Aires (Argentina); Dorado, A.O. [CONICET, Buenos Aires (Argentina)

    1994-12-31

    This paper describes the tests conducted to determine the conditions leading to cracking of a specified grain of metal, during the iodine stress corrosion cracking (SCC) of zirconium alloys, focusing on the crystallographic orientation of crack paths, the critical stress conditions, and the significance of the fractographic features encountered. In order to perform crystalline orientation of fracture surfaces, a specially heat-treated Zircaloy-4 having very large grains, grown up to the wall thickness, was used. Careful orientation work has proved that intracrystalline pseudo-cleavage occurs only along basal planes. the effects of anisotropy, plasticity, triaxiality, and residual stresses originated in thermal contraction have to be considered to account for the influence of the stress state. A grain-by-grain calculation led to the conclusion that transgranular cracking always takes place on those bearing the maximum resolved tensile stress perpendicular to basal planes. Propagation along twin boundaries has been identified among the different fracture modes encountered.

  6. Strengthening, Crack Arrest And Multiple Cracking In Brittle Materials Using Residual Stresses.

    DOE Patents [OSTI]

    Green, David J. (State College, PA); Sglavo, Vincenzo M. (Roncegno, IT); Tandon, Rajan (Fremont, CA)

    2003-02-11

    Embodiments include a method for forming a glass which displays visible cracking prior to failure when subjected to predetermined stress level that is greater than a predetermined minimum stress level and less than a failure stress level. The method includes determining a critical flaw size in the glass and introducing a residual stress profile to the glass so that a plurality of visible cracks are formed prior to failure when the glass is subjected to a stress that is greater than the minimum stress level and lower than the critical stress. One method for forming the residual stress profile includes performing a first ion exchange so that a first plurality of ions of a first element in the glass are exchanged with a second plurality of ions of a second element that have a larger volume than the first ions. A second ion exchange is also performed so that a plurality of the second ions in the glass are exchanged back to ions of the first element.

  7. Electrically modulated dynamic spreading of drops on soft surfaces

    E-Print Network [OSTI]

    Ranabir Dey; Ashish Daga; Sunando DasGupta; Suman Chakraborty

    2015-04-07

    The intricate interaction between the deformability of a substrate and the dynamic spreading of a liquid drop on the same, under the application of an electrical voltage, has remained far from being well understood. Here, we demonstrate that electrospreading dynamics on soft substrates is dictated by the combined interplay of electrocapillarity, the wetting line friction and the viscoelastic energy dissipation at the contact line. Our results reveal that during such electro-elastocapillarity mediated spreading of a sessile drop, the contact radius evolution exhibits a universal power law in a substrate elasticity based non-dimensional time, with an electric potential dependent spreading exponent. Simultaneously, the macroscopic dynamic contact angle variation follows a general power law in the contact line velocity, normalized by elasticity dependent characteristic velocity scale. Our results are likely to provide the foundation for the development of a plethora of new applications involving droplet manipulations by exploiting the interplay between electrically triggered spreading and substrate-compliance over interfacial scales.

  8. Hierarchical Bayesian Models for Predicting The Spread of Ecological Processes

    E-Print Network [OSTI]

    Hierarchical Bayesian Models for Predicting The Spread of Ecological Processes Christopher K. Wikle Department of Statistics, University of Missouri To appear: Ecology June 10, 2002 Key Words: Bayesian, Diffusion, Forecast, Hierarchical, House Finch, Invasive, Malthu- sian, State Space, Uncertainty Abstract

  9. Physical Proximity and Spreading in Dynamic Social Networks

    E-Print Network [OSTI]

    Stopczynski, Arkadiusz; Lehmann, Sune

    2015-01-01

    Most infectious diseases spread on a dynamic network of human interactions. Recent studies of social dynamics have provided evidence that spreading patterns may depend strongly on detailed micro-dynamics of the social system. We have recorded every single interaction within a large population, mapping out---for the first time at scale---the complete proximity network for a densely-connected system. Here we show the striking impact of interaction-distance on the network structure and dynamics of spreading processes. We create networks supporting close (intimate network, up to ~1m) and longer distance (ambient network, up to ~10m) modes of transmission. The intimate network is fragmented, with weak ties bridging densely-connected neighborhoods, whereas the ambient network supports spread driven by random contacts between strangers. While there is no trivial mapping from the micro-dynamics of proximity networks to empirical epidemics, these networks provide a telling approximation of droplet and airborne modes o...

  10. Nature of Flow and Gas Dynamics Below Spreading Ponds

    E-Print Network [OSTI]

    Clark, Jordan F; Avisar, Dror; Hudson, G. Bryant

    2005-01-01

    breakthrough curve at El Rio #8. Pond 2 El Rio #5 El Rio #6Ne and Xe concentrations in Pond 2 and groundwater samples.vadose zone beneath a spreading pond in more detail than was

  11. Bearing estimation techniques for improved performance spread spectrum receivers 

    E-Print Network [OSTI]

    Thompson, John S

    The main topic of this thesis is the use of bearing estimation techniques combined with multiple antenna elements for spread spectrum receivers. The motivation behind this work is twofold: firstly, this type of receiver structure may offer...

  12. Epidemic spreading in time-varying community networks

    SciTech Connect (OSTI)

    Ren, Guangming E-mail: ren-guang-ming@163.com; Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 ; Wang, Xingyuan E-mail: ren-guang-ming@163.com

    2014-06-15

    The spreading processes of many infectious diseases have comparable time scale as the network evolution. Here, we present a simple networks model with time-varying community structure, and investigate susceptible-infected-susceptible epidemic spreading processes in this model. By both theoretic analysis and numerical simulations, we show that the efficiency of epidemic spreading in this model depends intensively on the mobility rate q of the individuals among communities. We also find that there exists a mobility rate threshold q{sub c}. The epidemic will survive when q?>?q{sub c} and die when q?spreading in complex networks with community structure.

  13. Intense spreading of radar echoes from ionospheric plasmas

    E-Print Network [OSTI]

    Dorfman, Seth E

    2005-01-01

    On December 25, 2004, a large-scale ionospheric plasma bubble was observed over Arecibo Observatory in Puerto Rico, inducing significant range spreading on ionograms. This phenomena may be explained by means of the E x B ...

  14. Fatigue crack growth behavior of Al-Li alloy 1441

    SciTech Connect (OSTI)

    Prakash, R.V.; Parida, B.K.

    1995-12-31

    Fatigue crack growth behavior of Al-Li alloy 1441 having a marginally lower lithium content, compared to 80xx and 20xx series Al-Li alloys is presented in this paper. This investigation was conducted on single edge tension--SE(T)--specimens, under constant amplitude as well as under MiniLCA flight spectrum loading with the specific objective of determining the effects of stress ratio, orientation, thickness and cladding. Three thicknesses were considered: 1.2 mm(clad and unclad), 2.0 mm(clad and unclad) and 8.0 mm unclad. Constant amplitude fatigue tests were conducted at stress ratios of {minus}0.3, 0.1 and 0.7. Testing was performed under ambient conditions and along three orientations, namely L-T, T-L and L+45 degrees. Crack growth characteristics of this alloy are compared with that of BS:L73 (2014-T4 equivalent) for assessing the possibility of replacing BS:L73. Significant effect of stress ratio on crack growth rate was observed in all thicknesses. However, in case of 1.2 and 2.0 mm thick sheets, the effect was minimal at intermediate-crack growth regime. The orientation of the specimen does not adversely affect the fatigue crack growth behavior of 8.0 mm and 2.0 mm thick specimens. However, for 1.2 mm unclad sheet crack growth resistance in L-T direction was found to be superior to that along T-L direction. In majority of test cases considered, no significant effect was observed on crack growth rate due to thickness or cladding. Crack growth characteristics of Al-Li alloy 1441 and Al-Cu alloy BS:L73 under constant amplitude as well as MiniLCA spectrum loading are similar in the low and intermediate-crack growth rate regime. Based on these observations, it is felt that this Al-Li alloy has the potential for future aerospace applications.

  15. Boundary integral formulation for interfacial cracks in thermodiffusive bimaterials

    E-Print Network [OSTI]

    L. Morini; A. Piccolroaz

    2015-04-29

    An original boundary integral formulation is proposed for the problem of a semi-infinite crack at the interface between two dissimilar elastic materials in the presence of heat flows and mass diffusion. Symmetric and skew-symmetric weight function matrices are used together with a generalized Betti's reciprocity theorem in order to derive a system of integral equations that relate the applied loading, the temperature and mass concentration fields, the heat and mass fluxes on the fracture surfaces and the resulting crack opening. The obtained integral identities can have many relevant applications, such as for the modelling of crack and damage processes at the interface between different components in electrochemical energy devices characterized by multi-layered structures (solid oxide fuel cells and lithium ions batteries).

  16. Rejuvenation and reuse of spent fluid cracking catalysts

    SciTech Connect (OSTI)

    Elvin, F.J. (ChemCat Corp., New Orleans, LA (US))

    1988-01-01

    Refineries processing heavy, high metals feedstocks have reused other refineries' spent cracking catalyst for the past ten years without observing any yield debits. ChemCat has developed a process whereby a refinery can reuse its own spent catalyst without suffering any yield debits. The new DEMET process is being demonstrated in the world's first commercial fluid cracking catalyst rejuvenation and demetallization plant. The plant is located in Meraux, Louisiana and processes 20 tons/day of spent cracking catalyst for local refineries. The plant removes contaminant metals from zeolite catalysts, while simultaneously increasingly the zeolite and matrix surface areas. The demetallized catalyst has a higher activity and better selectivity than the undemetallized spent catalyst. The demetallized catalyst is also more hydrothermally stable than the spent catalyst. ChemCat's DEMET process enables refiners to eliminate the high cost of spent FCCU catalyst disposal and to significantly reduce their consumption and cost of fresh catalyst.

  17. Method for fabrication of crack-free ceramic dielectric films

    DOE Patents [OSTI]

    Ma, Beihai; Balachandran, Uthamalingam; Chao, Sheng; Liu, Shanshan; Narayanan, Manoj

    2014-02-11

    The invention provides a process for forming crack-free dielectric films on a substrate. The process comprise the application of a dielectric precursor layer of a thickness from about 0.3 .mu.m to about 1.0 .mu.m to a substrate. The deposition is followed by low temperature heat pretreatment, prepyrolysis, pyrolysis and crystallization step for each layer. The deposition, heat pretreatment, prepyrolysis, pyrolysis and crystallization are repeated until the dielectric film forms an overall thickness of from about 1.5 .mu.m to about 20.0 .mu.m and providing a final crystallization treatment to form a thick dielectric film. Also provided was a thick crack-free dielectric film on a substrate, the dielectric forming a dense thick crack-free dielectric having an overall dielectric thickness of from about 1.5 .mu.m to about 20.0 .mu.m.

  18. Relationships between stress corrosion cracking tests and utility operating experience

    SciTech Connect (OSTI)

    Baum, Allen

    1999-10-22

    Several utility steam generator and stress corrosion cracking databases are synthesized with the view of identifying the crevice chemistry that is most consistent with the plant cracking data. Superheated steam and neutral solution environments are found to be inconsistent with the large variations in the observed SCC between different plants, different support plates within a plant, and different crevice locations. While the eddy current response of laboratory tests performed with caustic chemistries approximates the response of the most extensively affected steam generator tubes, the crack propagation kinetics in these tests differ horn plant experience. The observations suggest that there is a gradual conversion of the environment responsible for most steam generator ODSCC from a concentrated, alkaline-forming solution to a progressively more steam-enriched environment.

  19. Weld solidification cracking in 304 to 204L stainless steel

    SciTech Connect (OSTI)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-09-15

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  20. Weld solidification cracking in 304 to 304L stainless steel

    SciTech Connect (OSTI)

    Hochanadel, Patrick W [Los Alamos National Laboratory; Lienert, Thomas J [Los Alamos National Laboratory; Martinez, Jesse N [Los Alamos National Laboratory; Martinez, Raymond J [Los Alamos National Laboratory; Johnson, Matthew Q [Los Alamos National Laboratory

    2010-01-01

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  1. Dynamic crack initiation toughness : experiments and peridynamic modeling.

    SciTech Connect (OSTI)

    Foster, John T.

    2009-10-01

    This is a dissertation on research conducted studying the dynamic crack initiation toughness of a 4340 steel. Researchers have been conducting experimental testing of dynamic crack initiation toughness, K{sub Ic}, for many years, using many experimental techniques with vastly different trends in the results when reporting K{sub Ic} as a function of loading rate. The dissertation describes a novel experimental technique for measuring K{sub Ic} in metals using the Kolsky bar. The method borrows from improvements made in recent years in traditional Kolsky bar testing by using pulse shaping techniques to ensure a constant loading rate applied to the sample before crack initiation. Dynamic crack initiation measurements were reported on a 4340 steel at two different loading rates. The steel was shown to exhibit a rate dependence, with the recorded values of K{sub Ic} being much higher at the higher loading rate. Using the knowledge of this rate dependence as a motivation in attempting to model the fracture events, a viscoplastic constitutive model was implemented into a peridynamic computational mechanics code. Peridynamics is a newly developed theory in solid mechanics that replaces the classical partial differential equations of motion with integral-differential equations which do not require the existence of spatial derivatives in the displacement field. This allows for the straightforward modeling of unguided crack initiation and growth. To date, peridynamic implementations have used severely restricted constitutive models. This research represents the first implementation of a complex material model and its validation. After showing results comparing deformations to experimental Taylor anvil impact for the viscoplastic material model, a novel failure criterion is introduced to model the dynamic crack initiation toughness experiments. The failure model is based on an energy criterion and uses the K{sub Ic} values recorded experimentally as an input. The failure model is then validated against one class of problems showing good agreement with experimental results.

  2. Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

    E-Print Network [OSTI]

    Bakeman, M.S.

    2011-01-01

    Laser Wakefield Accelerator Electron Beam Energy Spread andposition detection of electron beams from laser-plasmaLPA) to measure electron beam energy spread and emittance

  3. Failure probability of axially cracked steam generator tubes; A probabilistic fracture mechanics model

    SciTech Connect (OSTI)

    Mavko, B.; Cizelj, L. (Jozef Stefan Inst., Reactor Engineering Div., P.O. Box 100, 61111 Ljubljana, Slovenia (YU))

    1992-05-01

    In this paper a model for estimating the failure probability of axially cracked steam generator tubes is proposed. The model compares observed crack length distribution with critical crack length distribution by means of probabilistic fracture mechanics. The observed crack length is influenced by measured data, measurement reliability, sizing accuracy, and predicted crack growth rate. The critical crack length is defined by a deterministic mechanical model. All cracks are conservatively assumed to extend through the tube wall. The effect of the plugging limit is studied along with the number of cracked tubes to perform risk-based lifetime optimization of steam generators. A numerical example presented considers hypothetical accidental operating conditions during a feedwater line break.

  4. The application of a logic framework for fatigue crack growth analyses to microstructural effects

    SciTech Connect (OSTI)

    Xu, J.G.; Liu, H.W.

    1995-12-31

    {Delta}K has been widely used to correlate da/dN data. The relation between da/dN and {Delta}K is usually found empirically. However, fatigue crack growth relations can also be derived theoretically. Three fatigue crack growth theories are derived for the state of small scale yielding and plane strain. These three theories constitute a logic framework useful for fatigue crack growth analyses. The application of the logic framework to the analyses of microstructural effects on fatigue crack growth is illustrated. The fatigue crack growth curve of 7075-T651 aluminum alloy has five distinct regions. A fatigue crack grows by crack-tip shear decohesion forming striations and by brittle fractures of particles followed by localized shear decohesion at these microcracks forming dimples. The logic framework helps to relate the fatigue crack growth behaviors in these five regions to the fractures of inclusions and to the resistance of grain boundaries and dispersoids to shear decohesion.

  5. Monitoring Cracking of a Smectitic Vertisol using Three-dimensional Electrical Resistivity Tomography 

    E-Print Network [OSTI]

    Ackerson, Jason Paul

    2013-11-20

    Upon desiccation, the matrix of Vertisols and other expansive soils shrinks. Matrix shrinkage results in the formation of cracks that can alter the hydrology of the soil. Despite the importance of cracks, many hydrologic models do not account...

  6. Numerical simulation of oxidation and its effect on the crack growth resistance of titanium alloys 

    E-Print Network [OSTI]

    Triharjanto, Robertus Heru

    1997-01-01

    though the oxidation generally degrades the MMC, the oxidation from the crack surfaces may improve the crack growth resistance of the metal matrix. Titanium alloys are potential candidates for use in MMC. Therefore, a more thorough understanding...

  7. Agglutination of single catalyst particles during fluid catalytic cracking as observed by X-ray nanotomography

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Meirer, F.; Kalirai, S.; Weker, J. Nelson; Liu, Y.; Andrews, J. C.; Weckhuysen, B. M.

    2015-04-14

    Metal accumulation at the catalyst particle surface plays a role in particle agglutination during fluid catalytic cracking.

  8. Dependence of dynamic fracture resistance on crack velocity in tungsten: Pt. II. Bicrystals and polycrystals

    SciTech Connect (OSTI)

    Liv, J.M.; Shen, B.W.

    1986-06-01

    The experimental techniques for crack velocity measurements have been applied to bicrystals of tungsten with twist orientations about (100) and polycrystals. The hesitation of the propagating cleavage crack in the vicinity of the grain boundary is examined. The contributions to energy dissipation from deformation and fracture processes in the grain boundary region as well as the in direct effects of crack deceleration are discussed. These findings have been applied to explain th dynamic fracture resistance and crack arrest in polycrystals.

  9. Incipient Crack Detection in Composite Wind Turbine Blades

    SciTech Connect (OSTI)

    Taylor, Stuart G. [Los Alamos National Laboratory; Choi, Mijin [Chonbuk National University, Korea; Jeong, Hyomi [Chonbuk National University, Korea; Jang, Jae Kyeong [Chonbuk National University, Korea; Park, Gyuhae [Chonnam National University, Korea; Farinholt, Kevin [Commonwealth Center for Advanced Manufacturing, VA; Farrar, Charles R. [Los Alamos National Laboratory; Ammerman, Curtt N. [Los Alamos National Laboratory; Todd, Michael D. [Los Alamos National Laboratory; Lee, Jung-Ryul [Chonbuk National University, Korea

    2012-08-28

    This paper presents some analysis results for incipient crack detection in a 9-meter CX-100 wind turbine blade that underwent fatigue loading to failure. The blade was manufactured to standard specifications, and it underwent harmonic excitation at its first resonance using a hydraulically-actuated excitation system until reaching catastrophic failure. This work investigates the ability of an ultrasonic guided wave approach to detect incipient damage prior to the surfacing of a visible, catastrophic crack. The blade was instrumented with piezoelectric transducers, which were used in an active, pitchcatch mode with guided waves over a range of excitation frequencies. The performance results in detecting incipient crack formation in the fiberglass skin of the blade is assessed over the range of frequencies in order to determine the point at which the incipient crack became detectable. Higher excitation frequencies provide consistent results for paths along the rotor blade's carbon fiber spar cap, but performance falls off with increasing excitation frequencies for paths off of the spar cap. Lower excitation frequencies provide more consistent performance across all sensor paths.

  10. CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR

    E-Print Network [OSTI]

    CONTAINED PLASTIC DEFORMATION NEAR CRACKS AND NOTCHES UNDER LONGITUDINAL SHEAR James R. Rice* ABSTRACT An exact linear elastic-perfectly plastic solution is presented for the problem of a sharp notch coordinates corresponding to given stresses, position of the elastic-plastic boundary, and accompanying

  11. Thin film with oriented cracks on a flexible substrate

    DOE Patents [OSTI]

    Feng, Bao; McGilvray, Andrew; Shi, Bo

    2010-07-27

    A thermoelectric film is disclosed. The thermoelectric film includes a substrate that is substantially electrically non-conductive and flexible and a thermoelectric material that is deposited on at least one surface of the substrate. The thermoelectric film also includes multiple cracks oriented in a predetermined direction.

  12. Solvent control of crack dynamics in a reversible hydrogel

    E-Print Network [OSTI]

    Tristan Baumberger; Christiane Caroli; David Martina

    2006-05-16

    The resistance to fracture of reversible biopolymer hydrogels is an important control factor of the cutting/slicing and eating characteristics of food gels. It is also critical for their utilization in tissue engineering, for which mechanical protection of encapsulated components is needed. Its dependence on loading rate and, recently, on the density and strength of cross-links has been investigated. But no attention was paid so far to solvent nor to environment effects. Here we report a systematic study of crack dynamics in gels of gelatin in water/glycerol mixtures. We show on this model system that: (i) increasing solvent viscosity slows down cracks; (ii) soaking with solvent increases markedly gel fragility; (iii) tuning the viscosity of the (miscible) environmental liquid affects crack propagation via diffusive invasion of the crack tip vicinity. The results point toward the fact that fracture occurs by viscoplastic chain pull-out. This mechanism, as well as the related phenomenology, should be common to all reversibly cross-linked (physical) gels.

  13. Crack-resistant siloxane molding compounds. [Patent application

    DOE Patents [OSTI]

    McFarland, J.W.; Swearngin, C.B.

    1980-11-03

    The crack resistance of phenyl silicone molding resins containing siliceous fillers is improved by incorporating therein about 0.5 to 5.5% by weight of ..beta..-eucryptite, a lithium aluminum silicate having a negative thermal expansion coefficient. These molding resins are particularly suitable for encapsulating electronic devices such as diodes, coils, resistors, and the like.

  14. Method of making crack-free zirconium hydride

    DOE Patents [OSTI]

    Sullivan, Richard W. (Denver, CO)

    1980-01-01

    Crack-free hydrides of zirconium and zirconium-uranium alloys are produced by alloying the zirconium or zirconium-uranium alloy with beryllium, or nickel, or beryllium and scandium, or nickel and scandium, or beryllium and nickel, or beryllium, nickel and scandium and thereafter hydriding.

  15. PENNY--SHAPED CRACK BRIDGED BY N.V. Movchan,

    E-Print Network [OSTI]

    Bath, University of

    PENNY--SHAPED CRACK BRIDGED BY FIBRES N.V. Movchan, School of Mathematical Sciences, University and Theoretical Physics, Silver Street, Cambridge, CB3 9EW, U.K. Abstract An axi--symmetric problem for a penny traction distribution. In the present paper we deal only with the second step, namely we consider a penny

  16. 1. INTRODUCTION Current design methods focus on crack growth curves which are material properties for given

    E-Print Network [OSTI]

    Hively, Lee M.

    propagation. This technique has been demonstrated by test and analysis in fiberglass composite, aircraft fatigue, as well as Mode I low-temperature creep and stress corrosion. During the 1930s, A. A. Griffith sustained loading of cracks) and stress corrosion cracking (KI scc, JI scc, sustained loading of cracks

  17. Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D

    E-Print Network [OSTI]

    Zhou, Wei

    Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D W. Zhou*, T. Z. Long and C. K of the plates were produced using tungsten inert gas (TIG) welding method. The TIG arc was also used to deposit welding beads on some of the thin plates. No cracking was found in the butt joints. However, hot cracking

  18. Brittle film-induced cracking of ductile substrates , Lijie Qiao a,

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Brittle film-induced cracking of ductile substrates Tao Guo a , Lijie Qiao a, , Xiaolu Pang b 29 May 2015 Revised 22 July 2015 Accepted 23 July 2015 Keywords: Brittle film Ductile substrate Film-induced cracking Dislocations Crack velocity a b s t r a c t Film and substrate mechanical integrity is essential

  19. Mechanics and mechanisms of fatigue damage and crack growth in advanced materials

    E-Print Network [OSTI]

    Ritchie, Robert

    Mechanics and mechanisms of fatigue damage and crack growth in advanced materials R.O. Ritchie*, C 94720-1760, USA Abstract The mechanisms of fatigue-crack propagation in ceramics and intermetallics growth is considered to be a mutual competition between intrinsic mechanisms of crack advance ahead

  20. Permeability and elastic properties of cracked glass under pressure A. OugierSimonin,1

    E-Print Network [OSTI]

    Fortin, Jérôme

    for independent controls of the confining pressure, the axial stress, and pore pressure. We produced cracks with identified average aspect ratio and crack aperture, (2) a very small permeability which decreases as a power behavior of a cracked elastic brittle solid is reversible and independent of the fluid nature. Two

  1. A cracked beam finite element for rotating shaft dynamics and stability analysis

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    A cracked beam finite element for rotating shaft dynamics and stability analysis Saber El Arem Palaiseau, France Abstract In this paper, a method for the construction of a cracked beam finite element is presented. The additional flexibility due to the cracks is identified from three- dimensional finite element

  2. Automated Detection of Cracked Railway Axle Journals Using an Ultrasonic Phased Array Technique 

    E-Print Network [OSTI]

    Baik, Jaeyong

    2014-06-27

    ) automated detection system of a cracked axle journal using the ultrasonic phased array technique, 2) detection of a cracked axle journal using a chain scanner, and 3) cracked axle journal detection using surface waves. An ultrasonic phased array system has a...

  3. Fatigue-Crack Growth Behavior in the Superelastic and Shape-Memory Alloy Nitinol

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue-Crack Growth Behavior in the Superelastic and Shape-Memory Alloy Nitinol A.L. McKELVEY and R.O. RITCHIE This article presents a study of fatigue-crack propagation behavior in Nitinol, a 50Ni, and constitutive behavior on crack-growth rates in NiTi.* NITINOL is a thermoelastic alloy with a composition

  4. A penny-shaped cohesive crack model for material damage G. Wang, S.F. Li *

    E-Print Network [OSTI]

    Li, Shaofan

    A penny-shaped cohesive crack model for material damage G. Wang, S.F. Li * Department of Civil solids with ran- domly distributed penny-shaped cohesive micro-cracks (Barenblatt­Dugdale type). Energy are derived based on homogenization of randomly distributed penny-shaped cohesive cracks (Barenblatt

  5. Crack Response to Blast Vibrations and Moisture Induced Volumetric Changes in Foundation Soils

    E-Print Network [OSTI]

    Crack Response to Blast Vibrations and Moisture Induced Volumetric Changes in Foundation Soils By C, Evanston, IL. Abstract In this paper vibratory crack response is compared to that produced by volumetric over a period of weeks to several months. On the other hand, crack response produced by volumetric

  6. New algorithms for adaptive optics point-spread function reconstruction

    E-Print Network [OSTI]

    Eric Gendron; Yann Clénet; Thierry Fusco; Gérard Rousset

    2006-06-28

    Context. The knowledge of the point-spread function compensated by adaptive optics is of prime importance in several image restoration techniques such as deconvolution and astrometric/photometric algorithms. Wavefront-related data from the adaptive optics real-time computer can be used to accurately estimate the point-spread function in adaptive optics observations. The only point-spread function reconstruction algorithm implemented on astronomical adaptive optics system makes use of particular functions, named $U\\_{ij}$. These $U\\_{ij}$ functions are derived from the mirror modes, and their number is proportional to the square number of these mirror modes. Aims. We present here two new algorithms for point-spread function reconstruction that aim at suppressing the use of these $U\\_{ij}$ functions to avoid the storage of a large amount of data and to shorten the computation time of this PSF reconstruction. Methods. Both algorithms take advantage of the eigen decomposition of the residual parallel phase covariance matrix. In the first algorithm, the use of a basis in which the latter matrix is diagonal reduces the number of $U\\_{ij}$ functions to the number of mirror modes. In the second algorithm, this eigen decomposition is used to compute phase screens that follow the same statistics as the residual parallel phase covariance matrix, and thus suppress the need for these $U\\_{ij}$ functions. Results. Our algorithms dramatically reduce the number of $U\\_{ij}$ functions to be computed for the point-spread function reconstruction. Adaptive optics simulations show the good accuracy of both algorithms to reconstruct the point-spread function.

  7. Scanning Raman spectroscopy for characterizing compositionally spread films

    E-Print Network [OSTI]

    Venimadhav, A.; Yates, K. A.; Blamire, Mark G.

    2004-01-01

    compositionally spread films Venimadhav. A?, Yates K. A., Blamire M. G. Department of Materials Science, University of Cambridge, Pembroke Street, Cambridge, CB2 3QZ, UK Abstract Composition-spread La1-xSrxMnO3 thin films were prepared by pulsed laser... . This is close to the the phase coexistence predicted for LSMO single crystals at x = 0.17 [23]. Above x = 0.2, the 640 cm-1 mode completely disappears. The intensity of the 436 cm-1 peak in figure 4(b) shows maximum at x = 0.35. It is worth mentioning...

  8. Heat-affected zone liquation crack on resistance spot welded TWIP steels

    SciTech Connect (OSTI)

    Saha, Dulal Chandra [Department of Advanced Materials Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of); Chang, InSung [Automotive Production Development Division, Hyundai Motor Company (Korea, Republic of); Park, Yeong-Do, E-mail: ypark@deu.ac.kr [Department of Advanced Materials Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of)

    2014-07-01

    In this study, the heat affected zone (HAZ) liquation crack and segregation behavior of the resistance spot welded twinning induced plasticity (TWIP) steel have been reported. Cracks appeared in the post-welded joints that originated at the partially melted zone (PMZ) and propagated from the PMZ through the heat affected zone (HAZ) to the base metal (BM). The crack length and crack opening widths were observed increasing with heat input; and the welding current was identified to be the most influencing parameter for crack formation. Cracks appeared at the PMZ when nugget diameter reached at 4.50 mm or above; and the liquation cracks were found to occur along two sides of the notch tip in the sheet direction rather than in the electrode direction. Cracks were backfilled with the liquid films which has lamellar structure and supposed to be the eutectic constituent. Co-segregation of alloy elements such as, C and Mn were detected on the liquid films by electron-probe microanalysis (EPMA) line scanning and element map which suggests that the liquid film was enrich of Mn and C. The eutectic constituent was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation. Preliminary experimental results showed that cracks have less/no significant effect on the static cross-tensile strength (CTS) and the tensile-shear strength (TSS). In addition, possible ways to avoid cracking were discussed. - Highlights: • The HAZ liquation crack during resistance spot welding of TWIP steel was examined. • Cracks were completely backfilled and healed with divorced eutectic secondary phase. • Co-segregation of C and Mn was detected in the cracked zone. • Heat input was the most influencing factor to initiate liquation crack. • Cracks have less/no significant effect on static tensile properties.

  9. Salary Spread Request Instructions: Please complete and print this form to elect or cancel salary spread. Once completed, the form should be sent

    E-Print Network [OSTI]

    Pillow, Jonathan

    Salary Spread Request Instructions: Please complete and print this form to elect or cancel salary. ________________________________________________________________________________________________________ REQUIREMENTS: Employees with a nine-month basis assignment may be eligible to spread their salary evenly over the 12 months of the fiscal year by completing this Salary Spread Request form. Once elected, the salary

  10. Wireless spread-spectrum telesensor chip with synchronous digital architecture

    DOE Patents [OSTI]

    Smith, Stephen F.; Turner, Gary W.; Wintenberg, Alan L.; Emery, Michael Steven

    2005-03-08

    A fully integrated wireless spread-spectrum sensor incorporating all elements of an "intelligent" sensor on a single circuit chip is capable of telemetering data to a receiver. Synchronous control of all elements of the chip provides low-cost, low-noise, and highly robust data transmission, in turn enabling the use of low-cost monolithic receivers.

  11. On the Spread of Viruses on the Internet Noam Berger

    E-Print Network [OSTI]

    Saberi, Amin

    distribution [14], this work is relevant both in the context of the spread of computer viruses on the Internet of antivirus software. Computers with the software installed are not permanently immune from the virus, but they are regularly scanned for the presence of the virus, and the software removes the virus if the computer is found

  12. On the Spread of Viruses on the Internet Noam Berger

    E-Print Network [OSTI]

    Chayes, Jennifer Tour

    , and the software removes the virus if the computer is found to be infected. A computer can be infected by the same. In this case, the antivirus software prevents any given computer from being reinfected with the same virusOn the Spread of Viruses on the Internet Noam Berger Christian Borgs Jennifer T. Chayes Amin

  13. Efficient Communication over Highly Spread Underwater Acoustic Channels

    E-Print Network [OSTI]

    Schniter, Philip

    unforgiving wireless medium" [2]. In fact, re- liable high-rate underwater acoustic communication remains a principal challenge in the construction of underwater net- works. The physical characteristics of the UAC of optimal and fail altogether in very highly spread environments such as the surf zone [20

  14. ACOUSTIC PULSE SPREADING IN A RANDOM FRACTAL KNUT S LNA

    E-Print Network [OSTI]

    Solna, Knut

    ACOUSTIC PULSE SPREADING IN A RANDOM FRACTAL KNUT S#28;LNA #3; Abstract. Fractal medium models are used to model for instance the heterogeneous earth and the turbulent atmosphere. A wave pulse with the medium uctuations. The modi#12;cation in the pulse shape depends on the roughness of the medium and can

  15. Building a Simulation of the Spread of a Virus

    E-Print Network [OSTI]

    Repenning, Alexander

    Building a Simulation of the Spread of a Virus Using the AgentSheets simulation-authoring tool of how to use the AgentSheets® simulation-authoring tool to 1) create a simulation of a virus attack. Create a simulation of a virus attack To illustrate how an AgentSheets simulation is created from scratch

  16. UMTS Capacity and Throughput Maximization for Different Spreading Factors

    E-Print Network [OSTI]

    Akl, Robert

    for signal-to-interference threshold from 5 dB to 10 dB and spreading factor values of 256, 64, 16, and 4 Erlang capacity based on the Lost Call Held (LCH) model as described in [4]. This algorithm calculates expression of Erlang capacity for a single type of traffic loading and compare analytical results

  17. Paper No. : 0317 LATERAL SPREADING DURING CENTRIFUGE MODEL

    E-Print Network [OSTI]

    Haigh, Stuart

    Paper No. : 0317 LATERAL SPREADING DURING CENTRIFUGE MODEL EARTHQUAKES Stuart K. Haigh1 , S sand marker lines within centrifuge models. A series of dynamic centrifuge model tests have been these free boundaries from previous earthquakes. Dynamic centrifuge modelling was carried out using sloping

  18. Blunt-crack band propagation in finite-element analysis for concrete structures. [LMFBR

    SciTech Connect (OSTI)

    Pfeiffer, P.A.; Bazant, Z.P.; Marchertas, A.H.

    1983-01-01

    The knowledge of concrete fracture is needed in nuclear reactor safety. The question of safety arises from the potential of concrete to crack under thermal loading. It has been postulated that structural concrete could be exposed to very high temperature, which may result from hot reactor coolant or even core debris coming in direct contact with the concrete. The utilization of the blunt crack approach for simulating concrete cracking in a general-purpose code is explored. The difficulties encountered in establishing the proper direction of crack propagation in an arbitrary discretization are described. Crack propagation is considered within the context of two types of solution techniques: (1) implicit solution of the static crack advance, and (2) explicit time integration using a dynamic relaxation technique to simulate the static crack advance. Also, in both solution techniques an elastic model is used to characterize the concrete.

  19. Fatigue and Creep Crack Propagation behaviour of Alloy 617 in the Annealed and Aged Conditions

    SciTech Connect (OSTI)

    Julian K. Benz; Richard N. Wright

    2013-10-01

    The crack propagation behaviour of Alloy 617 was studied under various conditions. Elevated temperature fatigue and creep-fatigue crack growth experiments were conducted at 650 and 800 degrees C under constant stress intensity (triangle K) conditions and triangular or trapezoidal waveforms at various frequencies on as-received, aged, and carburized material. Environmental conditions included both laboratory air and characteristic VHTR impure helium. As-received Alloy 617 displayed an increase in the crack growth rate (da/dN) as the frequency was decreased in air which indicated a time-dependent contribution component in fatigue crack propagation. Material aged at 650°C did not display any influence on the fatigue crack growth rates nor the increasing trend of crack growth rate with decreasing frequency even though significant microstructural evolution, including y’ (Ni3Al) after short times, occurred during aging. In contrast, carburized Alloy 617 showed an increase in crack growth rates at all frequencies tested compared to the material in the standard annealed condition. Crack growth studies under quasi-constant K (i.e. creep) conditions were also completed at 650 degrees C and a stress intensity of K = 40 MPa9 (square root)m. The results indicate that crack growth is primarily intergranular and increased creep crack growth rates exist in the impure helium environment when compared to the results in laboratory air. Furthermore, the propagation rates (da/dt) continually increased for the duration of the creep crack growth either due to material aging or evolution of a crack tip creep zone. Finally, fatigue crack propagation tests at 800 degrees C on annealed Alloy 617 indicated that crack propagation rates were higher in air than impure helium at the largest frequencies and lowest stress intensities. The rates in helium, however, eventually surpass the rates in air as the frequency is reduced and the stress intensity is decreased which was not observed at 650 degrees C.

  20. Penny-shaped and half-plane cracks in a transversely isotropic piezoelectric solid under arbitrary loading

    E-Print Network [OSTI]

    Sevostianov, Igor

    Penny-shaped and half-plane cracks in a transversely isotropic piezoelectric solid under arbitrary loading E. Karapetian, I. Sevostianov, M. Kachanov Summary The problem of a penny-shaped crack for a piezoelectric medium with a crack. Solutions for penny-shaped and half-plane cracks in an in®nite medium loaded

  1. Method for making dense crack free thin films

    DOE Patents [OSTI]

    Jacobson, Craig P. (Lafayette, CA); Visco, Steven J. (Berkeley, CA); De Jonghe, Lutgard C. (Lafayette, CA)

    2007-01-16

    The process described herein provides a simple and cost effective method for making crack free, high density thin ceramic film. The steps involve depositing a layer of a ceramic material on a porous or dense substrate. The deposited layer is compacted and then the resultant laminate is sintered to achieve a higher density than would have been possible without the pre-firing compaction step.

