National Library of Energy BETA

Sample records for fatigue design curves

  1. FATIGUE DESIGN CURVES FOR

    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 Administration would like submitKansasCommunitiesofExtrans - Permeation Measurement2 0 thFATIGUE DESIGN CURVES

  2. Effects of LWR coolant environments on fatigue design curves of carbon and low-alloy steels

    SciTech Connect (OSTI)

    Chopra, O.K.; Shack, W.J. [Argonne National Lab., IL (United States)

    1998-03-01

    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. While effects of reactor coolant environments are not explicitly addressed by the design curves, test data indicate that the Code fatigue curves may not always be adequate in coolant environments. This report summarizes work performed by Argonne National Laboratory on fatigue of carbon and low-alloy steels in light water reactor (LWR) environments. The existing fatigue S-N data have been evaluated to establish the effects of various material and loading variables such as steel type, dissolved oxygen level, strain range, strain rate, temperature, orientation, and sulfur content on the fatigue life of these steels. Statistical models have been developed for estimating the fatigue S-N curves as a function of material, loading, and environmental variables. The results have been used to estimate the probability of fatigue cracking of reactor components. The different methods for incorporating the effects of LWR coolant environments on the ASME Code fatigue design curves are presented.

  3. Review of the margins for ASME code fatigue design curve - effects of surface roughness and material variability.

    SciTech Connect (OSTI)

    Chopra, O. K.; Shack, W. J.; Energy Technology

    2003-10-03

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. The Code specifies 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 the existing fatigue {var_epsilon}-N data for carbon and low-alloy steels and wrought and cast austenitic SSs to define the effects of key material, loading, and environmental parameters on the fatigue lives of the steels. Experimental data are presented on the effects of surface roughness on the fatigue life of these steels in air and LWR environments. Statistical models are presented for estimating the fatigue {var_epsilon}-N curves as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are discussed. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue evaluations. A critical review of the margins for ASME Code fatigue design curves is presented.

  4. Ali Fatemi -University of Toledo All Rights Reserved Chapter 2Fatigue Design Methods 1 FATIGUE DESIGN METHODS

    E-Print Network [OSTI]

    Fatemi, Ali

    Methods 8 FATIGUE DESIGN CRITERIA (CONT'D) Infinite-Life Design Unlimited safety is the oldest criterion Methods 2 FATIGUE DESIGN METHODS STRATEGIES IN FATIGUE DESIGN FATIGUE DESIGN CRITERIA ANALYSIS Design Methods 7 FATIGUE DESIGN CRITERIA Criteria for fatigue design have evolved from infinite life

  5. Fatigue threshold R-curves for predicting reliability of ceramics under cyclic loading

    E-Print Network [OSTI]

    Ritchie, Robert

    Fatigue threshold R-curves for predicting reliability of ceramics under cyclic loading J.J. Kruzic, grain-bridging ceramics, the crack-size dependence of the fatigue threshold during bridging zone-thickness, fatigue cracks via an accurately measured crack bridging stress profile. Both an alumina ceramic

  6. Effects of LWR coolant environments on fatigue S-N curves for carbon and low-alloy steels

    SciTech Connect (OSTI)

    Chopra, O.K.; Shack, W.J.

    1996-06-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Figure I-90 of Appendix I to Section III of the Code specifies 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. Recent test data indicate significant decreases in fatigue lives of carbon and low-alloy steels in LWR environments when five conditions are satisfied simultaneously: applied strain range, temperature, dissolved oxygen in the water, and S content of the steel are above minimum threshold levels, and loading strain rate is below a threshold value. Only moderate decrease in fatigue life is observed when any one of these conditions is not satisfied. This paper presents several methods that have been proposed for evaluating the effects of LWR coolant environments on fatigue S-N curves for carbon and low-alloy steels. Estimations of fatigue lives under actual loading histories are discussed.

  7. Analysis and Design of Power Acceptability Curves

    E-Print Network [OSTI]

    Analysis and Design of Power Acceptability Curves for Industrial Loads Masters Thesis and Final Analysis and Design of Power Acceptability Curves for Industrial Loads Thesis and Final Report John Kyei

  8. PARAMETRIC MODELS FOR ESTIMATING WIND TURBINE FATIGUE LOADS FOR DESIGN

    E-Print Network [OSTI]

    Sweetman, Bert

    1 PARAMETRIC MODELS FOR ESTIMATING WIND TURBINE FATIGUE LOADS FOR DESIGN Lance Manuel1 Paul S-4020 ABSTRACT International standards for wind turbine certification depend on finding long-term fatigue load loads. #12;2 INTRODUCTION Design constraints for wind turbine structures fall into either extreme load

  9. Computational design with curved creases : David Huffman's approach to paperfolding

    E-Print Network [OSTI]

    Koschitz, Richard Duks

    2014-01-01

    This dissertation provides a new framework for defining design approaches with curved creases by investigating the work of David A. Huffman, famous computer scientist and pioneer of curved-crease paperfolding. The history ...

  10. Effects of LWR environments on fatigue life of carbon and low-alloy steels

    SciTech Connect (OSTI)

    Chopra, O.K.; Shack, W.J.

    1995-03-01

    SME Boiler and Pressure Vessel Code provides construction of nuclear power plant components. Figure I-90 Appendix I to Section III of the Code specifies fatigue design curves for structural materials. While effects of environments are not explicitly addressed by the design curves, test data suggest that the Code fatigue curves may not always be adequate in coolant environments. This paper reports the results of recent fatigue tests that examine the effects of steel type, strain rate, dissolved oxygen level, strain range, loading waveform, and surface morphology on the fatigue life of A 106-Gr B carbon steel and A533-Gr B low-alloy steel in water.

  11. Effects of material and loading variables on fatigue life of carbon and low-alloy steels in LWR environments

    SciTech Connect (OSTI)

    Chopra, O.K.; Shack, W.J.

    1995-03-01

    The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components. Section III of the Code specifies fatigue design curves for structural materials. While effects of reactor coolant environments are not explicitly addressed by the design curves, test data suggest that the Code fatigue curves may not always be adequate in coolant environments. This paper reports the results of recent fatigue tests that examine the effects of steel type, strain rate, dissolved oxygen level, strain range, loading waveform, and surface morphology on the fatigue life of A106-Gr B carbon steel and A533-Gr B low-alloy steel in water.

  12. Update and Improve Subsection NH –– Alternative Simplified Creep-Fatigue Design Methods

    SciTech Connect (OSTI)

    Tai Asayama

    2009-10-26

    This report described the results of investigation on Task 10 of DOE/ASME Materials NGNP/Generation IV Project based on a contract between ASME Standards Technology, LLC (ASME ST-LLC) and Japan Atomic Energy Agency (JAEA). Task 10 is to Update and Improve Subsection NH -- Alternative Simplified Creep-Fatigue Design Methods. Five newly proposed promising creep-fatigue evaluation methods were investigated. Those are (1) modified ductility exhaustion method, (2) strain range separation method, (3) approach for pressure vessel application, (4) hybrid method of time fraction and ductility exhaustion, and (5) simplified model test approach. The outlines of those methods are presented first, and predictability of experimental results of these methods is demonstrated using the creep-fatigue data collected in previous Tasks 3 and 5. All the methods (except the simplified model test approach which is not ready for application) predicted experimental results fairly accurately. On the other hand, predicted creep-fatigue life in long-term regions showed considerable differences among the methodologies. These differences come from the concepts each method is based on. All the new methods investigated in this report have advantages over the currently employed time fraction rule and offer technical insights that should be thought much of in the improvement of creep-fatigue evaluation procedures. The main points of the modified ductility exhaustion method, the strain range separation method, the approach for pressure vessel application and the hybrid method can be reflected in the improvement of the current time fraction rule. The simplified mode test approach would offer a whole new advantage including robustness and simplicity which are definitely attractive but this approach is yet to be validated for implementation at this point. Therefore, this report recommends the following two steps as a course of improvement of NH based on newly proposed creep-fatigue evaluation methodologies. The first step is to modify the current approach by incorporating the partial advantages the new method offer, and the second step is to replace the current method by the simplified test approach when it has become technically mature enough. The recommendations are basically in line with the work scope of the Task Force on Creep-Fatigue of the Subgroup on Elevated Temperature Design of the Standards Committee of the ASME Boiler and Pressure Vessel Committee Section III.