  2. Methodology for predicting asphalt concrete overlay life against reflection cracking 

    E-Print Network [OSTI]

    Jayawickrama, Priyantha Warnasuriya

    1985-01-01

    METHODOLOGY FOR PREDICTING ASPHALT CONCRETE OVERLAY Lr 8 AGAINST REFLECTION CRACKING A Thesis by PRIYANTHA NARNASURIYA JAYAWICKRAMA Submitted to the Graduate College of Texas A8M University in Partial fulfillment of the requirements.... Experimental investigations carried out at Ohio State University ( 1, 2, 3) and Texas A8M University ( 4, 5, 6 ) have verified the applicability of fracture mechanics principles in predicting fatigue life of asphalt TIP OF THE CRACX /~ // N/i OVERLAY OLD...

  3. Catalytic cracking receives heavy attention at Q and A meeting

    SciTech Connect (OSTI)

    Not Available

    1993-04-19

    Refiners discussed fluid catalytic cracking (FCC) - the workhorse of the modern refinery - in great detail at the most recent National Petroleum Refiners Association's annual question and answer session on refining and petrochemical technology. Among the topics covered were the newest FCC refractory lining and particulate-control methods. The panel of experts also answered questions on the role of FCC in reducing gasoline benzene to meet reformulated gasoline specifications. This paper discusses refractories; particulate control; gasoline feeds; and benzene reduction.

  4. Crack growth monitoring in harsh environments by electrical potential measurements

    SciTech Connect (OSTI)

    W. R. Lloyd; W. G. Reuter; D. M. Weinberg

    1999-09-19

    Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. Where conventional NDE methods typically require localized human interaction, the EPM technique developed at the Idaho National Engineering and Environmental Laboratory (INEEL) can be operated remotely and automatically. Once a crack-like defect is discovered via conventional means, EPM can be applied to monitor local crack size changes. This is of particular interest in situations where an identified structural defect is not immediately rejectable from a fitness-for-service viewpoint, but due to operational and environmental conditions may grow to an unsafe size with continuing operation. If the location is in a harsh environment where periodic monitoring by normal means is either too costly or not possible, a very expensive repair may be immediately mandated. However, the proposed EPM methodology may offer a unique monitoring capability that would allow for continuing service. INEEL has developed this methodology, supporting equipment, and calibration information to apply EPM in a field environment for just this purpose. Laboratory and pilot scale tests on full-size engineering structures (pressure vessels and piping) have been successfully performed. The technique is applicable to many severe environments because the sensitive equipment (electronics, operators) can be situated in a remote location, with only current and voltage probe electrical leads entering into the harsh environment. Experimental results showing the utility of the methodology are presented, and unique application concepts that have been examined by multiple experiments are discussed.

  5. Crack Growth Monitoring in Harsh Environments by Electric Potential Measurements

    SciTech Connect (OSTI)

    Lloyd, Wilson Randolph; Reuter, Walter Graham; Weinberg, David Michael

    1999-09-01

    Electric potential measurement (EPM) technology offers an attractive alternative to conventional nondestructive evaluation (NDE) for monitoring crack growth in harsh environments. Where conventional NDE methods typically require localized human interaction, the EPM technique developed at the Idaho National Engineering and Environmental Laboratory (INEEL) can be operated remotely and automatically. Once a crack-like defect is discovered via conventional means, EPM can be applied to monitor local crack size changes. This is of particular interest in situations where an identified structural defect is not immediately rejectable from a fitness-for-service viewpoint, but due to operational and environmental conditions may grow to an unsafe size with continuing operation. If the location is in a harsh environment where periodic monitoring by normal means is either too costly or not possible, a very expensive repair may be immediately mandated. However, the proposed EPM methodology may offer a unique monitoring capability that would allow for continuing service. INEEL has developed this methodology, supporting equipment, and calibration information to apply EPM in a field environment for just this purpose. Laboratory and pilot scale tests on full-size engineering structures (pressure vessels and piping) have been successfully performed. The technique applicable is many severe environments because the sensitive equipment (electronics, operators) can be situated in a remote location, with only current and voltage probe electrical leads entering into the harsh environment. Experimental results showing the utility of the methodology are presented, and unique application concepts that have been examined by multiple experiments are discussed.

  6. Advances in crack-arrest technology for reactor pressure vessels

    SciTech Connect (OSTI)

    Bass, B.R.; Pugh, C.E.

    1988-01-01

    The Heavy-Section Steel Technology (HSST) Program at the Oak Ridge National Laboratory (ORNL) under the sponsorship of the US Nuclear Regulatory Commission is continuing to improve the understanding of conditions that govern the initiation, rapid propagation, arrest, and ductile tearing of cracks in reactor pressure vessel (RPV) steels. This paper describes recent advances in a coordinated effort being conducted under the HSST Program by ORNL and several subcontracting groups to develop the crack-arrest data base and the analytical tools required to construct inelastic dynamic fracture models for RPV steels. Large-scale tests are being carried out to generate crack-arrest toughness data at temperatures approaching and above the onset of Charpy upper-shelf behavior. Small- and intermediate-size specimens subjected to static and dynamic loading are being developed and tested to provide additional fracture data for RPV steels. Viscoplastic effects are being included in dynamic fracture models and computer programs and their utility validated through analyses of data from carefully controlled experiments. Recent studies are described that examine convergence problems associated with energy-based fracture parameters in viscoplastic-dynamic fracture applications. Alternative techniques that have potential for achieving convergent solutions for fracture parameters in the context of viscoplastic-dynamic models are discussed. 46 refs., 15 figs., 3 tabs.

  7. Crack stability analysis of low alloy steel primary coolant pipe

    SciTech Connect (OSTI)

    Tanaka, T.; Kameyama, M. [Kansai Electric Power Company, Osaka (Japan); Urabe, Y. [Mitsubishi Heavy Industries, Ltd., Takasago (Japan)] [and others

    1997-04-01

    At present, cast duplex stainless steel has been used for the primary coolant piping of PWRs in Japan and joints of dissimilar material have been applied for welding to reactor vessels and steam generators. For the primary coolant piping of the next APWR plants, application of low alloy steel that results in designing main loops with the same material is being studied. It means that there is no need to weld low alloy steel with stainless steel and that makes it possible to reduce the welding length. Attenuation of Ultra Sonic Wave Intensity is lower for low alloy steel than for stainless steel and they have advantageous inspection characteristics. In addition to that, the thermal expansion rate is smaller for low alloy steel than for stainless steel. In consideration of the above features of low alloy steel, the overall reliability of primary coolant piping is expected to be improved. Therefore, for the evaluation of crack stability of low alloy steel piping to be applied for primary loops, elastic-plastic future mechanics analysis was performed by means of a three-dimensioned FEM. The evaluation results for the low alloy steel pipings show that cracks will not grow into unstable fractures under maximum design load conditions, even when such a circumferential crack is assumed to be 6 times the size of the wall thickness.

  8. To Crack or Not to Crack: Strain in High TemperatureSuperconductors

    SciTech Connect (OSTI)

    Godeke, Arno

    2007-08-22

    Round wire Bi 2212 is emerging as a viable successor ofNb3Sn in High Energy Physics and Nuclear Magnetic Resonance, to generatemagnetic fields that surpass the intrinsic limitations of Nb3Sn. Ratherbold claims are made on achievable magnetic fields in applications usingBi 2212, due to the materials' estimated critical magnetic field of 100 Tor higher. High transport currents in high magnetic fields, however, leadto large stress on, and resulting large strain in the superconductor. Theeffect of strain on the critical properties of Bi-2212 is far fromunderstood, and strain is, as with Nb3Sn, often treated as a secondaryparameter in the design of superconducting magnets. Reversibility of thestrain induced change of the critical surface of Nb3Sn, points to anelectronic origin of the observed strain dependence. Record breaking highfield magnets are enabled by virtue of such reversible behavior. Straineffects on the critical surface of Bi-2212, in contrast, are mainlyirreversible and suggest a non-electronic origin of the observed straindependence, which appears to be dominated by the formation of cracks inthe superconductor volumes. A review is presented of available results onthe effects of strain on the critical surface of Bi-2212, Bi-2223 andYBCO. It is shown how a generic behavior emerges for the (axial) straindependence of the critical current density, and how the irreversiblereduction of the critical current density is dominated by strain inducedcrack formation in the superconductor. From this generic model it becomesclear that magnets using high temperature superconductors will be strainlimited far before the intrinsic magnetic field limitations will beapproached, or possibly even before the magnetic field limitation ofNb3Sn can be surpassed. On a positive note, in a very promising recentresult from NIST on the axial strain dependence of the critical currentdensity in extremely well aligned YBCO, reversible behavior was observed.This result emphasizes the need for further conductor development,specifically for round wire Bi-2212, to generate a wire with a similarreversible dependence on strain. Availability of such a wire will enablethe construction of magnets that can indeed generate fields that farsurpass the limitations of Nb3Sn superconductors.

  9. Asphalt overlay design methods for rigid pavements considering rutting, reflection cracking, and fatigue cracking. Research report September 1996--August 1997

    SciTech Connect (OSTI)

    Cho, Y.H.; Liu, C.; Dossey, T.; McCullough, B.F.

    1998-10-01

    An asphalt concrete pavement (ACP) overlay over a rigid pavement represents a viable rehabilitation strategy. It can provide good serviceability at an initial construction cost that is substantially less than that of a rigid overlay rehabilitation. In addition, ACP overlays require less construction time, which can reduce user costs during construction. However, it may not be the most economical solution for long-term rehabilitation. Because of their relatively short service life, ACP overlays may require maintenance sooner than rigid overlays. And one of the more critical distresses that effectively determine the life span of the structure is reflection cracking. This report investigates alternative strategies that seek to prevent reflection cracking on ACP overlays.

  10. An Efficient Local Strategy to Control Information Spreading in Network

    E-Print Network [OSTI]

    Mehta, Anoop

    2015-01-01

    In social networks, control of rumor spread is an active area of research. SIR model is generally used to study the rumor dynamics in network while considering the rumor as an epidemic. In disease spreading model, epidemic is controlled by removing central nodes in the network. Full network information is needed for such removal. To have the information of complete network is difficult proposition. As a consequence, the search of an algorithm that may control epidemic without needing global information is a matter of great interest. In this paper, an immunization strategy is proposed that uses only local information available at a node, viz. degree of the node and average degree of its neighbour nodes. Proposed algorithm has been evaluated for scale-free network using SIR model. Numerical results show that proposed method has less complexity and gives significantly better results in comparison with other strategies while using only local information.

  11. Dependence of dynamic fracture resistance on crack velocity in tungsten: Pt. 1. Single crystals

    SciTech Connect (OSTI)

    Liv, J.M.; Shen, B.W.

    1984-06-01

    The dependence of dynamic fracture resistance on crack propagation velocity on (100) in tungsten has been examined. A correlation is obtained between the measured local crack velocity with the surfac and subsurface deformations. Based on the experimental results on one pass, two passes, and prestrained, electron beam zone refined single crystals, a discussion is given on the slip modes activated at the crack tip, the contributions to the dynamic fracture resistance from dislocations and surface features and from the preexisting deformed microstructure.

  12. Identifying and Understanding Environment-Induced Crack propagation Behavior in Ni-based Superalloy INCONEL 617

    SciTech Connect (OSTI)

    Ma, Longzhou

    2012-11-30

    The nickel-based superalloy INCONEL 617 is a candidate material for heat exchanger applications in the next-generation nuclear plant (NGNP) system. This project will study the crack propagation process of alloy 617 at temperatures of 650°C-950°C in air under static/cyclic loading conditions. The goal is to identify the environmental and mechanical damage components and to understand in-depth the failure mechanism. Researchers will measure the fatigue crack propagation (FCP) rate (da/dn) under cyclic and hold-time fatigue conditions, and sustained crack growth rates (da/dt) at elevated temperatures. The independent FCP process will be identified and the rate-controlled sustained loading crack process will be correlated with the thermal activation equation to estimate the oxygen thermal activation energy. The FCP-dependent model indicates that if the sustained loading crack growth rate, da/dt, can be correlated with the FCP rate, da/dn, at the full time dependent stage, researchers can confirm stress-accelerated grain-boundary oxygen embrittlement (SAGBOE) as a predominate effect. Following the crack propagation tests, the research team will examine the fracture surface of materials in various cracking stages using a scanning electron microscope (SEM) and an optical microscope. In particular, the microstructure of the crack tip region will be analyzed in depth using high resolution transmission electron microscopy (TEM) and electron energy loss spectrum (EELS) mapping techniques to identify oxygen penetration along the grain boundary and to examine the diffused oxygen distribution profile around the crack tip. The cracked sample will be prepared by focused ion beam nanofabrication technology, allowing researchers to accurately fabricate the TEM samples from the crack tip while minimizing artifacts. Researchers will use these microscopic and spectroscopic results to interpret the crack propagation process, as well as distinguish and understand the environment or SAGBOE damage process under hold-time fatigue and sustained loading conditions

  13. Three-dimensional EBSD characterization of thermo-mechanical fatigue crack morphology in compacted graphite iron

    SciTech Connect (OSTI)

    Pirgazi, Hadi, E-mail: Hadi.pirgazi@ugent.be [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, 9052 Gent (Belgium); Ghodrat, Sepideh, E-mail: s.ghodrat@tudelft.nl [Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft (Netherlands); Kestens, Leo A.I., E-mail: leo.kestens@ugent.be [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, 9052 Gent (Belgium); Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628 CD, Delft (Netherlands)

    2014-04-01

    In cylinder heads made of compacted graphitic iron (CGI), heating and cooling cycles can lead to localized cracking due to thermo-mechanical fatigue (TMF). To meticulously characterize the complex crack path morphology of CGI under TMF condition, in relation to microstructural features and to find out how and by which mechanisms the cracks predominantly develop, three-dimensional electron back scattering diffraction (EBSD) was employed. Based on the precise quantitative microstructural analysis, it is found that graphite particles not only play a crucial role in the crack initiation, but also are of primary significance for crack propagation, i.e. crack growth is enhanced by the presence of graphite particles. Furthermore, the density of graphite particles on the fracture plane is more than double as high as in any other arbitrary plane of the structure. The obtained results did not indicate a particular crystallographic preference of fracture plane, i.e. the crystal plane parallel to the fracture plane was nearly of random orientation. - Highlights: • Crystallographic features of a thermo-mechanical fatigue (TMF) crack were studied. • Wide-field 3D EBSD is used to characterize the TMF crack morphology. • Data processing was applied on a large length scale of the order of millimeters. • Graphite density in the fracture plane is much higher than any other random plane. • It is revealed that crack growth is enhanced by the presence of graphite particles.

  14. J-integral for a semi-elliptical surface crack at a bimaterial interface

    SciTech Connect (OSTI)

    Sharobeam, M.H.; Landes, J.D.

    1995-12-31

    Surface cracks are common defects in welded, bonded, and composite structures. The elastic-plastic fracture of these defects may be analyzed using the J-integral. The authors have recently developed a new approach to evaluate the J-integral for semi-elliptical surface cracks in panels made of homogeneous materials and subject to remote tension. This approach, which is based on load separation, allows the evaluation of J for such a three-dimensional geometry using a single specimen test record. It is analogous to the single specimen technique in two-dimensional geometries. In this article, the authors extend their study to surface cracks at bimaterial interfaces. A three-dimensional finite element model is developed to model such a crack. The J-integral is evaluated along the crack front using the virtual crack extension method. The elastic-plastic fracture behavior of the crack is studied. Load separation is also examined and the new single specimen approach for surface cracks in single material panels is extended to those at bimaterial interfaces. The study also includes a comparison between the results of surface cracks in single material panels and those at bimaterial interfaces.

  15. Simulation of the ultrasonic array response from real branched cracks using an efficient finite element method

    SciTech Connect (OSTI)

    Felice, Maria V. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, United Kingdom and Rolls-Royce plc., Bristol BS34 7QE (United Kingdom); Velichko, Alexander; Wilcox, Paul D. [Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR (United Kingdom); Barden, Tim J.; Dunhill, Tony K. [Rolls-Royce plc., Bristol BS34 7QE (United Kingdom)

    2014-02-18

    A hybrid model to simulate the ultrasonic array response from stress corrosion cracks is presented. These cracks are branched and difficult to detect so the model is required to enable optimization of an array design. An efficient frequency-domain finite element method is described and selected to simulate the ultrasonic scattering. Experimental validation results are presented, followed by an example of the simulated ultrasonic array response from a real stress corrosion crack whose geometry is obtained from an X-ray Computed Tomography image. A simulation-assisted array design methodology, which includes the model and use of real crack geometries, is proposed.

  16. Standard test method for measurement of creep crack growth times in metals

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This test method covers the determination of creep crack growth (CCG) in metals at elevated temperatures using pre-cracked specimens subjected to static or quasi-static loading conditions. The time (CCI), t0.2 to an initial crack extension ?ai = 0.2 mm from the onset of first applied force and creep crack growth rate, ?a or da/dt is expressed in terms of the magnitude of creep crack growth relating parameters, C* or K. With C* defined as the steady state determination of the crack tip stresses derived in principal from C*(t) and Ct (1-14). The crack growth derived in this manner is identified as a material property which can be used in modeling and life assessment methods (15-25). 1.1.1 The choice of the crack growth correlating parameter C*, C*(t), Ct, or K depends on the material creep properties, geometry and size of the specimen. Two types of material behavior are generally observed during creep crack growth tests; creep-ductile (1-14) and creep-brittle (26-37). In creep ductile materials, where cr...

  17. Grain boundary chemistry effects on environment-induced crack growth of iron-based alloys

    SciTech Connect (OSTI)

    Jones, R.H.

    1992-11-01

    Relation between grain boundary chemistry and environment-induced crack growth of Fe-based alloys is reviewed. The importance of the cleanliness of steels is clearly demonstrated by direct relations between grain boundary chemistry and crack growth behavior for both H and anodic dissolution-induced crack growth. Relationships between strain to failure, work of fracture, K[sub ISCC], crack velocity and fracture mode and grain boundary chemistry are presented. Only results in which the grain boundary chemistry has been measured directly by Auger electron spectroscopy (AES) on intergranular surfaces exposed by in situ fracture have been considered in this review.

  18. Grain boundary chemistry effects on environment-induced crack growth of iron-based alloys

    SciTech Connect (OSTI)

    Jones, R.H.

    1992-11-01

    Relation between grain boundary chemistry and environment-induced crack growth of Fe-based alloys is reviewed. The importance of the cleanliness of steels is clearly demonstrated by direct relations between grain boundary chemistry and crack growth behavior for both H and anodic dissolution-induced crack growth. Relationships between strain to failure, work of fracture, K{sub ISCC}, crack velocity and fracture mode and grain boundary chemistry are presented. Only results in which the grain boundary chemistry has been measured directly by Auger electron spectroscopy (AES) on intergranular surfaces exposed by in situ fracture have been considered in this review.

  19. Innovative Approach to Establish Root Causes for Cracking in Aggressive Reactor Environments

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.; Thomas, Larry E.; Vetrano, John S.; Simonen, Edward P.

    2003-10-31

    The research focuses on the high-resolution characterization of degradation microstructures and microchemistries in specimens tested under controlled conditions for the environment and for the material where in-service complexities can be minimized. Thermodynamic and kinetic modeling of crack-tip processes is employed to analyze corrosion-induced structures and gain insights into degradation mechanisms. Novel mechanistic ''fingerprinting'' of crack-tip structures is used to isolate causes of environmental cracking in tandem with quantitative measurements of crack growth. Sample preparation methods and advanced analytical techniques are used to characterize corrosion/oxidation reactions and crack-tip structures at near atomic dimensions in order to gain insight into fundamental environmental cracking mechanisms. Reactions at buried interfaces, not accessible by conventional approaches, are being systematically interrogated. Crack-growth experiments in high-temperature water environments are evaluating and isolating the effects of material condition (matrix strength, grain boundary composition and precipitation) on stress corrosion cracking (SCC). The fundamental understanding of crack advance mechanisms will establish the basis to design new corrosion-resistant alloys for current light-water reactors and advanced reactor systems.

  20. Investigation of cracking and leaking of nuclear reactor pools 

    E-Print Network [OSTI]

    Cooper, William Bernard

    1965-01-01

    . Typical Gage Points on Pool Wall 12 8. s, . Locations of Leakage b. Locations of Leakage c. Locations of Leakage 13 14 15 9 ~ Structural Model 10. Creep Test 11. Shrinkage of Various Concrete Specimens (Dry ), 12. Permeability Test 16 26 28...'LLCS H. ~ Typi cB1 LCBkage T)n Q13gi'I th 8 PQol Wall ~ ln 196Q~ ax attempt was made to control tbe leakage by grani, in~ =". lean cemert, mix Under' high pressure into the cracks in tbe concrete pool vail in. an attempt, to fill the existing voids...

  1. On the approximation of crack shapes found during inservice inspection

    SciTech Connect (OSTI)

    Bhate, S.R.; Chawla, D.S.; Kushwaha, H.S. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01

    This paper addresses the characterization of axial internal flaw found during inservice inspection of a pipe. J-integral distribution for various flaw shapes is obtained using line spring finite, element method. The peak J-value and its distribution across the crack is found to be characteristic feature of each shape. The triangular shape yields peak J-value away from the center, the point of depth. The elliptic approximation results in large overestimate of J-value for unsymmetric flaws. Triangular approximation is recommended for such flaws so that further service can be obtained from the component.

  2. Risk Analysis, Vol. 24, No. 4, 2004 Assessing the Risk of Invasive Spread

    E-Print Network [OSTI]

    With, Kimberly A.

    Risk Analysis, Vol. 24, No. 4, 2004 Assessing the Risk of Invasive Spread in Fragmented Landscapes in the field of landscape ecology, provide a tool for assessing the risk of invasive spread in fragmented landscapes. A percolation-based analysis of the potential for invasive spread in fragmented landscapes

  3. Approximations for Bit Error Probabilities in SSMA Communication Systems Using Spreading

    E-Print Network [OSTI]

    Keller, Gerhard

    Approximations for Bit Error Probabilities in SSMA Communication Systems Using Spreading Sequences@mi.uni-erlangen.de Abstract-- In previous research, we considered SSMA (spread spectrum multiple access) communication systems of spread spectrum multiple access (SSMA) communication systems, the standard Gaussian approximation (SGA

  4. Efficiency and Energy Spread in Laser-Wakefield Acceleration A. J. W. Reitsma,1

    E-Print Network [OSTI]

    Strathclyde, University of

    Efficiency and Energy Spread in Laser-Wakefield Acceleration A. J. W. Reitsma,1 R. A. Cairns,2 R 2004; published 4 March 2005) The theoretical limits on efficiency and energy spread of the laser. An inherent trade-off between energy spread and efficiency exists. DOI: 10.1103/PhysRevLett.94.085004 PACS

  5. Spread of North American wind-dispersed trees in future environments

    E-Print Network [OSTI]

    He, Yanping

    LETTER Spread of North American wind-dispersed trees in future environments Ran Nathan,1 * Nir a formidable challenge to be confronted. We modelled the spread of North American wind- dispersed trees species, predicted wind-driven spread will match future climate changes, conditioned on seed abscission

  6. A Markov model for the spread of Hepatitis C

    E-Print Network [OSTI]

    Coutin, Laure; Dhersin, Jean-Stephane

    2008-01-01

    We propose a Markov model for the spread of Hepatitis C virus (HCV) among drug users who use injections. We then proceed to an asymptotic analysis (large initial population) and show that the Markov process is close to the solution of a non linear autonomous differential system. We prove both a law of large numbers and functional central limit theorem to precise the speed of convergence towards the limiting system. The deterministic system itself converges, as time goes to infinity, to an equilibrium point. This corroborates the empirical observations about the prevalence of HCV.

  7. Golden Spread Electric Cooperative, Inc | Open Energy Information

    Open Energy Info (EERE)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on QA:QA J-E-1 SECTION J APPENDIX E LISTStar2-0057-EA Jump to:ofEniaElectric JumpAtlasBridge Strategies Jump to:Spread

  8. Airborne spread of foot-and-mouth disease - model intercomparison

    SciTech Connect (OSTI)

    Gloster, J; Jones, A; Redington, A; Burgin, L; Sorensen, J H; Turner, R; Dillon, M; Hullinger, P; Simpson, M; Astrup, P; Garner, G; Stewart, P; D'Amours, R; Sellers, R; Paton, D

    2008-09-04

    Foot-and-mouth disease is a highly infectious vesicular disease of cloven-hoofed animals caused by foot-and-mouth disease virus. It spreads by direct contact between animals, by animal products (milk, meat and semen), by mechanical transfer on people or fomites and by the airborne route - with the relative importance of each mechanism depending on the particular outbreak characteristics. Over the years a number of workers have developed or adapted atmospheric dispersion models to assess the risk of foot-and-mouth disease virus spread through the air. Six of these models were compared at a workshop hosted by the Institute for Animal Health/Met Office during 2008. A number of key issues emerged from the workshop and subsequent modelling work: (1) in general all of the models predicted similar directions for 'at risk' livestock with much of the remaining differences strongly related to differences in the meteorological data used; (2) determination of an accurate sequence of events is highly important, especially if the meteorological conditions vary substantially during the virus emission period; and (3) differences in assumptions made about virus release, environmental fate, and subsequent infection can substantially modify the size and location of the downwind risk area. Close relationships have now been established between participants, which in the event of an outbreak of disease could be readily activated to supply advice or modelling support.

  9. Understanding Spreading Patterns on Social Networks Based on Network Topology

    E-Print Network [OSTI]

    Saxena, Akrati; Gupta, Yayati

    2015-01-01

    Ever since the proposal of first epidemic model, scientists have been attempting to estimate the growth of a disease/contagion while in its premature stage. Despite being the focus of researchers for a long time, understanding epidemiology remains as error prone as a weather forecast, mainly because of the unavailability of large amount of data. An epidemic spread is analogous to the diffusion of memes in social networking sites. Diffusion of memes can be easily studied provided large datasets and computational powers to extract information from online networks. So, studying a meme spreading pattern can help us in understanding epidemiology. In this paper, we analyse the impact of the topology of a social network, specifically its meso scale properties- community structure and core-periphery structure, on a meme traversing over it. We propose a meme propagation model for synthetic scale free graphs which resemble real world graphs and observe the process of a meme going viral on such a network. We also valida...

  10. Classification of Message Spreading in a Heterogeneous Social Network

    E-Print Network [OSTI]

    Jendoubi, Siwar; Liétard, Ludovic; Yaghlane, Boutheina Ben

    2015-01-01

    Nowadays, social networks such as Twitter, Facebook and LinkedIn become increasingly popular. In fact, they introduced new habits, new ways of communication and they collect every day several information that have different sources. Most existing research works fo-cus on the analysis of homogeneous social networks, i.e. we have a single type of node and link in the network. However, in the real world, social networks offer several types of nodes and links. Hence, with a view to preserve as much information as possible, it is important to consider so-cial networks as heterogeneous and uncertain. The goal of our paper is to classify the social message based on its spreading in the network and the theory of belief functions. The proposed classifier interprets the spread of messages on the network, crossed paths and types of links. We tested our classifier on a real word network that we collected from Twitter, and our experiments show the performance of our belief classifier.

  11. Credit Spreads and Bond Price-Based Pricing Credit Spreads and Bond Price-Based Pricing Chapter 3

    E-Print Network [OSTI]

    Ciocan-Fontanine, Ionut

    ;Defaultable Floater Coupons paid at time Tkn are Libor + spread n-1(L(Tkn-1 , Lkn ) + spar ) = ( 1 B(Tkn-1 , Lkn ) - 1) + spar n-1 The value of defaultable 1 B(Tkn-1 ,Lkn) at time Tkn-1 is: 1 B(Tkn-1 , Lkn ) ¯B III All together ¯C(0) = N n=1 n-1F(0, Tkn-1 , Tkn )¯B(0, Tkn ) +spar N n=1 n-1 ¯B(0, Tkn ) +¯B(0, Tk

  12. Low-Cracking High-Performance Concrete (LC-HPC) Bridge Decks: Shrinkage-Reducing Admixtures, Internal Curing, and Cracking Performance

    E-Print Network [OSTI]

    Pendergrass, Ben Andrew

    2014-05-31

    ABSTRACT The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks is described based on laboratory tests of mixtures containing shrinkage-reducing admixtures and mineral admixtures in conjunction...

  13. Modeling dynamic crack propagation in fiber reinforced composites including frictional effects q

    E-Print Network [OSTI]

    Espinosa, Horacio D.

    Modeling dynamic crack propagation in fiber reinforced composites including frictional effects q S Abstract Dynamic crack propagation in a unidirectional carbon/epoxy composite is studied through finite deformation anisotropic visco-plastic model is used to describe the constitutive response of the composite

  14. WATTS TOWERS: THE EFFECTS OF THERMAL CYCLES ON THE FORMATION AND BEHAVIOR OF CRACKS 

    E-Print Network [OSTI]

    Spencer, Matthew T

    2013-02-06

    of cracks located at different sections on the Towers was outfitted with strain gauges, force transducers, and thermocouples to collect data on the crack width as a function of the ambient temperature. Using the Finite Element Analysis program LS-DYNA, a...

  15. Cracks in martensite plates as hydrogen traps in a bearing steel

    E-Print Network [OSTI]

    Cambridge, University of

    Cracks in martensite plates as hydrogen traps in a bearing steel W. Solano-Alvareza , Eun Ju Songb stability requirements, and to improve the properties of the martensite [1]. Like most strong steels It is demonstrated that a macroscopically homogeneous distribution of tiny cracks introduced into a martensitic

  16. Theory of thin-skin eddy-current interaction with surface cracks N. Harfielda)

    E-Print Network [OSTI]

    Bowler, John R.

    Theory of thin-skin eddy-current interaction with surface cracks N. Harfielda) and J. R. Bowler; accepted for publication 14 July 1997 Eddy-current non-destructive evaluation is commonly performed of a typical crack. A thin-skin analysis of eddy currents is presented in which the electromagnetic fields

  17. Non-hypersingular boundary integral equations for 3-D non-planar crack dynamics

    E-Print Network [OSTI]

    Madariaga, Raúl

    Non-hypersingular boundary integral equations for 3-D non-planar crack dynamics T. Tada, E, are removed by way of a technique of regu- larization based on integration by parts. The variables are denoted, in time and space, of the slip along the crack and a set of integration kernels. Then a limiting process

  18. THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice*

    E-Print Network [OSTI]

    THE ELASTIC-PLASTIC MECHANICS OF CRACK EXTENSION James R. Rice* ABSTRACT This paper briefly reviews progres~in the elastic plastic analysisof crack extension. Analytical results for plane strain and plane stress deformation fields are noted, and elastic-plastic fracture instability as well as transitional

  19. Mixed Mode Static and Fatigue Crack Growth in Wind Blade Paste Adhesives

    E-Print Network [OSTI]

    1 Mixed Mode Static and Fatigue Crack Growth in Wind Blade Paste Adhesives Daniel D. Samborsky, static GIc and mixed mode fracture, and fatigue crack growth resistance. I. Introduction Wind turbine, then adhesively bonded together. The large size coupled with cost constraints result in bond lines at least

  20. THE DYNAMICS OF RAPIDLY MOVING TENSILE CRACKS IN BRITTLE AMORPHOUS MATERIAL

    E-Print Network [OSTI]

    Fineberg, Jay

    initiated during the second World War. These theories generalized the concept of energy balance, which, and a corresponding sharp increase of the fracture energy with the mean crack velocity. We present experimental occurs when the potential elastic energy per unit area released by a unit extension of a crack is equal

  1. Robust damage assessment of multiple cracks based on the Frequency Response Function and the Constitutive Relation

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Robust damage assessment of multiple cracks based on the Frequency Response Function a damage assessment technique for the non destructive detection and sizing of multiple open cracks in beams, many researchers have performed extensive investigations and damage assess- ment techniques based

  2. Assessing Hydrogen-Assisted Cracking Fracture Modes in High-Strength

    E-Print Network [OSTI]

    Eagar, Thomas W.

    I I Ii . I f. Assessing Hydrogen-Assisted Cracking Fracture Modes in High-Strength Steel Weldments Test results substantiate and extend the Beachem theory on hydrogen embrittlement ABSTRACT of the hydrogen content at the crack loca- tion. This relationship was used to assess previously proposed

  3. Statistical fracture modeling: crack path and fracture criteria with application to homogeneous and

    E-Print Network [OSTI]

    Ritchie, Robert

    Statistical fracture modeling: crack path and fracture criteria with application to homogeneous; accepted 23 January 2002 Abstract Analysis has been performed on fracture initiation near a crack in a brittle material with strength described by Weibull statistics. This nonlocal fracture model allows

  4. Brittle fracture in a periodic structure with internal potential energy. Spontaneous crack propagation

    E-Print Network [OSTI]

    Mark Ayzenberg-Stepanenko; Gennady Mishuris; Leonid Slepyan

    2014-02-12

    Spontaneous brittle fracture is studied based on the recently introduced model (Mishuris and Slepyan, Brittle fracture in a periodic structure with internal potential energy. Proc. Roy. Soc. A, in press). A periodic structure is considered, where only the prospective crack-path layer is specified as a discrete set of alternating initially stretched and compressed bonds. A bridged crack destroying initially stretched bonds may propagate under a certain level of the internal energy without external sources. The general analytical solution with the crack speed $-$ energy relation is presented in terms of the crack-related dynamic Green's function. For the anisotropic two-line chain and lattice considered earlier in quasi-statics, the dynamic problem is examined in detail. The crack speed is found to grow unboundedly as the energy approaches its upper limit. It is revealed that the spontaneous fracture can occur in the form of a pure bridged, partially bridged or fully open crack depending on the internal energy level. Generally, the steady-state mode of the crack propagation is found to be realised, whereas an irregular growth, clustering and the crack speed oscillations are detected in a vicinity of the lower bound of the energy.

  5. A stochastic model of fatigue crack propagation under variable-amplitude loading

    E-Print Network [OSTI]

    Ray, Asok

    -space model of fatigue crack propagation under variable-amplitude loading. The (non-stationary) statistic. Introduction Fatigue crack analysis is an essential tool for life prediction and maintenance of machinery/strain) factor b a constant model parameter larger than 1 (I 10) d increment operator DS eective stress range W 2

  6. Comparing Methods of Estimating Crack Volume in Shrink-Swell Soils 

    E-Print Network [OSTI]

    Rivera, Leonardo D.

    2011-08-04

    were measured on both soils. Vertical subsidence was measured at three locations in each soil with rods fixed at four depths. Rod movement was converted to soil crack volume by assuming equi-dimensional shrinkage. A second method for estimating crack...

  7. 3D MULTIPLE CRACK SYSTEM: EXTRACTION AND ANALYSIS USING MOTION-BASED IMAGE PROCESSING TECHNIQUE

    E-Print Network [OSTI]

    Nagy, George

    , including the number of cracks, surface area, volume, tortuosity, and permeability. Keywords: X-ray microtomography, image processing, concrete fracture. INTRODUCTION We examine the crack surfaces of concrete the fracture behavior of concrete, they have been ignored because "understanding of this problem

  8. Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic Composite

    E-Print Network [OSTI]

    Zok, Frank

    Effects of Matrix Cracks on the Thermal Diffusivity of a Fiber-Reinforced Ceramic Composite conductances coupled with a unit cell model for a fiber composite containing a periodic array of matrix cracks tolerance and notch insensitivity in continuous fiber ceramic composites (CFCCs).1 These mechanisms play

  9. Thermal resistance of bridged cracks in fiber-reinforced ceramic John Dryden

    E-Print Network [OSTI]

    Zok, Frank

    -reinforced ceramic composites obtain high toughness is through the de- velopment of multiple matrix cracksThermal resistance of bridged cracks in fiber-reinforced ceramic composites John Dryden Department in a fiber-reinforced ceramic composite is analyzed. The problem is cast in terms of a unit cell comprising

  10. The roles of toughness and cohesive strength on crack deflection at

    E-Print Network [OSTI]

    Thouless, Michael

    composite systems. Brittle materials such as ceramics, concrete or epoxies can be toughened by the addition & Engineering University of Michigan Ann Arbor, MI 48109 August 30, 2005 Abstract In order to design composites and the matrix. If crack deflection does not occur, a crack propagating through the matrix will continue

  11. Fatigue-crack propagation in Nitinol, a shape-memory and superelastic endovascular stent material

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue-crack propagation in Nitinol, a shape-memory and superelastic endovascular stent material A Nitinol. Specifically, the objective of this work was to study the effect of environ- ment on cyclic crack of Nitinol endovascular stents. The material selected for this study was heat treated

  12. Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites

    E-Print Network [OSTI]

    Ritchie, Robert

    Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites M. E of cracks, such as tensile ductil- ity, toughness, and fatigue resistance, can become severely compromised macroscopic ductility,3,4 such that the toughness is far lower than in comparable crystalline alloys

  13. Technical Note Fiducial marks as measures of thin film crack arrest toughness

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Technical Note Fiducial marks as measures of thin film crack arrest toughness Alex A. Volinsky a Published by Elsevier Science Ltd. Keywords: Fiducial marks; Adhesion; Fracture; Delamination; Crack arrest). This technique was shown to work with ductile metallic films (Al, Cu, Au, Cr) [2,4­9,15], ceramic (Ta2N) [10

  14. EFFECT OF VISCOUS GRAIN BRIDGING ON CYCLIC FATIGUE-CRACK GROWTH IN MONOLITHIC CERAMICS

    E-Print Network [OSTI]

    Ritchie, Robert

    EFFECT OF VISCOUS GRAIN BRIDGING ON CYCLIC FATIGUE-CRACK GROWTH IN MONOLITHIC CERAMICS AT ELEVATED crack under cyclic loading conditions at elevated temperatures in high-toughness, monolithic ceramics the frequency and temperature sensitivity not gen- erally observed in ceramics at room temperature. Solutions

  15. Channel cracks in a hermetic coating consisting of organic and inorganic layers

    E-Print Network [OSTI]

    Suo, Zhigang

    Channel cracks in a hermetic coating consisting of organic and inorganic layers Nicolas Cordero 2007 Flexible electronic devices often require hermetic coatings that can withstand applied strains. This letter calculates the critical strains for various configurations of channel cracks in a coating

  16. Effect of elastic coating on fracture behaviour of piezoelectric fibre with a penny-shaped crack

    E-Print Network [OSTI]

    Qin, Qinghua

    Effect of elastic coating on fracture behaviour of piezoelectric fibre with a penny-shaped crack, Tianjin University, Tianjin 300072, China Abstract In this paper, the problem of a penny-shaped crack of piezoelectric fibre composites. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Piezoelectric fibre; Penny

  17. Junction formation during desiccation cracking K. B. Toga and B. Erdem Alaca*

    E-Print Network [OSTI]

    Alaca, B. Erdem

    and different compounds such as nickel phosphate and ferric ferrocyanide 9 spread on substrates such as glass

  18. Fatigue crack propagation in a quasi one-dimensional elasto-plastic model

    E-Print Network [OSTI]

    Tomás M. Guozden; Eduardo A. Jagla

    2012-06-27

    Fatigue crack advance induced by the application of cyclic quasistatic loads is investigated both numerically and analytically using a lattice spring model. The system has a quasi-one-dimensional geometry, and consists in two symmetrical chains that are pulled apart, thus breaking springs which connect them, and producing the advance of a crack. Quasistatic crack advance occurs as a consequence of the plasticity included in the springs which form the chains, and that implies a history dependent stress-strain curve for each spring. The continuous limit of the model allows a detailed analytical treatment that gives physical insight of the propagation mechanism. This simple model captures key features that cause well known phenomenology in fatigue crack propagation, in particular a Paris-like law of crack advance under cyclic loading, and the overload retardation effect.