  13. Fatigue of ceramics at elevated temperatures: Microstructural design for optimal performance

    E-Print Network [OSTI]

    Ritchie, R.O.; Chen, D.; Zhang, X.F.

    2000-01-01

    D IVISION FATIGUE OF CERAMICS AT ELEVATED TEMPERATURES:76SF00098. FATIGUE OF CERAMICS AT ELEVATED TEMPERATURES:silicon carbide (SiC) ceramics offer many advantages,

  14. J. F. Mandell, D. D. Samborsky, and H. J. Sutherland, "Effects of Materials Parameters and Design Details on the Fatigue of Composite Materials for Wind Turbine Blades", 1999

    E-Print Network [OSTI]

    J. F. Mandell, D. D. Samborsky, and H. J. Sutherland, "Effects of Materials Parameters and Design Details on the Fatigue of Composite Materials for Wind Turbine Blades", 1999 EWEC, Nice, France, March 1-5, 1999. Effects of Materials Parameters and Design Details on the Fatigue of Composite Materials for Wind

  15. 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.

  16. 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.

  17. Effects of LWR coolant environments on fatigue lives of austenitic stainless steels

    SciTech Connect (OSTI)

    Chopra, O.K.; Gavenda, D.J. [Argonne National Lab., IL (United States). Energy Technology Div.

    1997-07-01

    The ASME Boiler and Pressure Vessel Code fatigue design curves for structural materials do not explicitly address the effects of reactor coolant environments on fatigue life. Recent test data indicate a significant decrease in fatigue life of pressure vessel and piping materials in light water reactor (LWR) environments. Fatigue tests have been conducted on Types 304 and 316NG stainless steel in air and LWR environments to evaluate the effects of various material and loading variables, e.g., steel type, strain rate, dissolved oxygen (DO) in water, and strain range, on fatigue lives of these steels. The results confirm the significant decrease in fatigue life in water. The environmentally assisted decrease in fatigue life depends both on strain rate and DO content in water. A decrease in strain rate from 0.4 to 0.004%/s decreases fatigue life by a factor of {approx} 8. However, unlike carbon and low-alloy steels, environmental effects are more pronounced in low-DO than in high-DO water. At {approx} 0.004%/s strain rate, reduction in fatigue life in water containing <10 ppb D is greater by a factor of {approx} 2 than in water containing {ge} 200 ppb DO. Experimental results have been compared with estimates of fatigue life based on the statistical model. The formation and growth of fatigue cracks in austenitic stainless steels in air and LWR environments are discussed.

  18. PROPER FILTER DESIGN PROCEDURE FOR VIBRATION SUPPRESSION USING DELAY-ERROR-ORDER CURVES

    E-Print Network [OSTI]

    Mavroidis, Constantinos

    PROPER FILTER DESIGN PROCEDURE FOR VIBRATION SUPPRESSION USING DELAY-ERROR-ORDER CURVES D. Economou of Mechanical Engineering, Mechanical Design and Control Systems Division, 9 Heroon Polytechniou Str., 15773@central.ntua.gr B Rutgers University, The State University of New Jersey, Department of Mechanical and Aerospace

  19. Fatigue crack initiation in carbon and low-alloy steels in light water reactor environments : mechanism and prediction.

    SciTech Connect (OSTI)

    Chopra, O. K.; Shack, W. J.

    1998-01-27

    Section 111 of the ASME Boiler and Pressure Vessel Code specifies fatigue design curves for structural materials. The effects of reactor coolant environments are not explicitly addressed by the Code design curves. Recent test data illustrate potentially significant effects of light water reactor (LWR) coolant environments on the fatigue resistance of carbon and low-alloy steels. Under certain loading and environmental conditions, fatigue lives of test specimens may be shorter than those in air by a factor of {approx}70. The crack initiation and crack growth characteristics of carbon and low-alloy steels in LWR environments are presented. Decreases in fatigue life of these steels in high-dissolved-oxygen water are caused primarily by the effect of environment on growth of short cracks < 100 {micro}m in depth. The material and loading parameters that influence fatigue life in LWR environments are defined. Fatigue life is decreased significantly when five conditions are satisfied simultaneously, viz., applied strain range, service temperature, dissolved oxygen in water, and S content in steel are above a threshold level, and loading strain rate is below a threshold value. Statistical models have been developed for estimating the fatigue life of these steels in LWR environments. The significance of the effect of environment on the current Code design curve is evaluated.

  20. 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.

  1. Machine Design -2 The figure below shows a picture of the splined end of a failed half-shaft. The fatigue failure occurred at the

    E-Print Network [OSTI]

    Battaglia, Francine

    Machine Design - 2 The figure below shows a picture of the splined end of a failed half-shaft. The fatigue failure occurred at the snap-ring groove. The half-shaft transmits engine torque on acceleration = +1617 in-lbf. The half-shaft material is a heat-treated, case-hardened 4340 steel, Sy = 234 kpsi, Sut

  2. An Energy Based Fatigue Life Prediction Framework for In-Service Structural Components

    SciTech Connect (OSTI)

    H. Ozaltun; M. H.H. Shen; T. George; C. Cross

    2011-06-01

    An energy based fatigue life prediction framework has been developed for calculation of remaining fatigue life of in service gas turbine materials. The purpose of the life prediction framework is to account aging effect caused by cyclic loadings on fatigue strength of gas turbine engines structural components which are usually designed for very long life. Previous studies indicate the total strain energy dissipated during a monotonic fracture process and a cyclic process is a material property that can be determined by measuring the area underneath the monotonic true stress-strain curve and the sum of the area within each hysteresis loop in the cyclic process, respectively. The energy-based fatigue life prediction framework consists of the following entities: (1) development of a testing procedure to achieve plastic energy dissipation per life cycle and (2) incorporation of an energy-based fatigue life calculation scheme to determine the remaining fatigue life of in-service gas turbine materials. The accuracy of the remaining fatigue life prediction method was verified by comparison between model approximation and experimental results of Aluminum 6061-T6. The comparison shows promising agreement, thus validating the capability of the framework to produce accurate fatigue life prediction.

  3. Methods for fatigue testing off-road bicycle handlebars based on assembly effects using two different stem designs

    E-Print Network [OSTI]

    McKenna, Sean P; Hill, Michael R; Hull, Maury L

    2003-01-01

    AND EVALUATION [2] “Trek Bicycle Corp. Announces Recall ofSafety Requirements for Bicycles, International Organizationfor Fatigue Testing Off-Road Bicycle Handlebars Based on

  4. Projection of fractures in ships for the evaluation of fatigue resistant designs

    E-Print Network [OSTI]

    Hadjiyiannis, Nicholas

    2009-01-01

    Cracks in ships have been of great concern to the maritime industry for a very long time. The problem is controlled by improving design, minimizing operating stresses and through regular inspections and repairs. The big ...

  5. Design, build and test of an axial flow hydrokinetic turbine with fatigue analysis

    E-Print Network [OSTI]

    Ketcham, Jerod W

    2010-01-01

    OpenProp is an open source propeller and turbine design and analysis code that has been in development since 2007 by MIT graduate students under the supervision of Professor Richard Kimball. In order to test the performance ...