  19. Energy Spread Reduction of Electron Beams Produced via Laser Wake

    SciTech Connect (OSTI)

    Pollock, B

    2012-03-19

    Laser wakefield acceleration of electrons holds great promise for producing ultra-compact stages of GeV scale, high quality electron beams for applications such as x-ray free electron lasers and high energy colliders. Ultra-high intensity laser pulses can be self-guided by relativistic plasma waves over tens of vacuum diffraction lengths, to give >1 GeV energy in cm-scale low density plasma using ionization-induced injection to inject charge into the wake at low densities. This thesis describes a series of experiments which investigates the physics of LWFA in the self-guided blowout regime. Beginning with high density gas jet experiments the scaling of the LWFA-produced electron beam energy with plasma electron density is found to be in excellent agreement with both phenomenological theory and with 3-D PIC simulations. It is also determined that self-trapping of background electrons into the wake exhibits a threshold as a function of the electron density, and at the densities required to produce electron beams with energies exceeding 1 GeV a different mechanism is required to trap charge into low density wakes. By introducing small concentrations of high-Z gas to the nominal He background the ionization-induced injection mechanism is enabled. Electron trapping is observed at densities as low as 1.3 x 10{sup 18} cm{sup -3} in a gas cell target, and 1.45 GeV electrons are demonstrated for the first time from LWFA. This is currently the highest electron energy ever produced from LWFA. The ionization-induced trapping mechanism is also shown to generate quasi-continuous electron beam energies, which is undesirable for accelerator applications. By limiting the region over which ionization-induced trapping occurs, the energy spread of the electron beams can be controlled. The development of a novel two-stage gas cell target provides the capability to tailor the gas composition in the longitudinal direction, and confine the trapping process to occur only in a limited, defined region. Using this technique a 460 MeV electron beam was produced with an energy spread of 5%. This technique is directly scalable to multi-GeV electron beam generation with sub-percent energy spreads.

  20. Growth of geologic fractures into large-strain populations: review of nomenclature, subcritical crack growth, and some implications

    E-Print Network [OSTI]

    crack growth, and some implications for rock engineering R.A. Schultz* Geomechanics-Rock Fracture Group

  1. Fusion rate enhancement due to energy spread of colliding nuclei

    E-Print Network [OSTI]

    G. Fiorentini; C. Rolfs; F. L. Villante; B. Ricci

    2002-10-24

    Experimental results for sub-barrier nuclear fusion reactions show cross section enhancements with respect to bare nuclei which are generally larger than those expected according to electron screening calculations. We point out that energy spread of target or projectile nuclei is a mechanism which generally provides fusion enhancement. We present a general formula for calculating the enhancement factor and we provide quantitative estimate for effects due to thermal motion, vibrations inside atomic, molecular or crystal system, and due to finite beam energy width. All these effects are marginal at the energies which are presently measurable, however they have to be considered in future experiments at still lower energies. This study allows to exclude several effects as possible explanation of the observed anomalous fusion enhancements, which remain a mistery.

  2. Model of crack propagation in a clay soil 

    E-Print Network [OSTI]

    Carriere, Patrick Edwidge

    1985-01-01

    of variance (ANOVA) to obtain the best selection to be included in the model. The ANOYA model was expressed by: Model = BO(H) + Bl(CL) + B2(M) + B3(H"M) + B4(H*CL) + B5(M*CL) + B6(H~M*CL) where: H = humidity effect, CL = clay content effect, M = initial.... 0280* T5 0. 7413 0. 5771 6. 16 0. 0001* T6 0. 2973 0. 2887 4. 94 0. 001* T7 0. 2065 0. 3432 2. 89 0. 0084* T8 0. 2543 0. 0767 15. 89 0. 0001* * significant at level 0. 05 30 Table 3. ANOVA results for crack de th. Source Sum of Degrees of Mean F...

  3. Specified pipe fittings susceptible to sulfide stress cracking

    SciTech Connect (OSTI)

    McIntyre, D.R.; Moore, E.M. Jr. [Saudi Aramco, Dhahran (Saudi Arabia)

    1996-01-01

    The NACE Standard MR0175 limit of HRC 22 is too high for cold-forged and stress-relieved ASTM A234 WPB pipe fittings. Hardness surveys and sulfide stress cracking test results per ASTM G 39 and NACE TM0177 Method B are presented to support this contention. More stringent inspection and a hardness limit of HB 197 (for cold-forged and stress-relieved fittings only) are recommended. The paper describes a case in which fittings were welded in place in wet sour service flow lines and gas-oil separating plants which were ready to start. The failure of a welded fitting shortly after start-up led to extensive field hardness testing on all fittings from this manufacturer.

  4. Vortex flow in the technology of radiation wave cracking (RWC)

    E-Print Network [OSTI]

    L. A. Tsoy; V. N. Kolushov; A. G. Komarov; A. N. Tsoy

    2012-09-16

    This article examines the theory of vortex flows in relation to the processes occurring in the radiation-wave cracking of crude oil, when the crude oil is sprayed into the gas stream in the form of a mist and then is fed into the reactor, where it is treated by the accelerated electrons and the UHF radiation. The output of this process are the products with the specified parameters (high-octane petroleum products). This process operates at the ambient pressure and temperature, which makes the process safer for industrial purposes. Besides the process itself, the authors described the equipment used in this process, as well as the parameters of the optimal process.

  5. Surface Tension regularizes the Crack Singularity of Adhesive Contacts

    E-Print Network [OSTI]

    Stefan Karpitschka; Leen van Wijngaarden; Jacco H. Snoeijer

    2015-08-14

    The elastic and adhesive properties of a solid surface can be quantified by indenting it with a rigid sphere. Indentation tests are classically described by the JKR-law when the solid is very stiff, while recent work highlights the importance of surface tension for exceedingly soft materials. Here we show that surface tension plays a crucial role even for stiff solids: it regularizes the crack-like singularity at the edge of the contact. We find that the edge region exhibits a universal, self-similar structure that emerges from the balance of surface tension and elasticity. The similarity theory provides a complete description for adhesive contacts, reconciling the global adhesion laws and local contact mechanics.

  6. CRACK GROWTH ANALYSIS OF SOLID OXIDE FUEL CELL ELECTROLYTES

    SciTech Connect (OSTI)

    S. Bandopadhyay; N. Nagabhushana

    2003-10-01

    Defects and Flaws control the structural and functional property of ceramics. In determining the reliability and lifetime of ceramics structures it is very important to quantify the crack growth behavior of the ceramics. In addition, because of the high variability of the strength and the relatively low toughness of ceramics, a statistical design approach is necessary. The statistical nature of the strength of ceramics is currently well recognized, and is usually accounted for by utilizing Weibull or similar statistical distributions. Design tools such as CARES using a combination of strength measurements, stress analysis, and statistics are available and reasonably well developed. These design codes also incorporate material data such as elastic constants as well as flaw distributions and time-dependent properties. The fast fracture reliability for ceramics is often different from their time-dependent reliability. Further confounding the design complexity, the time-dependent reliability varies with the environment/temperature/stress combination. Therefore, it becomes important to be able to accurately determine the behavior of ceramics under simulated application conditions to provide a better prediction of the lifetime and reliability for a given component. In the present study, Yttria stabilized Zirconia (YSZ) of 9.6 mol% Yttria composition was procured in the form of tubes of length 100 mm. The composition is of interest as tubular electrolytes for Solid Oxide Fuel Cells. Rings cut from the tubes were characterized for microstructure, phase stability, mechanical strength (Weibull modulus) and fracture mechanisms. The strength at operating condition of SOFCs (1000 C) decreased to 95 MPa as compared to room temperature strength of 230 MPa. However, the Weibull modulus remains relatively unchanged. Slow crack growth (SCG) parameter, n = 17 evaluated at room temperature in air was representative of well studied brittle materials. Based on the results, further work was planned to evaluate the strength degradation, modulus and failure in more representative environment of the SOFCs.

  7. Exploring the complex pattern of information spreading in online blog communities

    E-Print Network [OSTI]

    Pei, Sen; Tang, Shaoting; Zheng, Zhiming; Makse, Hernan A

    2015-01-01

    Information spreading in online social communities has attracted tremendous attention due to its utmost practical values in applications. Despite that several individual-level diffusion data have been investigated, we still lack the detailed understanding of the spreading pattern of information. Here, by comparing information flows and social links in a blog community, we find that the diffusion processes are induced by three different spreading mechanisms: social spreading, self-promotion and broadcast. Although numerous previous studies have employed epidemic spreading models to simulate information diffusion, we observe that such models fail to reproduce the realistic diffusion pattern. In respect to users behaviors, strikingly, we find that most users would stick to one specific diffusion mechanism. Moreover, our observations indicate that the social spreading is not only crucial for the structure of diffusion trees, but also capable of inducing more subsequent individuals to acquire the information. Our ...

  8. Fatigue cracking of a bare steel first wall in an inertial confinement fusion chamber

    SciTech Connect (OSTI)

    Hunt, R. M.; Abbott, R. P.; Havstad, M. A.; Dunne, A. M.

    2013-06-01

    Inertial confinement fusion power plants will deposit high energy X-rays onto the outer surfaces of the first wall many times a second for the lifetime of the plant. These X-rays create brief temperature spikes in the first few microns of the wall, which cause an associated highly compressive stress response on the surface of the material. The periodicity of this stress pulse is a concern due to the possibility of fatigue cracking of the wall. We have used finite element analyses to simulate the conditions present on the first wall in order to evaluate the driving force of crack propagation on fusion-facing surface cracks. Analysis results indicate that the X-ray induced plastic compressive stress creates a region of residual tension on the surface between pulses. This tension film will likely result in surface cracking upon repeated cycling. Additionally, the compressive pulse may induce plasticity ahead of the crack tip, leaving residual tension in its wake. However, the stress amplitude decreases dramatically for depths greater than 80–100 ?m into the fusion-facing surface. Crack propagation models as well as stress-life estimates agree that even though small cracks may form on the surface of the wall, they are unlikely to propagate further than 100 ?m without assistance from creep or grain erosion phenomena.

  9. Fracture analysis of axially cracked pressure tube of pressurized heavy water reactor

    SciTech Connect (OSTI)

    Krishnan, S.; Bhasin, V.; Mahajan, S.C. [Bhabha Atomic Research Centre, Bombay (India)] [and others

    1997-04-01

    Three Dimensional (313) finite element elastic plastic fracture analysis was done for through wall axially cracked thin pressure tubes of 220 MWe Indian Pressurized Heavy Water Reactor. The analysis was done for Zr-2 and Zr-2.5Nb pressure tubes operating at 300{degrees}C and subjected to 9.5 Mpa internal pressure. Critical crack length was determined based on tearing instability concept. The analysis included the effect of crack face pressure due to the leaking fluid from tube. This effect was found to be significant for pressure tubes. The available formulae for calculating J (for axially cracked tubes) do not take into account the effect of crack face pressure. 3D finite element analysis also gives insight into variation of J across the thickness of pressure tube. It was observed that J is highest at the mid-surface of tube. The results have been presented in the form of across the thickness average J value and a peak factor on J. Peak factor on J is ratio of J at mid surface to average J value. Crack opening area for different cracked lengths was calculated from finite element results. The fracture assessment of pressure tubes was also done using Central Electricity Generating Board R-6 method. Ductile tearing was considered.

  10. Impact of picolitre droplets on superhydrophobic surfaces with ultra-low spreading ratios

    E-Print Network [OSTI]

    Brown, P.S.; Berson, A.; Talbot, E.L.; Wood, T.J.; Schofield, W.C.E.; Bain, C.D.; Badyal, J.P.S.

    2011-01-01

    :24 1 IMPACT OF PICOLITRE DROPLETS ON SUPERHYDROPHOBIC SURFACES WITH ULTRA-LOW SPREADING RATIOS P. S. Brown, A. Berson, E. L. Talbot, T. J. Wood, W. C. E. Schofield, C. D. Bain†, and J. P. S. Badyal†* Department of Chemistry Science... the dynamics of wetting to be precisely controlled. Final spreading ratios as low as 0.63 can be achieved. Comparison of the maximum spreading ratio and droplet oscillation frequencies with models described in the literature shows that both are found...

  11. Simulations of Failure via Three-Dimensional Cracking in Fuel Cladding for Advanced Nuclear Fuels

    SciTech Connect (OSTI)

    Lu, Hongbing; Bukkapatnam, Satish; Harimkar, Sandip; Singh, Raman; Bardenhagen, Scott

    2014-01-09

    Enhancing performance of fuel cladding and duct alloys is a key means of increasing fuel burnup. This project will address the failure of fuel cladding via three-dimensional cracking models. Researchers will develop a simulation code for the failure of the fuel cladding and validate the code through experiments. The objective is to develop an algorithm to determine the failure of fuel cladding in the form of three-dimensional cracking due to prolonged exposure under varying conditions of pressure, temperature, chemical environment, and irradiation. This project encompasses the following tasks: 1. Simulate 3D crack initiation and growth under instantaneous and/or fatigue loads using a new variant of the material point method (MPM); 2. Simulate debonding of the materials in the crack path using cohesive elements, considering normal and shear traction separation laws; 3. Determine the crack propagation path, considering damage of the materials incorporated in the cohesive elements to allow the energy release rate to be minimized; 4. Simulate the three-dimensional fatigue crack growth as a function of loading histories; 5. Verify the simulation code by comparing results to theoretical and numerical studies available in the literature; 6. Conduct experiments to observe the crack path and surface profile in unused fuel cladding and validate against simulation results; and 7. Expand the adaptive mesh refinement infrastructure parallel processing environment to allow adaptive mesh refinement at the 3D crack fronts and adaptive mesh merging in the wake of cracks. Fuel cladding is made of materials such as stainless steels and ferritic steels with added alloying elements, which increase stability and durability under irradiation. As fuel cladding is subjected to water, chemicals, fission gas, pressure, high temperatures, and irradiation while in service, understanding performance is essential. In the fast fuel used in advanced burner reactors, simulations of the nuclear fuels are critical to understand the burnup, and thus the fuel efficiency.

  12. Static pushover analyses of pile groups in liquefied and laterally spreading ground in centrifuge tests

    E-Print Network [OSTI]

    Brandenberg, Scott J; Boulanger, R W; Kutter, Bruce L; Chang, Dongdong

    2007-01-01

    spreading ground during centrifuge tests. ” J. Geotech.and Liu, L. ?1995?. “Centrifuge modeling of liquefactionGonzales, L. ?2005?. “Centrifuge modeling of permeability

  13. Technique development for field inspection of cracking in seam welded ducts

    SciTech Connect (OSTI)

    Shell, Eric B.; Benson, Craig [Wyle Laboratories, Inc., Dayton, OH 45440 (United States); Liljestrom, Greg C.; Shanahan, Stephen [Wyle Laboratories, Inc., Oklahoma City, OK 73110 (United States)

    2014-02-18

    The resistance seam weld interfaces between alloyed and pure titanium are an in service concern due to precipitation of titanium hydride and resulting embrittlement and cracking. Several inspection techniques were developed and evaluated for field use to characterize the damage in the fleet. Electromagnetic, ultrasonic, florescent penetrant, thermographic, and radiographic techniques were considered. The ultrasonic and electromagnetic approaches were both found suitable. However, the electromagnetic approach is more desirable for field inspections, due to consistency and ease of use. The electromagnetic inspection procedure is able to discriminate between precursor damage and through cracking with sufficient sensitivity to small cracks.

  14. Signature of wide-spread clumping in B supergiant winds

    E-Print Network [OSTI]

    Prinja, Raman

    2010-01-01

    We seek to establish additional observational signatures of the effects of clumping in OB star winds. The action of clumping on strategic wind-formed spectral lines is tested to steer the development of models for clumped winds and thus improve the reliability of mass-loss determinations for massive stars.The SiIV 1400 resonance line doublets of B0 to B5 supergiants are analysed using empirical line-synthesis models. The focus is on decoding information on wind clumping from measurements of ratios of the radial optical depths (tau_(rad)(w)) of the red and blue components of the SiIV doublet. We exploit in particular the fact that the two doublet components are decoupled and formed independently for targets with relatively low wind terminal velocities. Line-synthesis analyses reveal that the mean ratio of tau_(rad)(w) of the blue to red SiIV components are rarely close to the canonical value of ~ 2 (expected from atomic constants), and spread instead over a range of values between ~1 and 2. These results are i...

  15. The effect of complex inclusion geometries on fracture and crack coalescence behavior in brittle material

    E-Print Network [OSTI]

    Morgan, Stephen Philip

    2011-01-01

    This research study investigates the cracking processes in a brittle material associated with inclusions of varying shape, orientation and materials. Specifically, this study summarizes a series of uniaxial compression ...

  16. Effects of thermal aging on Stress Corrosion Cracking and mechanical properties of stainless steel weld metals

    E-Print Network [OSTI]

    Hixon, Jeff

    2006-01-01

    Stress Corrosion Cracking (SCC) in and around primary loop piping welds in Boiling Water Reactors has been observed worldwide as plants continue to operate at temperatures and pressures near 2880C (5500F) and 6.9 MPa (1000 ...

  17. Cracks in Martensite Plates as Hydrogen Traps in a Bearing Steel

    E-Print Network [OSTI]

    Solano-Alvarez, W.; Song, Eun Ju; Han, Do Kyeong; Suh, Dong-Woo; Bhadeshia, H. K. D. H.

    2014-12-03

    It is demonstrated that a macroscopically homogeneous distribution of tiny cracks introduced into a martensitic bearing steel sample can provide powerful hydrogen traps. The phenomenon has been investigated through thermal desorption spectroscopy...

  18. Stress corrosion cracking of steel Stressed-Out Metals: Predicting their Response from the Bottom Up

    E-Print Network [OSTI]

    Simons, Jack

    Stress corrosion cracking of steel Stressed-Out Metals: Predicting their Response from the Bottom;Shocked Iron Ground state bcc undergoes a martensitic phase transformation to hcp at ~13 GPa

  19. Cracked lifting lug welds on ten-ton UF{sub 6} cylinders

    SciTech Connect (OSTI)

    Dorning, R.E. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States)

    1991-12-31

    Ten-ton, Type 48X, UF{sub 6} cylinders are used at the Portsmouth Gaseous Diffusion Plant to withdraw enriched uranium hexafluoride from the cascade, transfer enriched uranium hexafluoride to customer cylinders, and feed enriched product to the cascade. To accomplish these activities, the cylinders are lifted by cranes and straddle carriers which engage the cylinder lifting lugs. In August of 1988, weld cracks on two lifting lugs were discovered during preparation to lift a cylinder. The cylinder was rejected and tagged out, and an investigating committee formed to determine the cause of cracking and recommend remedial actions. Further investigation revealed the problem may be general to this class of cylinder in this use cycle. This paper discusses the actions taken at the Portsmouth site to deal with the cracked lifting lug weld problem. The actions include inspection activities, interim corrective actions, metallurgical evaluation of cracked welds, weld repairs, and current monitoring/inspection program.

  20. Keep Customers-and Energy-From Slipping Through the Cracks |...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Keep Customers-and Energy-From Slipping Through the Cracks A photo of three people standing and talking to each other, two men and a woman, inside a home. The most successful...

  1. August 27, 2006 CRACKING OF LAMINATES SUBJECTED TO BIAXIAL TENSILE STRAINS

    E-Print Network [OSTI]

    Suo, Zhigang

    ] developed a strain energy release rate expression for the tunnel crack in layers subjected to biaxial tensile stress in the zirconia layer [14] r = r EZr 1- Zr 1+ t w EZr / 1- Zr( ) EAl/ Zr / 1- Al / Zr

  2. Integrating Gas Turbines with Cracking Heaters - Impact on Emissions and Energy Efficiency 

    E-Print Network [OSTI]

    Platvoet, E.

    2011-01-01

    Turbine Exhaust Gas (TEG) contains high levels of oxygen, typically 15 vol. percent, due to gas turbine blade material temperature limits. As such it can be used as an oxidant for combustion in cracking furnaces and reformers. Its high temperature...

  3. Assessment of Initial Test Conditions for Experiments to Assess Irradiation Assisted Stress Corrosion Cracking Mechanisms

    Broader source: Energy.gov [DOE]

    Irradiation-assisted stress corrosion cracking is a key materials degradation issue in today’s nuclear power reactor fleet and affects critical structural components within the reactor core. The...

  4. Linear elastic fracture mechanics in anisotropic solids : application to fluid-driven crack propagation

    E-Print Network [OSTI]

    Laubie, Hadrien Hyacinthe

    2013-01-01

    Fracture mechanics is a field of continuum mechanics with the objective to predict how cracks initiate and propagate in solids. It has a wide domain of application. While aerospace engineers want to make sure a defect in ...

  5. Fatigue failure in thin-film polysilicon is due to subcritical cracking within the oxide layer

    E-Print Network [OSTI]

    Alsem, D.H.; Muhlstein, C.L.; Stach, E.A.; Ritchie, R.O.

    2005-01-01

    and manual fracture: no oxide layer thickening (principalCRACKING WITHIN THE OXIDE LAYER D. H. Alsem, a),b),c) E. A.air with thickened oxide layer around the notch root (

  6. Effect of Voids on the Crack Kinking in Single Lap Joints 

    E-Print Network [OSTI]

    Sengab, Ahmed M

    2015-05-12

    Polymer matrix composites are used extensively for their exceptional mechanical properties. The effect of voids on the energy release rate of interface crack has been studied before; however none of the studies investigated ...

  7. Integral identities for a semi-infinite interfacial crack in 2D and 3D elasticity

    E-Print Network [OSTI]

    Piccolroaz, Andrea

    2011-01-01

    The paper is concerned with the problem of a semi-infinite crack at the interface between two dissimilar elastic half-spaces, loaded by a general asymmetrical system of forces distributed along the crack faces. On the basis of the weight function approach and the fundamental reciprocal identity (Betti formula), we formulate the elasticity problem in terms of singular integral equations relating the applied loading and the resulting crack opening. Such formulation is fundamental in the theory of elasticity and extensively used to solve several problems in linear elastic fracture mechanics (for instance various classic crack problems in homogeneous and heterogeneous media). This formulation is also crucial in important recent multiphysics applications, where the elastic problem is coupled with other concurrent physical phenomena. A paradigmatic example is hydraulic fracturing, where the elasticity equations are coupled with fluid dynamics.

  8. Integral identities for a semi-infinite interfacial crack in 2D and 3D elasticity

    E-Print Network [OSTI]

    Andrea Piccolroaz; Gennady Mishuris

    2012-06-06

    The paper is concerned with the problem of a semi-infinite crack at the interface between two dissimilar elastic half-spaces, loaded by a general asymmetrical system of forces distributed along the crack faces. On the basis of the weight function approach and the fundamental reciprocal identity (Betti formula), we formulate the elasticity problem in terms of singular integral equations relating the applied loading and the resulting crack opening. Such formulation is fundamental in the theory of elasticity and extensively used to solve several problems in linear elastic fracture mechanics (for instance various classic crack problems in homogeneous and heterogeneous media). This formulation is also crucial in important recent multiphysics applications, where the elastic problem is coupled with other concurrent physical phenomena. A paradigmatic example is hydraulic fracturing, where the elasticity equations are coupled with fluid dynamics.

  9. Effect of oxygen potential on high temperature crack growth in alloy 617

    E-Print Network [OSTI]

    Benz, Julian K

    2009-01-01

    The effect of oxygen partial pressure on crack growth rates in Alloy 617 has been studied using both static and fatigue loading at 650°C. Tests were conducted at a constant stress intensity factor, K, for static loading ...

  10. Electrical Impedance Tomographic Methods for Sensing Strain Fields and Crack Damage in Cementitious Structures

    E-Print Network [OSTI]

    Lynch, Jerome P.

    of their origins (Bungey et al., 2006). After suspicious cracks are encountered, non- destructive (for example, ultrasonic inspection) and partially destructive (for example, core holes) testing can be carried out

  11. On the fracture toughness of ferroelectric ceramics with electric field applied parallel to the crack front

    E-Print Network [OSTI]

    On the fracture toughness of ferroelectric ceramics with electric field applied parallel crack growth. The effects of electric field on the fracture toughness of both initially unpoled and poled materials are investigated. Results for the predicted fracture toughness, remanent strain

  12. Spatial and Temporal Distribution of Desiccation Cracks in Shrink-Swell Soils 

    E-Print Network [OSTI]

    Neely, Haly Lury

    2014-04-17

    Soil crack volume estimates, which are important for hydrology models on shrink-swell soils, are currently based on field measurements of vertical shrinkage and an assumption of isotropic shrinkage; however, few studies have validated the resulting...

  13. A program to design asphalt concrete overlays to mitigate reflection cracking 

    E-Print Network [OSTI]

    Satyanarayana Rao, Sindhu

    2002-01-01

    . Various engineering reinforcing grids have been used in recent years to mitigate the occurrence and propagation of reflection cracking. Reinforcing grids made of fiberglass or polypropylene has been used for this purpose. The main objectives...

  14. Analytical Investigation of Repair Methods for Fatigue Cracks in Steel Bridges

    E-Print Network [OSTI]

    Richardson, Temple

    2012-08-31

    Numerous retrofits have been used to stop distortion-induced fatigue cracks from initiating and propagating in steel bridges. Some decrease stiffness in the web gap region to transfer the load path to an area of higher stiffness, while others...

  15. Webinar: Impacts of Impurities on Hydrogen Assisted Fatigue Crack Growth in Structural Steels

    Broader source: Energy.gov [DOE]

    The Energy Department will present a live webinar titled "Impacts of Impurities on Hydrogen Assisted Fatigue Crack Growth in Structural Steels" on Tuesday, January 12, from 12 to 1 p.m. EST.

  16. Evaluation of the filler effects on fatique cracking and permanent deformation of asphalt concrete mixtures 

    E-Print Network [OSTI]

    Izzo, Richard P

    1997-01-01

    The addition of hydrated lime to asphalt has shown to be beneficial with an improvement in the Theological properties of the binder, as well as resistance to permanent deformation (rutting) and fatigue cracking of asphalt concrete mixtures...

  17. Identification of asphalt binder properties that affect cracking performance of hot mixed asphalt concrete pavements 

    E-Print Network [OSTI]

    Hastings, Charles Patrick

    1997-01-01

    with the original mixture designs, compacted in the laboratory, and tested using the National Cooperative Highway Research Program (NCHRP) asphalt aggregate mixture analysis system (AAMAS) test protocols to assess relative resistance to fatigue cracking. Field cores...

  18. Reaction kinetics of olefin saturation in the hydrodesulfurization of fluid catalytic cracked naphtha 

    E-Print Network [OSTI]

    Schumann, Brian Herbert

    1995-01-01

    U.S. governmental agencies are calling for strict environmental regulations on the quality of gasoline. Fluid catalytic cracked naphtha is an important blending component of the gasoline pool. The majority of the sulfur in the gasoline pool comes...

  19. Prediction of crack propagation paths in the unit cell of SOFC stacks

    SciTech Connect (OSTI)

    Joulaee, N.; Makradi, A.; Ahzi, Said; Khaleel, Mohammad A.; Koeppel, Brian J.

    2009-08-01

    Planar Solid Oxide Fuel Cells (SOFC) stacks are multi-material layered systems with different thermo-mechanical properties. Due to their severe thermal loading, these layers have to meet high demands to preserve their mechanical integrity without initiation and propagation of fracture. Here, we focus on a typical unit cell of the stack which consists of positive electrode-electrolyte-negative electrode (PEN). Based on the mechanical properties of each layer and their interfaces, an energy criterion as a function of crack length is used for the prediction of possible crack extensions in the PEN. This criterion is a pure local criterion, independent of applied loads and geometry of the specimen. An analysis of the competition between crack deflections in the interfaces and crack penetration in layers is presented.

  20. Methodology for extracting local constants from petroleum cracking flows

    DOE Patents [OSTI]

    Chang, Shen-Lin (Woodridge, IL); Lottes, Steven A. (Naperville, IL); Zhou, Chenn Q. (Munster, IN)

    2000-01-01

    A methodology provides for the extraction of local chemical kinetic model constants for use in a reacting flow computational fluid dynamics (CFD) computer code with chemical kinetic computations to optimize the operating conditions or design of the system, including retrofit design improvements to existing systems. The coupled CFD and kinetic computer code are used in combination with data obtained from a matrix of experimental tests to extract the kinetic constants. Local fluid dynamic effects are implicitly included in the extracted local kinetic constants for each particular application system to which the methodology is applied. The extracted local kinetic model constants work well over a fairly broad range of operating conditions for specific and complex reaction sets in specific and complex reactor systems. While disclosed in terms of use in a Fluid Catalytic Cracking (FCC) riser, the inventive methodology has application in virtually any reaction set to extract constants for any particular application and reaction set formulation. The methodology includes the step of: (1) selecting the test data sets for various conditions; (2) establishing the general trend of the parametric effect on the measured product yields; (3) calculating product yields for the selected test conditions using coupled computational fluid dynamics and chemical kinetics; (4) adjusting the local kinetic constants to match calculated product yields with experimental data; and (5) validating the determined set of local kinetic constants by comparing the calculated results with experimental data from additional test runs at different operating conditions.

  1. In situ investigation of high humidity stress corrosion cracking of 7075 aluminum alloy by three-dimensional (3D) X-ray synchrotron tomography

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Singh, S. S.; Williams, J. J.; Lin, M. F.; Xiao, X.; De Carlo, F.; Chawla, N.

    2014-05-14

    In situ X-ray synchrotron tomography was used to investigate the stress corrosion cracking behavior of under-aged Al–Zn–Mg–Cu alloy in moisture. The discontinuous surface cracks (crack jumps) mentioned in the literature are actually a single continuous and tortuous crack when observed in three dimension (3D). Contrary to 2D measurements made at the surface which suggest non-uniform crack growth rates, 3D measurements of the crack length led to a much more accurate measurement of crack growth rates.

  2. Tests and analyses for fully plastic fracture mechanics of plane strain mode I crack growth

    SciTech Connect (OSTI)

    McClintock, F.A.; Parks, D.M.; Kim, Y.J.

    1995-12-31

    Under monotonic loading, structures should ideally be ductile enough to provide continued resistance during crack growth. For fully plastic crack growth in low strength alloys, existing asymptotic solutions for elastic-plastic growing cracks are not applicable because they reach the fracture strain only in regions small compared to the inhomogeneities of the actual fracture process. For the limiting case of non-hardening fully-plastic plane strain crack growth, in a number of geometries and loadings the near-tip fields are characterized in terms of three parameters: an effective angle 2{theta}{sub s} between a pair of slip planes, and the normal stress {sigma}{sub s} and the increment of displacement {delta}u{sub s} across the planes. This three-parameter characterization is in contrast to the one- or two-parameter (K or J and T or Q) characterization in linear or non-linear elastic fracture mechanics. These {theta}{sub s}, {sigma}{sub s}, and {delta}u{sub s} parameters are found form the far-field geometries and loadings through slip line fields or least upper bound analyses based on circular arcs. The resulting crack growth, in terms of the crack tip opening angle (CTOA), is a function of {theta}{sub s}, {sigma}{sub s}, and the material. The geometry of the crack growing between two moving slip planes emanating from its tip reduces this function to the critical fracture shear strain left behind the slip planes, {gamma}f, as a function of {sigma}{sub s}. {gamma}f({sigma}{sub s}) is found theoretically from a hole initiation and growth model. It is also found from preliminary fully plastic crack growth experiments on unequally grooved specimens with fixed-grip extension or 4-point bending of a 1018 CF steel.

  3. GIS-Based Epidemiological Modeling of an Emerging Forest Disease: Spread of

    E-Print Network [OSTI]

    247 GIS-Based Epidemiological Modeling of an Emerging Forest Disease: Spread of Sudden Oak Death applied in a GIS to real-world wildland landscapes. In this paper, we present and evaluate a GIS model was implemented (1990-2005) in a GIS to simulate disease spread across California at a spatial

  4. A Computational Study of the Spreading of Oil Underneath a Sheet of Ice Mark Sussman

    E-Print Network [OSTI]

    Sussman, Mark

    A Computational Study of the Spreading of Oil Underneath a Sheet of Ice Mark Sussman Department) The spreading of oil underneath a sheet of ice is computed using an adaptive level set method for incompressible of a body of oil under ice in water. The computational models are used to make further observations

  5. A Computational Study of the Spreading of Oil Underneath a Sheet of Ice

    E-Print Network [OSTI]

    Ferguson, Thomas S.

    A Computational Study of the Spreading of Oil Underneath a Sheet of Ice Mark Sussman Department) Abstract The spreading of oil underneath a sheet of ice is computed using an adaptive level set method the final steady profile of a body of oil under ice in water. The computational models are used to make

  6. Short Paper: OFDM in Deep Water Acoustic Channels with Extremely Long Delay Spread

    E-Print Network [OSTI]

    Zhou, Shengli

    Short Paper: OFDM in Deep Water Acoustic Channels with Extremely Long Delay Spread Zhaohui Wang ABSTRACT Deep water horizontal channels usually have very long de- lay spreads relative to shallow water-block-interference (IBI) in the received signals. In this paper, we consider the application of ZP-OFDM in deep water

  7. Spread spectrum communication system with chaotic frequency A. R. Volkovskii,a

    E-Print Network [OSTI]

    Tsimring, Lev S.

    Spread spectrum communication system with chaotic frequency modulation A. R. Volkovskii,a L. Sh spread spectrum communication system utilizing chaotic frequency modulation of sinusoidal signals-based communication system. © 2005 American Institute of Physics. DOI: 10.1063/1.1942327 The ability of chaotic

  8. Slug pellet spreading: the double-disc performances available with a single disc spreader

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Slug pellet spreading: the double-disc performances available with a single disc spreader D for slug pellets application. The principal aim of this paper is to show the chosen way to reach spreading pellets 1 Introduction In France, slugs are considered as a harmful destroyer for crops. Their activities

  9. Quantifying fluctuations in market liquidity: Analysis of the bid-ask spread Vasiliki Plerou,* Parameswaran Gopikrishnan,

    E-Print Network [OSTI]

    Stanley, H. Eugene

    Quantifying fluctuations in market liquidity: Analysis of the bid-ask spread Vasiliki Plerou the statistical features of the bid-ask spread offers the possibility of understanding some aspects of market liquidity. Using quote data for the 116 most frequently traded stocks on the New York Stock Exchange over

  10. Crack initiation in smooth fatigue specimens of austenitic stainless steel in light water reactor environments.

    SciTech Connect (OSTI)

    Chopra, O. K.; Smith, J. L.

    1999-04-08

    The fatigue design curves for structural materials specified in Section III of the ASME Boiler and Pressure Vessel Code are based on tests of smooth polished specimens at room temperature in air. The effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves; however, recent test data illustrate the detrimental effects of LWR coolant environments on the fatigue resistance of austenitic stainless steels (SSs). Certain loading and environmental conditions have led to test specimen fatigue lives that are significantly shorter than those obtained in air. Results of fatigue tests that examine the influence of reactor environments on crack initiation and crack growth of austenitic SSs are presented. Block loading was used to mark the fracture surface to determine crack length as a function of fatigue cycles in water environments, Crack lengths were measured by scanning electron microscopy. The mechanism for decreased fatigue life in LWR environments is discussed, and crack growth rates in the smooth fatigue specimens are compared with existing data from studies of crack growth rates.

  11. Stress-corrosion fatigue-crack growth in a Zr-based bulk amorphousmetal

    SciTech Connect (OSTI)

    Schroeder, V.; Ritchie, R.O.

    2005-09-21

    Electrochemical and mechanical experiments were conducted to analyze the environmentally-influenced cracking behavior of a bulk amorphous metal, Zr41.2Ti13.8Cu12.5Ni10Be22.5. This study was motivated by a scientific interest in mechanisms of fatigue-crack propagation in an amorphous metal, and by a practical interest in the use of this amorphous metal in applications that take advantage of its unique properties, including high specific strength, large elastic strains and low damping. The objective of the work was to determine the rate and mechanisms of subcritical crack growth in this metallic glass in an aggressive environment. Specifically, fatigue-crack propagation behavior was investigated at a range of stress intensities in air and aqueous salt solutions by examining the effects of loading cycle, stress-intensity range, solution concentration, anion identity, solution de-aeration, and bulk electrochemical potential. Results indicate that crack growth in aqueous solution in this alloy is driven by a stress-assisted anodic reaction at the crack tip. Rate-determining steps for such behavior are reasoned to be electrochemical, stress-dependent reaction at near-threshold levels, and mass transport at higher (steady-state) growth rates.

  12. Sonic IR crack detection of aircraft turbine engine blades with multi-frequency ultrasound excitations

    SciTech Connect (OSTI)

    Zhang, Ding; Han, Xiaoyan; Newaz, Golam

    2014-02-18

    Effectively and accurately detecting cracks or defects in critical engine components, such as turbine engine blades, is very important for aircraft safety. Sonic Infrared (IR) Imaging is such a technology with great potential for these applications. This technology combines ultrasound excitation and IR imaging to identify cracks and flaws in targets. In general, failure of engine components, such as blades, begins with tiny cracks. Since the attenuation of the ultrasound wave propagation in turbine engine blades is small, the efficiency of crack detection in turbine engine blades can be quite high. The authors at Wayne State University have been developing the technology as a reliable tool for the future field use in aircraft engines and engine parts. One part of the development is to use finite element modeling to assist our understanding of effects of different parameters on crack heating while experimentally hard to achieve. The development has been focused with single frequency ultrasound excitation and some results have been presented in a previous conference. We are currently working on multi-frequency excitation models. The study will provide results and insights of the efficiency of different frequency excitation sources to foster the development of the technology for crack detection in aircraft engine components.

  13. Detecting the Influence of Spreading in Social Networks with Excitable Sensor Networks

    E-Print Network [OSTI]

    Pei, Sen; Zheng, Zhiming

    2015-01-01

    Detecting spreading outbreaks in social networks with sensors is of great significance in applications. Inspired by the formation mechanism of human's physical sensations to external stimuli, we propose a new method to detect the influence of spreading by constructing excitable sensor networks. Exploiting the amplifying effect of excitable sensor networks, our method can better detect small-scale spreading processes. At the same time, it can also distinguish large-scale diffusion instances due to the self-inhibition effect of excitable elements. Through simulations of diverse spreading dynamics on typical real-world social networks (facebook, coauthor and email social networks), we find that the excitable senor networks are capable of detecting and ranking spreading processes in a much wider range of influence than other commonly used sensor placement methods, such as random, targeted, acquaintance and distance strategies. In addition, we validate the efficacy of our method with diffusion data from a real-wor...

  14. Effects of q-profile structure on turbulence spreading: A fluctuation intensity transport analysis

    SciTech Connect (OSTI)

    Yi, S.; Kwon, J. M.; Diamond, P. H.; Hahm, T. S.

    2014-09-15

    This paper studies effects of q-profile structure on turbulence spreading. It reports results of numerical experiments using global gyrokinetic simulations. We examine propagation of turbulence, triggered by an identical linear instability in a source region, into an adjacent, linearly stable region with variable q-profile. The numerical experiments are designed so as to separate the physics of turbulence spreading from that of linear stability. The strength of turbulence spreading is measured by the penetration depth of turbulence. Dynamics of spreading are elucidated by fluctuation intensity balance analysis, using a model intensity evolution equation which retains nonlinear diffusion and damping, and linear growth. It is found that turbulence spreading is strongly affected by magnetic shear s, but is hardly altered by the safety factor q itself. There is an optimal range of modest magnetic shear which maximizes turbulence spreading. For high to modest shear values, the spreading is enhanced by the increase of the mode correlation length with decreasing magnetic shear. However, the efficiency of spreading drops for sufficiently low magnetic shear even though the mode correlation length is comparable to that for the case of optimal magnetic shear. The reduction of spreading is attributed to the increase in time required for the requisite nonlinear mode-mode interactions. The effect of increased interaction time dominates that of increased mode correlation length. Our findings of the reduction of spreading and the increase in interaction time at weak magnetic shear are consistent with the well-known benefit of weak or reversed magnetic shear for core confinement enhancement. Weak shear is shown to promote locality, as well as stability.

  15. Inuence of foreign-object damage on crack initiation and early crack growth during high-cycle fatigue of Ti6Al4V

    E-Print Network [OSTI]

    Ritchie, Robert

    ; Ti±6Al±4V 1. Introduction The high-cycle fatigue (HCF) of aircraft gas-turbine engine components has-cycle fatigue of Ti±6Al±4V J.O. Peters, R.O. Ritchie * Department of Materials Science and Mineral Engineering of small surface fatigue cracks in a Ti±6Al±4V alloy, processed for typical turbine blade applications

  16. Cracking of n-butane catalyzed by iron- and maganese-promoted sulfated zirconia

    SciTech Connect (OSTI)

    Cheung, T.K.; d`Itri, J.L.; Gates, B.C.

    1995-05-01

    Fe- and Mn-promoted sulfated zirconia was used to catalyze the conversion of n-butane at atmospheric pressure and n-butane partial pressures in the range of 0.0025-0.01 atm. At temperatures <225{degrees}C, the significant reactions were isomerization and disproportionation; in the range of 225-300{degrees}C, these reactions were accompanied by cracking, and at temperatures >350{degrees}C, cracking and isomerization occurred. Catalyst deactivation, resulting at least in part from coke formation, was rapid. The primary cracking products were methane, ethane, ethylene, and propylene. The observation of these products along with an ethane/ethylene molar ratio of nearly 1 at 450{degrees}C is consistent with cracking occurring, at least in part, by the Haag-Dessau mechanism, whereby the strongly acidic catalyst protonates n-butane to give carbonium ions. The rate of methane formation from n-butane cracking catalyzed by Fe- and Mn-promoted sulfated zirconia at 450{degrees}C was about 3 x 10{sup {minus}9}mol/(g of catalyst {center_dot}s). This comparison suggests that the catalytic activity of the promoted sulfated zirconia at 450{degrees}C is about the same as that of the zeolite, although its activity for n-butane isomerization and disproportionation at temperatures <100{degrees}C is orders of magnitude greater than those of zeolites. Thus the indication of superacidity of the promoted sulfated zirconia does not extend to high temperatures. The results raise questions about the nature of the presumed superacidity: perhaps the low-temperature reactions may involve catalyst functions other than the acidic function responsible for high-temperature cracking reactions or perhaps superacidic sites may be very rapidly poisoned at cracking temperatures. 14 refs., 8 figs., 3 tabs.

  17. Irradiation-Assisted Stress Corrosion Cracking of Austenitic Stainless Steels in BWR Environments

    SciTech Connect (OSTI)

    Chen, Y.; Chopra, O. K.; Gruber, Eugene E.; Shack, William J.

    2010-06-01

    The internal components of light water reactors are exposed to high-energy neutron irradiation and high-temperature reactor coolant. The exposure to neutron irradiation increases the susceptibility of austenitic stainless steels (SSs) to stress corrosion cracking (SCC) because of the elevated corrosion potential of the reactor coolant and the introduction of new embrittlement mechanisms through radiation damage. Various nonsensitized SSs and nickel alloys have been found to be prone to intergranular cracking after extended neutron exposure. Such cracks have been seen in a number of internal components in boiling water reactors (BWRs). The elevated susceptibility to SCC in irradiated materials, commonly referred to as irradiation-assisted stress corrosion cracking (IASCC), is a complex phenomenon that involves simultaneous actions of irradiation, stress, and corrosion. In recent years, as nuclear power plants have aged and irradiation dose increased, IASCC has become an increasingly important issue. Post-irradiation crack growth rate and fracture toughness tests have been performed to provide data and technical support for the NRC to address various issues related to aging degradation of reactor-core internal structures and components. This report summarizes the results of the last group of tests on compact tension specimens from the Halden-II irradiation. The IASCC susceptibility of austenitic SSs and heat-affected-zone (HAZ) materials sectioned from submerged arc and shielded metal arc welds was evaluated by conducting crack growth rate and fracture toughness tests in a simulated BWR environment. The fracture and cracking behavior of HAZ materials, thermally sensitized SSs and grain-boundary engineered SSs was investigated at several doses (?3 dpa). These latest results were combined with previous results from Halden-I and II irradiations to analyze the effects of neutron dose, water chemistry, alloy compositions, and welding and processing conditions on IASCC. The effect of neutron irradiation on the fracture toughness of austenitic SSs was also evaluated at dose levels relevant to BWR internals.

  18. The effect of residuals on the presence of intergranular surface cracks on continuously cast billets

    SciTech Connect (OSTI)

    Wijngaarden, M.J.U.T. van; Visagie, G.P.

    1996-12-31

    During 1991, Iscor Vereeniging experienced a dramatic increase in the rejection rate of specialty steel bars rolled from continuously cast billets due to the presence of seams on the bars. The seams originated from tearing of the billets during the first 2 passes in the roughing mill during hot rolling. The defective billets were found to contain fine intergranular cracks on the surface. Such cracks have been described in the literature and have been attributed to the presence of high levels of residuals resulting in the well-known phenomenon of surface hot shortness which results from the enrichment of residuals at the grain boundaries after preferential oxidation of iron during scaling of the steel. The present investigation revealed that the effect of residuals on intergranular surface cracking is a complex interaction between steel composition and casting conditions such as casting speed, intensity of secondary cooling, section size, and mold type. This paper quantifies the effect of residuals on the intergranular surface cracking of continuously cast billets and quantitatively relates the incidence of these cracks to parameters which can be controlled during steelmaking and continuous casting.

  19. Cracking of simulated oil refinery off-gas over a coal char, petroleum coke, and quartz

    SciTech Connect (OSTI)

    Yuan Zhang; Jin-hu Wu; Dong-ke Zhang

    2008-03-15

    The cracking of oil refinery off-gas, simulated with a gas mixture containing methane (51%), ethylene (21.4%), ethane (21.1%), and propane (6.5%), over a coal char, petroleum coke, and quartz, respectively, has been studied in a fixed bed reactor. The experiments were performed at temperatures between 850 and 1000{sup o}C and at atmospheric pressure. The results show that the conversions of all species considered increased with increasing temperature. Ethane and propane completely decomposed over all three bed materials in the temperature range investigated. However, the higher initial conversion rates of methane and ethylene cracking at all temperatures were observed only over the coal char and not on the petroleum coke and quartz, indicating a significant catalytic effect of the coal char on methane and ethylene cracking. Methane and ethylene conversions decreased with reaction time due to deactivation of the coal char by carbon deposition on the char surface and, in the later stage of a cracking experiment, became negative, suggesting that methane and ethylene had been formed during the cracking of ethane and propane. 16 refs., 13 figs., 2 tabs.

  20. Detection of submicron scale cracks and other surface anomalies using positron emission tomography

    DOE Patents [OSTI]

    Cowan, Thomas E.; Howell, Richard H.; Colmenares, Carlos A.

    2004-02-17

    Detection of submicron scale cracks and other mechanical and chemical surface anomalies using PET. This surface technique has sufficient sensitivity to detect single voids or pits of sub-millimeter size and single cracks or fissures of millimeter size; and single cracks or fissures of millimeter-scale length, micrometer-scale depth, and nanometer-scale length, micrometer-scale depth, and nanometer-scale width. This technique can also be applied to detect surface regions of differing chemical reactivity. It may be utilized in a scanning or survey mode to simultaneously detect such mechanical or chemical features over large interior or exterior surface areas of parts as large as about 50 cm in diameter. The technique involves exposing a surface to short-lived radioactive gas for a time period, removing the excess gas to leave a partial monolayer, determining the location and shape of the cracks, voids, porous regions, etc., and calculating the width, depth, and length thereof. Detection of 0.01 mm deep cracks using a 3 mm detector resolution has been accomplished using this technique.

  1. Fracture toughness results and preliminary analysis for International Cooperative Test Program on specimens containing surface cracks

    SciTech Connect (OSTI)

    Reuter, W.G.; Elfer, N.C.; Hull, D.A.; Newman, J.C. Jr.; Munz, D.; Panontin, T.L.

    1997-12-31

    Specimens containing surface cracks were tested in either tension or bending to compare the stress intensity factor at failure with plane strain fracture toughness (K{sub Ic}) in an International Cooperative Test Program. The material was heat treated to {sigma}{sub ys} = 1 587 MPa and K{sub Ic} = 54 MPa m{sub 1/2}. Because substantial stable crack growth occurred for some specimens, the test plan was modified to include detecting the onset of crack growth. It is shown that P{sub max} and the original fatigue precrack size cannot be employed to calculate K{sub max} for comparison with K{sub Ic} when significant stable crack growth occurs. However, using P{sub init} (load at which stable crack growth is initiated) and the original fatigue precrack size to calculate K{sub max} or K{sub {phi}=30{degree}} provides a very useful comparison with K{sub Ic}. The influence of variations in fatigue precrack configuration on test results are also discussed.

  2. Acoustic Emission and Guided Wave Monitoring of Fatigue Crack Growth on a Full Pipe Specimen

    SciTech Connect (OSTI)

    Meyer, Ryan M.; Cumblidge, Stephen E.; Ramuhalli, Pradeep; Watson, Bruce E.; Doctor, Steven R.; Bond, Leonard J.

    2011-05-06

    Continuous on-line monitoring of active and passive systems, structures and components in nuclear power plants will be critical to extending the lifetimes of nuclear power plants in the US beyond 60 years. Acoustic emission and guided ultrasonic waves are two tools for continuously monitoring passive systems, structures and components within nuclear power plants and are the focus of this study. These tools are used to monitor fatigue damage induced in a SA 312 TP304 stainless steel pipe specimen. The results of acoustic emission monitoring indicate that crack propagation signals were not directly detected. However, acoustic emission monitoring exposed crack formation prior to visual confirmation through the detection of signals caused by crack closure friction. The results of guided ultrasonic wave monitoring indicate that this technology is sensitive to the presence and size of cracks. The sensitivity and complexity of GUW signals is observed to vary with respect to signal frequency and path traveled by the guided ultrasonic wave relative to the crack orientation.

  3. Fracture behavior of ceramic laminates in bending-I. Modeling of crack propagation

    SciTech Connect (OSTI)

    Phillipps, A.J.; Clegg, W.J.; Clyne, T.W. . Dept. of Materials Science and Metallurgy)

    1993-03-01

    This paper concerns the fracture behavior of specimens made up of ceramic sheets, separated by thin interlayers, which act to deflect cracks and thus to prevent catastrophic failure of the specimen. The treatment is divided into two parts. In this paper, the behavior of this type of material during bending is quantitatively modeled. The model is based on through-thickness cracks propagating when a critical stress is reached and interfacial cracks then advancing a distance dictated by the available energy. The variation in laminae strengths is modeled using a Monte Carlo method to determine the strength of successive laminae for a given Weibull modulus. The model is used to predict load/displacement plots and to explore the effects of changes in loading geometry and specimen variables, including Young's modulus, lamina strength, loading span, interfacial toughness, as well as lamina and sample thickness. A distinction is drawn between the energy actually absorbed in causing complete failure of the specimen as measured from the area under the load/displacement curve, and the amount of energy necessary to cause the crack propagation which occurred. These differ if the energy available to drive the interfacial cracks is more than sufficient for them to reach the ends of the specimen or if energy is dissipated elsewhere in the system. A criterion is derived by which specimens can be designed so as to minimize the difference between these two quantities. The significance of this concept in optimizing the toughness of these laminated materials is briefly discussed.

  4. VR/Urban: Spread.gun Design Process and Challenges in Developing a Shared Encounter for Media Faades

    E-Print Network [OSTI]

    Hornecker, Eva

    VR/Urban: Spread.gun ­ Design Process and Challenges in Developing a Shared Encounter for Media intervention tool called Spread.gun, which was created for the Media Façade Festival 2008 in Berlin. Main social change. In this paper, we discuss our Spread.gun installation as a case study exemplifying

  5. Energy spread reduction of electron beams produced via laser wakefield acceleration

    E-Print Network [OSTI]

    Pollock, Bradley Bolt

    2012-01-01

    Chapter 5 Chapter 6 Electron Beam Energy Spread Reduction bywake?eld-accelerated electron beams,” Phys. Rev. Lett. (S. M. Hooker, “Gev electron beams from a centimetre-scale

  6. A Hidden Markov Chain Model for the Term Structure of Bond Credit Risk Spreads 

    E-Print Network [OSTI]

    Thomas, L; Allen, David E; Morkel-Kingsbury, N

    1998-01-01

    This paper provides a Markov chain model for the term structure and credit risk spreads of bond processes. It allows dependency between the stochastic process modeling the interest rate and the Markov chain process describing ...

  7. Beam energy spread in FERMI@elettra gun and linac induced by intrabeam scattering

    E-Print Network [OSTI]

    Zholents, Alexander A

    2008-01-01

    spread in FERMI@elettra gun and linac induced by intrabeamcathode area in the electron guns know in the literature asmost visible within the electron gun where the electron beam

  8. Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

    E-Print Network [OSTI]

    Bakeman, M.S.

    2011-01-01

    Accelerator, Undulator, Electron Beam Diagnostic PACS: 52 .of an undulator-based electron beam diagnostic to be used inElectron Beam Energy Spread and Emittance Diagnostic M.S.

  9. The spread of violent civil conflict : rare state-driven, and preventable

    E-Print Network [OSTI]

    Black, Nathan Wolcott

    2012-01-01

    This dissertation advances and tests an explanation for the spread of violent civil conflict from one state to another. The fear of such "substate conflict contagion" is frequently invoked by American policymakers as a ...

  10. The tectonics and three-dimensional structure of spreading centers--microearthquake studies and tomographic inversions

    E-Print Network [OSTI]

    Toomey, Douglas R

    1987-01-01

    Two-thirds of the Earth's surface has been formed along a global system of spreading centers that are presently manifested in several different structural forms, including the classic rift valley of the Mid-Atlantic Ridge, ...

  11. Auxiliary material for Observation of the Spread of Slow Deformation in Greece Following the

    E-Print Network [OSTI]

    Cerveny, Vlastislav

    Auxiliary material for Observation of the Spread of Slow Deformation in Greece Following of Engineering Seismology and Earthquake Engineering ITSAK, P.O. Box 53, 55102 Thessaloniki, Greece 4 Université

  12. Catalysts of conflict : how refugee crises lead to the spread of civil war

    E-Print Network [OSTI]

    Lischer, Sarah Kenyon

    2002-01-01

    The spread of civil war due to refugee crises has occurred repeatedly throughout history. In some refugee crises, the sending state pursues the refugees, subjecting them to military attack. In other cases, militant exiles ...

  13. Reviewed research article Crustal deformation in Iceland: Plate spreading and earthquake

    E-Print Network [OSTI]

    Árnadóttir, Þóra

    Reviewed research article Crustal deformation in Iceland: Plate spreading and earthquake, Institute of Earth Sciences, University of Iceland, IS-101 Reykjavík, Iceland 2 Physics Department, Icelandic Meteorological Office, Reykjavík, Iceland 3 GPS Research Center, Wuhan University 129 Luoyu Road

  14. RESEARCH ARTICLE Spatial spread of an alien tree species in a heterogeneous

    E-Print Network [OSTI]

    Petite, Samuel

    RESEARCH ARTICLE Spatial spread of an alien tree species in a heterogeneous forest landscape the observed invasion patterns of an alien tree species, Prunus serotina Ehrh., in a heterogeneous managed

  15. Two-Dimensional Droplet Spreading over Random Topographical Substrates Nikos Savva,1

    E-Print Network [OSTI]

    Pavliotis, Grigorios

    Kalliadasis,1 and Grigorios A. Pavliotis2 1 Department of Chemical Engineering, Imperial College London, London SW7 2AZ, United Kingdom 2 Department of Mathematics, Imperial College London, London SW7 2AZ from transport phenomena in porous media and reaction-diffusion- advection systems to crack propagation

  16. Landau damping effects and evolutions of energy spread in small isochronous ring

    SciTech Connect (OSTI)

    Li, Yingjie [Michigan State University; Wang, Langfa [SLAC; Lin, Fanglei [JLAB

    2014-11-01

    This paper presents the Landau damping effects on the microwave instability of a coasting long bunch in an isochronous ring due to finite energy spread and emittance. Our two-dimensional (2D) dispersion relation gives more accurate predictions of the microwave instability growth rates of short-wavelength perturbations than the conventional 1D formula. The long-term evolution of energy spread is also studied by measurements and simulations.

  17. Wake fields and energy spread for the eRHIC ERL

    SciTech Connect (OSTI)

    Fedotov, A.; Kayran, D.

    2011-10-16

    Wake fields in high-current ERLs can cause significant beam quality degradations. Here we summarize effects of coherent synchrotron radiation, resistive wall, accelerating cavities and wall roughness for ERL parameters of the eRHIC project. A possibility of compensation of such correlated energy spread is also presented. An emphasis in the discussion is made on the suppression of coherent synchrotron radiation due to shielding and a possible reduction of wall roughness effects for realistic surfaces. In this report we discuss the wake fields with a focus on their effect on the energy spread of the beam. Other effects of wake fields are addressed elsewhere. An energy spread builds up during a pass though a very long beam transport in the eRHIC ERL under design. Such energy spread become important when beam is decelerated to low energy, and needs to be corrected. Several effects, such as Coherent Synchrotron Radiation (CSR), Resistive Wall (RW), accelerating RF cavities (RF) and Wall Roughness (WR) were considered. In this paper, we briefly summarize major contributions to energy spread from the wake fields for eRHIC parameters, and present possible energy spread compensation for decelerated beam. In the rest of the report we discuss effects which we believe are suppressed for the eRHIC parameters.

  18. Information Spread Over an Internet-mediated Social Network: Phases, Speed, Width, and Effects of Promotion

    E-Print Network [OSTI]

    Salvania, Abigail C

    2015-01-01

    In this study, we looked at the effect of promotion in the speed and width of spread of information on the Internet by tracking the diffusion of news articles over a social network. Speed of spread means the number of readers that the news has reached in a given time, while width of spread means how far the story has travelled from the news originator within the social network. After analyzing six stories in a 30-hour time span, we found out that the lifetime of a story's popularity among the members of the social network has three phases: Expansion, Front-page, and Saturation. Expansion phase starts when a story is published and the article spreads from a source node to nodes within a connected component of the social network. Front-page phase happens when a news aggregator promotes the story in its front page resulting to the story's faster rate of spread among the connected nodes while at the same time spreading the article to nodes outside the original connected component of the social network. Saturation...

  19. Method for cracking hydrocarbon compositions using a submerged reactive plasma system

    DOE Patents [OSTI]

    Kong, P.C.

    1997-05-06

    A method is described for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap there between. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition. 6 figs.

  20. Ultrasonic inspection of austenitic stainless steel welds with artificially produced stress corrosion cracks

    SciTech Connect (OSTI)

    Dugan, Sandra; Wagner, Sabine [Materials Testing Institute University of Stuttgart (MPA), Pfaffenwaldring 32, 70569 Stuttgart (Germany)

    2014-02-18

    Austenitic stainless steel welds and nickel alloy welds, which are widely used in nuclear power plants, present major challenges for ultrasonic inspection due to the grain structure in the weld. Large grains in combination with the elastic anisotropy of the material lead to increased scattering and affect sound wave propagation in the weld. This results in a reduced signal-to-noise ratio, and complicates the interpretation of signals and the localization of defects. Mechanized ultrasonic inspection was applied to study austenitic stainless steel test blocks with different types of flaws, including inter-granular stress corrosion cracks (IGSCC). The results show that cracks located in the heat affected zone of the weld are easily detected when inspection from both sides of the weld is possible. In cases of limited accessibility, when ultrasonic inspection can be carried out only from one side of a weld, it may be difficult to distinguish between signals from scattering in the weld and signals from cracks.

  1. Method for cracking hydrocarbon compositions using a submerged reactive plasma system

    DOE Patents [OSTI]

    Kong, Peter C. (Idaho Falls, ID)

    1997-01-01

    A method for cracking a liquid hydrocarbon composition (e.g. crude oil) to produce a cracked hydrocarbon product. A liquid hydrocarbon composition is initially provided. An electrical arc is generated directly within the hydrocarbon composition so that the arc is entirely submerged in the composition. Arc generation is preferably accomplished using a primary and secondary electrode each having a first end submerged in the composition. The first ends of the electrodes are separated from each other to form a gap therebetween. An electrical potential is then applied to the electrodes to generate the arc within the gap. A reactive gas is thereafter delivered to the arc which forms a bubble around the arc. Gas delivery may be accomplished by providing a passageway through each electrode and delivering the gas through the passageways. The arc and gas cooperate to produce a plasma which efficiently cracks the hydrocarbon composition.

  2. Can surface cracks and unipolar arcs explain breakdown and gradient limits?

    SciTech Connect (OSTI)

    Insepov, Zeke; Norem, Jim

    2013-01-15

    The authors argue that the physics of unipolar arcs and surface cracks can help understand rf breakdown and vacuum arc data. They outline a model of the basic mechanisms involved in breakdown and explore how the physics of unipolar arcs and cracks can simplify the picture of breakdown and gradient limits in accelerators, tokamaks as well as laser ablation, micrometeorites, and other applications. Cracks are commonly seen in SEM images of arc damage and they are produced as the liquid metal cools. They can produce the required field enhancements to explain field emission data and can produce mechanical failure of the surface that would trigger breakdown events. Unipolar arcs can produce currents sufficient to short out rf structures, and can cause the sort of damage seen in SEM images. They should be unstable, and possibly self-quenching, as seen in optical fluctuations and surface damage. The authors describe some details and consider the predictions of this simple model.

  3. Method and apparatus for detecting external cracks from within a metal tube

    DOE Patents [OSTI]

    Caffey, Thurlow W. H. (Albuquerque, NM)

    2001-08-07

    A method and tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is described for the detection of external sidewall cracks and other anomalies in boiler tubes and other enclosures. The invention utilizes the concept of radar backscatter rather than eddy-currents or ultrasound, which are sometimes used in prior art crack-detection methods. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to -40 dB in thin-walled boiler tubes.

  4. Study on grain boundary character and strain distribution of intergranular cracking in the CGHAZ of T23 steel

    SciTech Connect (OSTI)

    Jin, Y.J.; Lu, H., E-mail: shweld@sjtu.edu.cn; Yu, C.; Xu, J.J.

    2013-10-15

    Intergranular reheat cracking in the coarse-grained heat-affected zone of T23 steel was produced by strain to fracture tests on a Gleeble 3500 thermal–mechanical simulator. Then the grain boundary character, as well as the strain distribution after reheat crack propagation, was studied by electron backscatter diffraction technique. The results showed that incoherent ?3 boundaries were seldom found on the prior austenite grain boundaries. Therefore, only the type of random high-angle boundaries played a crucial role in the intergranular cracking. Microstructurally cavities and small cracks were preferentially initiated from high-angle grain boundaries. Low-angle grain boundaries and high-angle ones with misorientation angles less than 15° were more resistant to the cracking. More importantly, the fraction of high-angle grain boundaries increased with the plastic strain induced by both temperature gradient and stress in the coarse-grained heat-affected zone, which contributed to the crack initiation and propagation. Furthermore, the strain distributions in the vicinity of cavities and cracks revealed the accommodation processes of plastic deformation during stress relaxation. It also reflected the strength differences between grain interior and grain boundary at different heat-treated temperatures, which had a large influence on the cracking mechanism. - Highlights: • The coincidence site lattice boundaries play little role in the reheat cracking. • Cavity and crack occur at high-angle grain boundaries rather than low-angle ones. • The strain leads low-angle grain boundaries to transform to high-angle ones. • Strain distribution differs for cavity and crack zones at different temperatures.

  5. Mechanisms for fracture and fatigue-crack propagation in a bulk metallic glass

    SciTech Connect (OSTI)

    Gilbert, C.J.; Schroeder, V.; Ritchie, R.O. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1999-07-01

    The fracture and fatigue properties of a newly developed bulk metallic glass alloy, Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} (at. pct), have been examined. Experimental measurements using conventional fatigue precracked compact-tension C(T) specimens ({approximately}7-mm thick) indicated that the fully amorphous alloy has a plane-strain fracture toughness comparable to polycrystalline aluminum alloys. However, significant variability was observed and possible sources are identified. The fracture surfaces exhibited a vein morphology typical of metallic glasses, and, in some cases, evidence for local melting was observed. Attempts were made to rationalize the fracture toughness in terms of a previously developed micromechanical model based on the Taylor instability, as well as on the observation of extensive crack branching and deflection. Upon partial or complete crystallization, however, the alloy was severely embrittled, with toughnesses dropping to {approximately}1 MPa {radical}m. Commensurate with this drop in toughness was a marginal increase in hardness and a reduction in ductility (as measured via depth-sensing indentation experiments). Under cyclic loading, crack-propagation behavior in the amorphous structure was similar to that observed in polycrystalline steel and aluminum alloys. Moreover, the crack-advance mechanism was associated with alternating blunting and resharpening of the crack tip. This was evidenced by striations on fatigue fracture surfaces. Conversely, the (unnotched) stress/life (S/N) properties were markedly different. Crack initiation and subsequent growth occurred quite readily, due to the lack of microstructural barriers that would normally provide local crack-arrest points. This resulted in a low fatigue limit of {approximately}4 pct of ultimate tensile strength.

  6. EDDY CURRENT SYSTEM FOR DETECTION OF CRACKING BENEATH BRAIDING IN CORRUGATED METAL HOSE

    SciTech Connect (OSTI)

    Wincheski, Buzz [NASA Langley Research Center, Hampton, VA 23681 (United States); Simpson, John [Lockheed Martin Space Operations, Hampton, VA 23681 (United States); Hall, George [George Washington University, Washington, D.C. 20052 (United States)

    2009-03-03

    In this paper an eddy current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing technique is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.

  7. A tool to detect external cracks from within a metal tube

    SciTech Connect (OSTI)

    Caffey, T.W.H.

    1997-01-01

    A tool using a continuous electromagnetic wave from a transverse magnetic-dipole source with a coaxial electric-dipole receiver is outlined for the detection of external sidewall cracks in boiler tubes. A numerical study of the distribution of the fields shows that the direct transmission from the source to the receiver is reduced from that in free space. Further, if the diameter of the receiver dipole is made sufficiently small, it should be possible to detect cracks with a scattering loss of up to 40dB in thin-walled boiler tubes.

  8. Spreading of crude petroleum in brash ice; Effects of oil`s physical properties and water current

    SciTech Connect (OSTI)

    Sayed, M.; Kotlyar, L.S.; Sparks, B.D.

    1994-12-31

    Experiments were conducted in a refrigerated, circulating current flume to examine crude oil spreading in brash ice. Amauligak, Hibernia and Norman Wells crudes were tested. Measurements of the physical properties of the oils were also conducted, including: surface and interfacial tensions as well as viscosities. Spreading coefficients were calculated from measured surface and interfacial tensions. Results were obtained for original and weathered oils. For the spreading tests, spill volumes up to 3 liters and water currents up to 0.55 m/s were used. Tests were done using both fresh water ice and saline ice. Slick dimensions were measured, and modes of oil spreading were observed. Slick dimensions depended on oil type, but were not influenced by water current. Oils of high spreading coefficient and low viscosity spread over larger areas than those with low spreading coefficient and high viscosity.

  9. GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, How pore fluid pressurization influences crack tip processes

    E-Print Network [OSTI]

    GEOPHYSICAL RESEARCH LETTERS, VOL. ???, XXXX, DOI:10.1029/, How pore fluid pressurization temperature and pore pressure rises along a steadily propagating shear crack, assuming a given shear stress profile along the crack (i.e., initially neglecting effects of pore pressure on shear stress

  10. Thin Film Cracking Modulated by Underlayer Creep by J. Liang, R. Huang, J.H. Prvost, and Z. Suo

    E-Print Network [OSTI]

    Huang, Rui

    coatings in gas-turbine engines, and multilayers in medical implants.1­10 The applications typically ABSTRACT--In devices that integrate dissimilar materials in small dimensions, crack extension in one material often ac- companies inelastic deformation in another. In this paper we analyze a channel crack

  11. Evolution of crack-tip transformation zones in superelastic Nitinol subjected to in situ fatigue: A fracture mechanics

    E-Print Network [OSTI]

    Ritchie, Robert

    Evolution of crack-tip transformation zones in superelastic Nitinol subjected to in situ fatigue, Berkeley, CA 94720, USA b Stanford Synchrotron Radiation Laboratory, Menlo Park, CA 94025, USA c Nitinol of a growing fatigue crack (100 cycles in situ) in superelastic Nitinol. The results provide some surprising

  12. Mixed-Mode, High-Cycle Fatigue-Crack Growth Thresholds in Ti-6Al-4V

    E-Print Network [OSTI]

    Ritchie, Robert

    and control of failure due to high cycle fatigue (HCF) in turbine engine components is currently one and Engineering University of California, Berkeley, CA 94720-1760 ABSTRACT: There are few experimental results-cycle fatigue-crack growth thresholds with crack size and shape are reported for a Ti-6Al-4V turbine blade alloy

  13. Diffusion and Catalytic Cracking of 1,3,5 Tri-iso-propyl-benzene in FCC Catalysts

    E-Print Network [OSTI]

    Al-Khattaf, Sulaiman

    1 Diffusion and Catalytic Cracking of 1,3,5 Tri-iso- propyl-benzene in FCC Catalysts S.Al-Khattaf1 describes catalytic cracking experiments developed in a novel CREC Riser Simulator using 1,3,5-Tri-iso-propyl-benzene

  14. The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical bone

    E-Print Network [OSTI]

    Ritchie, Robert

    The significance of crack-resistance curves to the mixed-mode fracture toughness of human cortical cortical bone Mixed-mode fracture Fracture toughness Crack-growth resistance curve a b s t r a c t The majority of fracture mechanics studies on the toughness of bone have been performed under tensile loading

  15. Crack Propagation Fracture Toughness of Several Wood Species Elijah Wilson, Meisam Shir Mohammadi, and John A. Nairn

    E-Print Network [OSTI]

    Nairn, John A.

    1 Crack Propagation Fracture Toughness of Several Wood Species Elijah Wilson, Meisam Shir Mohammadi In materials with process zones, such as fiber bridging zones in wood, it is crucial to characterize fracture toughness as a function of crack growth, known as the material's R curve. Here, a new fracture testing

  16. Production of low axial energy spread ion beams with multicusp sources

    SciTech Connect (OSTI)

    Lee, Y.H.Y.

    1998-05-01

    Multicusp ion sources are capable of producing ions with low axial energy spread which are necessary in applications such as: ion projection lithography (IPL) and focused ion beams for the next generation lithographic tools and nuclear science experiments such as radioactive ion beam production. The axial ion energy spread for multicusp source is approximately 6 eV which is too large for IPL and radioactive ion beam applications. The addition of a magnetic filter which consists of a pair of permanent magnets to the multicusp source reduces the energy spread considerably. The reduction is due to the improvement in the uniformity of the axial plasma potential distribution in the discharge region. Axial ion energy spread of the filament driven ion source has been measured using three different techniques. In all cases, it was found to be less than 2 eV. Energy spread of the radio frequency (RF) driven source has also been explored, and it was found to be less than 3 eV with the proper RF-shielding. A new multicusp source configuration has been designed and constructed to further reduce the energy spread. To achieve a more uniform axial plasma potential distribution, a cylindrical magnetic filter has been designed and constructed for a 2-cm-diameter source. This new source configuration, the co-axial source, is new in its kind. The energy spread in this source has been measured to be a record low of 0.6 eV. Because of the novelty of this device, some plasma parameters inside the source have been studied. Langmuir probe has been used to measure the plasma potential, the electron temperature and the density distribution.

  17. Catalytic cracking. (Latest citations from the NTIS data base). Published Search

    SciTech Connect (OSTI)

    Not Available

    1992-05-01

    The bibliography contains citations concerning applications of catalytic cracking in fluidized beds, moving beds, refineries, vacuum distillation, and reformers. Design criteria, models, controls, and operating procedures are also discussed. (Contains 250 citations and includes a subject term index and title list.)

  18. Catalytic cracking. (Latest citations from the NTIS Bibliographic database). Published Search

    SciTech Connect (OSTI)

    Not Available

    1993-09-01

    The bibliography contains citations concerning applications of catalytic cracking in fluidized beds, moving beds, refineries, vacuum distillation, and reformers. Design criteria, models, controls, and operating procedures are also discussed. (Contains 250 citations and includes a subject term index and title list.)