  6. Bunk Fatigue 

    E-Print Network [OSTI]

    Unknown

    2011-09-05

    The objective of this thesis is to determine fatigue stresses in the stringer to floor beam connections of through plate girder (TPG) and through truss (TT) bridges in order to predict failure. Field observations by the ...

  7. 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

  8. An evaluation of alternative horizontal curve design approaches for rural two-lane highways 

    E-Print Network [OSTI]

    Voigt, Anthony Paul

    1995-01-01

    STATEMENT It has been recognized that accidents are more likely to occur on horizontal curves than on tangent sections of rural two-lane highways. Previous studies have found that accident &equency and severity are greater on the curve sections of rural... Distance L v a Case 2 Distance r- c a' C Case 3 Distance FIGURE 2. Speed Profile Model Cases (4). 16 Superelevation Deficiency Thete have been several ellbrts to determine relationships among accident rates on horizontal curves and independent...

  9. Learning and Design of Principal Curves Balazs Kegl, Student Member, IEEE, Adam Krzyzak, Senior Member, IEEE,

    E-Print Network [OSTI]

    Zeger, Kenneth

    curve learning from training data and it also leads to a new practical construction. Our theoretical of the vertices are updated so that they minimize a penalized squared distance criterion. Simulation results one-dimensional approxi- mation to the distribution of and the projection of to this line gives

  10. A Fatigue Approach to Wind Turbine Control

    E-Print Network [OSTI]

    A Fatigue Approach to Wind Turbine Control Keld Hammerum Kongens Lyngby 2006 #12;Technical to the turbulent nature of wind, the structural components of a wind turbine are exposed to highly varying loads. Therefore, fatigue damage is a major consideration when designing wind turbines. The control scheme applied

  11. On the Fatigue Analysis of Wind Turbines

    SciTech Connect (OSTI)

    Sutherland, Herbert J.

    1999-06-01

    Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the wind turbine community to develop fatigue analysis capabilities for wind turbines. Our ability to analyze the fatigue behavior of wind turbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a wind turbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of wind turbines.

  12. Probabilistic fatigue methodology and wind turbine reliability

    SciTech Connect (OSTI)

    Lange, C.H. [Stanford Univ., CA (United States)

    1996-05-01

    Wind turbines subjected to highly irregular loadings due to wind, gravity, and gyroscopic effects are especially vulnerable to fatigue damage. The objective of this study is to develop and illustrate methods for the probabilistic analysis and design of fatigue-sensitive wind turbine components. A computer program (CYCLES) that estimates fatigue reliability of structural and mechanical components has been developed. A FORM/SORM analysis is used to compute failure probabilities and importance factors of the random variables. The limit state equation includes uncertainty in environmental loading, gross structural response, and local fatigue properties. Several techniques are shown to better study fatigue loads data. Common one-parameter models, such as the Rayleigh and exponential models are shown to produce dramatically different estimates of load distributions and fatigue damage. Improved fits may be achieved with the two-parameter Weibull model. High b values require better modeling of relatively large stress ranges; this is effectively done by matching at least two moments (Weibull) and better by matching still higher moments. For this purpose, a new, four-moment {open_quotes}generalized Weibull{close_quotes} model is introduced. Load and resistance factor design (LRFD) methodology for design against fatigue is proposed and demonstrated using data from two horizontal-axis wind turbines. To estimate fatigue damage, wind turbine blade loads have been represented by their first three statistical moments across a range of wind conditions. Based on the moments {mu}{sub 1}{hor_ellipsis}{mu}{sub 3}, new {open_quotes}quadratic Weibull{close_quotes} load distribution models are introduced. The fatigue reliability is found to be notably affected by the choice of load distribution model.

  13. Development of Yield and Tensile Strength Design Curves for Alloy 617

    SciTech Connect (OSTI)

    Nancy Lybeck; T. -L. Sham

    2013-10-01

    The U.S. Department of Energy Very High Temperature Reactor Program is acquiring data in preparation for developing an Alloy 617 Code Case for inclusion in the nuclear section of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code. A draft code case was previously developed, but effort was suspended before acceptance by ASME. As part of the draft code case effort, a database was compiled of yield and tensile strength data from tests performed in air. Yield strength and tensile strength at temperature are used to set time independent allowable stress for construction materials in B&PV Code, Section III, Subsection NH. The yield and tensile strength data used for the draft code case has been augmented with additional data generated by Idaho National Laboratory and Oak Ridge National Laboratory in the U.S. and CEA in France. The standard ASME Section II procedure for generating yield and tensile strength at temperature is presented, along with alternate methods that accommodate the change in temperature trends seen at high temperatures, resulting in a more consistent design margin over the temperature range of interest.

  14. Quantum curves

    E-Print Network [OSTI]

    Albert Schwarz

    2014-08-16

    One says that a pair (P,Q) of ordinary differential operators specify a quantum curve if [P,Q]=const. If a pair of difference operators (K,L) obey the relation KL=const LK we say that they specify a discrete quantum curve. This terminology is prompted by well known results about commuting differential and difference operators, relating pairs of such operators with pairs of meromorphic functions on algebraic curves obeying some conditions. The goal of this paper is to study the moduli spaces of quantum curves. We will show how to quantize a pair of commuting differential or difference operators (i.e. to construct the corresponding quantum curve or discrete quantum curve). The KP-hierarchy acts on the moduli space of quantum curves; we prove that similarly the discrete KP-hierarchy acts on the moduli space of discrete quantum curves.

  15. Collect Available Creep-Fatigue Data and Study Existing Creep-Fatigue Evaluation Procedures for Grade 91 and Hastelloy XR

    SciTech Connect (OSTI)

    Tai Asayama; Yukio Tachibana

    2007-09-30

    This report describes the results of investigation on Task 5 of DOE/ASME Materials Project based on a contract between ASME Standards Technology, LLC (ASME ST-LLC) and Japan Atomic Energy Agency (JAEA). Task 5 is to collect available creep-fatigue data and study existing creep-fatigue evaluation procedures for Grade 91 steel and Hastelloy XR. Part I of this report is devoted to Grade 91 steel. Existing creep-fatigue data were collected (Appendix A) and analyzed from the viewpoints of establishing a creep-fatigue procedure for VHTR design. A fair amount of creep-fatigue data has been obtained and creep-fatigue phenomena have been clarified to develop design standards mainly for fast breeder reactors. Following this, existing creep-fatigue procedures were studied and it was clarified that the creep-fatigue evaluation procedure of the ASME-NH has a lot of conservatisms and they were analyzed in detail from the viewpoints of the evaluation of creep damage of material. Based on the above studies, suggestions to improve the ASME-NH procedure along with necessary research and development items were presented. Part II of this report is devoted to Hastelloy XR. Existing creep-fatigue data used for development of the high temperature structural design guideline for High Temperature Gas-cooled Reactor (HTGR) were collected. Creep-fatigue evaluation procedure in the design guideline and its application to design of the intermediate heat exchanger (IHX) for High Temperature Engineering Test Reactor (HTTR) was described. Finally, some necessary research and development items in relation to creep-fatigue evaluation for Gen IV and VHTR reactors were presented.

  16. 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.

  17. Cyclic fatigue mechanisms in partially stabilized zirconia

    SciTech Connect (OSTI)

    Hoffman, M.J.; Wakayama, Shuichi; Kawahara, Masanori; Mai, Y.W.; Kishi, Teruo

    1995-12-31

    Cyclic fatigue crack growth rate and crack resistance curve testing were undertaken on 6 different grades of Mg-PSZ. The width of the transformation zone at the flanks of the cracks was determined using Raman spectroscopy and, combined with R-curve toughening values, used to ascertain the level of crack-tip shielding during cyclic fatigue crack growth and hence the crack-tip stress intensity factor amplitude. By normalizing the crack-tip stress intensity factor amplitude with the intrinsic toughness of the material, it was found that the cyclic fatigue threshold stress intensity factor was independent of the extent of crack-tip shielding and a function of the stress intensity factor at the crack tip. In situ SEM observations of cyclic fatigue revealed crack bridging by uncracked ligaments and the precipitate phase. Under cyclic loading the precipitate bridges were postulated to undergo frictional degradation at the precipitate/matrix interface with the degree of degradation determined by the cyclic amplitude. Acoustic emission testing revealed acoustic emissions at three distinct levels during the loading cycle: firstly, near the maximum applied stress intensity factor caused by crack propagation; secondly, at the mid-range of the applied stress intensity factor attributed to crack closure near the crack tip, presumably as a result of transformation induced dilation; and thirdly, intermittently near the base of the loading cycle as a result of fracture surface contact due to surface roughness at a significant distance behind the crack tip. Crack closure near the crack tip due to dilation is proposed to significantly reduce the crack tip stress intensity factor amplitude and hence the degree of cyclic fatigue.

  18. Mental fatigue evaluation by steroid level measurement in Parotid fluid 

    E-Print Network [OSTI]

    Singh, Harpal

    1968-01-01

    in fatigue, particularly mental fatigue, has arisen because of the concept of system design. Before the system concept of design and development, a piece of machinery was designed and the operator fitted the needs of the machine. But in the system concept... Play 1968 Major Subject. : Inc'ustrial Engineering MENTAL FATIGUE EVALUATION BY STEROID LEVEL MEASURLMENT. IN PAROTID FLUID A Thesis by HARPAL SINGH ApproveH as to tyle and. content by: P'hpirman of Committee) (Memb sr ) 1 1 PREFACE Alta...

  19. Contributions to an Improved Oxygen and Thermal Transport Model and Development of Fatigue Analysis Software for Asphalt Pavements 

    E-Print Network [OSTI]

    Jin, Xin

    2012-02-14

    Fatigue cracking is one primary distress in asphalt pavements, dominant especially in later years of service. Prediction of mixture fatigue resistance is critical for various applications, e.g., pavement design and ...

  20. FATIGUE AND FRACTURE BEHAVIOR OF HIGH TEMPERATURE MATERIALS

    E-Print Network [OSTI]

    Ritchie, Robert

    toughness (R- In an attempt to enhance the ductility and fracture toughness of curve) and fatigue, they are plagued by poor ductility and toughness candidate material which could be used at significantly higher of the silicidesis severelylimited by their low ductility and poor fracture relatively ductile Mo phase

  1. NEW REACTOR DESIGN AND ANALYSIS OF NON LINEAR VIBRATIONS OF DOUBLY CURVED SHALLOW SHELL UNDER A THERMAL GRADIENT

    SciTech Connect (OSTI)

    Chanda, S.

    2004-10-06

    The present study concerns with the effects of material orthotropy,curvature, shear ratio and circumferential modulus under the influence of a temperature distribution throughout the shell structure. Here analysis is restricted to the study of nonlinear vibration of a doubly curved shell structure considering the periodic response of a simple bending mode due to curtailment of pages. Solutions of the problems with suitable illustrations are also presented.

  2. Learning Curve

    Broader source: Directives, Delegations, and Requirements [Office of Management (MA)]

    1997-03-28

    It is a fundamental human characteristic that a person engaged in a repetitive task will improve his performance over time. If data are gathered on this phenomenon, a curve representing a decrease in effort per unit for repetitive operations can be developed. This phenomenon is real and has a specific application in cost analysis, cost estimating, or profitability studies related to the examination of future costs and confidence levels in an analysis. This chapter discusses the development and application of the learning curve.

  3. Design and development of a high-concentration and high-efficiency photovoltaic concentrator using a curved Fresnel lens

    SciTech Connect (OSTI)

    Scharlack, R.S.; Moffat, A.

    1983-08-01

    Thermo Electron has designed a high concentration photovoltaic module that uses a domed, point-focus Fresnel lens. Their design, design optimization process, and results from lens and receiver tests are described in this report. A complete module has not been fabricated and probably will not be fabricated in the future; however, Thermo Electron's optical design, analysis, and testing of both secondary optical units and domed Fresnel lenses have made a significant contribution to our project. Tooling errors prevented the lens from reaching its potential efficiency by the end of the contract, and resolution of these tooling problems is currently being attempted with a follow-on contract, No. 68-9463.

  4. Standard test method for creep-fatigue testing

    E-Print Network [OSTI]

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method covers the determination of mechanical properties pertaining to creep-fatigue deformation or crack formation in nominally homogeneous materials, or both by the use of test specimens subjected to uniaxial forces under isothermal conditions. It concerns fatigue testing at strain rates or with cycles involving sufficiently long hold times to be responsible for the cyclic deformation response and cycles to crack formation to be affected by creep (and oxidation). It is intended as a test method for fatigue testing performed in support of such activities as materials research and development, mechanical design, process and quality control, product performance, and failure analysis. The cyclic conditions responsible for creep-fatigue deformation and cracking vary with material and with temperature for a given material. 1.2 The use of this test method is limited to specimens and does not cover testing of full-scale components, structures, or consumer products. 1.3 This test method is primarily ...

  5. Curved Space or Curved Vacuum?

    E-Print Network [OSTI]

    Eric V. Linder

    2005-10-11

    While the simple picture of a spatially flat, matter plus cosmological constant universe fits current observation of the accelerated expansion, strong consideration has also been given to models with dynamical vacuum energy. We examine the tradeoff of ``curving'' the vacuum but retaining spatial flatness, vs. curving space but retaining the cosmological constant. These different breakdowns in the simple picture could readily be distinguished by combined high accuracy supernovae and cosmic microwave background distance measurements. If we allow the uneasy situation of both breakdowns, the curvature can still be measured to 1%, but at the price of degrading estimation of the equation of state time variation by 60% or more, unless additional information (such as weak lensing data or a tight matter density prior) is included.

  6. Selection of Wind Turbine Blade Materials for Fatigue Resistance

    E-Print Network [OSTI]

    Selection of Wind Turbine Blade Materials for Fatigue Resistance John Mandell Montana State reversed tension-compression. ­ Data used in blade design can be of uncertainData used in blade design can (Power Law Most Common)q ( ) #12;Statistical Confidence Limit Representation, Power Law and Three-ParameterPower

  7. Reversal bending fatigue testing

    DOE Patents [OSTI]

    Wang, Jy-An John; Wang, Hong; Tan, Ting

    2014-10-21

    Embodiments for apparatuses for testing reversal bending fatigue in an elongated beam are disclosed. Embodiments are configured to be coupled to first and second end portions of the beam and to apply a bending moment to the beam and create a pure bending condition in an intermediate portion of the beam. Embodiments are further configured to cyclically alternate the direction of the bending moment applied to the beam such that the intermediate portion of the beam cyclically bends in opposite directions in a pure bending condition.

  8. 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.

  9. A MODIFIED ENERGY-BASED LOW CYCLE FATIGUE MODEL FOR EUTECTIC SOLDER ALLOY

    E-Print Network [OSTI]

    Zhou, Wei

    the component and the board. Fatigue failure of solder joints is recognized as a major cause of failure was carefully ground on fine SiC paper and polished using 1 m diamond paste. Afterwards, the fatigue specimens tests were conducted on a servo-valve-controlled electro-hydraulic testing machine newly designed by MTS

  10. Development of criteria for fatigue repairs in bridge girders damaged by out-of-plane distortion 

    E-Print Network [OSTI]

    Wilson, Scott David

    1994-01-01

    Numerous highway bridge girders across the United States have experienced fatigue cracking due to repetitive out-of-plane distortion at unstiffened web gaps caused by poorly designed diaphragm connection details. Due to ...