  19. 128 CEREAL CHEMISTRY Effects of Alkali Debranning, Roller Mill Cracking and Gap Setting, and Alkali

    E-Print Network [OSTI]

    . Cracking the pericarp-free corn in a roller mill is done to further reduce kernel size so that steep time fiber, and gluten are separated. This procedure gave a practical compar- able starch yield of 67 was developed for the purpose of obtaining bran-free corn that was further processed into edible corn products

  20. THE INFLUENCE OF THE GRAIN STRUCTURE SIZE ON MICROSTRUCTURALLY SHORT CRACKS

    E-Print Network [OSTI]

    Cizelj, Leon

    ; crystal plasticity ABSTRACT The dominant processes in the initialization and propagation elasticity and crystal plasticity constitutive models are employed at the grain size scale. It is shown& strain rate tensor p kl& plastic strain rate tensoR crack direction ij stress tensor ij& stress rate

  1. Analysis of cracked piezoelectric solids by a mixed three-dimensional BE approach

    E-Print Network [OSTI]

    Ariza Moreno, Pilar

    regularization and evaluation of boundary integrals. Quadratic boundary elements and quarter-point boundary isotropy. Piezoelectric ceramics are used for construction of sensors, transducers, actuators as well, these brittle materials are likely to develop cracks. The under- standing and evaluation of the fracture process

  2. Analysis of the tube-sheet cracking in slurry oil steam , L.J. Qiao a,

    E-Print Network [OSTI]

    Volinsky, Alex A.

    , People's Republic of China b Jinzhou Petrochemical Corporation, China National Petroleum Corporation the tubes and the tube sheets, shown in Fig. 2. During the heat exchange process, the temperature analysis performed to simulate the hydraulic expansion process showed that this kind of cracking

  3. INFLUENCE OF HYDRIDE MICROSTRUCTURE ON THROUGH-THICKNESS CRACK GROWTH IN ZIRCALOY-4 SHEET

    E-Print Network [OSTI]

    Motta, Arthur T.

    1 INFLUENCE OF HYDRIDE MICROSTRUCTURE ON THROUGH-THICKNESS CRACK GROWTH IN ZIRCALOY-4 SHEET P. A and Engineering, The Pennsylvania State University, University Park, PA 16802 2 Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 3 Southwest Research

  4. Microstructure effect on hydrogen-induced cracking in TM210 maraging steel

    E-Print Network [OSTI]

    Volinsky, Alex A.

    August 2013 Keywords: Maraging steel Hydrogen embrittlement Reverted austenite Martensite lath boundaries formability. Solution- treated maraging steels have martensite with high dislocation density and a pronouncedMicrostructure effect on hydrogen-induced cracking in TM210 maraging steel Gang Wang a , Yu Yan

  5. Dynamics of fluid-filled gelatin cracks www.math.utwente.nl/bokhoveo/

    E-Print Network [OSTI]

    Al Hanbali, Ahmad

    Dynamics of fluid-filled gelatin cracks www.math.utwente.nl/bokhoveo/ Koji Kiyosugi, Onno Bokhove analog experiment, wherein gelatin is the elastic solid and water the intruding fluid: #12;Fluid cavity new dikes. Sketch of observations: gelatin gelatin frontal view 1 2 side view top view 32 32 1 1 1 3 2

  6. Radar interferometry for measuring tidal strains across cracks on David Sandwell,1

    E-Print Network [OSTI]

    Sandwell, David T.

    Radar interferometry for measuring tidal strains across cracks on Europa David Sandwell,1 Paul and the plate has been relatively thin ($2 km) [Carr et al., 1998]. However, the present-day average shell relationships and a variety of morphologic characteristics [Carr et al., 1998; Greenberg et al., 1998]. Simple

  7. Eddy-current interaction with an ideal crack. II. The inverse problem John FL Bowler

    E-Print Network [OSTI]

    Bowler, John R.

    Eddy-current interaction with an ideal crack. II. The inverse problem John FL Bowler The University 1994) Eddy-current inversion is the process whereby the geometry of a flaw in a metal is derived from eddy-current probe impedance measurements. The approach is based on an optimization scheme that seeks

  8. Eddy-current interaction with an ideal crack. I. The forward problem J. R. Bowler

    E-Print Network [OSTI]

    Bowler, John R.

    Eddy-current interaction with an ideal crack. I. The forward problem J. R. Bowler The University February 1994) The impedance of an eddy-current probe changes when the current it induces in an electrical to introduce idealizations about the nature of the flaw. Eddy-current interaction is considered with an ideal

  9. A protocol to develop crack-free biomimetic coatings on Ti6Al4V substrates

    E-Print Network [OSTI]

    Tas, A. Cuneyt

    A protocol to develop crack-free biomimetic coatings on Ti6Al4V substrates Sahil Jalota,a) Sutapa/Kadikoy, Istanbul 34755, Turkey (Received 22 November 2006; accepted 16 February 2007) Biomimetic coating in implantology. While this paper specifically refers to coating Ti6Al4V, the results are valid with other related

  10. Elastic-Plastic Models for Stable Crack Growtht *James R. Rice

    E-Print Network [OSTI]

    Elastic-Plastic Models for Stable Crack Growtht by *James R. Rice Mareh 1973 'PCAbh ~ ~ e c.\\. (n do not fully recover their strain upon unloading. The idealized non-linear elastic (left) and rigid-plastic,. there is ~ strain concentration created at the cut-ahead tip in the rigid-plastic material and the deformation field

  11. Geophys. J. Int. (2007) 000, 000000 Cracks, pulses and macroscopic asymmetry of dynamic rupture on a

    E-Print Network [OSTI]

    Ampuero, Jean Paul

    2007-01-01

    ruptures behave as cracks or pulses, decaying or sustained, bilateral or unilat- eral. With strongly stems from the difference in the criticality conditions for self-sustained propagation in each rupture architecture of a fault zone, bimaterial interfaces asso- ciated with rock damage are present with various

  12. NORTHWESTERN UNIVERSITY Crack Response of a Historic Structure to Weather Effects and

    E-Print Network [OSTI]

    of the rewards the relationship provides. My advisor Professor Charles Dowding is warmly thanked for his guidance and the "Indian house" on Garnett; and to the mixture of Beethoven, Satie, The Smashing Pumpkins, Mozart, Chopin;A mon père et au petit qui va naître. vi #12;Abstract Cosmetic cracks are very common in structures

  13. Numerical Green's Functions for Line Force and Dislocation around Multiple Cracks

    E-Print Network [OSTI]

    Denda, Mitsunori "Mitch"

    ) by the dislocation dipole distribution, embed the r crack tip behavior, and integrate the resulting singular/hyper are present in two-dimensional isotropic solids. Such Green's functions are called the numerical Green- tion and enabled the derivation of the Green's functions for more complex two- dimensional and three-dimensional

  14. Numerical modeling and experiments of creep crack growth under cyclic loading

    SciTech Connect (OSTI)

    Brust, F.W.

    1995-12-31

    This paper presents a summary of some recent studies of creep crack growth under history dependent load conditions. The effect of a proper constitutive law is illustrated. Moreover, the asymptotic fields are reconsidered under cyclic creep conditions. In addition, several experiments are modeled and the behavior of integral parameters is discussed.

  15. Pulse-like and crack-like ruptures in experiments mimicking crustal earthquakes

    E-Print Network [OSTI]

    Lapusta, Nadia

    Pulse-like and crack-like ruptures in experiments mimicking crustal earthquakes Xiao Lu , Nadia ruptures may propagate in a self-healing pulse-like mode. A number of expla- nations for the existence of slip pulses have been proposed and continue to be vigorously debated. This study presents experimen

  16. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    SciTech Connect (OSTI)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M. [and others

    1996-12-01

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

  17. Channel cracks in atomic-layer and molecular-layer deposited multilayer thin film coatings

    SciTech Connect (OSTI)

    Long, Rong, E-mail: rlongmech@gmail.com [Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta T6G 2G8 (Canada); Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Dunn, Martin L. [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States); Singapore University of Technology and Design, Singapore 138682 (Singapore)

    2014-06-21

    Metal oxide thin film coatings produced by atomic layer deposition have been shown to be an effective permeation barrier. The primary failure mode of such coatings under tensile loads is the propagation of channel cracks that penetrate vertically into the coating films. Recently, multi-layer structures that combine the metal oxide material with relatively soft polymeric layers produced by molecular layer deposition have been proposed to create composite thin films with desired properties, including potentially enhanced resistance to fracture. In this paper, we study the effects of layer geometry and material properties on the critical strain for channel crack propagation in the multi-layer composite films. Using finite element simulations and a thin-film fracture mechanics formalism, we show that if the fracture energy of the polymeric layer is lower than that of the metal oxide layer, the channel crack tends to penetrate through the entire composite film, and dividing the metal oxide and polymeric materials into thinner layers leads to a smaller critical strain. However, if the fracture energy of the polymeric material is high so that cracks only run through the metal oxide layers, more layers can result in a larger critical strain. For intermediate fracture energy of the polymer material, we developed a design map that identifies the optimal structure for given fracture energies and thicknesses of the metal oxide and polymeric layers. These results can facilitate the design of mechanically robust permeation barriers, an important component for the development of flexible electronics.

  18. Cracks in glass under triaxial conditions Audrey Ougier-Simonin a,*, Jrme Fortin a

    E-Print Network [OSTI]

    Fortin, Jérôme

    Cracks in glass under triaxial conditions Audrey Ougier-Simonin a,*, Jérôme Fortin a , Yves Guéguen-Sur-Cèze Cedex, France a r t i c l e i n f o Article history: Available online xxxx Keywords: Glass Pressure evolution of synthetic glass (SON68) under compressive triaxial stresses (hydrostatic and deviatoric

  19. A model for turbulent hydraulic fracture and application to crack propagation at glacier beds

    E-Print Network [OSTI]

    Tsai, Victor C.

    Click Here for Full Article A model for turbulent hydraulic fracture and application to crack suggest that fluidinduced hydraulic fracture of an ice sheet from its bed sometimes occurs quickly. Citation: Tsai, V. C., and J. R. Rice (2010), A model for turbulent hydraulic fracture and application

  20. A feasibility study of wind turbine blade surface crack detection using an optical inspection method

    E-Print Network [OSTI]

    McCalley, James D.

    A feasibility study of wind turbine blade surface crack detection using an optical inspection method Huiyi Zhang1 , John Jackman Wind Energy Manufacturing Laboratory Dept. of Industrial technique was investigated to assess its ability to detect surface flaws on an on-tower wind turbine blade

  1. Materials Science and Engineering A 404 (2005) 2632 Numerical simulations of crack formation from pegs in

    E-Print Network [OSTI]

    Fleck, Norman A.

    2005-01-01

    in gas turbines for propulsion and power generation [1­4]. The systems are susceptible to performanceMaterials Science and Engineering A 404 (2005) 26­32 Numerical simulations of crack formation from pegs in thermal barrier systems with NiCoCrAlY bond coats H.X. Zhua, N.A. Flecka,, A.C.F. Cocksb, A

  2. Stress Corrosion Cracking and Delayed Increase in Penetration Resistance after Dynamic Compaction of Sand

    E-Print Network [OSTI]

    Michalowski, Radoslaw L.

    of Sand R.L. Michalowski1 , F. ASCE and S. S. Nadukuru2 , Student Member, ASCE 1 University of Michigan Engineering, Ann Arbor, MI 48109-2125, U.S.A.; siddu@umich.edu ABSTRACT Dynamically compacted sands exhibit on the process of stress corrosion cracking of the micro-morphological features on the surface of the sand grains

  3. Role of oxide thickening in fatigue crack initiation in LIGA nickel MEMS thin films

    E-Print Network [OSTI]

    Shan, Wanliang

    Role of oxide thickening in fatigue crack initiation in LIGA nickel MEMS thin films W.L. Shan a 2012 Accepted 16 October 2012 Available online 24 October 2012 Keywords: LIGA Ni MEMS thin films Oxide micro-electro-mechanical-systems (MEMS) structures. & 2012 Elsevier B.V. All rights reserved. 1

  4. Determining crack-tip stress-field parameters from mixed-mode displacement fields 

    E-Print Network [OSTI]

    Matsumoto, Kay Yuri

    1995-01-01

    that can develop at interfaces in composites and ceramics after prolonged exposure to elevated temperatures and adverse environments. The local crack-tip stress field in these cases will have a Mode II component even when the global loading is purely...

  5. Overlapping double etch technique for evaluation of metallic alloys to stress corrosion cracking

    DOE Patents [OSTI]

    Steeves, Arthur F. (Schenectady, NY); Stewart, James C. (Loudonville, NY)

    1981-01-01

    A double overlapping etch zone technique for evaluation of the resistance of metallic alloys to stress corrosion cracking. The technique involves evaluating the metallic alloy along the line of demarcation between an overlapping double etch zone and single etch zone formed on the metallic alloy surface.

  6. The crystallography of fatigue crack initiation in Incoloy-908 and A-286 steel

    SciTech Connect (OSTI)

    Krenn, C.R. |

    1996-12-01

    Fatigue crack initiation in the austenitic Fe-Ni superalloys Incoloy-908 and A-286 is examined using local crystallographic orientation measurements. Results are consistent with sharp transgranular initiation and propagation occurring almost exclusively on {l_brace}111{r_brace} planes in Incoloy-908 but on a variety of low index planes in A-286. This difference is attributed to the influence of the semicoherent grain boundary {eta} phase in A-286. Initiation in each alloy occurred both intergranularly and transgranularly and was often associated with blocky surface oxide and carbide inclusions. Taylor factor and resolved shear stress and strain crack initiation hypotheses were tested, but despite an inconclusive suggestion of a minimum required {l_brace}111{r_brace} shear stress, none of the hypotheses were found to convincingly describe preferred initiation sites, even within the subsets of transgranular cracks apparently free from the influence of surface inclusions. Subsurface inclusions are thought to play a significant role in crack initiation. These materials have applications for use in structural conduit for high field superconducting magnets designed for fusion energy use.

  7. Biomaterials 26 (2005) 11951204 Mechanistic aspects of in vitro fatigue-crack growth in dentin

    E-Print Network [OSTI]

    Ritchie, Robert O.

    2005-01-01

    Biomaterials 26 (2005) 1195­1204 Mechanistic aspects of in vitro fatigue-crack growth in dentin J,13]. These notches are often the ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2004.04.051 ÃCorresponding

  8. Fatigue-crack growth properties of thin-walled superelastic austenitic Nitinol tube for endovascular stents

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue-crack growth properties of thin-walled superelastic austenitic Nitinol tube Nitinol has found widespread application in the manufacture of small-scale biomedical devices of defects on such lifetimes. Unfortunately, frac- ture mechanics studies on fatigue in Nitinol are scarce

  9. Standard test method for crack-tip opening displacement (CTOD) fracture toughness measurement

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers the determination of critical crack-tip opening displacement (CTOD) values at one or more of several crack extension events, and may be used to measure cleavage crack initiation toughness for materials that exhibit a change from ductile to brittle behavior with decreasing temperature, such as ferritic steels. This test method applies specifically to notched specimens sharpened by fatigue cracking. The recommended specimens are three-point bend [SE(B)], compact [C(T)], or arc-shaped bend [A(B)] specimens. The loading rate is slow and influences of environment (other than temperature) are not covered. The specimens are tested under crosshead or clip gage displacement controlled loading. 1.1.1 The recommended specimen thickness, B, for the SE(B) and C(T) specimens is that of the material in thicknesses intended for an application. For the A(B) specimen, the recommended depth, W, is the wall thickness of the tube or pipe from which the specimen is obtained. Superficial surface machini...

  10. A NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED

    E-Print Network [OSTI]

    Paulino, Glaucio H.

    A NOVEL TECHNIQUE TO GENERATE SHARP CRACKS IN METALLIC/CERAMIC FUNCTIONALLY GRADED MATERIALS and fracture toughness; Metals; Structural ceramics; Precracks Introduction Functionally graded materials (FGMs) containing metallic and ceramic phases offer a viable solution to modern design problems requiring structural

  11. ON THE FATIGUE BEHAVIOR OF g-BASED TITANIUM ALUMINIDES: ROLE OF SMALL CRACKS

    E-Print Network [OSTI]

    Ritchie, Robert

    attention for potential elevated temperature ap- plications in gas-turbine engines. However, although expected critical crack sizes for some targeted appli- cations (e.g. gas-turbine engine blades) may be less applications [1, 2]. In comparison to conven- tional gas-turbine engine materials [1±4], titanium aluminides

  12. Fatigue of polycrystalline silicon for MEMS applications: Crack growth and stability under resonant loading conditions

    SciTech Connect (OSTI)

    Muhlstein, C.L.; Howe, R.T.; Ritchie, R.O.

    2001-12-05

    Although bulk silicon is not known to exhibit susceptibility to cyclic fatigue, micron-scale structures made from silicon films are known to be vulnerable to degradation by fatigue in ambient air environments, a phenomenon that has been recently modeled in terms of a mechanism of sequential oxidation and stress-corrosion cracking of the native oxide layer.

  13. CHARACTERISATION OF AGED HDPE PIPES FROM DRINKING WATER DISTRIBUTION: INVESTIGATION OF CRACK DEPTH BY NOL RING

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    BY NOL RING TESTS UNDER CREEP LOADING C. Devilliers 1), 2), 3) , L. Laiarinandrasana 1) , B. Fayolle 2. KEYWORDS HDPE pipes, Nol Ring creep test, ageing effects, fracture mechanism, crack depth ratio, aged layer loading than a monotonic tensile loading. It is to be noticed that the Nol Ring test subjected to a creep

  14. A creep model for austenitic stainless steels incorporating cavitation and wedge cracking

    E-Print Network [OSTI]

    Mahesh, Sivasambu

    A creep model for austenitic stainless steels incorporating cavitation and wedge cracking S Mahesh, Kalpakkam 603102. India Abstract. A model of damage evolution in austenitic stainless steels under creep experimental data for a type 316 austenitic stainless steel under uniaxial creep loading. Deformation

  15. Stainless steel pitting and early-stage stress corrosion cracking under ultra-low elastic load

    E-Print Network [OSTI]

    Volinsky, Alex A.

    Stainless steel pitting and early-stage stress corrosion cracking under ultra-low elastic load Available online 7 September 2013 Keywords: A. Stainless steel B. SEM B. Modeling studies C. Stress] in stainless steel (SS), are key factors inducing the preferential pitting initiation. For homoge- neous

  16. Using Crack Propagation Fracture Toughness to Characterize the Durability of Wood and Wood Composites

    E-Print Network [OSTI]

    Nairn, John A.

    Using Crack Propagation Fracture Toughness to Characterize the Durability of Wood and Wood, Corvallis, OR 97330, USA Abstract We measured fracture resistance curves (or R curves) for laminated veneer. The LVL and solid wood R curves were the same for initiation of fracture, but the LVL toughness rose much

  17. Post-Tanner stages of droplet spreading: the energy balance approach revisited

    E-Print Network [OSTI]

    Serguei Mechkov; Anne-Marie Cazabat; Gleb Oshanin

    2009-09-10

    The spreading of a circular liquid drop on a solid substrate can be described by the time evolution of its base radius R(t). In complete wetting the quasistationary regime (far away from initial and final transients) typically obeys the so-called Tanner law, with R t^alpha_T, alpha_T=1/10. Late-time spreading may differ significantly from the Tanner law: in some cases the drop does not thin down to a molecular film and instead reaches an equilibrium pancake-like shape; in other situations, as revealed by recent experiments with spontaneously spreading nematic crystals, the growth of the base radius accelerates after the Tanner stage. Here we demonstrate that these two seemingly conflicting trends can be reconciled within a suitably revisited energy balance approach, by taking into account the line tension contribution to the driving force of spreading: a positive line tension is responsible for the formation of pancake-like structures, whereas a negative line tension tends to lengthen the contact line and induces an accelerated spreading (a transition to a faster power law for R(t) than in the Tanner stage).

  18. Results of crack-arrest tests on irradiated a 508 class 3 steel

    SciTech Connect (OSTI)

    Iskander, S.K.; Milella, P.P.; Pini, M.A.

    1998-02-01

    Ten crack-arrest toughness values for irradiated specimens of A 508 class 3 forging steel have been obtained. The tests were performed according to the American Society for Testing and Materials (ASTM) Standard Test Method for Determining Plane-Strain Crack-Arrest Fracture Toughness, K{sub la} of Ferritic Steels, E 1221-88. None of these values are strictly valid in all five ASTM E 1221-88 validity criteria. However, they are useful when compared to unirradiated crack-arrest specimen toughness values since they show the small (averaging approximately 10{degrees}C) shifts in the mean and lower-bound crack-arrest toughness curves. This confirms that a low copper content in ASTM A 508 class 3 forging material can be expected to result in small shifts of the transition toughness curve. The shifts due to neutron irradiation of the lower bound and mean toughness curves are approximately the same as the Charpy V-notch (CVN) 41-J temperature shift. The nine crack-arrest specimens were irradiated at temperatures varying from 243 to 280{degrees}C, and to a fluence varying from 1.7 to 2.7 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV). The test results were normalized to reference values that correspond to those of CVN specimens irradiated at 284{degrees}C to a fluence of 3.2 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV) in the same capsule as the crack-arrest specimens. This adjustment resulted in a shift to lower temperatures of all the data, and in particular moved two data points that appeared to lie close to or lower than the American Society of Mechanical Engineers K{sub la} curve to positions that seemed more reasonable with respect to the remaining data. A special fixture was designed, fabricated, and successfully used in the testing. For reasons explained in the text, special blocks to receive the Oak Ridge National Laboratory clip gage were designed, and greater-than-standard crack-mouth opening displacements measured were accounted for. 24 refs., 13 figs., 12 tabs.

  19. Modeling and Optimization of Direct Chill Casting to Reduce Ingot Cracking

    SciTech Connect (OSTI)

    Das, S.K.; Ningileri, S.; Long, Z.; Saito, K.; Khraisheh, M.; Hassan, M.H.; Kuwana, K.; Han, Q.; Viswanathan, S.; Sabau, A.S.; Clark, J.; Hyrn, J. (ANL)

    2006-08-15

    Approximately 68% of the aluminum produced in the United States is first cast into ingots prior to further processing into sheet, plate, extrusions, or foil. The direct chill (DC) semi-continuous casting process has been the mainstay of the aluminum industry for the production of ingots due largely to its robust nature and relative simplicity. Though the basic process of DC casting is in principle straightforward, the interaction of process parameters with heat extraction, microstructural evolution, and development of solidification stresses is too complex to analyze by intuition or practical experience. One issue in DC casting is the formation of stress cracks [1-15]. In particular, the move toward larger ingot cross-sections, the use of higher casting speeds, and an ever-increasing array of mold technologies have increased industry efficiencies but have made it more difficult to predict the occurrence of stress crack defects. The Aluminum Industry Technology Roadmap [16] has recognized the challenges inherent in the DC casting process and the control of stress cracks and selected the development of 'fundamental information on solidification of alloys to predict microstructure, surface properties, and stresses and strains' as a high-priority research need, and the 'lack of understanding of mechanisms of cracking as a function of alloy' and 'insufficient understanding of the aluminum solidification process', which is 'difficult to model', as technology barriers in aluminum casting processes. The goal of this Aluminum Industry of the Future (IOF) project was to assist the aluminum industry in reducing the incidence of stress cracks from the current level of 5% to 2%. Decreasing stress crack incidence is important for improving product quality and consistency as well as for saving resources and energy, since considerable amounts of cast metal could be saved by eliminating ingot cracking, by reducing the scalping thickness of the ingot before rolling, and by eliminating butt sawing. Full-scale industrial implementation of the results of the proposed research would lead to energy savings in excess of 6 trillion Btu by the year 2020. The research undertaken in this project aimed to achieve this objective by a collaboration of industry, university, and national laboratory personnel through Secat, Inc., a consortium of aluminum companies. During the four-year project, the industrial partners and the research team met in 16 quarterly meetings to discuss research results and research direction. The industrial partners provided guidance, facilities, and experience to the research team. The research team went to two industrial plants to measure temperature distributions in commercial 60,000-lb DC casting ingot production. The project focused on the development of a fundamental understanding of ingot cracking and detailed models of thermal conditions, solidification, microstructural evolution, and stress development during the initial transient in DC castings of the aluminum alloys 3004 and 5182. The microstructure of the DC casting ingots was systematically characterized. Carefully designed experiments were carried out at the national laboratory and university facilities as well as at the industrial locations using the industrial production facilities. The advanced computational capabilities of the national laboratories were used for thermodynamic and kinetic simulations of phase transformation, heat transfer and fluid flow, solidification, and stress-strain evolution during DC casting. The achievements of the project are the following: (1) Identified the nature of crack formation during DC casting; (2) Developed a novel method for determining the mechanical properties of an alloy at the nonequilibrium mushy zone of the alloy; (3) Measured heat transfer coefficients (HTCs) between the solidifying ingot and the cooling water jet; (4) Determined the material constitutive model at high temperatures; and (5) Developed computational capabilities for the simulation of cracking formation in DC casting ingot. The models and the database de

  20. ht.I. EngngSri.1975,Vol.13,pp.815-829.PcrgamonPress. Printedin GrealBritain THE PENNY-SHAPED CRACK IN SHEAR AND

    E-Print Network [OSTI]

    Barber, James R.

    ht.I. EngngSri.1975,Vol.13,pp.815-829.PcrgamonPress. Printedin GrealBritain THE PENNY-SHAPED CRACK. The solution is used to solve the problem of the penny-shaped crack subjected to an arbitrary and to the penny-shaped crack inuniformshearandintorsionabouta diametralaxis. 1. INTRODUCTION IN A PREVIOUS paper

  1. Simultaneous boiling and spreading of liquefied petroleum gas on water. Final report, December 12, 1978-March 31, 1981

    SciTech Connect (OSTI)

    Chang, H.R.; Reid, R.C.

    1981-04-01

    An experimental and theoretical investigation was carried out to study the boiling and spreading of liquid nitrogen, liquid methane and liquefied petroleum gas (LPG) on water in a one-dimensional configuration. Primary emphasis was placed on the LPG studies. Experimental work involved the design and construction of a spill/spread/boil apparatus which permitted the measurement of spreading and local boil-off rates. With the equations of continuity and momentum transfer, a mathematical model was developed to describe the boiling-spreading phenomena of cryogens spilled on water. The model accounted for a decrease in the density of the cryogenic liquid due to bubble formation. The boiling and spreading rates of LPG were found to be the same as those of pure propane. An LPG spill was characterized by the very rapid and violent boiling initially and highly irregular ice formation on the water surface. The measured local boil-off rates of LPG agreed reasonably well with theoretical predictions from a moving boundary heat transfer model. The spreading velocity of an LPG spill was found to be constant and determined by the size of the distributor opening. The maximum spreading distance was found to be unaffected by the spilling rate. These observations can be explained by assuming that the ice formation on the water surface controls the spreading of LPG spills. While the mathematical model did not predict the spreading front adequately, it predicted the maximum spreading distance reasonably well.

  2. Melt spreading code assessment, modifications, and application to the EPR core catcher design.

    SciTech Connect (OSTI)

    Farmer, M. T .; Nuclear Engineering Division

    2009-03-30

    The Evolutionary Power Reactor (EPR) is under consideration by various utilities in the United States to provide base load electrical production, and as a result the design is undergoing a certification review by the U.S. Nuclear Regulatory Commission (NRC). The severe accident design philosophy for this reactor is based upon the fact that the projected power rating results in a narrow margin for in-vessel melt retention by external cooling of the reactor vessel. As a result, the design addresses ex-vessel core melt stabilization using a mitigation strategy that includes: (1) an external core melt retention system to temporarily hold core melt released from the vessel; (2) a layer of 'sacrificial' material that is admixed with the melt while in the core melt retention system; (3) a melt plug in the lower part of the retention system that, when failed, provides a pathway for the mixture to spread to a large core spreading chamber; and finally, (4) cooling and stabilization of the spread melt by controlled top and bottom flooding. The overall concept is illustrated in Figure 1.1. The melt spreading process relies heavily on inertial flow of a low-viscosity admixed melt to a segmented spreading chamber, and assumes that the melt mass will be distributed to a uniform height in the chamber. The spreading phenomenon thus needs to be modeled properly in order to adequately assess the EPR design. The MELTSPREAD code, developed at Argonne National Laboratory, can model segmented, and both uniform and nonuniform spreading. The NRC is thus utilizing MELTSPREAD to evaluate melt spreading in the EPR design. MELTSPREAD was originally developed to support resolution of the Mark I containment shell vulnerability issue. Following closure of this issue, development of MELTSPREAD ceased in the early 1990's, at which time the melt spreading database upon which the code had been validated was rather limited. In particular, the database that was utilized for initial validation consisted of: (1) comparison to an analytical solution for the dam break problem, (2) water spreading tests in a 1/10 linear scale model of the Mark I containment by Theofanous et al., and (3) steel spreading tests by Suzuki et al. that were also conducted in a geometry similar to the Mark I. The objective of this work was to utilize the MELTSPREAD code to check the assumption of uniform melt spreading in the EPR core catcher design. As a starting point for the project, the code was validated against the worldwide melt spreading database that emerged after the code was originally written in the very early 1990's. As part of this exercise, the code was extensively modified and upgraded to incorporate findings from these various analytical and experiment programs. In terms of expanding the ability of the code to analyze various melt simulant experiments, the options to input user-specified melt and/or substrate material properties was added. The ability to perform invisicid and/or adiabatic spreading analysis was also added so that comparisons with analytical solutions and isothermal spreading tests could be carried out. In terms of refining the capability to carry out reactor material melt spreading analyses, the code was upgraded with a new melt viscosity model; the capability was added to treat situations in which solid fraction buildup between the liquidus-solidus is non-linear; and finally, the ability to treat an interfacial heat transfer resistance between the melt and substrate was incorporated. This last set of changes substantially improved the predictive capability of the code in terms of addressing reactor material melt spreading tests. Aside from improvements and upgrades, a method was developed to fit the model to the various melt spreading tests in a manner that allowed uncertainties in the model predictions to be statistically characterized. With these results, a sensitivity study was performed to investigate the assumption of uniform spreading in the EPR core catcher that addressed parametric variations in: (1) melt pour mass, (2) melt composition, (3) me

  3. Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals

    DOE Patents [OSTI]

    Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A

    2014-10-14

    A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

  4. Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals

    DOE Patents [OSTI]

    Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A

    2014-05-20

    A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.

  5. Events Determine Spreading Patterns: Information Transmission via Internal and External Influences on Social Networks

    E-Print Network [OSTI]

    Liu, Chuang; Zhang, Zi-Ke; Sun, Gui-Quan; Hui, Pak Ming

    2015-01-01

    Recently, information transmission models motivated by the classical epidemic propagation, have been applied to a wide-range of social systems, generally assume that information mainly transmits among individuals via peer-to-peer interactions on social networks. In this paper, we consider one more approach for users to get information: the out-of-social-network influence. Empirical analyses of eight typical events' diffusion on a very large micro-blogging system, \\emph{Sina Weibo}, show that the external influence has significant impact on information spreading along with social activities. In addition, we propose a theoretical model to interpret the spreading process via both internal and external channels, considering three essential properties: (i) memory effect; (ii) role of spreaders; and (iii) non-redundancy of contacts. Experimental and mathematical results indicate that the information indeed spreads much quicker and broader with mutual effects of the internal and external influences. More importantly...

  6. Methods and apparatuses for self-generating fault-tolerant keys in spread-spectrum systems

    DOE Patents [OSTI]

    Moradi, Hussein; Farhang, Behrouz; Subramanian, Vijayarangam

    2015-12-15

    Self-generating fault-tolerant keys for use in spread-spectrum systems are disclosed. At a communication device, beacon signals are received from another communication device and impulse responses are determined from the beacon signals. The impulse responses are circularly shifted to place a largest sample at a predefined position. The impulse responses are converted to a set of frequency responses in a frequency domain. The frequency responses are shuffled with a predetermined shuffle scheme to develop a set of shuffled frequency responses. A set of phase differences is determined as a difference between an angle of the frequency response and an angle of the shuffled frequency response at each element of the corresponding sets. Each phase difference is quantized to develop a set of secret-key quantized phases and a set of spreading codes is developed wherein each spreading code includes a corresponding phase of the set of secret-key quantized phases.

  7. Methods and apparatuses for self-generating fault-tolerant keys in spread-spectrum systems

    DOE Patents [OSTI]

    Moradi, Hussein; Farhang, Behrouz; Subramanian, Vijayarangam

    2015-12-22

    Self-generating fault-tolerant keys for use in spread-spectrum systems are disclosed. At a communication device, beacon signals are received from another communication device and impulse responses are determined from the beacon signals. The impulse responses are circularly shifted to place a largest sample at a predefined position. The impulse responses are converted to a set of frequency responses in a frequency domain. The frequency responses are shuffled with a predetermined shuffle scheme to develop a set of shuffled frequency responses. A set of phase differences is determined as a difference between an angle of the frequency response and an angle of the shuffled frequency response at each element of the corresponding sets. Each phase difference is quantized to develop a set of secret-key quantized phases and a set of spreading codes is developed wherein each spreading code includes a corresponding phase of the set of secret-key quantized phases.

  8. Use of incomplete energy recovery for the energy compression of large energy spread charged particle beams

    DOE Patents [OSTI]

    Douglas, David R. (Newport News, VA); Benson, Stephen V. (Yorktown, VA)

    2007-01-23

    A method of energy recovery for RF-base linear charged particle accelerators that allows energy recovery without large relative momentum spread of the particle beam involving first accelerating a waveform particle beam having a crest and a centroid with an injection energy E.sub.o with the centroid of the particle beam at a phase offset f.sub.o from the crest of the accelerating waveform to an energy E.sub.full and then recovering the beam energy centroid a phase f.sub.o+Df relative to the crest of the waveform particle beam such that (E.sub.full-E.sub.o)(1+cos(f.sub.o+Df))>dE/2 wherein dE=the full energy spread, dE/2=the full energy half spread and Df=the wave form phase distance.

  9. Creep and Creep-Fatigue Crack Growth at Structural Discontinuities and Welds

    SciTech Connect (OSTI)

    Dr. F. W. Brust; Dr. G. M. Wilkowski; Dr. P. Krishnaswamy; Mr. Keith Wichman

    2010-01-27

    The subsection ASME NH high temperature design procedure does not admit crack-like defects into the structural components. The US NRC identified the lack of treatment of crack growth within NH as a limitation of the code and thus this effort was undertaken. This effort is broken into two parts. Part 1, summarized here, involved examining all high temperature creep-fatigue crack growth codes being used today and from these, the task objective was to choose a methodology that is appropriate for possible implementation within NH. The second part of this task, which has just started, is to develop design rules for possible implementation within NH. This second part is a challenge since all codes require step-by-step analysis procedures to be undertaken in order to assess the crack growth and life of the component. Simple rules for design do not exist in any code at present. The codes examined in this effort included R5, RCC-MR (A16), BS 7910, API 579, and ATK (and some lesser known codes). There are several reasons that the capability for assessing cracks in high temperature nuclear components is desirable. These include: (1) Some components that are part of GEN IV reactors may have geometries that have sharp corners - which are essentially cracks. Design of these components within the traditional ASME NH procedure is quite challenging. It is natural to ensure adequate life design by modeling these features as cracks within a creep-fatigue crack growth procedure. (2) Workmanship flaws in welds sometimes occur and are accepted in some ASME code sections. It can be convenient to consider these as flaws when making a design life assessment. (3) Non-destructive Evaluation (NDE) and inspection methods after fabrication are limited in the size of the crack or flaw that can be detected. It is often convenient to perform a life assessment using a flaw of a size that represents the maximum size that can elude detection. (4) Flaws that are observed using in-service detection methods often need to be addressed as plants age. Shutdown inspection intervals can only be designed using creep and creep-fatigue crack growth techniques. (5) The use of crack growth procedures can aid in examining the seriousness of creep damage in structural components. How cracks grow can be used to assess margins on components and lead to further safe operation. After examining the pros and cons of all these methods, the R5 code was chosen as the most up-to-date and validated high temperature creep and creep fatigue code currently used in the world at present. R5 is considered the leader because the code: (1) has well established and validated rules, (2) has a team of experts continually improving and updating it, (3) has software that can be used by designers, (4) extensive validation in many parts with available data from BE resources as well as input from Imperial college's database, and (5) was specifically developed for use in nuclear plants. R5 was specifically developed for use in gas cooled nuclear reactors which operate in the UK and much of the experience is based on materials and temperatures which are experienced in these reactors. If the next generation advanced reactors to be built in the US used these same materials within the same temperature ranges as these reactors, then R5 may be appropriate for consideration of direct implementation within ASME code NH or Section XI. However, until more verification and validation of these creep/fatigue crack growth rules for the specific materials and temperatures to be used in the GEN IV reactors is complete, ASME should consider delaying this implementation. With this in mind, it is this authors opinion that R5 methods are the best available for code use today. The focus of this work was to examine the literature for creep and creep-fatigue crack growth procedures that are well established in codes in other countries and choose a procedure to consider implementation into ASME NH. It is very important to recognize that all creep and creep fatigue crack growth procedures that are part of high temperature

  10. Predictive study on the risk of malaria spreading due to global warming

    SciTech Connect (OSTI)

    Ono, Masaji

    1996-12-31

    Global warming will bring about a temperature elevation, and the habitat of vectors of infectious diseases, such as malaria and dengue fever, will spread into subtropical or temperate zone. The purpose of this study is to simulate the spreading of these diseases through reexamination of existing data and collection of some additional information by field survey. From these data, the author will establish the relationship between meteorological conditions, vector density and malaria occurrence. And then he will simulate and predict the malaria epidemics in case of temperature elevation in southeast Asia and Japan.