  11. An analysis of muscle fatigue due to complex tasks and its relation to the strain index 

    E-Print Network [OSTI]

    Stephens, John-Paul

    2009-06-02

    The Strain Index was originally designed to analyze mono-task jobs. An experiment using a grip dynamometer was used to simulate six multiple task jobs to study the effect of complex tasks on localized muscle fatigue and ...

  12. An Analytical Evaluation of Distortion-Induced Fatigue in Steel Bridges

    E-Print Network [OSTI]

    Hassel, Heidi L.

    2011-02-04

    Multi-girder steel bridges designed prior to the mid-1980's, have developed cracks due to distortion-induced fatigue. An analytical evaluation was conducted to better understand the effects of bridge configurations and ...

  13. Solution to the problem of the poor cyclic fatigue resistance of bulk metallic glasses

    E-Print Network [OSTI]

    Ritchie, Robert

    of magnitude, making these ``designed'' composites as resistant to fatigue dam- age as high-strength steels embrittled on annealing due to structural relaxation and associated loss of free volume, elastic stiffening

  14. Curves and The Photon

    E-Print Network [OSTI]

    L. Stodolsky

    2005-11-28

    The study of the number of photons leads to a new way of characterizing curves and to a novel integral invariant over curves.

  15. 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.

  16. 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...

  17. Quantization of classical curves

    E-Print Network [OSTI]

    Xiaojun Liu; Albert Schwarz

    2014-08-18

    We discuss the relation between quantum curves (defined as solutions of equation $[P,Q]=\\hbar$, where $P,Q$ are ordinary differential operators) and classical curves. We illustrate this relation for the case of quantum curve that corresponds to the $(p,q)$-minimal model coupled to 2D gravity.

  18. SANDIA CONTRACTORS REPORT FATIGUE OF COMPOSITE MATERIALS AND

    E-Print Network [OSTI]

    SANDIA CONTRACTORS REPORT FATIGUE OF COMPOSITE MATERIALS AND SUBSTRUCTURES FOR WIND TURBINE BLADES Abstract ThisreportpresentsthemajorfindingsoftheMontanaStateUniversityCompositeMaterialsFatigue Program Fatigue Database. Additions of greatest interest to the database in this time period include environmental

  19. 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

  20. Auto/Steel Partnership: Fatigue of AHSS Strain Rate Characterization...

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

    Fatigue of AHSS Strain Rate Characterization AutoSteel Partnership: Fatigue of AHSS Strain Rate Characterization 2009 DOE Hydrogen Program and Vehicle Technologies Program Annual...

  1. Thermal Cycling on Fatigue Failure of the Plutonium Vitrification Melter

    SciTech Connect (OSTI)

    Jordan, Jeffrey; Gorczyca, Jennifer

    2009-02-11

    One method for disposition of excess plutonium is vitrification into cylindrical wasteforms. Due to the hazards of working with plutonium, the vitrification process must be carried out remotely in a shielded environment. Thus, the equipment must be easily maintained. With their simple design, induction melters satisfy this criterion, making them ideal candidates for plutonium vitrification. However, due to repeated heating and cooling cycles and differences in coefficients of thermal expansion of contacting materials fatigue failure of the induction melter is of concern. Due to the cost of the melter, the number of cycles to failure is critical. This paper presents a method for determining the cycles to failure for an induction melter by using the results from thermal and structural analyses as input to a fatigue failure model.

  2. Creep-fatigue criteria and inelastic behavior of modified 9Cr-1Mo steel at elevated temperatures. Final report

    SciTech Connect (OSTI)

    Ruggles, M.B. [Oak Ridge National Lab., TN (United States); Ogata, T. [Central Research Inst. of Electric Power Industry, Tokyo (Japan). Komae Research Lab.

    1994-02-01

    The ever increasing demand for safety requires that stringent and conservative methodology be developed for design and analysis of reactor components. At present modified 9Cr-1Mo steel is a candidate material for construction of steam generators in fast breeder reactors. Therefore high-temperature material properties and extensive insight into deformation behavior and creep-fatigue life are required to develop design guidelines for use of modified 9Cr-1Mo steel in actual plant components. However, existing information on creep-fatigue and deformation response of modified 9Cr-1Mo steel is insufficient, and further experimental and modeling efforts are needed. A joint effort between the Electric Power Research Institute (EPRI) in the United States and the Central Research Institute of Electric Power Industry (CRIEPI) in Japan was started in 1991 to investigate the inelastic behavior of and to develop creep-fatigue criteria for modified 9Cr-1Mo steel at elevated temperatures. The current program focuses on uniaxial and biaxial fatigue, creep, and creep-fatigue tests. Results of this effort are presented in this report. Section 2 introduces the test material and experimental arrangement. Uniaxial exploratory deformation tests and unified constitutive equations for inelastic analysis of modified 9Cr-1Mo steel are presented in Sections 3 and 4, respectively. Axial fatigue and creep-fatigue test results are discussed in Section 5. Section 6 is devoted to constant stress creep tests. Biaxial fatigue and creep-fatigue tests are described in Section 7. Progress in creep-fatigue life evaluation is reported in Section 8.

  3. Prediction of the Creep-Fatigue Lifetime of Alloy 617: An Application of Non-destructive Evaluation and Information Integration

    SciTech Connect (OSTI)

    Vivek Agarwal; Richard Wright; Timothy Roney

    2014-08-01

    A relatively simple method using the nominal constant average stress information and the creep rupture model is developed to predict the creep-fatigue lifetime of Alloy 617, in terms of time to rupture. The nominal constant average stress is computed using the stress relaxation curve. The predicted time to rupture can be converted to number of cycles to failure using the strain range, the strain rate during each cycle, and the hold time information. The predicted creep-fatigue lifetime is validated against the experimental measurements of the creep-fatigue lifetime collected using conventional laboratory creep-fatigue tests. High temperature creep-fatigue tests of Alloy 617 were conducted in air at 950°C with a tensile hold period of up to 1800s in a cycle at total strain ranges of 0.3% and 0.6%. It was observed that the proposed method is conservative in that the predicted lifetime is less than the experimentally determined values. The approach would be relevant to calculate the remaining useful life to a component like a steam generator that might fail by the creep-fatigue mechanism.

  4. Modeling Thermal Fatigue in CPV Cell Assemblies (Presentation)

    SciTech Connect (OSTI)

    Bosco, N.; Panchagade, D.; Kurtz, S.

    2011-02-01

    This presentation outlines the modeling of thermal fatigue in concentrating photovoltaic (CPV) assemblies.

  5. Seismic fragility curves for reinforced concrete A Dissertation Submitted in Partial Fulfilment of the Requirements

    E-Print Network [OSTI]

    Seismic fragility curves for reinforced concrete buildings A Dissertation Submitted in Partial dissertation entitled "Seismic fragility curves for reinforced concrete frame and wall- frame buildings. Buildings designed for seismic loading, and buildings designed only for gravity loads, are considered

  6. A study of fatigue in drill collars 

    E-Print Network [OSTI]

    Fowler, Joe Robert

    1969-01-01

    equipped with -S/N- Fatigue Life Gages, and finally made up to 7, 000 ft-lb of torque. The test connec- tion, now in essence one piece, was filled with water for purposes of crack detection, and installed in the test machine. The test connectors had...A STUDY OF FATIGUE IN DRILL COLLARS A Thesis by Joe Robert Feeler Approved as to style and content by: Chairman of Committee Head of Department Member /n/X~l~~ Member Member January 1969 ABSTRACT A Study of Fatigue in Drill Collars...

  7. Crude oil supply curves

    E-Print Network [OSTI]

    Adelman, Morris Albert

    1998-01-01

    Short-run cost curves shift over time as depletion counters increasing knowledge. Under competition, a rightward (leftward) shift indicates lower (higher) cost and greater (lesser) productivity. A simple coefficient captures ...

  8. Damage and fatigue Continuum damage mechanics modeling

    E-Print Network [OSTI]

    -CLÉS : endommagement, fatigue, métaux, béton, élastomères, roche REGC ­ 10/2006. Geomechanics in energy production, pages 849 to 877 #12;850 REGC ­ 10/2006. Geomechanics in energy production 1. Introduction Continuum

  9. "Lyme": Chronic Fatigue Syndrome By Another Name?

    E-Print Network [OSTI]

    Barbour, AG

    2015-01-01

    chronic fatigue syndrome (CFS) patients in their symptoms,with patients with the diagnosis of CFS. Patrick et al.on historical reference to CFS. Where I think the Patrick et

  10. Contact fatigue : life prediction and palliatives

    E-Print Network [OSTI]

    Conner, Brett P. (Brett Page), 1975-

    2002-01-01

    Fretting fatigue is defined as damage resulting from small magnitude (0.5-50 microns) displacement between contacting bodies where at least one of the bodies has an applied bulk stress. The applicability and limits of a ...

  11. PREDICTORS OF POST-STROKE FATIGUE

    E-Print Network [OSTI]

    Tseng, Benjamin Yichen

    2009-01-29

    PURPOSE: Fatigue is a commonly neglected issue despite the high incidence rate reported in people with chronic stroke. It can impact daily functions and quality of life and has been linked with a higher mortality rate after ...

  12. Actuation Fatigue of Shape Memory Alloys 

    E-Print Network [OSTI]

    Calhoun, Christopher

    2012-07-16

    A testing method was developed to cycle quickly and repeatably Ni60Ti40 (wt. %) SMA specimens through temperature-induced transformation while under constant stress until failure. Previous works have shown fatigue cracks ...

  13. Optimal Railroad Rail Grinding for Fatigue Mitigation 

    E-Print Network [OSTI]

    Tangtragulwong, Potchara

    2012-02-14

    This dissertation aims to study the benefit of rail grinding on service life of railroad rails, focusing on failures due to rolling contact fatigue (RCF) at the rail head. Assuming a tangent rail with one-point contact at ...

  14. AIAA-2003-0692 NEW FATIGUE DATA FOR W IND TURBINE BLADE M ATERIALS

    E-Print Network [OSTI]

    1 AIAA-2003-0692 NEW FATIGUE DATA FOR W IND TURBINE BLADE M ATERIALS John F. Mandell, Daniel D the expected cycle range for turbines. While the data cannot be used directly in design due to the specialized AND RESULTS Introduction Composite wind turbine blade materials may experience between 108 to 109 significant

  15. 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.

  16. Fatigue failure in thin-film polysilicon is due to subcriticalcracking within the oxide layer

    SciTech Connect (OSTI)

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

    2005-01-11

    It has been established that microelectromechanical systems (MEMS) created from polycrystalline silicon thin-films are subject to cyclic fatigue. Prior work by the authors has suggested that although bulk silicon is not susceptible to fatigue failure in ambient air, fatigue in micron-scale silicon is a result of a ''reaction-layer'' process, whereby high stresses induce a thickening of the post-release oxide at stress concentrations such as notches, which subsequently undergoes moisture-assisted cracking. However, there exists some controversy regarding the post-release oxide thickness of the samples used in the prior study. In this Letter, we present data from devices from a more recent fabrication run that confirm our prior observations. Additionally, new data from tests in high vacuum show that these devices do not fatigue when oxidation and moisture are suppressed. Each of these observations lends credence to the '''reaction-layer'' mechanism. Recent advances in the design of microelectromechanical systems (MEMS) have increased the demand for more reliable microscale structures. Although silicon is an effective and widely used structural material at the microscale, it is very brittle. Consequently, reliability is a limiting factor for commercial and defense applications. Since the surface to volume ratio of these structural films is very large, classical models for failure modes in bulk materials cannot always be applied. For example, whereas bulk silicon is immune to cyclic fatigue failure thin micron-scale structural films of silicon appear to be highly susceptible. It is clear that at these size scales, surface effects may become dominant in controlling mechanical properties. The main reliability issues for MEMS are stiction, fatigue and wear. Fatigue is important in cases where devices are subjected to a large number of loading cycles with amplitudes below their (single-cycle) fracture stress, which may arise due to vibrations intentionally induced in the structure (i.e. a resonator) or those which arise from the service environment. While the reliability of MEMS has received extensive attention, the physical mechanisms responsible for these failure modes have yet to be conclusively determined. This is particularly true for fatigue, where the mechanisms have been subject to intense debate. Recently we have proposed that the fatigue of micron-scale polysilicon is associated with stress-induced surface oxide thickening and moisture-assisted subcritical cracking in the amorphous SiO{sub 2} oxide layer (''reaction-layer'' fatigue). The mechanism of oxide thickening is as yet unknown, but is likely related to some form of stress-assisted diffusion. Allameh et al. suggest a complementary mechanism involving stress-assisted oxide thickening, caused by dissolution of the surface oxide which forms deep grooves that are sites for crack initiation. Kahn et al. have criticized these mechanisms and proposed that, instead, fatigue is caused by subcritical cracking due to contacting surface asperities in the compressive part of the cycle. To the authors' knowledge, there is no direct experimental observation of such asperity contact. Also, their model cannot explain why micron-scale silicon, and not bulk silicon, is susceptible to fatigue. Moreover, Kahn et al. do not acknowledge the role of stress-induced oxide thickening, which has been observed directly using TEM and indirectly using atomic-force microscope measurements by several investigators, and have questioned whether the materials utilized by Muhlstein et al. and Allameh et al. were representative due to the relatively thick oxide scales. Accordingly, the goal of the present research is to seek a definitive understanding of the physical mechanisms responsible for fatigue in polysilicon structural thin-films. Our approach is to combine on-chip testing methods with electron microscopy by fatiguing thin-film samples and observing them, in an unthinned condition, using high-voltage transmission electron microscopy (HVTEM). Two principal results are found from this work: (1

  17. Extinction curves in AGN

    E-Print Network [OSTI]

    B. Czerny

    2006-12-16

    The presence of the dust in the circumnuclear region strongly affects our view of the nucleus itself. The effect is strong in type 2 objects but weaker effect is likely to be present in type 1 objects as well. In these objects a correction to the observed optical/UV spectrum must be done in order to recover the intrinsic spectrum of a nucleus. The approach based on the extinction curve is convenient for that purpose so significant effort has been recently done in order to determine the extinction curve for the circumnuclear material. It seems clear that the circumnuclear dust is different from the average properties of the dust in the Interstellar Medium in our galaxy: the well known 2175 A feature is weak or absent in AGN nuclear dust, and the extinction curve at shorter wavelength does not seem to be rising as steeply. The circumnuclear dust is therefore more similar to SMC dust, or more likely, to the dust in very dense molecular clouds in our Galaxy. However, the exact shape of the extinction curve in the far UV is still a matter of debate, and various effects are difficult to disentangle.

  18. On a solution to the problem of the poor cyclic fatigue resistance of bulk metallic glasses

    SciTech Connect (OSTI)

    Launey, Maximilien E.; Hofmann, Douglas C.; Johnson, William L.; Ritchie, Robert O.