  11. An investigation of penetrant techniques for detection of machining-induced surface-breaking cracks on monolithic ceramics

    SciTech Connect (OSTI)

    Forster, G.A.; Ellingson, W.A.

    1996-02-01

    The purpose of this effort was to evaluate penetrant methods for their ability to detect surface-breaking cracks in monolithic ceramic materials with an emphasis on detection of cracks generated by machining. There are two basic penetrant types, visible and fluorescent. The visible penetrant method is usually augmented by powder developers and cracks detected can be seen in visible light. Cracks detected by fluorescent penetrant are visible only under ultraviolet light used with or without a developer. The developer is basically a powder that wicks up penetrant from a crack to make it more observable. Although fluorescent penetrants were recommended in the literature survey conducted early in this effort, visible penetrants and two non-standard techniques, a capillary gaseous diffusion method under development at the institute of Chemical Physics in Moscow, and the {open_quotes}statiflux{close_quotes} method which involves use of electrically charged particles, were also investigated. SiAlON ring specimens (1 in. diameter, 3/4 in. wide) which had been subjected to different thermal-shock cycles were used for these tests. The capillary gaseous diffusion method is based on ammonia; the detector is a specially impregnated paper much like litmus paper. As expected, visible dye penetrants offered no detection sensitivity for tight, surface-breaking cracks in ceramics. Although the non-standard statiflux method showed promise on high-crack-density specimens, it was ineffective on limited-crack-density specimens. The fluorescent penetrant method was superior for surface-breaking crack detection, but successful application of this procedure depends greatly on the skill of the user. Two presently available high-sensitivity fluorescent penetrants were then evaluated for detection of microcracks on Si{sub 3}N{sub 4} and SiC from different suppliers. Although 50X optical magnification may be sufficient for many applications, 200X magnification provides excellent delectability.

  12. In-Line Crack and Stress Detection in Silicon Solar Cells Using Resonance Ultrasonic Vibrations

    SciTech Connect (OSTI)

    Ostapenko, Sergei

    2013-04-03

    Statement of Problem and Objectives. Wafer breakage in automated solar cell production lines is identified as a major technical problem and a barrier for further cost reduction of silicon solar module manufacturing. To the best of our knowledge, there are no commercial systems addressing critical needs for in-line inspection of the mechanical quality of solar wafers and cells. The principal objective of the SBIR program is to validate through experiments and computer modeling the applicability of the Resonance Ultrasonic Vibrations system, which ultimately can be used as a real-time in-line manufacturing quality control tool for fast detection of mechanically unstable silicon solar cells caused by cracks. The specific objective of Phase II is to move the technology of in-line crack detection from the laboratory level to commercial demonstration through development of a system prototype. The fragility of silicon wafers possessing low mechanical strength is attributed to peripheral and bulk millimeter-length cracks. The research program is based on feasibility results obtained during Phase I, which established that: (i) the Resonance Ultrasonic Vibrations method is applicable to as-cut, processed wafers and finished cells; (ii) the method sensitivity depends on the specific processing step; it is highest in as-cut wafers and lowest in wafers with metallization pattern and grid contacts; (iii) the system is capable of matching the 2.0 seconds per wafer throughput rate of state-of-art solar cell production lines; (iv) finite element modeling provides vibration mode analysis along with peak shift versus crack length and crack location dependence; (v) a high 91% crack rejection rate was confirmed through experimentation and statistical analysis. The Phase II project has the following specific tasks: (i) specify optimal configurations of the in-line system�¢����s component hardware and software; (ii) develop and justify a system prototype that meets major specifications for an in-line crack detection unit, such as high throughput rate, high level of stability, reproducibility of data acquisition and analysis, and high sensitivity with respect to crack length and crack location; (iii) design a system platform that allows easy integration within and adaptation to various solar cell belt-type production lines; (iv) develop a testing protocol providing quality certification of the production-grade system. Commercial Application of the proposed activity consists of bringing to the solar market a new high-tech product based on an innovative solution and patented methodology to contribute to cost reduction of silicon solar module production. The solar industry, with crystalline silicon as a dominant segment, shows outstanding performance, with approximately 25% yearly growth during the last years. Despite a slowdown with only 5.6 GW installations in 2009, solar module production for the 2010 and 2011 years was recovered. According to European Photonics Industry Consortium new solar PV installations grow by 56% compared to 2010 reached 64.7 GW in 2011. Revenues in the PV industry reached a record high of $93 billion in 2011, a 13.4 percent gain over 2010 â�� and 150 percent over 2009. This growth was forecasted to continue in 2013 with double digits growth. The solar industry is economically driven to make solar panels of the highest conversion efficiency and reliability at the lowest production cost. The Resonance Ultrasonic Vibration system addresses critical needs of the silicon-based solar industry by providing a quality control method and tool, which will improve productivity, increase reliability of products and reduce manufacturing cost of solar panels.

  13. Laminin isoforms differentially regulate adhesion, spreading, proliferation, and ERK activation of h1 integrin-null cells

    E-Print Network [OSTI]

    Campbell, Kevin P.

    Laminin isoforms differentially regulate adhesion, spreading, proliferation, and ERK activation signal-regulated kinase (ERK) activation, whereas all these responses occurred in response to adhesion

  14. Environmentally assisted cracking in light water reactors : semiannual report, July 2000 - December 2000.

    SciTech Connect (OSTI)

    Chopra, O. K.; Chung, H. M.; Gruber, E. E.; Shack, W. J.; Soppet, W. K.; Strain, R. V.; Energy Technology

    2002-04-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from July 2000 to December 2000. Topics that have been investigated include (a) environmental effects on fatigue S-N behavior of primary pressure boundary materials, (b) irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels (SSs), and (c) EAC of Alloys 600 and 690. The fatigue strain-vs.-life data are summarized for the effects of various material, loading, and environmental parameters on the fatigue lives of carbon and low-alloy steels and austenitic SSs. Effects of the reactor coolant environment on the mechanism of fatigue crack initiation are discussed. Two methods for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations are presented. Slow-strain-rate tensile tests and posttest fractographic analyses were conducted on several model SS alloys irradiated to {approx}0.9 x 10{sup 21} n {center_dot} cm{sup -2} (E > 1 MeV) in He at 289 C in the Halden reactor. The results were used to determine the influence of alloying and impurity elements on the susceptibility of these steels to IASCC. A fracture toughness J-R curve test was conducted on a commercial heat of Type 304 SS that was irradiated to {approx}2.0 x 10{sup 21} n {center_dot} cm{sup -2} in the Halden reactor. The results were compared with the data obtained earlier on steels irradiated to 0.3 and 0.9 x 10{sup 21} n {center_dot} cm{sup -2} (E > 1 MeV) (0.45 and 1.35 dpa). Neutron irradiation at 288 C was found to decrease the fracture toughness of austenitic SSs. Tests were conducted on compact-tension specimens of Alloy 600 under cyclic loading to evaluate the enhancement of crack growth rates in LWR environments. Then, the existing fatigue crack growth data on Alloys 600 and 690 were analyzed to establish the effects of temperature, load ratio, frequency, and stress intensity range on crack growth rates in air.

  15. 1 Spreading and convective dissolution of carbon dioxide in vertically 2 confined, horizontal aquifers

    E-Print Network [OSTI]

    Neufeld, Jerome A.

    1 Spreading and convective dissolution of carbon dioxide in vertically 2 confined, horizontal] Injection of carbon dioxide (CO2) into saline aquifers is a promising tool for reducing 6 anthropogenic CO2 emissions. At reservoir conditions, the injected CO2 is buoyant relative 7 to the ambient groundwater

  16. Spreading and convective dissolution of carbon dioxide in vertically confined, horizontal aquifers

    E-Print Network [OSTI]

    Huppert, Herbert

    Spreading and convective dissolution of carbon dioxide in vertically confined, horizontal aquifers of carbon dioxide (CO2) into saline aquifers is a promising tool for reducing anthropogenic CO2 emissions. At reservoir conditions, the injected CO2 is buoyant relative to the ambient groundwater. The buoyant plume

  17. ORIGINAL PAPER Predicting regional spread of non-native species using

    E-Print Network [OSTI]

    Dhindsa, Rajinder

    that are transported by ocean currents. Given the importance of currents in steering these propagules, ocean- ographic- ingly made use of oceanographic circulation models to estimate currents and track species dispersal models designed to estimate and forecast currents could be valuable for forecasting the spread (Queiroga

  18. EXPERIMENTAL STUDY OF ENERGY SPREAD IN A SPACE-CHARGE DOMINATED ELECTRON BEAM *

    E-Print Network [OSTI]

    Valfells, Ágúst

    EXPERIMENTAL STUDY OF ENERGY SPREAD IN A SPACE-CHARGE DOMINATED ELECTRON BEAM * Y. Cui , Y. Zou, A. Experimental Setup Electron Beam Ground Shielding High Voltage Cylinder Retarding Mesh Collector High Voltage. Valfells, I. Haber, R. Kishek, M. Reiser, P. G. O'Shea Institute for Research in Electronics and Applied

  19. Assessing fire risk using Monte Carlo simulations of fire spread Yohay Carmel a,

    E-Print Network [OSTI]

    Assessing fire risk using Monte Carlo simulations of fire spread Yohay Carmel a, *, Shlomit Paz b of Haifa, Haifa, Israel 1. Introduction Fires are a major source of forest destruction in the Mediterranean., 2000). Mediterranean fires are largely determined by climatic conditions; long, dry summers with high

  20. Spreading of the Free Boundary of an Ideal Fluid in a Vacuum

    E-Print Network [OSTI]

    Bigelow, Stephen

    Spreading of the Free Boundary of an Ideal Fluid in a Vacuum Thomas C. Sideris Department by an ideal fluid surrounded by vacuum will be shown to grow linearly in time provided the pressure an ideal fluid occupying a bounded region in space surrounded by vacuum. The boundary of this region

  1. Job Opportunities through Entertainment: Virally Spread Speech-Based Services for Low-Literate Users

    E-Print Network [OSTI]

    Lahore Uni. of Mgmt. Sciences Lahore, Pakistan {farhan.haq, zain.tariq, umar}@lums.edu.pk ABSTRACT We in 2011, we report on its first large-scale sustained deployment. In 24/7 operation in Pakistan since May among low- skilled office workers in Lahore, Pakistan, in 3 weeks Polly spread to 2,000 users and logged

  2. The reciprocity properties of geometrical spreading Roel Snieder1,2

    E-Print Network [OSTI]

    Snieder, Roel

    , the acoustic wave equation or the elastic wave equation satisfy reciprocity. This implies that when a point-geometric approximation of the acoustic wave equation satis¢es reciprocity. The analysis is based on the equations for the geometrical spreading for the acoustic wave equation therefore also hold for the elastic wave equation

  3. Dynamics of capillary spreading along hydrophilic microstripes Anton A. Darhuber and Sandra M. Troian*

    E-Print Network [OSTI]

    Troian, Sandra M.

    interesting approaches for fluid migration and flow control in confining networks. The capillary spreading of liquids on corrugated surfaces can be enhanced by capillary migration and wicking into narrow surface speed as a function of distance is proportional to the groove depth 12,15 . In this paper we consider

  4. Block Spreading for MUI/ISI-Resilient Generalized Multi-carrier CDMA with Multirate Capabilities

    E-Print Network [OSTI]

    Giannakis, Georgios

    1 of 5 Block Spreading for MUI/ISI-Resilient Generalized Multi-carrier CDMA with Multirate) and intersymbol interference (ISI) arising due to wireless multipath propagation, motivate well multirate wideband Quality of Service (QoS) and rate- scalability, have low complexity, and exhibit resilience to MUI and ISI

  5. Recent Advances in Modelling of Liquefaction and Lateral Spreading S.P.G. Madabhushi*

    E-Print Network [OSTI]

    Haigh, Stuart

    59 Recent Advances in Modelling of Liquefaction and Lateral Spreading S.P.G. Madabhushi* , B Teymur, SK Haigh and AJ Brennan Department of Engineering, Schofield Centrifuge Centre, University of Cambridge, CB2 1PZ, UNITED KINGDOM, mspg1@eng.cam.ac.uk Use of geotechnical centrifuges to investigate

  6. A simple bioclogging model that accounts for spatial spreading of bacteria

    E-Print Network [OSTI]

    Demaret, Laurent

    A simple bioclogging model that accounts for spatial spreading of bacteria HJ Eberla , L Demaretb is presented that accounts for spatial expansion of the bacterial popu- lation in the soil. The bacteria move harmful environ- mental factors and mechanical washout. Naturally occurring bacteria are a major

  7. Yarkovsky-Driven Spreading of the Eureka Family of Mars Trojans Matija Cuk1

    E-Print Network [OSTI]

    Yarkovsky-Driven Spreading of the Eureka Family of Mars Trojans Matija ´Cuk1 , Apostolos A orbital grouping that was affected by a negative acceleration (i.e. one against the orbital motion above about 25 (Murray and Dermott, 1999). In our Solar System, only Jupiter, Neptune and Mars are known

  8. LONG EXPOSURE POINT SPREAD FUNCTION ESTIMATION FROM SOLAR ADAPTIVE OPTICS LOOP DATA

    E-Print Network [OSTI]

    Astronomer, National Solar Observatory, New Mexico, USA Dr. Haimin Wang, Dissertation Co-Advisor DateABSTRACT LONG EXPOSURE POINT SPREAD FUNCTION ESTIMATION FROM SOLAR ADAPTIVE OPTICS LOOP DATA during solar observations due to the lack of point sources in the field-of-view. Moreover, the highly

  9. EECE 595: SPREAD SPECTRUM COMMUNICATIONS 1 Distributed Power Control in CDMA Cellular

    E-Print Network [OSTI]

    station will corrupt the other signals. Another reason for power control is the battery life time. High of each mobile station. The transmission power of the mobile stations is determined solely on localEECE 595: SPREAD SPECTRUM COMMUNICATIONS 1 Distributed Power Control in CDMA Cellular System Aly El

  10. FireStream: Sensor Stream Processing for Monitoring Fire Spread Venkatesh Raghavan1

    E-Print Network [OSTI]

    locations required for spatial analysis, the Sen- sor Store, a collection of metadata pertinent to sensorsFireStream: Sensor Stream Processing for Monitoring Fire Spread Venkatesh Raghavan1 , ElkeStream, a sensor stream processing system which provides services for run-time de- tection, monitoring

  11. Lifeasweknowit To understand the human genome, researchers must spread their wings to all branches of life.

    E-Print Network [OSTI]

    Pratt, Vaughan

    and a worm to its ENCODE project, which aims to catalogue all the functional parts of the human genome is moving more forcefully into purely human genomics. The biggest new projects recently announcedLifeasweknowit To understand the human genome, researchers must spread their wings to all branches

  12. New Florida Cattle Identification Program to Protect Florida's Cattle Industry; Mitigate Spread of Disease

    E-Print Network [OSTI]

    Hill, Jeffrey E.

    New Florida Cattle Identification Program to Protect Florida's Cattle Industry; Mitigate Spread. In the past, Florida cattle have struggled with animal disease outbreaks, such as Brucellosis and Tuberculosis and those diseases, present in other states, still threaten our cattle today. The Florida Department

  13. Successful spread of a biocontrol agent reveals a biosecurity failure: elucidating long distance invasion pathways

    E-Print Network [OSTI]

    Hoddle, Mark S.

    Successful spread of a biocontrol agent reveals a biosecurity failure: elucidating long distance to successful invasion. In this study, the dispersal of a classical biological control agent, the mymarid egg. Survey results suggest that invasive orga- nisms, like deliberately released biological control agents

  14. Doppler Spread Estimation for Wireless OFDM Tevfik Yucek, Ramy M. A. Tannious, and Huseyin Arslan

    E-Print Network [OSTI]

    Arslan, Hüseyin

    and signal-to-noise ratio (SNR) values in Rayleigh fading channels. I. INTRODUCTION OFDM has been applied and licensed-exempt bands, various delay spreads, asymmetric traffic loads in downlink and uplink and wide considerably within one OFDM symbol because of high MSS mobility, orthogonality between subcarriers is lost

  15. Observation of the spread of slow deformation in Greece following the breakup of the slab

    E-Print Network [OSTI]

    Cerveny, Vlastislav

    Observation of the spread of slow deformation in Greece following the breakup of the slab Virginie Engineering, ITSAK, Thessaloniki, Greece, 4 Université de Savoie, ISTerre, Le Bourget du Lac, France, 5 analyze here a "storm" of earthquakes in Greece and show that their interaction provides remarkable

  16. The Power of a Good Idea: Quantitative Modeling of the Spread of Ideas from Epidemiological Models

    SciTech Connect (OSTI)

    Bettencourt, L. M. A. (LANL); Cintron-Arias, A. (Cornell University); Kaiser, D. I. (MIT); Castillo-Chavez, C. (Arizona State University)

    2005-05-05

    The population dynamics underlying the diffusion of ideas hold many qualitative similarities to those involved in the spread of infections. In spite of much suggestive evidence this analogy is hardly ever quantified in useful ways. The standard benefit of modeling epidemics is the ability to estimate quantitatively population average parameters, such as interpersonal contact rates, incubation times, duration of infectious periods, etc. In most cases such quantities generalize naturally to the spread of ideas and provide a simple means of quantifying sociological and behavioral patterns. Here we apply several paradigmatic models of epidemics to empirical data on the advent and spread of Feynman diagrams through the theoretical physics communities of the USA, Japan, and the USSR in the period immediately after World War II. This test case has the advantage of having been studied historically in great detail, which allows validation of our results. We estimate the effectiveness of adoption of the idea in the three communities and find values for parameters reflecting both intentional social organization and long lifetimes for the idea. These features are probably general characteristics of the spread of ideas, but not of common epidemics.

  17. Examination of wind speed thresholds for vorticity-driven lateral fire spread

    E-Print Network [OSTI]

    Evans, Jason

    , to specifically consider the effect of wind speed in generating the fire-induced vorticity necessary to drive wind speed, below which the prevailing winds are too weak to drive the vorticity-generating interactionExamination of wind speed thresholds for vorticity-driven lateral fire spread J.J. Sharples a , C

  18. Surprising spread of volcanic ash key to solving Earth's mysteries: U of A grad

    E-Print Network [OSTI]

    Wang, Hao "Howard"

    Surprising spread of volcanic ash key to solving Earth's mysteries: U of A grad EDMONTON Volcanic ash, which can provide valuable snapshots of Earth's history, appears to drift much farther than of science that uses layers of "tephra," or ash, to link and date events in Earth's history. When a volcano

  19. A Spreading Activation Framework for Ontology-enhanced Adaptive Information Access

    E-Print Network [OSTI]

    A Spreading Activation Framework for Ontology-enhanced Adaptive Information Access Md Maruf Hasan for Ontology-enhanced Adaptive Information Access Md Maruf Hasan, Enrico Motta, John B. Domingue, Simon. Expert's feedback is captured and the network weights are continuously adapted. This framework

  20. Wakefield Induced Correlated Energy Spread and Emittance Growth at TTF FEL

    E-Print Network [OSTI]

    1 Wakefield Induced Correlated Energy Spread and Emittance Growth at TTF FEL Feng ZHOU DESY) at DESY. During FEL operations, the longitudinal and transverse wakefields which are generated by vacuum and emittance growth at the TTF FEL of phase I and II. 1 Introduction The Free Electron Laser at the TESLA Test

  1. Chemical Wave Packet Propagation, Reflection, and Spreading Lingfa Yang and Irving R. Epstein*

    E-Print Network [OSTI]

    Epstein, Irving R.

    or away from an initiating perturbation, are found in a reaction-diffusion model with a finite wave. The phase velocity, group velocity, and spreading velocity calculated by linear stability analysis packets in reaction-diffusion systems are rarely seen, even though wave packets have been intensively

  2. Chemical Wave Packet Propagation, Reflection, and Spreading Lingfa Yang and Irving R. Epstein*

    E-Print Network [OSTI]

    Yang, Lingfa

    Chemical Wave Packet Propagation, Reflection, and Spreading Lingfa Yang and Irving R. Epstein 02454-9110 ReceiVed: May 8, 2002; In Final Form: July 10, 2002 Chemical waves can travel in well-defined packets. Two types of phase wave packets, distinguished by whether their component waves move toward

  3. Icelandic rhythmics: Annual modulation of land elevation and plate spreading by snow load

    E-Print Network [OSTI]

    Grapenthin, Ronni

    Icelandic rhythmics: Annual modulation of land elevation and plate spreading by snow load Ronni to annual snow load in Iceland. The load is modeled using Green's functions for an elastic halfspace and a simple sinusoidal load history on Iceland's four largest ice caps. We derive E = 40 ± 15 GPa as a minimum

  4. Energy Loss and Energy Spread Growth in a Planar Undulator(LCC-0086)

    SciTech Connect (OSTI)

    Sheppard, J

    2003-10-07

    The change in beam energy spread due to transmission through a long, planar undulator is calculated. This change is shown to be gaussian as expected from the central limit theorem and large number of photons emitted per electron. These results are compared with Saldin et al. [2] expressions. Numerical results for the case of the TESLA beam and for an NLC beam are given.

  5. ORIGINAL PAPER Species diversity and drivers of spread of alien fungi

    E-Print Network [OSTI]

    ORIGINAL PAPER Species diversity and drivers of spread of alien fungi (sensu lato) in Europe February 2009 Ó Springer Science+Business Media B.V. 2009 Abstract A first comprehensive inventory of alien at the two spatial scales. Some taxonomic/phylogenetic orders were shown to be over-represented in alien

  6. Spreading of EGF Receptor Activity into EGF-free Regions and Molecular Therapies of Cancer

    E-Print Network [OSTI]

    Garrit Jentsch; Reiner Kree

    2008-03-18

    The primary activation of the epidermal growth factor receptor (EGFR) has become a prominent target for molecular therapies against several forms of cancer. But despite considerable progress during the last years, many of its aspects remain poorly understood. Experiments on lateral spreading of receptor activity into ligand-free regions challenge the current standard models of EGFR activation. Here, we propose and study a theoretical model, which explains spreading into ligand-free regions without introducing any new, unknown kinetic parameters. The model exhibits bistability of activity, induced by a generic reaction mechanism, which consists of activation via dimerization and deactivation via a Michaelis-Menten reaction. It possesses slow propagating front solutions and faster initial transients. We analyze relevant experiments and find that they are in quantitative accordance with the fast initial modes of spreading, but not with the slow propagating front. We point out that lateral spreading of activity is linked to pathological levels of persistent receptor activity as observed in cancer cells and exemplify uses of this link for the design and quick evaluation of molecular therapies targeting primary activation of EGFR.

  7. Observational Estimates of Entrainment and Vertical Salt Flux in the Interior of a Spreading River Plume

    E-Print Network [OSTI]

    MacCready, Parker

    Observational Estimates of Entrainment and Vertical Salt Flux in the Interior of a Spreading River@ocean.washington.edu #12;Abstract: Observational estimates of entrainment and vertical salt flux into the tidally- pulsed are used to determine the plume depth and entrainment velocity throughout the experiment. This approach

  8. Hurricane Activity and the Large-Scale Pattern of Spread of an Invasive Plant Species

    E-Print Network [OSTI]

    Cronin, James T.

    Hurricane Activity and the Large-Scale Pattern of Spread of an Invasive Plant Species Ganesh P of invasive species. However, the effects of large-scale disturbances, such as hurricanes and tropical storms. australis stands expanded in size by 6­35% per year. Based on tropical storm and hurricane activity over

  9. Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations

    SciTech Connect (OSTI)

    Chakraborty, Manoneeta; Bhattacharyya, Sudip E-mail: sudip@tifr.res.in

    2014-09-01

    Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from 10 neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such a trend. Moreover, it is important to note that an opposite trend is not found in any of the bursts. The concave shape of the fractional amplitude profiles for all the bursts suggests latitude-dependent flame speeds, possibly due to the effects of the Coriolis force. We also systematically study the roles of low fractional amplitude and low count rate for non-detection and intermittent detections of rise oscillations, and attempt to understand them within the flame spreading scenario. Our results support a weak turbulent viscosity for flame spreading, and imply that burst rise oscillations originate from an expanding hot spot, thus making these oscillations a more reliable tool to constrain the neutron star equations of state.

  10. Self-replicating cracks: a collaborative fracture mode in thin films

    E-Print Network [OSTI]

    Joel Marthelot; Benoit Roman; Jose Bico; Jeremie Teisseire; Davy Dalmas; Francisco Melo

    2014-08-20

    Straight cracks are observed in thin coatings under residual tensile stress, resulting into the classical network pattern observed in china crockery, old paintings or dry mud. Here, we present a novel fracture mechanism where delamination and propagation occur simultaneously, leading to the spontaneous self-replication of an initial template. Surprisingly, this mechanism is active below the standard critical tensile load for channel cracks and selects a robust interaction length scale on the order of 30 times the film thickness. Depending on triggering mechanisms, crescent alleys, spirals or long bands are generated over a wide range of experimental parameters. We describe with a simple physical model the selection of the fracture path and provide a configuration diagram displaying the different failure modes.

  11. Stress Corrosion Cracking of Ferritic Materials for Fossil Power Generation Applications

    SciTech Connect (OSTI)

    Pawel, Steven J [ORNL] [ORNL; Siefert, John A. [Electric Power Research Institute (EPRI)] [Electric Power Research Institute (EPRI)

    2014-01-01

    Creep strength enhanced ferritic (CSEF) steels Grades 23, 24, 91, and 92 have been widely implemented in the fossil fired industry for over two decades. The stress corrosion cracking (SCC) behavior of these materials with respect to mainstay Cr-Mo steels (such as Grades 11, 12 and 22) has not been properly assessed, particularly in consideration of recent reported issues of SCC in CSEF steels. This report details the results of Jones test exposures of a wide range of materials (Grades 11, 22, 23, 24, and 92), material conditions (as-received, improper heat treatments, normalized, weldments) and environments (salt fog; tube cleaning environments including decreasing, scale removal, and passivation; and high temperature water) to compare the susceptibility to cracking of these steels. In the as-received (normalized and tempered) condition, none of these materials are susceptible to SCC in the environments examined. However, in the hardened condition, certain combinations of environment and alloy reveal substantial SCC susceptibility.

  12. Microstructure-based approach for predicting crack initiation and early growth in metals.

    SciTech Connect (OSTI)

    Cox, James V.; Emery, John M.; Brewer, Luke N.; Reedy, Earl David, Jr.; Puskar, Joseph David; Bartel, Timothy James; Dingreville, Remi P. M.; Foulk, James W., III; Battaile, Corbett Chandler; Boyce, Brad Lee

    2009-09-01

    Fatigue cracking in metals has been and is an area of great importance to the science and technology of structural materials for quite some time. The earliest stages of fatigue crack nucleation and growth are dominated by the microstructure and yet few models are able to predict the fatigue behavior during these stages because of a lack of microstructural physics in the models. This program has developed several new simulation tools to increase the microstructural physics available for fatigue prediction. In addition, this program has extended and developed microscale experimental methods to allow the validation of new microstructural models for deformation in metals. We have applied these developments to fatigue experiments in metals where the microstructure has been intentionally varied.

  13. Geometric approach to detecting and locating cracks in thin plates by Lamb wave reflection: case of moving transducer

    E-Print Network [OSTI]

    Kreinovich, Vladik

    of structures and mechanisms, such as buildings, heavy machinery, pipes, offshore structures and aircrafts of deterioration. This deterioration can manifest in forms of internal cracking, flaws, corrosion in metallic parts

  14. Irradiation-Assisted Stress Corrosion Cracking of Austenitic Stainless Steels and Alloy 690 from Halden Phase-II Irradiations

    SciTech Connect (OSTI)

    Chen, Y.; Chopra, O. K.; Soppet, W. K.; Dietz Rago, Nancy L.; Shack, W. J.

    2008-09-01

    This work is an ongoing effort at Argonne National Laboratory on the mechanistic study of irradiation-assisted stress corrosion cracking (IASCC) in the core internals of light water reactors.

  15. Spatial Imaging of Cracks in Fiber Reinforced Cementitious Composites by EIT Tsung-Chin Hou, Jerome P. Lynch

    E-Print Network [OSTI]

    Lynch, Jerome P.

    in New York City. INTRODUCTION Cementitious materials, such as reinforced concrete, are widely used energy is primarily dissipated by cracking. In the past three decades, new cementitious materials P. Lynch Synopsis: Cementitious materials are generally classified as semi

  16. A unified method for the analysis of nonlinear viscoelasticity and fatigue cracking of asphalt mixtures using the dynamic mechanical analyzer 

    E-Print Network [OSTI]

    Castelo Branco, Veronica Teixeira Franco

    2009-05-15

    Fatigue cracking is one of the primary modes of distress in asphalt pavements that has an important economic impact. Fatigue resistance characterization of an asphalt mixture is a complex issue due to: (i) composite ...

  17. Prediction of early-age cracking of UHPC materials and structures : a thremo-chemo-mechanics approach

    E-Print Network [OSTI]

    Shim, JongMin, 1975-

    2005-01-01

    Ultra-High Performance Concrete [UHPC] has remarkable performance in mechanical properties, ductility, economical benefit, etc., but early-age cracking of UHPC can become an issue during the manufacturing process due to ...

  18. Sulfide stress cracking susceptible pipe fittings bought to NACE MR0175

    SciTech Connect (OSTI)

    McIntyre, D.R.; Moore, E.M. Jr. [Saudi Aramco, Dhahran (Saudi Arabia)

    1995-09-01

    The NACE MR0175 limit of R{sub c} 22 is non-conservative for cold-forged and stress relieved ASTM A234 WPB pipe fittings. Hardness surveys and sulfide stress cracking test results per ASTM G39 and NACE TMO177 Method B are presented. More stringent inspection and a hardness limit of BHN 197 (for cold-forged and stress relieved fittings only) are recommended to rectify this situation.

  19. Composite tube cracking in kraft recovery boilers: A state-of-the-art review

    SciTech Connect (OSTI)

    Singbeil, D.L.; Prescott, R.; Keiser, J.R.; Swindeman, R.W.

    1997-07-01

    Beginning in the mid-1960s, increasing energy costs in Finland and Sweden made energy recovery more critical to the cost-effective operation of a kraft pulp mill. Boiler designers responded to this need by raising the steam operating pressure, but almost immediately the wall tubes in these new boilers began to corrode rapidly. Test panels installed in the walls of the most severely corroding boiler identified austenitic stainless steel as sufficiently resistant to the new corrosive conditions, and discussions with Sandvik AB, a Swedish tube manufacturer, led to the suggestion that coextruded tubes be used for water wall service in kraft recovery boilers. Replacement of carbon steel by coextruded tubes has solved most of the corrosion problems experienced by carbon steel wall tubes, however, these tubes have not been problem-free. Beginning in early 1995, a multidisciplinary research program funded by the US Department of Energy was established to investigate the cause of cracking in coextruded tubes and to develop improved materials for use in water walls and floors of kraft recovery boilers. One portion of that program, a state-of-the-art review of public- and private-domain documents related to coextruded tube cracking in kraft recovery boilers is reported here. Sources of information that were consulted for this review include the following: tube manufacturers, boiler manufacturers, public-domain literature, companies operating kraft recovery boilers, consultants and failure analysis laboratories, and failure analyses conducted specifically for this project. Much of the information contained in this report involves cracking problems experienced in recovery boiler floors and those aspects of spout and air-port-opening cracking not readily attributable to thermal fatigue. 61 refs.

  20. Biomaterials 28 (2007) 49014911 Stresscorrosion crack growth of SiNaKMgCaPO bioactive

    E-Print Network [OSTI]

    Ritchie, Robert

    2007-01-01

    Biomaterials 28 (2007) 4901­4911 Stress­corrosion crack growth of Si­Na­K­Mg­Ca­P­O bioactive the thermal expansion (in the range of 8.8­15.1 Â 10À6 1CÀ1 ) [19] ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials

  1. Spark Spread

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home RoomPreservation ofAlbuquerque|SensitiveApril 2, 2014 Smith Named asInitiativesApache SparkSpark

  2. Crack growth rates of irradiated austenitic stainless steel weld heat affected zone in BWR environments.

    SciTech Connect (OSTI)

    Chopra, O. K.; Alexandreanu, B.; Gruber, E. E.; Daum, R. S.; Shack, W. J.; Energy Technology

    2006-01-31

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of reactor pressure vessels because of their superior fracture toughness. However, exposure to high levels of neutron irradiation for extended periods can exacerbate the corrosion fatigue and stress corrosion cracking (SCC) behavior of these steels by affecting the material microchemistry, material microstructure, and water chemistry. Experimental data are presented on crack growth rates of the heat affected zone (HAZ) in Types 304L and 304 SS weld specimens before and after they were irradiated to a fluence of 5.0 x 10{sup 20} n/cm{sup 2} (E > 1 MeV) ({approx} 0.75 dpa) at {approx}288 C. Crack growth tests were conducted under cycling loading and long hold time trapezoidal loading in simulated boiling water reactor environments on Type 304L SS HAZ of the H5 weld from the Grand Gulf reactor core shroud and on Type 304 SS HAZ of a laboratory-prepared weld. The effects of material composition, irradiation, and water chemistry on growth rates are discussed.

  3. Results of crack-arrest tests on two irradiated high-copper welds

    SciTech Connect (OSTI)

    Iskander, S.K.; Corwin, W.R.; Nanstead, R.K. (Oak Ridge National Lab., TN (USA))

    1990-12-01

    The objective of this study was to determine the effect of neutron irradiation on the shift and shape of the lower-bound curve to crack-arrest data. Two submerged-arc welds with copper contents of 0.23 and 0.31 wt % were commercially fabricated in 220-mm-thick plate. Crack-arrest specimens fabricated from these welds were irradiated at a nominal temperature of 288{degree}C to an average fluence of 1.9 {times} 10{sup 19} neutrons/cm{sup 2} (>1 MeV). Evaluation of the results shows that the neutron-irradiation-induced crack-arrest toughness temperature shift is about the same as the Charpy V-notch impact temperature shift at the 41-J energy level. The shape of the lower-bound curves (for the range of test temperatures covered) did not seem to have been altered by irradiation compared to those of the ASME K{sub Ia} curve. 9 refs., 21 figs., 10 tabs.

  4. Adaptation of Crack Growth Detection Techniques to US Material Test Reactors

    SciTech Connect (OSTI)

    A. Joseph Palmer; Sebastien P. Teysseyre; Kurt L. Davis; Joy L. Rempe; Gordon Kohse; Yakov Ostrovsky; David M. Carpenter

    2014-04-01

    A key component in evaluating the ability of Light Water Reactors to operate beyond 60 years is characterizing the degradation of materials exposed to radiation and various water chemistries. Of particular concern is the response of reactor materials to Irradiation Assisted Stress Corrosion Cracking (IASCC). Some materials testing reactors (MTRs) outside the U.S., such as the Halden Boiling Water Reactor (HBWR), have deployed a technique to measure crack growth propagation during irradiation. This technique incorporates a compact loading mechanism to stress the specimen during irradiation. A crack in the specimen is monitored using the Direct Current Potential Drop (DCPD) method. A project is underway to develop and demonstrate the performance of a similar type of test rig for use in U.S. MTRs. The first year of this three year project was devoted to designing, analyzing, fabricating, and bench top testing a mechanism capable of applying a controlled stress to specimens while they are irradiated in a pressurized water loop (simulating PWR reactor conditions). During the second year, the mechanism will be tested in autoclaves containing high pressure, high temperature water with representative water chemistries. In addition, necessary documentation and safety reviews for testing in a reactor environment will be completed. In the third year, the assembly will be tested in the Massachusetts Institute of Technology Reactor (MITR) and Post Irradiation Examinations (PIE) will be performed.

  5. Experimental study of crack initiation and propagation in high- and gigacycle fatigue in titanium alloys

    SciTech Connect (OSTI)

    Bannikov, Mikhail E-mail: oborin@icmm.ru Oborin, Vladimir E-mail: oborin@icmm.ru Naimark, Oleg E-mail: oborin@icmm.ru

    2014-11-14

    Fatigue (high- and gigacycle) crack initiation and its propagation in titanium alloys with coarse and fine grain structure are studied by fractography analysis of fracture surface. Fractured specimens were analyzed by interferometer microscope and SEM to improve methods of monitoring of damage accumulation during fatigue test and to verify the models for fatigue crack kinetics. Fatigue strength was estimated for high cycle fatigue regime using the Luong method [1] by “in-situ” infrared scanning of the sample surface for the step-wise loading history for different grain size metals. Fine grain alloys demonstrated higher fatigue resistance for both high cycle fatigue and gigacycle fatigue regimes. Fracture surface analysis for plane and cylindrical samples was carried out using optical and electronic microscopy method. High resolution profilometry (interferometer-profiler New View 5010) data of fracture surface roughness allowed us to estimate scale invariance (the Hurst exponent) and to establish the existence of two characteristic areas of damage localization (different values of the Hurst exponent). Area 1 with diameter ?300 ?m has the pronounced roughness and is associated with damage localization hotspot. Area 2 shows less amplitude roughness, occupies the rest fracture surface and considered as the trace of the fatigue crack path corresponding to the Paris kinetics.

  6. Recommendations for the shallow-crack fracture toughness testing task within the HSST (Heavy-Section Steel Technology) Program

    SciTech Connect (OSTI)

    Theiss, T.J. (Oak Ridge National Lab., TN (USA))

    1990-09-01

    Recommendations for Heavy-Section Steel Technology Program's investigation into the influence of crack depth on the fracture toughness of a steel prototypic of those in a reactor pressure vessel are included in this report. The motivation for this investigation lies in the fact that probabilistic fracture mechanics evaluations show that shallow flaws play a dominant role in the likelihood of vessel failure, and shallow-flaw specimens have exhibited an elevated toughness compared with conventional deep-notch fracture toughness specimens. Accordingly, the actual margin of safety of vessels may be greater than that predicted using existing deep-notch fracture-toughness results. The primary goal of the shallow-crack project is to investigate the influence of crack depth on fracture toughness under conditions prototypic of a reactor vessel. A limited data base of fracture toughness values will be assembled using a beam specimen of prototypic reactor vessel material and with a depth of 100 mm (4 in.). This will permit comparison of fracture-toughness data from deep-cracked and shallow-crack specimens, and this will be done for several test temperatures. Fracture-toughness data will be expressed in terms of the stress-intensity factor and crack-tip-opening displacement. Results of this investigation are expected to improve the understanding of shallow-flaw behavior in pressure vessels, thereby providing more realistic information for application to the pressurized-thermal shock issues. 33 refs., 17 figs.

  7. Cyclic fatigue-crack propagation in ceramics: Behavior in overaged and partially-stabilized MgO-zirconia

    SciTech Connect (OSTI)

    Dauskardt, R.H.; Marshall, D.B.; Ritchie, R.O.; Rockwell International Corp., Thousand Oaks, CA; Lawrence Berkeley Lab., CA )

    1988-06-01

    The growth of fatigue cracks under (tension-tension) cyclic loading is unequivocally demonstrated for ceramic materials, based on experiments using compact-tension specimens of a MgO partially-stabilized zirconia (PSZ), heat treated to vary the fracture toughness K{sub c} from {approximately}3 MPa{radical}m (overaged condition) to 16 MPa{radical}m (peak-toughness condition) and tested in inert and moist environments. Analogous to behavior in metals, cyclic fatigue-crack growth rates (over the range 10{sup {minus}11} to 10{sup {minus}5} m/cycle) are found to be a function of the stress-intensity range, environment, fracture toughness and load ratio, and to show evidence of crack closure. Similarly under variable-amplitude cyclic loading conditions, crack-growth rates show transient accelerations following low-high block overloads and transient retardations following high-low block overloads or single tensile overloads, again analogous to behavior commonly observed in ductile meals. Cyclic crack-growth rates are observed at stress intensities as low as 50% of K{sub c}, and are typically some 7 orders of magnitude faster than corresponding stress-corrosion crack-growth rates under sustained-loading conditions. 23 refs., 6 figs.

  8. Generation of tsunamis by a slowly spreading uplift of the sea oor Maria I. Todorovska*, Mihailo D. Trifunac

    E-Print Network [OSTI]

    Southern California, University of

    Generation of tsunamis by a slowly spreading uplift of the sea ¯oor Maria I. Todorovska*, Mihailo D spreading of the sea ¯oor uplift. A linearized solution for constant water depth is derived by transform methods (Laplace in time and Fourier in space), for sea ¯oor uplift represented by a sliding Heaviside

  9. Towards predictive simulation of wildfire spread at regional scale using ensemble-based data assimilation to correct the fire front

    E-Print Network [OSTI]

    - tation properties and wind conditions based on Rothermel's model; a series of observations of the fire;1. INTRODUCTION Computer-based wildfire spread modeling has emerged during the past two decades as a powerful toolTowards predictive simulation of wildfire spread at regional scale using ensemble-based data

  10. Early India-Australia spreading history revealed by newly detected Mesozoic magnetic anomalies in the Perth Abyssal Plain

    E-Print Network [OSTI]

    Granot, Roi

    Early India-Australia spreading history revealed by newly detected Mesozoic magnetic anomalies the early spreading history between India and Australia during the Mesozoic breakup of Gondwana. However from Australia with Greater India during initial breakup at ~130 Ma, then rifted from India following

  11. RIDGE 2000 Integrated Study Site Proposal for Hotspot-Influenced Oceanic Spreading Centers: Iceland and the Reykjanes and Kolbeinsey Ridges

    E-Print Network [OSTI]

    Menke, William

    RIDGE 2000 Integrated Study Site Proposal for Hotspot-Influenced Oceanic Spreading Centers: Iceland and the Reykjanes and Kolbeinsey Ridges Summary We propose that the Reykjanes Ridge, Iceland, and the Kolbeinsey efforts have focused on spreading rate as the primary variable, the Iceland-MAR system offers

  12. 0 10 20 30 40 50 60 70 80 90 100 Half spreading rate (mm per year)

    E-Print Network [OSTI]

    Müller, Dietmar

    60° 30° 0° 30° 60° 0 10 20 30 40 50 60 70 80 90 100 Half spreading rate (mm per year) Pacific Ocean you increase the speed of a continent ploughing through Earth's viscous, churning mantle? Kumar et al palaeomagnetic data and rates of seafloor spreading, and sets India apart from all its neighbours. Africa, Antarc

  13. Social Media: Weather-Ready Wednesday Please help the NWS spread these important safety messages on social media! Everyone is

    E-Print Network [OSTI]

    Social Media: Weather-Ready Wednesday #WRW Please help the NWS spread these important safety build a WeatherReady Nation. WeatherReady Wednesday is a National Weather Service initiative to help spread weather safety messages each week. Each week you can pick a different topic to share. It can

  14. Environmentally assisted cracking in light water reactors - annual report, January-December 2001.

    SciTech Connect (OSTI)

    Chopra, O. K.; Chung, H. M.; Clark, R. W.; Gruber, E. E; Hiller, R. W.; Shack, W. J.; Soppet, W. K.; Strain, R. V.; Energy Technology

    2003-06-01

    This report summarizes work performed by Argonne National Laboratory on fatigue and environmentally assisted cracking (EAC) in light water reactors (LWRs) from January to December 2001. Topics that have been investigated include (a) environmental effects on fatigue S-N behavior of austenitic stainless steels (SSs), (b) irradiation-assisted stress corrosion cracking (IASCC) of austenitic SSs, and (c) EAC of Alloy 600. The effects of key material and loading variables, such as strain amplitude, strain rate, temperature, dissolved oxygen (DO) level in water, and material heat treatment, on the fatigue lives of wrought and cast austenitic SSs in air and LWR environments have been evaluated. The mechanism of fatigue crack initiation in austenitic SSs in LWR environments has also been examined. The results indicate that the presence of a surface oxide film or difference in the characteristics of the oxide film has no effect on fatigue crack initiation in austenitic SSs in LWR environments. Slow-strain-rate tensile tests and post-test fractographic analyses were conducted on several model SS alloys irradiated to {approx}2 x 10{sup 21} n {center_dot} cm{sup -2} (E > 1 MeV) ({approx}3 dpa) in He at 289 C in the Halden reactor. The results were used to determine the influence of alloying and impurity elements on the susceptibility of these steels to IASCC. Corrosion fatigue tests were conducted on nonirradiated austenitic SSs in high-purity water at 289 C to establish the test procedure and conditions that will be used for the tests on irradiated materials. A comprehensive irradiation experiment was initiated to obtain many tensile and disk specimens irradiated under simulated pressurized water reactor conditions at {approx}325 C to 5, 10, 20, and 40 dpa. Crack growth tests were completed on 30% cold-worked Alloy 600 in high-purity water under various environmental and loading conditions. The results are compared with data obtained earlier on several heats of Alloy 600 tested in high-DO water under several heat treatment conditions.

  15. Environmentally assisted cracking in light water reactors annual report January - December 2005.

    SciTech Connect (OSTI)

    Alexandreanu, B.; Chen, Y.; Chopra, O. K.; Chung, H. M.; Gruber, E. E.; Shack, W. J.; Soppet, W. K.

    2007-08-31

    This report summarizes work performed from January to December 2005 by Argonne National Laboratory on fatigue and environmentally assisted cracking in light water reactors (LWRs). Existing statistical models for estimating the fatigue life of carbon and low-alloy steels and austenitic stainless steels (SSs) as a function of material, loading, and environmental conditions were updated. Also, the ASME Code fatigue adjustment factors of 2 on stress and 20 on life were critically reviewed to assess the possible conservatism in the current choice of the margins. An approach, based on an environmental fatigue correction factor, for incorporating the effects of LWR environments into ASME Section III fatigue evaluations is discussed. The susceptibility of austenitic stainless steels and their welds to irradiation-assisted stress corrosion cracking (IASCC) is being evaluated as a function of the fluence level, water chemistry, material chemistry, and fabrication history. For this task, crack growth rate (CGR) tests and slow strain rate tensile (SSRT) tests are being conducted on various austenitic SSs irradiated in the Halden boiling water reactor. The SSRT tests are currently focused on investigating the effects of the grain boundary engineering process on the IASCC of the austenitic SSs. The CGR tests were conducted on Type 316 SSs irradiated to 0.45-3.0 dpa, and on sensitized Type 304 SS and SS weld heat-affected-zone material irradiated to 2.16 dpa. The CGR tests on materials irradiated to 2.16 dpa were followed by a fracture toughness test in a water environment. The effects of material composition, irradiation, and water chemistry on growth rates are discussed. The susceptibility of austenitic SS core internals to IASCC and void swelling is also being evaluated for pressurized water reactors. Both SSRT tests and microstructural examinations are being conducted on specimens irradiated in the BOR-60 reactor in Russia to doses up to 20 dpa. Crack growth rate data, obtained in the pressurized water reactor environment, are presented on Ni-alloy welds prepared in the laboratory or obtained from the nozzle-to-pipe weld of the V. C. Summer reactor. The experimental CGRs under cyclic and constant load are compared with the existing CGR data for Ni-alloy welds to determine the relative susceptibility of these materials to environmentally enhanced cracking under a variety of loading conditions.

  16. Impacts of complex behavioral responses on asymmetric interacting spreading dynamics in multiplex networks

    E-Print Network [OSTI]

    Liu, Quan-Hui; Tang, Ming; Zhang, Hai-Feng

    2015-01-01

    Information diffusion and disease spreading in communication-contact layered network are typically asymmetrically coupled with each other, in which how an individual being aware of disease responds to the disease can significantly affect the disease spreading. Many recent studies have demonstrated that human behavioral adoption is a complex and non-Markovian process, where the probability of adopting one behavior is dependent on the cumulative times of the received information and the social reinforcement effect of these cumulative information. We study the impact of such a non-Markovian vaccination adoption behavior on the epidemic dynamics and the control effects. We find that this complex adoption behavior caused from the communication layer can significantly increase the epidemic threshold and reduce the final infection rate. By defining the social cost as the sum of the cost of vaccination and the cost of treatment, we show that there exists an optimal social reinforcement effect or optimal information t...

  17. Revealing latent factors of temporal networks for mesoscale intervention in epidemic spread

    E-Print Network [OSTI]

    Gauvin, Laetitia; Barrat, Alain; Cattuto, Ciro

    2015-01-01

    The customary perspective to reason about epidemic mitigation in temporal networks hinges on the identification of nodes with specific features or network roles. The ensuing individual-based control strategies, however, are difficult to carry out in practice and ignore important correlations between topological and temporal patterns. Here we adopt a mesoscopic perspective and present a principled framework to identify collective features at multiple scales and rank their importance for epidemic spread. We use tensor decomposition techniques to build an additive representation of a temporal network in terms of mesostructures, such as cohesive clusters and temporally-localized mixing patterns. This representation allows to determine the impact of individual mesostructures on epidemic spread and to assess the effect of targeted interventions that remove chosen structures. We illustrate this approach using high-resolution social network data on face-to-face interactions in a school and show that our method afford...

  18. On the spreading of Weddell Sea deep water in the southwestern Atlantic Ocean 

    E-Print Network [OSTI]

    Locarnini, Ricardo A

    1991-01-01

    that this WSDW, flowing northeastward through the Georgia Passage, might supply part of the coldest bottom water that enters the Argentine Basin through the Falkland Ridge Gap. 23 THE SCOTIA SEA AND THE WEDDELL SEA DEEP WATER OUTFLOW The occurrence...ON THE SPREADING OF WEDDELL SEA DEEP WATER IN THE SOUTHWESTERN ATLANTIC OCEAN A Thesis by RICARDO ALEJANDRO LOCARNINI Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements...

  19. Obtaining statistics of cascading line outages spreading in an electric transmission network from standard utility data

    E-Print Network [OSTI]

    Dobson, Ian

    2015-01-01

    We show how to use standard transmission line outage historical data to obtain the network topology in such a way that cascades of line outages can be easily located on the network. Then we obtain statistics quantifying how cascading outages typically spread on the network. Processing real outage data is fundamental for understanding cascading and for evaluating the validity of the many different models and simulations that have been proposed for cascading in power networks.

  20. Evidence of thermonuclear flame spreading on neutron stars from burst rise oscillations

    E-Print Network [OSTI]

    Chakraborty, Manoneeta

    2014-01-01

    Burst oscillations during the rising phases of thermonuclear X-ray bursts are usually believed to originate from flame spreading on the neutron star surface. However, the decrease of fractional oscillation amplitude with rise time, which provides a main observational support for the flame spreading model, have so far been reported from only a few bursts. Moreover, the non-detection and intermittent detections of rise oscillations from many bursts are not yet understood considering the flame spreading scenario. Here, we report the decreasing trend of fractional oscillation amplitude from an extensive analysis of a large sample of Rossi X-ray Timing Explorer Proportional Counter Array bursts from ten neutron star low-mass X-ray binaries. This trend is 99.99% significant for the best case, which provides, to the best of our knowledge, by far the strongest evidence of such trend. Moreover, it is important to note that an opposite trend is not found from any of the bursts. The concave shape of the fractional ampli...

  1. Predicting the extinction of Ebola spreading in Liberia due to mitigation strategies

    E-Print Network [OSTI]

    Valdez, L D; Stanley, H E; Braunstein, L A

    2015-01-01

    The Ebola virus is spreading throughout West Africa, causing thousands of deaths. When developing strategies to slow or halt the epidemic, mathematical models that reproduce the spread of this virus are essential for understanding which variables are relevant. We study the propagation of the Ebola virus through Liberia by using a model in which people travel from one county to another in order to quantify the effectiveness of different strategies. For the initial months in which the Ebola virus spreads, we find that the arrival times of the disease into the counties predicted by our model are in good agreement with World Health Organization data. We also find that reducing mobility delays the arrival of Ebola virus in each county by only a few weeks, and as a consequence, is insufficient to contain the epidemic. Finally we study the effect of a strategy focused on increasing safe burials and hospitalization under two scenarios: (i) one implemented in mid-July 2014 and (ii) one in mid-August, which was the act...

  2. On compensating tune spread induced by space charge in bunched beams

    SciTech Connect (OSTI)

    Litvinenko, V. N.; Wang, G.

    2014-05-09

    Space charge effects play significant role in modern-day accelerators. These effects frequently constrain attainable beam parameters in an accelerator, or, in an accelerator chain. They also could limit the luminosity of hadron colliders operating either at low energies or with a sub-TeV high brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. A number of schemes for compensating space charge effects in a coasting (e.g. continuous) hadron beam were proposed and some of them had been tested. Using a proper transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But all of these methods do not address the issue of tune spread compensation of a bunched hadron beam, e.g. the tune shift dependence on the longitudinal position inside the bunch. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present a number of practical examples of such system.

  3. Analysis Of Ductile Crack Growth In Pipe Test In STYLE Project

    SciTech Connect (OSTI)

    Yin, Shengjun; Williams, Paul T; Klasky, Hilda B; Bass, Bennett Richard

    2012-01-01

    The Oak Ridge National Laboratory (ORNL) is conducting structural analyses, both deterministic and probabilistic, to simulate a large scale mock-up experiment planned within the European Network for Structural Integrity for Lifetime Management non-RPV Components (STYLE). The paper summarizes current ORNL analyses of STYLE s Mock-up3 experiment to simulate/evaluate ductile crack growth in a cladded ferritic pipe. Deterministic analyses of the large-scale bending test of ferritic surge pipe, with an internal circumferential crack, are simulated with a number of local micromechanical approaches, such as Gurson-Tvergaard-Needleman (GTN) model and cohesive-zone model. Both WARP 3D and ABAQUS general purpose finite element programs are being used to predict the failure load and the failure mode, i.e. ductile tearing or net-section collapse, as part of the pre-test phase of the project. Companion probabilistic analyses of the experiment are utilizing the ORNL developed open-source Structural Integrity Assessment Modular - Probabilistic Fracture Mechanics (SIAM-PFM) framework. SIAM-PFM contains engineering assessment methodology such as the tearing instability (J-T analysis) module developed for inner surface cracks under bending load. The driving force J-integral estimations are based on the SC.ENG1 or SC.ENG2 models. The J-A2 methodology is used to transfer (constraint-adjust) J-R curve material data from standard test specimens to the Mock-up3 experiment configuration. The probabilistic results of the Mock-Up3 experiment obtained from SIAM-PFM will be compared to those generated using the deterministic finite element modeling approach. The objective of the probabilistic analysis is to provide uncertainty bounds that will assist in assessing the more detailed 3D finite-element solutions and to also assess the level of confidence that can be placed in the best-estimate finite-element solutions.

  4. Effect of irradiation on the stress corrosion cracking behavior of Alloy X-750 and Alloy 625

    SciTech Connect (OSTI)

    Mills, W.J.; Lebo, M.R.; Kearns, J.J.; Hoffman, R.C.; Korinko, J.J.; Luther, R.F.; Sykes, G.B.

    1993-10-01

    In-reactor testing of bolt-loaded precracked and as-notched compact tension specimens was performed in 360{degrees}C water to determine effect of irradiation on SCC of Condition HTH and Condition BH Alloy X-750 and age-hardened Alloy 625. Variables were stress intensity factor (K{sub I}) level, fluence, grade of HTH material, prestraining and material chemistry. Effects of irradiation on high temperature SCC and the rapid cracking that occurs during cooldown below 150{degrees}C were characterized. Significant degradation in the in-reactor SCC resistance of HTH material was observed at initial K{sub I} levels above 30 MPa{radical}m and fluences greater than 10{sup 19} n/cm{sup 2} (E > 1 MeV). A small degradation in SCC resistance of HTH material was observed at low fluences (<10{sup 16} n/cm{sup 2}). As-notched specimens displayed less degradation in SCC resistance than precracked specimens. Prestraining greatly improved in-flux and out-of-flux SCC resistance of HTH material, as little or no SCC was observed in precracked specimens prestrained 20 to 30%, whereas extensive cracking was observed in nonprestrained specimens. Condition HTH heats with low boron (10 ppM or less) had improved in-reactor SCC resistance compared to heats with high and intermediate boron (>20 ppM). Age-hardened Alloy 625 exhibited superior in-reactor SCC behavior compared to HTH material as no crack extension occurred in any of the precracked Alloy 625 specimens tested at initial K{sub I} levels up to 80 MPa{radical}m.

  5. Pacific Northwest National Laboratory Investigation of the Stress Corrosion Cracking in Nickel-Base Alloys, Volume 2

    SciTech Connect (OSTI)

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.

    2012-03-01

    The objective of this program is to evaluate the primary water stress corrosion cracking (PWSCC) susceptibility of high chromium alloy 690 and its weld metals, establish quantitative measurements of crack-growth rates and determine relationships among cracking susceptibility, environmental conditions and metallurgical characteristics. Stress-corrosion, crack-growth rates have been determined for 12 alloy 690 specimens, 11 alloy 152/52/52M weld metal specimens, 4 alloy 52M/182 overlay specimens and 2 alloy 52M/82 inlay specimens in simulated PWR primary water environments. The alloy 690 test materials included three different heats of extruded control-rod-drive mechanism (CRDM) tubing with variations in the initial material condition and degree of cold work for one heat. Two cold-rolled (CR) alloy 690 plate heats were also obtained and evaluated enabling comparisons to the CR CRDM materials. Weld metal, overlay and inlay specimens were machined from industry mock ups to provide plant-representative materials for testing. Specimens have been tested for one alloy 152 weld, two alloy 52 welds and three alloy 52M welds. The overlay and inlay specimens were prepared to propagate stress-corrosion cracks from the alloy 182 or 82 material into the more resistant alloy 52M. In all cases, crack extension was monitored in situ by direct current potential drop (DCPD) with length resolution of about +1 µm making it possible to measure extremely low growth rates approaching 5x10-10 mm/s. Most SCC tests were performed at 325-360°C with hydrogen concentrations from 11-29 cc/kg; however, environmental conditions were modified during a few experiments to evaluate the influence of temperature, water chemistry or electrochemical potential on propagation rates. In addition, low-temperature (~50°C) cracking behavior was examined for selected alloy 690 and weld metal specimens. Extensive characterizations have been performed on material microstructures and stress-corrosion cracks by optical and electron microscopy techniques and linked to crack-growth test results to help define material and environmental parameters controlling SCC susceptibility.

  6. Fischer-Tropsch indirect coal liquefaction design/economics-mild hydrocracking vs. fluid catalytic cracking

    SciTech Connect (OSTI)

    Choi, G.N.; Kramer, S.J.; Tam, S.S. [Bechtel Corp., San Francisco, CA (United States); Reagan, W.J. [Amoco Oil Co., Naperville, IL (United States)] [and others

    1996-12-31

    In order to evaluate the economics of Fischer-Tropsch (F-T) indirect coal liquefaction, conceptual plant designs and detailed cost estimates were developed for plants producing environmentally acceptable, high-quality, liquid transportation fuels meeting the Clean Air Act requirements. The designs incorporate the latest developments in coal gasification technology and advanced (F-T) slurry reactor design. In addition, an ASPEN Plus process simulation model was developed to predict plant material and energy balances, utility requirements, operating and capital costs at varying design conditions. This paper compares mild hydrocracking and fluid catalytic cracking as alternative methods for upgrading the F-T wax.

  7. Mode I transverse cracking in an epoxy and a graphite fiber reinforced epoxy 

    E-Print Network [OSTI]

    Williams, David Robert

    1981-01-01

    to the fracture toughness of a material, which is a measure of its resistance to the growth of a flaw. The fracture behavior of laminated composit. es is great- ly complicated by the interaction between fiber and matrix. The energy required to create a new... the number of chemical bonds span- ning the cross-section of the specimen as a function of time and applied load. The viscoelastic character of epoxies should result in time-dependent crack growth behavior in composites. If the fracture mechanism does...

  8. Transient Eddy Current Response Due to a Subsurface Crack in a Conductive Plate

    SciTech Connect (OSTI)

    Fangwei Fu

    2006-08-09

    Eddy current nondestructive evaluation (NDE) is usually carried out by exciting a time harmonic field using an inductive probe. However, a viable alternative is to use transient eddy current NDE in which a current pulse in a driver coil produces a transient .eld in a conductor that decays at a rate dependent on the conductivity and the permeability of the material and the coil configuration. By using transient eddy current, it is possible to estimate the properties of the conductive medium and to locate and size potential .aws from the measured probe response. The fundamental study described in this dissertation seeks to establish a theoretical understanding of the transient eddy current NDE. Compared with the Fourier transform method, the derived analytical formulations are more convenient when the transient eddy current response within a narrow time range is evaluated. The theoretical analysis provides a valuable tool to study the effect of layer thickness, location of defect, crack opening as well as the optimization of probe design. Analytical expressions have been developed to evaluate the transient response due to eddy currents in a conductive plate based on two asymptotic series. One series converges rapidly for a short time regime and the other for a long time regime and both of them agree with the results calculated by fast Fourier transform over all the times considered. The idea of asymptotic expansion is further applied to determine the induced electromotive force (EMF) in a pick-up coil due to eddy currents in a cylindrical rod. Starting from frequency domain representation, a quasi-static time domain dyadic Green's function for an electric source in a conductive plate has been derived. The resulting expression has three parts; a free space term, multiple image terms and partial reflection terms. The dyadic Green's function serves as the kernel of an electric field integral equation which defines the interaction of an ideal crack with the transient eddy currents in a conductive plate. The crack response is found using the reciprocity theorem. Good agreement is observed between the predictions of the magnetic field due to the crack and experimental measurements.

  9. Integral identities for an interfacial crack in an anisotropic bimaterial with an imperfect interface

    E-Print Network [OSTI]

    Lewis Pryce; Adam Vellender; Alexander Zagnetko

    2014-11-25

    We study a crack lying along an imperfect interface in an anisotropic bimaterial. A method is devised where known weight functions for the perfect interface problem are used to obtain singular integral equations relating the tractions and displacements for both the in-plane and out-of-plane fields. The integral equations for the out-of-plane problem are solved numerically for orthotropic bimaterials with differing orientations of anisotropy and for different extents of interfacial imperfection. These results are then compared with finite element computations.

  10. Developing Fatigue Pre-crack Procedure to Evaluate Fracture Toughness of Pipeline Steels Using Spiral Notch Torsion Test

    SciTech Connect (OSTI)

    Wang, Jy-An John; Tan, Ting; Jiang, Hao; Zhang, Wei; Feng, Zhili

    2012-10-01

    The spiral notch torsion test (SNTT) has been utilized to investigate the crack growth behavior of X52 steel base and welded materials used for hydrogen infrastructures. The X52 steel materials are received from a welded pipe using friction stir welding techniques. Finite element models were established to study the crack growth behavior of steel SNTT steel samples, which were assumed to be isotropic material. A series SNTT models were set up to cover various crack penetration cases, of which the ratios between crack depth to diameter (a/D ratio) ranging from 0.10 to 0.45. The evolution of compliance and energy release rates in the SNTT method have been investigated with different cases, including different geometries and materials. Indices of characteristic compliance and energy release rates have been proposed. Good agreement has been achieved between predictions from different cases in the same trend. These work shed lights on a successful protocol for SNTT application in wide range of structural materials. The further effort needed for compliance function development is to extend the current developed compliance function to the deep crack penetration arena, in the range of 0.55 to 0.85 to effectively determine fracture toughness for extremely tough materials.

  11. Acid-catalyzed cracking of paraffinic hydrocarbons. 3. Evidence for the protonated cyclopropane mechanism from hydrocracking/hydroisomerization experiments

    SciTech Connect (OSTI)

    Tiong Sie, S. (Koninklijke/Shell-Lab., Amsterdam (Netherlands))

    1993-03-01

    The mechanism for acid-catalyzed cracking proposed in the first paper of this series, which assumes a protonated dialkylcyclopropane carbonium ion as intermediate instead of a classical carbenium ion, has been applied to rationalize experimental results obtained in the hydrocracking/hydroisomerization of normal paraffins. The new mechanism is shown to be capable of explaining many characteristics of the hydrocracking process which cannot be understood via the classical theory, such as the virtual absence of methane and ethane as cracked products, the relatively low production of propane as compared to the higher hydrocarbons, and characteristic patterns in the branching of the cracked fragments. The new mechanism also makes it clear why crackability increases so rapidly with increasing number of carbon atoms above n-heptane and why n-hexane and lower hydrocarbons are so difficult to crack. An explanation is also offered for the ease with which high selectivities can be achieved in the isomerization of C[sub 5]/C[sub 6], as contrasted with the difficulty of isomerizing C[sub 7+] without significant cracking.

  12. Interference of wedge-shaped protrusions on the faces of a Griffith crack in biaxial stress. Final report

    SciTech Connect (OSTI)

    Boulet, J.A.M. [Tennessee Univ., Knoxville, TN (United States)

    1992-04-01

    An initial investigation of the influence of protrusion interference on the fracture toughness required to prevent unstable propagation of a Griffith crack in a brittle material is described. The interference is caused by relative shear displacement of the crack faces when subjected to remote biaxial stress with neither principal stress parallel to the crack. It is shown that for room temperature cracks smaller than about one centimeter in silicon carbide, or about one millimeter in silicon nitride, the presence of interference changes the fracture stress. A mathematical model based on linear elasticity solutions and including multiple interference sites at arbitrarily specified positions on the crack is presented. Computations of the change in required fracture toughness and its dependence on wedge geometry (size and vertex angle), applied stresses (orientation and magnitude), and location of the interference site are discussed. Results indicate that a single interference site has only a slight effect on required toughness. However, the influence of interference increases monotonically with the number of interference sites. The two-dimensional model described herein is not accurate when the interference sites are closely spaced.

  13. Russia's Wild Wild South: Two Tales of Economic Woes, Political Corruption and Spreading Insurgent Violence in Ingushetia and Dagestan

    E-Print Network [OSTI]

    Grandstaff, John M.

    2011-05-14

    The Northern Caucasus has been a troubled region for the Russian Federation for nearly two decades. In the 1990s, two wars took place in Chechnya and violence spread into the neighboring republics of Ingushetia and Dagestan. ...

  14. Agricultural pathogen decontamination technology-reducing the threat of infectious agent spread.

    SciTech Connect (OSTI)

    Betty, Rita G.; Bieker, Jill Marie; Tucker, Mark David

    2005-10-01

    Outbreaks of infectious agricultural diseases, whether natural occurring or introduced intentionally, could have catastrophic impacts on the U.S. economy. Examples of such agricultural pathogens include foot and mouth disease (FMD), avian influenza (AI), citrus canker, wheat and soy rust, etc. Current approaches to mitigate the spread of agricultural pathogens include quarantine, development of vaccines for animal diseases, and development of pathogen resistant crop strains in the case of plant diseases. None of these approaches is rapid, and none address the potential persistence of the pathogen in the environment, which could lead to further spread of the agent and damage after quarantine is lifted. Pathogen spread in agricultural environments commonly occurs via transfer on agricultural equipment (transportation trailers, tractors, trucks, combines, etc.), having components made from a broad range of materials (galvanized and painted steel, rubber tires, glass and Plexiglas shields, etc), and under conditions of heavy organic load (mud, soil, feces, litter, etc). A key element of stemming the spread of an outbreak is to ensure complete inactivation of the pathogens in the agricultural environment and on the equipment used in those environments. Through the combination of enhanced agricultural pathogen decontamination chemistry and a validated inactivation verification methodology, important technologies for incorporation as components of a robust response capability will be enabled. Because of the potentially devastating economic impact that could result from the spread of infectious agricultural diseases, the proposed capability components will promote critical infrastructure protection and greater border and food supply security. We investigated and developed agricultural pathogen decontamination technologies to reduce the threat of infectious-agent spread, and thus enhance agricultural biosecurity. Specifically, enhanced detergency versions of the patented Sandia decontamination chemistry were developed and tested against a few surrogate pathogens under conditions of relatively heavy organic load. Tests were conducted on surfaces commonly found in agricultural environments. Wide spectrum decontamination efficacy, low corrosivity, and biodegradability issues were addressed in developing an enhanced detergency formulation. A method for rapid assessment of loss of pathogenic activity (inactivation) was also assessed. This enhanced technology will enable rapid assessment of contamination following an intentional event, and will also be extremely useful in routine assessment of agricultural environments. The primary effort during the second year was progress towards a demonstration of both decontamination and viral inactivation technologies of Foot and Mouth virus (FMDv) using the modified SNL chemistry developed through this project. Lab studies using a surrogate virus (bovine enterovirus) were conducted using DF200, modified DF200 chemistry, and decontaminants currently recommended for use in heavily loaded organic, agricultural environments (VirkonS, 10% bleach, sodium hydroxide and citric acid). Tests using actual FMD virus will be performed at the Department of Homeland Security's Plum Island facilities in the fall of 2005. Success and the insight gained from this project will lead to enhanced response capability, which will benefit agencies such as USDA, DHS, DOD, and the agricultural industry.

  15. Development of a system for quantifying the rate of spread of oak wilt using remote sensing and geographic information systems 

    E-Print Network [OSTI]

    Ware, Charles William

    1990-01-01

    DEVELOPMENT OF A SYSTEM FOR QUANTIFYING THE RATE OF SPREAD OF OAR WILT USING REMOTE SENSING AND GEOGRAPHIC INFORMATION SYSTEMS A Thesis by CHARLES WILLIAM WARE Submitted to the Office of Graduate Studies of Texas ASM University in partial... of Spread of Oak Wilt Using Remote Sensing and Geographic Information Systems. (December 1990) Charles William Ware, B. S. , Stephen F. Austin St. Univ. Chair of Advisory Committee: Dr. Robert Maggio Oak wilt, caused by the fungus Ce atoc st's fa...

  16. Corrosion fatigue crack growth in clad low-alloy steel. Part 2, Water flow rate effects in high sulfur plate steel

    SciTech Connect (OSTI)

    James, L.A; Lee, H.B.; Wire, G.L.; Novak, S.R.; Cullen, W.H.

    1996-04-01

    Corrosion fatigue crack propagation tests were conducted on a high- sulfur ASTM A302-B plate steel overlaid with weld-deposited Alloy EN82H cladding. The specimens featured semi-elliptical surface cracks penetrating approximately 6.3 mm of cladding into the underlying steel. The initial crack sizes were relatively large with surface lengths of 22.8--27.3 mm, and depths of 10.5--14.1 mm. The experiments were initiated in a quasi-stagnant low-oxygen (O{sub 2} < 10 ppb) aqueous environment at 243{degrees}C, under loading conditions ({Delta}K, R, cyclic frequency) conducive to environmentally-assisted cracking (EAC) under quasi-stagnant conditions. Following fatigue testing under quasi-stagnant conditions where EAC was observed, the specimens were then fatigue tested under conditions where active water flow of either 1.7 m/sec. or 4.7 m/sec. was applied parallel to the crack. Earlier experiments on unclad surface-cracked specimens of the same steel exhibited EAC under quasi- stagnant conditions, but water flow rates at 1.7 m/sec. and 5.0 m/sec. parallel to the crack mitigated EAC. In the present experiments on clad specimens, water flow at approximately the same as the lower of these velocities did not mitigate EAC, and a free stream velocity approximately the same as the higher of these velocities resulted in sluggish mitigation of EAC. The lack of robust EAC mitigation was attributed to the greater crack surface roughness in the cladding interfering with flow induced within the crack cavity. An analysis employing the computational fluid dynamics code, FIDAP, confirmed that frictional forces associated with the cladding crack surface roughness reduced the interaction between the free stream and the crack cavity.

  17. Multiple use of waste catalysts with and without regeneration for waste polymer cracking

    SciTech Connect (OSTI)

    Salmiaton, A.; Garforth, A.A.

    2011-06-15

    Waste plastics contain a substantial number of valuable chemicals. The wastes from post-consumer as well as from industrial production can be recycled to valuable chemical feedstock, which can be used in refineries and/or petrochemical industries. This chemical recycling process is an ideal approach in recycling the waste for a better environment. Polymer cracking using a laboratory fluidised bed reactor concentrated on the used highly contaminated catalyst, E-Cat 2. Even though E-Cat 2 had low activity due to fewer acid sites, the products yielded were similar with amorphous ASA and were far better than thermal cracking. The high levels of heavy metals, namely nickel and vanadium, deposited during their lifetime as an FCC catalyst, did not greatly affect on the catalyst activity. It was also shown that E-Cat 2 could be used with and without regeneration. Although there was more deactivation when there was no regeneration step, the yield of gases (C{sub 2}-C{sub 7}) remained fairly constant. For the first time, these results indicate that 'waste' FCC catalyst (E-Cat) is a good candidate for future feedstock recycling of polymer waste. The major benefits of using E-Cat are a low market price, the ability to tolerate reuse and regeneration capacity.

  18. Effect of material heat treatment on fatigue crack initiation in austenitic stainless steels in LWR environments.

    SciTech Connect (OSTI)

    Chopra, O. K.; Alexandreanu, B.; Shack, W. J.; Energy Technology

    2005-07-31

    The ASME Boiler and Pressure Vessel Code provides rules for the design of Class 1 components of nuclear power plants. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify design curves for applicable structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. The existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. Under certain environmental and loading conditions, fatigue lives of austenitic stainless steels (SSs) can be a factor of 20 lower in water than in air. This report presents experimental data on the effect of heat treatment on fatigue crack initiation in austenitic Type 304 SS in LWR coolant environments. A detailed metallographic examination of fatigue test specimens was performed to characterize the crack morphology and fracture morphology. The key material, loading, and environmental parameters and their effect on the fatigue life of these steels are also described. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic SSs as a function of material, loading, and environmental parameters. Two methods for incorporating the effects of LWR coolant environments into the ASME Code fatigue evaluations are presented.

  19. Mechanism and estimation of fatigue crack initiation in austenitic stainless steels in LWR environments.

    SciTech Connect (OSTI)

    Chopra, O. K.; Energy Technology

    2002-08-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figures I-9.1 through I-9.6 of Appendix I to Section III of the Code specify fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain-vs.-life ({var_epsilon}-N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This report provides an overview of fatigue crack initiation in austenitic stainless steels in LWR coolant environments. The existing fatigue {var_epsilon}-N data have been evaluated to establish the effects of key material, loading, and environmental parameters (such as steel type, strain range, strain rate, temperature, dissolved-oxygen level in water, and flow rate) on the fatigue lives of these steels. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. The influence of reactor environments on the mechanism of fatigue crack initiation in these steels is also discussed.