    2009-01-09

    The recent development of metallic glass-matrix composites represents a particular milestone in engineering materials for structural applications owing to their remarkable combinations of strength and toughness. However, metallic glasses are highly susceptible to cyclic fatigue damage and previous attempts to solve this problem have been largely disappointing. Here we propose and demonstrate a microstructural design strategy to overcome this limitation by matching the microstructural length scales (of the second phase) to mechanical crack-length scales. Specifically, semi-solid processing is used to optimize the volume fraction, morphology, and size of second phase dendrites to confine any initial deformation (shear banding) to the glassy regions separating dendrite arms having length scales of {approx} 2 {micro}m, i.e., to less than the critical crack size for failure. Confinement of the damage to such interdendritic regions results in enhancement of fatigue lifetimes and increases the fatigue limit by an order of magnitude making these 'designed' composites as resistant to fatigue damage as high-strength steels and aluminum alloys. These design strategies can be universally applied to any other metallic glass systems.

  19. Improving Fatigue Performance of AHSS Welds

    SciTech Connect (OSTI)

    Feng, Zhili; Yu, Xinghua; Erdman, III, Donald L.; Wang, Yanli; Kelly, Steve; Hou, Wenkao; Yan, Benda; Wang, Zhifeng; Yu, Zhenzhen; Liu, Stephen

    2015-03-01

    Reported herein is technical progress on a U.S. Department of Energy CRADA project with industry cost-share aimed at developing the technical basis and demonstrate the viability of innovative in-situ weld residual stresses mitigation technology that can substantially improve the weld fatigue performance and durability of auto-body structures. The developed technology would be costeffective and practical in high-volume vehicle production environment. Enhancing weld fatigue performance would address a critical technology gap that impedes the widespread use of advanced high-strength steels (AHSS) and other lightweight materials for auto body structure light-weighting. This means that the automotive industry can take full advantage of the AHSS in strength, durability and crashworthiness without the concern of the relatively weak weld fatigue performance. The project comprises both technological innovations in weld residual stress mitigation and due-diligence residual stress measurement and fatigue performance evaluation. Two approaches were investigated. The first one was the use of low temperature phase transformation (LTPT) weld filler wire, and the second focused on novel thermo-mechanical stress management technique. Both technical approaches have resulted in considerable improvement in fatigue lives of welded joints made of high-strength steels. Synchrotron diffraction measurement confirmed the reduction of high tensile weld residual stresses by the two weld residual stress mitigation techniques.

  20. Fatigue behavior of alpha-zirconium phosphate/epoxy nanocomposites 

    E-Print Network [OSTI]

    Varadharajan, Balaji R.

    2006-04-12

    Fatigue crack growth in ±-Zirconium phosphate/epoxy nanocomposites was investigated. A new fatigue testing technique was implemented for miniature samples. Two different methods ?strength of materials and Rayleigh-Ritz - ...

  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. Reversible Bending Fatigue Testing on Zry-4 Surrogate Rods

    SciTech Connect (OSTI)

    Wang, Jy-An John; Wang, Hong; Bevard, Bruce Balkcom; Howard, Rob L

    2014-01-01

    Testing high-burnup spent nuclear fuel (SNF) presents many challenges in areas such as specimen preparation, specimen installation, mechanical loading, load control, measurements, data acquisition, and specimen disposal because these tasks are complicated by the radioactivity of the test specimens. Research and comparison studies conducted at Oak Ridge National Laboratory (ORNL) resulted in a new concept in 2010 for a U-frame testing setup on which to perform hot-cell reversible bending fatigue testing. Subsequently, the three-dimensional finite element analysis and the engineering design of components were completed. In 2013 the ORNL team finalized the upgrade of the U-frame testing setup and the integration of the U-frame setup into a Bose dual linear motor test bench to develop a cyclic integrated reversible-bending fatigue tester (CIRFT). A final check was conducted on the CIRFT test system in August 2013, and the CIRFT was installed in the hot cell in September 2013 to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The fatigue responses of Zircaloy-4 (Zry-4) cladding and the role of pellet pellet and pellet clad interactions are critical to SNF vibration integrity, but such data are not available due to the unavailability of an effective testing system. While the deployment of the developed CIRFT test system in a hot cell will provide the opportunity to generate the data, the use of a surrogate rod has proven quite effective in identifying the underlying deformation mechanism of an SNF composite rod under an equivalent loading condition. This paper presents the experimental results of using surrogate rods under CIRFT reversible cyclic loading. Specifically, monotonic and cyclic bending tests were conducted on surrogate rods made of a Zry-4 tube and alumina pellet inserts, both with and without an epoxy bond.

  3. Connecting curves for dynamical systems

    E-Print Network [OSTI]

    R. Gilmore; Jean-Marc Ginoux; Timothy Jones; C. Letellier; U. S. Freitas

    2010-03-08

    We introduce one dimensional sets to help describe and constrain the integral curves of an $n$ dimensional dynamical system. These curves provide more information about the system than the zero-dimensional sets (fixed points) do. In fact, these curves pass through the fixed points. Connecting curves are introduced using two different but equivalent definitions, one from dynamical systems theory, the other from differential geometry. We describe how to compute these curves and illustrate their properties by showing the connecting curves for a number of dynamical systems.

  4. COMPARISON OF FATIGUE BEHAVIOR FOR CENTRIFUGALLY CAST AND

    E-Print Network [OSTI]

    Beckermann, Christoph

    COMPARISON OF FATIGUE BEHAVIOR FOR CENTRIFUGALLY CAST AND KEEL BLOCK CAST STEEL J.J. Gradman1 , R The objective of this research was to determine if location through the wall thickness of centrifugal castings affects fatigue properties and to compare fatigue and monotonic tensile properties of centrifugal castings

  5. Fatigue of Wind Blade Laminates:Fatigue of Wind Blade Laminates: Effects of Resin and Fabric Structure

    E-Print Network [OSTI]

    Fatigue of Wind Blade Laminates:Fatigue of Wind Blade Laminates: Effects of Resin and Fabric University MCARE 2012 #12;Outline · Overview of MSU Fatigue Program on Wind Blade MaterialsWind Blade Wind Blade Component Materials Acknowledgements: Sandia National Laboratories/DOE (Joshua Paquette

  6. A Journey Between Two Curves

    E-Print Network [OSTI]

    Sergey A. Cherkis

    2007-03-11

    A typical solution of an integrable system is described in terms of a holomorphic curve and a line bundle over it. The curve provides the action variables while the time evolution is a linear flow on the curve's Jacobian. Even though the system of Nahm equations is closely related to the Hitchin system, the curves appearing in these two cases have very different nature. The former can be described in terms of some classical scattering problem while the latter provides a solution to some Seiberg-Witten gauge theory. This note identifies the setup in which one can formulate the question of relating the two curves.