  20. Hydrocarbon Liquid Production via the bioCRACK Process and Catalytic Hydroprocessing of the Product Oil

    SciTech Connect (OSTI)

    Schwaiger, Nikolaus; Elliott, Douglas C.; Ritzberger, Jurgen; Wang, Huamin; Pucher, Peter; Siebenhofer, Matthaus

    2015-01-01

    Continuous hydroprocessing of liquid phase pyrolysis bio-oil, provided by BDI-BioEnergy International bioCRACK pilot plant at OMV Refinery in Schwechat/Vienna Austria was investigated. These hydroprocessing tests showed promising results using catalytic hydroprocessing strategies developed for unfractionated bio-oil. A sulfided base metal catalyst (CoMo on Al2O3) was evaluated. The bed of catalyst was operated at 400 °C in a continuous-flow reactor at a pressure of 12.1 MPa with flowing hydrogen. The condensed liquid products were analyzed and found that the hydrocarbon liquid was significantly hydrotreated so that nitrogen and sulfur were below the level of detection (<0.05), while the residual oxygen ranged from 0.7 to 1.2%. The density of the products varied from 0.71 g/mL up to 0.79 g/mL with a correlated change of the hydrogen to carbon atomic ratio from 2.1 down to 1.9. The product quality remained high throughout the extended tests suggesting minimal loss of catalyst activity through the test. These tests provided the data needed to assess the quality of liquid fuel products obtained from the bioCRACK process as well as the activity of the catalyst for comparison with products obtained from hydrotreated fast pyrolysis bio-oils from fluidized-bed operation.

  1. Predicting Fracture Energies and Crack-Tip Fields of Soft Tough Materials

    E-Print Network [OSTI]

    Teng Zhang; Shaoting Lin; Hyunwoo Yuk; Xuanhe Zhao

    2015-06-13

    Soft materials including elastomers and gels are pervasive in biological systems and technological applications. Whereas it is known that intrinsic fracture energies of soft materials are relatively low, how the intrinsic fracture energy cooperates with mechanical dissipation in process zone to give high fracture toughness of soft materials is not well understood. In addition, it is still challenging to predict fracture energies and crack-tip strain fields of soft tough materials. Here, we report a scaling theory that accounts for synergistic effects of intrinsic fracture energies and dissipation on the toughening of soft materials. We then develop a coupled cohesive-zone and Mullins-effect model capable of quantitatively predicting fracture energies of soft tough materials and strain fields around crack tips in soft materials under large deformation. The theory and model are quantitatively validated by experiments on fracture of soft tough materials under large deformations. We further provide a general toughening diagram that can guide the design of new soft tough materials.

  2. Assessment of NDE Technologies for Detection and Characterization of Stress Corrosion Cracking in LWRs

    SciTech Connect (OSTI)

    Meyer, Ryan M.; Ramuhalli, Pradeep; Toloczko, Mychailo B.; Bond, Leonard J.; Montgomery, Robert O.

    2012-12-31

    Stress corrosion cracking (SCC) in light water reactors (LWRs) has been a persistent form of degradation in the nuclear industry. Examples of SCC can be found for a range of materials in boiling and pressurized water reactor environments, including carbon steels, stainless steels, and nickel-base stainless alloys. The evolution of SCC is often characterized by a long initiation stage followed by a phase of more rapid crack growth to failure. This provides a relatively short window of opportunity to detect the start of observable SCC, and it is conceivable that SCC could progress from initiation to failure between subsequent examinations when managed by applying periodic in-service inspection techniques. Implementation of advanced aging management paradigms in the current fleet of LWRs will require adaptation of existing measurement technologies and development of new technologies to perform on-line measurements during reactor operation to ensure timely detection of material degradation and to support the implementation of advanced diagnostics and prognostics. This paper considers several non-destructive examination (NDE) technologies with known sensitivity to detection of indicators for SCC initiation and/or propagation, and assesses these technologies with respect to their ability to detect and accurately characterize the significance of an SCC flaw. Potential strategies to improve SCC inspection or monitoring performance are offered to benefit management of SCC degradation in LWRs.

  3. Hydrocarbon Liquid Production via the bioCRACK Process and Catalytic Hydroprocessing of the Product Oil

    SciTech Connect (OSTI)

    Schwaiger, Nikolaus; Elliott, Douglas C.; Ritzberger, Jurgen; Wang, Huamin; Pucher, Peter; Siebenhofer, Matthaus

    2015-02-13

    Continuous hydroprocessing of liquid phase pyrolysis bio-oil, provided by BDI-BioEnergy International bioCRACK pilot plant at OMV Refinery in Schwechat/Vienna Austria was investigated. These hydroprocessing tests showed promising results using catalytic hydroprocessing strategies developed for unfractionated bio-oil. A sulfided base metal catalyst (CoMo on Al2O3) was evaluated. The bed of catalyst was operated at 400 °C in a continuous-flow reactor at a pressure of 12.1 MPa with flowing hydrogen. The condensed liquid products were analyzed and found that the hydrocarbon liquid was significantly hydrotreated so that nitrogen and sulfur were below the level of detection (<0.05), while the residual oxygen ranged from 0.7 to 1.2%. The density of the products varied from 0.71 g/mL up to 0.79 g/mL with a correlated change of the hydrogen to carbon atomic ratio from 2.1 down to 1.9. The product quality remained high throughout the extended tests suggesting minimal loss of catalyst activity through the test. These tests provided the data needed to assess the quality of liquid fuel products obtained from the bioCRACK process as well as the activity of the catalyst for comparison with products obtained from hydrotreated fast pyrolysis bio-oils from fluidized-bed operation.

  4. Microwave Enhanced Direct Cracking of Hydrocarbon Feedstock for Energy Efficient Production of Ethylene and Propylene.

    SciTech Connect (OSTI)

    Shulman, Holly; Fall, Morgana; Wagner, Eric; Bowlin, Ricardo

    2012-02-13

    This project demonstrated microwave cracking of ethane with good product conversion and ethylene selectivity, with a short residence time ({approx}0.001 sec). The laboratory scale equipment was designed and built, along with concept designs for larger scale implementation. The system was operated below atmospheric pressures, in the range of 15-55 torr, with argon as a carrier gas. The measured products included hydrogen, methane, acetylene, and ethylene. The results followed similar trends to those predicted by the modeling software SPYRO{reg_sign}, with the exception that the microwave appeared to produce slightly lower amounts of ethylene and methane, although enhanced analytical analysis should reduce the difference. Continued testing will be required to verify these results and quantify the energy consumption of microwave vs. conventional. The microwave cracking process is an attractive option due to the possibility of selectively heating the reaction volume rather than the reactor walls, which may allow novel reactor designs that result in more efficient production of ethylene. Supplemental studies are needed to continue the laboratory testing and refine processing parameters.

  5. Technical Letter Report on the Cracking of Irradiated Cast Stainless Steels with Low Ferrite Content

    SciTech Connect (OSTI)

    Chen, Y.; Alexandreanu, B.; Natesan, K.

    2014-11-01

    Crack growth rate and fracture toughness J-R curve tests were performed on CF-3 and CF-8 cast austenite stainless steels (CASS) with 13-14% of ferrite. The tests were conducted at ~320°C in either high-purity water with low dissolved oxygen or in simulated PWR water. The cyclic crack growth rates of CF-8 were higher than that of CF-3, and the differences between the aged and unaged specimens were small. No elevated SCC susceptibility was observed among these samples, and the SCC CGRs of these materials were comparable to those of CASS alloys with >23% ferrite. The fracture toughness values of unirradiated CF-3 were similar between unaged and aged specimens, and neutron irradiation decreased the fracture toughness significantly. The fracture toughness of CF-8 was reduced after thermal aging, and declined further after irradiation. It appears that while lowering ferrite content may help reduce the tendency of thermal aging embrittlement, it is not very effective to mitigate irradiation-induced embrittlement. Under a combined condition of thermal aging and irradiation, neutron irradiation plays a dominant role in causing embrittlement in CASS alloys.

  6. Hydrocarbon Liquid Production via the bioCRACK Process and Catalytic Hydroprocessing of the Product Oil

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Schwaiger, Nikolaus; Elliott, Douglas C.; Ritzberger, Jurgen; Wang, Huamin; Pucher, Peter; Siebenhofer, Matthaus

    2015-02-13

    Continuous hydroprocessing of liquid phase pyrolysis bio-oil, provided by BDI-BioEnergy International bioCRACK pilot plant at OMV Refinery in Schwechat/Vienna Austria was investigated. These hydroprocessing tests showed promising results using catalytic hydroprocessing strategies developed for unfractionated bio-oil. A sulfided base metal catalyst (CoMo on Al2O3) was evaluated. The bed of catalyst was operated at 400 °C in a continuous-flow reactor at a pressure of 12.1 MPa with flowing hydrogen. The condensed liquid products were analyzed and found that the hydrocarbon liquid was significantly hydrotreated so that nitrogen and sulfur were below the level of detection (more »from 0.7 to 1.2%. The density of the products varied from 0.71 g/mL up to 0.79 g/mL with a correlated change of the hydrogen to carbon atomic ratio from 2.1 down to 1.9. The product quality remained high throughout the extended tests suggesting minimal loss of catalyst activity through the test. These tests provided the data needed to assess the quality of liquid fuel products obtained from the bioCRACK process as well as the activity of the catalyst for comparison with products obtained from hydrotreated fast pyrolysis bio-oils from fluidized-bed operation.« less

  7. Irradiation assisted stress corrosion cracking of HTH Alloy X-750 and Alloy 625

    SciTech Connect (OSTI)

    Mills, W.J.; Lebo, M.R.; Bajaj, R.; Kearns, J.J.; Hoffman, R.C.; Korinko, J.J.

    1994-06-01

    In-reactor testing of bolt-loaded precracked compact tension specimens was performed in 360{degree}C water to determine effect of irradiation on the SCC behavior of HTH Alloy X-750 and direct aged Alloy 625. Out-of-flux and autoclave control specimens provided baseline data. Primary test variables were stress intensity factor, fluence, chemistry, processing history, prestrain. Results for the first series of experiments were presented at a previous conference. Data from two more recent experiments are compared with previous results; they confirm that high irradiation levels significantly reduce SCC resistance in HTH Alloy X-750. Heat-to-heat differences in IASCC were related to differences in boron content, with low boron heats showing improved SCC resistance. The in-reactor SCC performance of Alloy 625 was superior to that for Alloy X-750, as no cracking was observed in any Alloy 625 specimens even though they were tested at very high K{sub 1} and fluence levels. A preliminary SCC usage model developed for Alloy X-750 indicates that in-reactor creep processes, which relax stresses but also increase crack tip strain rates, and radiolysis effects accelerate SCC. Hence, in-reactor SCC damage under high flux conditions may be more severe than that associated with postirradiation tests. In addition, preliminary mechanism studies were performed to determine the cause of IASCC In Alloy X-750.

  8. Load tests on five large spread footings on sand and evaluation of prediction methods 

    E-Print Network [OSTI]

    Gibbens, Robert Melvin

    1995-01-01

    . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cross-Hole Wave Tests. Dilatometer Tests . . Borehole Shear Tests. . Step Blade Tests. 5 9 17 22 28 34 34 39 45 54 56 64 64 LOAD TEST SETUP 3. 1 3. 2 3. 3 3. 4 3. 5 3. 6 General Setup. Spread Footing Construction Reaction Shaft... INVOLVED Mr. Mike Adams Dr. Allan Lutenegger Dr. Don Degroot Buchanan/Soil Mechanics Dr. Derek Morris Mr. Tony Yen Mr. John Del hia PiezoCone Penetration Test Dilatometer Tests Dilatometer Test w/Thrust Measurements Pressuremeter Tests Step...

  9. Spread and transmission of bacterial pathogens in experimental nematode populations of Caenorhabditis elegans.

    E-Print Network [OSTI]

    Diaz, S. Anaid; Restif, Olivier

    2014-06-22

    . After incubation the sample was 195 centrifuged (1500 rpm for 1 min) and washed twice with M9 to remove 196 antibiotics. The pelleted sample from each tube with the progeny was then 197 transferred to an agar plate containing antibiotics as before. We... Journal of Soil Biology. 540 42:S70–S78 541 542 13. Grewal PS. 1991. Effects of Caenorhabditis elegans on the spread of 543 the bacterium Pseudomonas tolaasii in mushrooms. Ann. appl. Biol. 118: 47-544 55. 545 546 14. Gibbs DS, Anderson GL...

  10. Spreading an Idea From the William Kamkwamba TED Talk | GE Global Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effect Photovoltaics -7541C.3 SpecialSponsor Guidelines Candidates fSpreading an

  11. How Do You Spread the Word About Saving Energy? | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious Rank EERE:FinancingPetroleum12,ExecutiveFinancingR Walls - Buildingof EnergyTown,FinanceWithatMoneySpread

  12. Hydrogen embrittlement, grain boundary segregation, and stress corrosion cracking of alloy X-750 in low- and high-temperature water

    SciTech Connect (OSTI)

    Mills, W. J.; Lebo, M. R.; Kearns, J. J. [Bettis Atomic Power Lab., West Mifflin, PA (United States)

    1997-04-01

    The nature of intergranular stress corrosion cracking (SCC) of alloy X-750 was characterized in low- and high-temperature water by testing as-notched and precracked fracture mechanics specimens. Materials given the AH, BH, and HTH heat treatments were studied. While all heat treatments were susceptible to rapid low-temperature crack propagation (LTCP) below 150 C, conditions AH and BH were particularly susceptible. Low-temperature tests under various loading conditions (e.g., constant displacement, constant load, and increasing load) revealed that the maximum stress intensity factors (K{sub P{sub max}}) from conventional rising load tests provide conservative estimates of the critical loading conditions in highly susceptible heats, regardless of the load path history. For resistant heats, K{sub P{sub max}} provides a reasonable, but not necessarily conservative, estimate of the critical stress intensity factor for LTCP. Testing of as-notched specimens showed that LTCP will not initiate at a smooth surface or notch, but will readily occur if a cracklike defect is present. Comparison of the cracking response in water with that for hydrogen-precharged specimens tested in air demonstrated that LTCP is associated with hydrogen embrittlement of grain boundaries. The stress corrosion crack initiation and growth does occur in high-temperature water (>250 C), but crack growth rates are orders of magnitude lower than LTCP rates. The SCC resistance of HTH heats is far superior to that of AH heats as crack initiation times are two to three orders of magnitude greater and growth rates are one to two orders of magnitude lower.

  13. An experimental study of CTOD for Mode I/Mode II stable crack growth in thin 2024-T3 aluminum specimens

    SciTech Connect (OSTI)

    Amstutz, B.E.; Sutton, M.A.; Dawicke, D.S.; Newman, J.C.

    1995-12-31

    An experimental study of crack tip opening displacement (CTOD) for Mode I/Mode II stable crack growth in thin sheet 2024-T3 aluminum has been conducted. To perform the experiments, an Arcan specimen and fixture was modified so that (1) slippage in the grips was eliminated, (2) large rotations of the fixture components were achievable and (3) bending stresses were minimized. Defining {Theta} to be the angle between the Mode I loading direction (perpendicular to the crack line) and the direction of applied loading, experimental results indicate that (a) for large amounts of crack extension, a {ge} 10mm, the value of CTOD at 1 mm behind the crack tip appears to approach a constant value of 0.1 mm for all modes of loading, (b) the direction of crack extension varied with applied mixed mode loading, (c) Mode I crack extension is predominant for 0{degree} {le} {Theta} {le} 60{degree}, (d) Mode II crack extension is predominant for 75{degree} {le} {Theta} {le} 90{degree} and (e) a transition zone exists for angles {Theta} near 75{degree}.

  14. I Am Crrarn Soc, 1 5 [2] 316-2r (1992) Distribution of Matrix Cracks in a Uniaxial Ceramic Composite

    E-Print Network [OSTI]

    Barber, James R.

    1992-01-01

    obtained for a unidirectional ceramic-matrix composite (Sic fibers in a calcium aluminosilicate matrixI Am Crrarn Soc, 1 5 [2] 316-2r (1992) journal Distribution of Matrix Cracks in a Uniaxial Ceramic cracking and debonding in uniaxial composites loaded in tension predict that the matrix stress varies only

  15. Applied Catalysis A: General 192 (2000) 227234 Hydrogen production via the direct cracking of methane over Ni/SiO2

    E-Print Network [OSTI]

    zur Loye, Hans-Conrad

    2000-01-01

    Applied Catalysis A: General 192 (2000) 227­234 Hydrogen production via the direct cracking is a potential route to the production of CO-free hydrogen and filamentous carbon. Eventually, however. ©2000 Elsevier Science B.V. All rights reserved. Keywords: Methane cracking; Hydrogen production

  16. Damage spreading in spatial and small-world random boolean networks

    SciTech Connect (OSTI)

    Lu, Qiming [Los Alamos National Laboratory; Teuscher, Christof [Los Alamos National Laboratory

    2008-01-01

    Random Boolean Networks (RBNs) are often used as generic models for certain dynamics of complex systems, ranging from social networks, neural networks, to gene or protein interaction networks. Traditionally, RBNs are interconnected randomly and without considering any spatial arrangement of the links and nodes. However, most real-world networks are spatially extended and arranged with regular, small-world, or other non-random connections. Here we explore the RBN network topology between extreme local connections, random small-world, and random networks, and study the damage spreading with small perturbations. We find that spatially local connections change the scaling of the relevant component at very low connectivities ({bar K} << 1) and that the critical connectivity of stability K{sub s} changes compared to random networks. At higher {bar K}, this scaling remains unchanged. We also show that the relevant component of spatially local networks scales with a power-law as the system size N increases, but with a different exponent for local and small-world networks. The scaling behaviors are obtained by finite-size scaling. We further investigate the wiring cost of the networks. From an engineering perspective, our new findings provide the key trade-offs between damage spreading (robustness), the network wiring cost, and the network's communication characteristics.

  17. A chemical trompe-l'\\oe{}il: no iron spread in the globular cluster M22

    E-Print Network [OSTI]

    Mucciarelli, A; Massari, D; Pancino, E; Stetson, P B; Ferraro, F R; Lanzoni, B; Lardo, C

    2015-01-01

    We present the analysis of high-resolution spectra obtained with UVES and UVES-FLAMES at the Very Large Telescope of 17 giants in the globular cluster M22, a stellar system suspected to have an intrinsic spread in the iron abundance. We find that when surface gravities are derived spectroscopically (by imposing to obtain the same iron abundance from FeI and FeII lines) the [Fe/H] distribution spans ~0.5 dex, according to previous analyses. However, the gravities obtained in this way correspond to unrealistic low stellar masses (0.1-0.5 Msun) for most of the surveyed giants. Instead, when photometric gravities are adopted, the [FeII/H] distribution shows no evidence of spread at variance with the [FeI/H] distribution. This difference has been recently observed in other clusters and could be due to non-local thermodynamical equilibrium effects driven by over-ionization mechanisms, that mainly affect the neutral species (thus providing lower [FeI/H]) but leave [FeII/H] unaltered. We confirm that the s-process el...

  18. X-ray Burst Oscillations: From Flame Spreading to the Cooling Wake

    E-Print Network [OSTI]

    Simin Mahmoodifar; Tod Strohmayer

    2015-10-16

    Type I X-ray bursts are thermonuclear flashes observed from the surface of accreting neutron stars in Low Mass X-ray Binaries. Oscillations have been observed during the rise and/or decay of some of these X-ray bursts. Those seen during the rise can be well explained by a spreading hot spot model, but to date there haven't been any quantitative studies that consistently track the oscillation amplitude both during the rise and decay (tail) of bursts. Here we compute the light curves and amplitudes of oscillations in X-ray burst models that realistically account for both flame spreading and subsequent cooling. We present results for two such "cooling wake" models, a "canonical" cooling model where each patch on the neutron star surface heats and cools identically, and an "asymmetric" model where parts of the star cool at different rates. We show that while canonical cooling models can generate oscillations in the tails of bursts, they cannot easily produce the highest observed modulation amplitudes. Alternatively, a simple model with asymmetric cooling can achieve higher amplitudes consistent with the observations.

  19. Marangoni spreading due to a localized alcohol supply on a thin water film

    E-Print Network [OSTI]

    Hernández-Sánchez, José Federico; Snoeijer, J H

    2013-01-01

    Bringing the interfaces of two miscible fluids into contact naturally generates strong gradients in surface tension. Here we investigate such a Marangoni-driven flow by continuously supplying isopropyl alcohol (IPA) on a film of water, using micron-sized droplets of IPA-water mixtures. These droplets create a localized depression in surface tension that leads to the opening of a circular and thin region in the water film. At the edge of the thin region, there is a rim growing and collecting the water of the film. We find that the spreading radius scales as $r \\sim t^{1/2}$. This result can be explained from a balance between Marangoni and viscous stresses, assuming that the gradients in surface tension are smoothened out over the entire size of the circular opening. We derive a scaling law that accurately predicts the influence of the IPA flux as well as the thickness of the thin film at the interior of the spreading front.

  20. Spreading layers in accreting objects: role of acoustic waves for angular momentum transport, mixing and thermodynamics

    E-Print Network [OSTI]

    Philippov, Alexander A; Stone, James M

    2015-01-01

    Disk accretion at high rate onto a white dwarf or a neutron star has been suggested to result in the formation of a spreading layer (SL) - a belt-like structure on the object's surface, in which the accreted matter steadily spreads in the poleward (meridional) direction while spinning down. To assess its basic characteristics we perform two-dimensional hydrodynamic simulations of supersonic SLs in the relevant morphology with a simple prescription for cooling. We demonstrate that supersonic shear naturally present at the base of the SL inevitably drives sonic instability that gives rise to large scale acoustic modes governing the evolution of the SL. These modes dominate the transport of momentum and energy, which is intrinsically global and cannot be characterized via some form of local effective viscosity (e.g. $\\alpha$-viscosity). The global nature of the wave-driven transport should have important implications for triggering Type I X-ray bursts in low mass X-ray binaries. The nonlinear evolution of waves ...

  1. Interplay between the local information based behavioral responses and the epidemic spreading in complex networks

    E-Print Network [OSTI]

    Liu, Can; Chen, Han-Shuang; Zhang, Hai-Feng; Tang, Ming

    2015-01-01

    The spreading of an infectious disease can trigger human behavior responses to the disease, which in turn plays a crucial role on the spreading of epidemic. In this study, to illustrate the impacts of the human behavioral responses, a new class of individuals, $S^F$, is introduced to the classical susceptible-infected-recovered ($SIR$) model. In the model, $S^F$ state represents that susceptible individuals who take self-initiate protective measures to lower the probability of being infected, and a susceptible individual may go to $S^F$ state with a response rate when contacting an infectious neighbor. Via the percolation method, the theoretical formulas for the epidemic threshold as well as the prevalence of epidemic are derived. Our finding indicates that, with the increasing of the response rate, the epidemic threshold is enhanced and the prevalence of epidemic is reduced. The analytical results are also verified by the numerical simulations. In addition, we demonstrate that, because the mean field method ...

  2. Thermonuclear Flame Spreading on Rapidly Spinning Neutron Stars: Indications of the Coriolis Force?

    E-Print Network [OSTI]

    Sudip Bhattacharyya; Tod E. Strohmayer

    2007-08-27

    Millisecond period brightness oscillations during the intensity rise of thermonuclear X-ray bursts are likely caused by an azimuthally asymmetric, expanding burning region on the stellar surface. The time evolution of the oscillation amplitude during the intensity rise encodes information on how the thermonuclear flames spread across the stellar surface. This process depends on properties of the accreted burning layer, surface fluid motions, and the surface magnetic field structure, and thus can provide insight into these stellar properties. We present two examples of bursts from different sources that show a decrease in oscillation amplitude during the intensity rise. Using theoretical modeling, we demonstrate that the observed amplitude evolution of these bursts is not well described by a uniformly expanding circular burning region. We further show that by including in our model the salient aspects of the Coriolis force (as described by Spitkovsky, Levin, and Ushomirsky) we can qualitatively reproduce the observed evolution curves. Our modeling shows that the evolutionary structure of burst oscillation amplitude is sensitive to the nature of flame spreading, while the actual amplitude values can be very useful to constrain some source parameters.

  3. Time-resolved measurement of photon emission during fast crack propagation in three-point bending fracture of silica glass and soda lime glass

    SciTech Connect (OSTI)

    Shiota, Tadashi, E-mail: tshiota@ceram.titech.ac.jp; Sato, Yoshitaka; Yasuda, Kouichi [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1-S7-13 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)] [Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1-S7-13 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2014-03-10

    Simultaneous time-resolved measurements of photon emission (PE) and fast crack propagation upon bending fracture were conducted in silica glass and soda lime glass. Observation of fracture surfaces revealed that macroscopic crack propagation behavior was similar between the silica glass and soda lime glass when fracture loads for these specimens were comparable and cracks propagated without branching. However, a large difference in the PE characteristics was found between the two glasses. In silica glass, PE (645–655?nm) was observed during the entire crack propagation process, whereas intense PE (430–490?nm and 500–600?nm) was observed during the initial stages of propagation. In contrast, only weak PE was detected in soda lime glass. These results show that there is a large difference in the atomic processes involved in fast crack propagation between these glasses, and that PE can be used to study brittle fracture on the atomic scale.

  4. Researchers have been using STFC's ISIS neutron and muon source to investigate cracking in train wheels and potential methods of

    E-Print Network [OSTI]

    Researchers have been using STFC's ISIS neutron and muon source to investigate cracking in train with a great business idea. For more information about how your business could benefit from access to ISIS: Tel: +44 (0)1925 603708 Email: innovations@stfc.ac.uk Twitter: @STFC_B2B Using ISIS to optimise train wheel

  5. TRIP-assisted steels: cracking of high-carbon S. Chatterjee and H. K. D. H. Bhadeshia*

    E-Print Network [OSTI]

    Cambridge, University of

    TRIP-assisted steels: cracking of high-carbon martensite S. Chatterjee and H. K. D. H. Bhadeshia fine martensite. It is the fine scale of the retained austenite in TRIP assisted steels that permits the martensite to be tolerated without endangering their mechanical properties. Keywords: TRIP-assisted steels

  6. Time dependent crack growth in polyethylene: characterizing the da/dt = AKn dependence and the effects of Igepal 

    E-Print Network [OSTI]

    Slay, Jeremy Buc

    1999-01-01

    slow crack growth (SCG) rate as a function of stress intensity. Constant load single-edge-notch bend (SENB) tests commonly know as ''three point bend'' tests have been performed on deeply notched specimens. The load-line displacement as a function...

  7. Sulfur distribution in the oil fractions obtained by thermal cracking of Jordanian El-Lajjun oil Shale

    E-Print Network [OSTI]

    Shawabkeh, Reyad A.

    by the thermal cracking process of the El-Lujjan oil shale showed that the yield of oil was around 12 wt of the boiling point for different distillate fractions. Sulfur in Jordanian oil shale was found to be mainly the dominant phases in these fractions. q 2005 Published by Elsevier Ltd. 1. Introduction Oil shale

  8. Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model and Computations

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Hydro-Mechanical Coupling in Damaged Porous Media Containing Isolated Cracks or/and Vugs: Model In this paper we present the development of the macroscopic model describing the hydro-mechanical coupling) In this paper we present the macroscopic model describing the hydro-mechanical behaviour of such class

  9. Proppant transport in hydraulic fracturing: Crack tip screen-out in KGD and P3D models

    E-Print Network [OSTI]

    Peirce, Anthony

    Proppant transport in hydraulic fracturing: Crack tip screen-out in KGD and P3D models E.V. Dontsov February 2015 Available online 14 March 2015 Keywords: Hydraulic fracturing Proppant transport Numerical, the equations that govern the propagation of hydraulic fractures and the proppant transport inside them

  10. The Fracture Toughness of Medium Density Fiberboard (MDF) Including the Effects of Fiber Bridging and Crack-Plane Interference

    E-Print Network [OSTI]

    Nairn, John A.

    1 The Fracture Toughness of Medium Density Fiberboard (MDF) Including the Effects of Fiber Bridging University, Corvallis, OR, USA Abstract The fracture toughness of medium density fiberboard (MDF) as a function of crack length (R curve) was measured. Fracture toughness was determined from force

  11. Materials Science and Engineering A 490 (2008) 2635 Mechanisms of cracking and delamination within thick thermal barrier

    E-Print Network [OSTI]

    Hutchinson, John W.

    2008-01-01

    that characterizes the susceptibility to delamination of thermal barrier coated (TBC) hot-section aero-turbine. Introduction The maximum temperature capability of thermal barrier systems used in gas turbines is oftenMaterials Science and Engineering A 490 (2008) 26­35 Mechanisms of cracking and delamination within

  12. An experimental investigation of crack initiation in thin sheets of nitinol S. Daly *, A. Miller, G. Ravichandran, K. Bhattacharya

    E-Print Network [OSTI]

    Bhattacharya, Kaushik

    An experimental investigation of crack initiation in thin sheets of nitinol S. Daly *, A. Miller, G nitinol sheets at room temperature was measured. The extent and nature of the phase transformation, the nearly equi- atomic nickel­titanium alloy (nitinol), attractive for a vari- ety of applications

  13. Fatigue Crack Growth Rate Model for Metallic Alloys R. C. Dimitriu and H. K. D. H. Bhadeshia

    E-Print Network [OSTI]

    Cambridge, University of

    ] expressed the crack growth rate in terms of the elastic modulus, toughness, and ductility: da dN = 32 1 2 1 2 f E(KIc - Kmax) 1 - K KIc 1 K 2 (3) where and are the fatigue ductility exponent and coefficient respectively, E is the elastic modulus, KIc is the critical stress intensity for fracture

  14. Identification of sublimation-type thermal contraction crack polygons at the proposed NASA Phoenix landing site: Implications for substrate

    E-Print Network [OSTI]

    Marchant, David R.

    Identification of sublimation-type thermal contraction crack polygons at the proposed NASA Phoenix within the NASA Phoenix landing site Area D characterized by boulder-topped, polygonally-patterned mounds of buried ice. On the basis of morphological similarities, we classify the Phoenix Box 1 polygons

  15. A new failure mechanism in thin film by collaborative fracture and delamination: interacting duos of cracks

    E-Print Network [OSTI]

    Joel Marthelot; Jose Bico; Francisco Melo; Benoit Roman

    2014-12-02

    When a thin film moderately adherent to a substrate is subjected to residual stress, the cooperation between fracture and delamination leads to unusual fracture patterns such as spirals, alleys of crescents and various types of strips, all characterized by a robust characteristic length scale. We focus on the propagation of a duo of cracks: two fractures in the film connected by a delamination front and progressively detaching a strip. We show experimentally that the system selects an equilibrium width on the order of 25 times the thickness of the coating and independent of both fracture and adhesion energies. We investigate numerically the selection of the width and the condition for propagation by considering Griffith's criterion and the principle of local symmetry. In addition, we propose a simplified model based on maximum of energy release rate, which provides insights of the physical mechanisms leading to these regular patterns, and predicts the effect of material properties on the selected with of the detaching strip.

  16. Methods of cracking a crude product to produce additional crude products

    DOE Patents [OSTI]

    Mo, Weijian (Sugar Land, TX); Roes, Augustinus Wilhelmus Maria (Houston, TX); Nair, Vijay (Katy, TX)

    2009-09-08

    A method for producing a crude product is disclosed. Formation fluid is produced from a subsurface in situ heat treatment process. The formation fluid is separated to produce a liquid stream and a first gas stream. The first gas stream includes olefins. The liquid stream is fractionated to produce one or more crude products. At least one of the crude products has a boiling range distribution from 38.degree. C. and 343.degree. C. as determined by ASTM Method D5307. The crude product having the boiling range distribution from 38.degree. C. and 343.degree. C. is catalytically cracked to produce one or more additional crude products. At least one of the additional crude products is a second gas stream. The second gas stream has a boiling point of at most 38.degree. C. at 0.101 MPa.

  17. Analogies between the cracking noise of ethanol-damped charcoal and earthquakes

    E-Print Network [OSTI]

    Ribeiro, H V; Alves, L G A; Santoro, P A; Picoli, S; Lenzi, E K; Mendes, R S

    2015-01-01

    We report on an extensive characterization of the cracking noise produced by charcoal samples when damped with ethanol. We argue that the evaporation of ethanol causes transient and irregularly distributed internal stresses that promotes the fragmentation of samples and mimic some situations found in mining process. The results show that, in general, the most fundamental seismic laws ruling earthquakes (Gutenberg-Richter law, unified scaling law for the recurrence times, Omori's law, productivity law and Bath's law) hold under the conditions of the experiment. Some discrepancies were also identified (a smaller exponent in Gutenberg-Richter law, a stationary behavior in the aftershocks rates for long times and a double power-law relationship in productivity law) and related to the different loading condition. Our results thus corroborate to elucidate the parallel between seismic laws and fracture experiments caused by a more complex loading condition that also occurs in natural and induced seismicity (such as ...

  18. Irradiation-assisted stress corrosion cracking of HTH Alloy X-750 and Alloy 625

    SciTech Connect (OSTI)

    Bajaj, R.; Mills, W.J.; Lebo, M.R.; Hyatt, B.Z.; Burke, M.G.

    1995-07-01

    In-reactor testing of bolt-loaded compact tension specimens was performed in 360 C water. New data confirms previous results that high irradiation levels reduce SCC resistance in Alloy X-750. Low boron heats show improved IASCC (irradiation-assisted stress corrosion cracking). Alloy 625 is resistant to IASCC. Microstructural, microchemical, and deformation studies were carried out. Irradiation of X-750 caused significant strengthening and ductility loss associated with formation of cavities and dislocation loops. High irradiation did not cause segregation in X-750. Irradiation of 625 resulted in formation of small dislocation loops and a fine body-centered-orthorhombic phase. The strengthening due to loops and precipitates was apparently offset in 625 by partial dissolution of {gamma} precipitates. Transmutation of boron to helium at grain boundaries, coupled with matrix strengthening, is believed to be responsible for IASCC in X-750, and the absence of these two effects results in superior IASCC resistance in 625.

  19. POTENTIAL FOR STRESS CORROSION CRACKING OF A537 CARBON STEEL NUCLEAR WASTE TANKS CONTAINING HIGHLY CAUSTIC SOLUTIONS

    SciTech Connect (OSTI)

    Lam, P.; Stripling, C.; Fisher, D.; Elder, J.

    2010-04-26

    The evaporator recycle streams of nuclear waste tanks may contain waste in a chemistry and temperature regime that exceeds the current corrosion control program, which imposes temperature limits to mitigate caustic stress corrosion cracking (CSCC). A review of the recent service history found that two of these A537 carbon steel tanks were operated in highly concentrated hydroxide solution at high temperature. Visual inspections, experimental testing, and a review of the tank service history have shown that CSCC has occurred in uncooled/un-stress relieved tanks of similar construction. Therefore, it appears that the efficacy of stress relief of welding residual stress is the primary corrosion-limiting mechanism. The objective of this experimental program is to test A537 carbon steel small scale welded U-bend specimens and large welded plates (30.48 x 30.38 x 2.54 cm) in a caustic solution with upper bound chemistry (12 M hydroxide and 1 M each of nitrate, nitrite, and aluminate) and temperature (125 C). These conditions simulate worst-case situations in these nuclear waste tanks. Both as-welded and stress-relieved specimens have been tested. No evidence of stress corrosion cracking was found in the U-bend specimens after 21 days of testing. The large plate test was completed after 12 weeks of immersion in a similar solution at 125 C except that the aluminate concentration was reduced to 0.3 M. Visual inspection of the plate revealed that stress corrosion cracking had not initiated from the machined crack tips in the weld or in the heat affected zone. NDE ultrasonic testing also confirmed subsurface cracking did not occur. Based on these results, it can be concluded that the environmental condition of these tests was unable to develop stress corrosion cracking within the test periods for the small welded U-bends and for the large plates, which were welded with an identical procedure as used in the construction of the actual nuclear waste tanks in the 1960s. The absence of evidence of stress corrosion cracking and general corrosion in the laboratory-scaled specimens indicate that this type of nuclear waste tank is not susceptible to highly caustic solutions up to 12 M hydroxide at 125 C when sufficient nitrite inhibitor is present.

  20. An Assessment of Remote Visual Methods to Detect Cracking in Reactor Components

    SciTech Connect (OSTI)

    Cumblidge, Stephen E.; Anderson, Michael T.; Doctor, Steven R.; Simonen, Fredric A.; Elliot, Anthony J.

    2008-01-01

    Recently, the U.S. nuclear industry has proposed replacing current volumetric and/or surface examinations of certain components in commercial nuclear power plants, as required by the American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI, “Inservice Inspection of Nuclear Power Plant Components,” with a simpler visual testing (VT) method. The advantages of VT are that these tests generally involve much less radiation exposure and time to perform the examination than do volumetric examinations such as ultrasonic testing. The issues relative to the reliability of VT in determining the structural integrity of reactor components were examined. Some piping and pressure vessel components in a nuclear power station are examined using VT as they are either in high radiation fields or component geometry precludes the use of ultrasonic testing (UT) methodology. Remote VT with radiation-hardened video systems has been used by nuclear utilities to find cracks in pressure vessel cladding in pressurized water reactors, core shrouds in boiling water reactors, and to investigate leaks in piping and reactor components. These visual tests are performed using a wide variety of procedures and equipment. The techniques for remote VT use submersible closed-circuit video cameras to examine reactor components and welds. PNNL conducted a parametric study that examined the important variables influencing the effectiveness of a remote visual test. Tested variables included lighting techniques, camera resolution, camera movement, and magnification. PNNL also conducted a limited laboratory test using a commercial visual testing camera system to experimentally determine the ability of the camera system to detect cracks of various widths under ideal conditions. The results of these studies and their implications are presented in this paper.