  7. CREEP AND CREEP-FATIGUE OF ALLOY 617 WELDMENTS

    SciTech Connect (OSTI)

    Wright, Jill; Carroll, Laura; Wright, Richard

    2014-08-01

    The Very High Temperature Reactor (VHTR) Intermediate Heat Exchanger (IHX) may be joined to piping or other components by welding. Creep-fatigue deformation is expected to be a predominant failure mechanism of the IHX1 and thus weldments used in its fabrication will experience varying cyclic stresses interrupted by periods of elevated temperature deformation. These periods of elevated temperature deformation are greatly influenced by a materials’ creep behavior. The nickel-base solid solution strengthened alloy, Alloy 617, is the primary material candidate for a VHTR-type IHX, and it is expected that Alloy 617 filler metal will be used for welds. Alloy 617 is not yet been integrated into Section III of the Boiler and Pressure Vessel Code, however, nuclear component design with Alloy 617 requires ASME (American Society of Mechanical Engineers) Code qualification. The Code will dictate design for welded construction through significant performance reductions. Despite the similar compositions of the weldment and base material, significantly different microstructures and mechanical properties are inevitable. Experience of nickel alloy welds in structural applications suggests that most high temperature failures occur at the weldments or in the heat-affected zone. Reliably guarding against this type of failure is particularly challenging at high temperatures due to the variations in the inelastic response of the constituent parts of the weldment (i.e., weld metal, heat-affected zone, and base metal) [ref]. This work focuses on the creep-fatigue behavior of nickel-based weldments, a need noted during the development of the draft Alloy 617 ASME Code Case. An understanding of Alloy 617 weldments when subjected to this important deformation mode will enable determination of the appropriate design parameters associated with their use. Specifically, the three main areas emphasized are the performance reduction due to a weld discontinuity in terms of the reduced number of the cycles to failure and whether a saturation in reduced cycle life with increased hold times is observed, the microstructural stability over long cycle times, and finally, the location of the generated weldment data on a creep-fatigue damage diagram (D-diagram).

  8. NETL F 451.1/1-1, Categorical Exclusion Designation Form

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

    thermal and pressure loading of a newretrofit AUSC plant header, predict thermalmechanical fatigue and creep effects over the design life, and improve reliability. Jason...

  9. Superfluids in Curved Spacetime

    E-Print Network [OSTI]

    Villegas, Kristian Hauser A

    2015-01-01

    Superfluids under an intense gravitational field are typically found in neutron star and quark star cores. Most treatments of these superfluids, however, are done in a flat spacetime background. In this paper, the effect of spacetime curvature on superfluidity is investigated. An effective four-fermion interaction is derived by integrating out the mediating scalar field. The fermions interacting via the mediating gauge vector bosons is also discussed. Two possible cases are considered in the mean-field treatment: antifermion-fermion and fermion-fermion pairings. An effective action, quadratic in fermion field, and a self-consistent equation are derived for both cases. The effective Euclidean action and the matrix elements of the heat kernel operator, which are very useful in curved-spacetime QFT calculations, are derived for the fermion-fermion pairing. Finally, explicit numerical calculation of the gravitational correction to the pairing order parameter is performed for the scalar superfluid case. It is foun...

  10. Superfluids in Curved Spacetime

    E-Print Network [OSTI]

    Kristian Hauser A. Villegas

    2015-11-07

    Superfluids under an intense gravitational field are typically found in neutron star and quark star cores. Most treatments of these superfluids, however, are done in a flat spacetime background. In this paper, the effect of spacetime curvature on superfluidity is investigated. An effective four-fermion interaction is derived by integrating out the mediating scalar field. The fermions interacting via the mediating gauge vector bosons is also discussed. Two possible cases are considered in the mean-field treatment: antifermion-fermion and fermion-fermion pairings. An effective action, quadratic in fermion field, and a self-consistent equation are derived for both cases. The effective Euclidean action and the matrix elements of the heat kernel operator, which are very useful in curved-spacetime QFT calculations, are derived for the fermion-fermion pairing. Finally, explicit numerical calculation of the gravitational correction to the pairing order parameter is performed for the scalar superfluid case. It is found that, to first order correction, gravity enhances the superfluidity.

  11. ,"SNL/MSU/DOE COMPOSITE MATERIAL FATIGUE DATABASE"

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

    and details." ,"2.Loading may be static (constant specified displacement rate in mms); fatigue (constant load amplitude" ," to failure, max and min stress (MPa), R-value...

  12. Intergranular Strain Evolution near Fatigue Crack Tips in Polycrystall...

    Office of Scientific and Technical Information (OSTI)

    interactions of the inhomogeneous deformation fields in neighboring grains) by neutron diffraction techniques has been performed for the fatigue test of a Ni-based...

  13. Wind Technology Testing Center Acquires New Blade Fatigue Test...

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

    multimegawatt wind turbine blade flap fatigue test. Addthis Related Articles DOE's New Large Blade Test Facility in Massachusetts Completes First Commercial Blade Tests...

  14. Residual Stresses for Structural Analysis and Fatigue Life Prediction...

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

    in Vehicle Components: Success stories from the High Temperature Materials Laboratory (HTML) User Program Residual Stresses for Structural Analysis and Fatigue Life Prediction in...

  15. Random Curves by Conformal Welding

    E-Print Network [OSTI]

    K. Astala; P. Jones; A. Kupiainen; E. Saksman

    2009-12-17

    We construct a conformally invariant random family of closed curves in the plane by welding of random homeomorphisms of the unit circle given in terms of the exponential of Gaussian Free Field. We conjecture that our curves are locally related to SLE$(\\kappa)$ for $\\kappa<4$.

  16. Random Curves by Conformal Welding

    E-Print Network [OSTI]

    Astala, K; Kupiainen, A; Saksman, E

    2009-01-01

    We construct a conformally invariant random family of closed curves in the plane by welding of random homeomorphisms of the unit circle given in terms of the exponential of Gaussian Free Field. We conjecture that our curves are locally related to SLE$(\\kappa)$ for $\\kappa<4$.

  17. Dragon curves revisited S. Tabachnikov

    E-Print Network [OSTI]

    Tabachnikov, Sergei

    mathematical object of comparable beauty, the Dragon curves, whose theory was created by Chandler Davis. The goal of this article is to bring Dragon curves to spotlight again and to pay tribute to Chandler Davis that if you folded a $1 bill repeatedly he thought it would make a random walk or something like that. (We

  18. Fourier duality of quantum curves

    E-Print Network [OSTI]

    Martin Luu; Albert Schwarz

    2015-04-07

    There are two different ways to deform a quantum curve along the flows of the KP hierarchy. We clarify the relation between the two KP orbits: In the framework of suitable connections attached to the quantum curve they are related by a local Fourier duality. As an application we give a conceptual proof of duality results in 2D quantum gravity.

  19. Fatigue in martensitic 100Cr6: Relationship between rolling contact fatigue microstructural transitions and repetitive push testing

    E-Print Network [OSTI]

    Kang, Jee-Hyun; Rivera-Díaz-del-Castillo, Pedro E. J.

    2014-07-14

    in determining the strain responsible for plastic de- formation in rolling contact fatigue, as well as for appraising the quality of bearing materials employed for bearing elements. Keywords: fatigue, martensite, steel, hardening, strain measurements, hardness... martensitic steels, the yield limit and strain hardening slope are within such ranges [7]. In this context, there is a need to obtain deformation data from stress controlled tests. In this study, a laboratory fatigue testing method is in- troduced to measure...

  20. New Rotary Engine Designs by Deviation Function Method

    E-Print Network [OSTI]

    Warren, Sarah

    2012-01-01

    Examples of rotary engine design . . . . . . . . . . . .Rotary Engine Design by Apex Seal7 Rotary Engine Profiles from Noncircular Pitch Curves

  1. Reduced complexity of activity patterns in patients with Chronic Fatigue Syndrome: a case control study 

    E-Print Network [OSTI]

    Burton, C.; Knoop, H.; Popovic, N.; Sharpe, M.; Bleijenberg, G.

    ABSTRACT: BACKGROUND: Chronic fatigue syndrome (CFS) is an illness characterised by pervasive physical and mental fatigue without specific identified pathological changes. Many patients with CFS show reduced physical ...

  2. Progress Report on Alloy 617 Isochronous Stress-Strain Curves

    SciTech Connect (OSTI)

    Jill K. Wright; Richard N. Wright; Nancy J. Lybeck

    2014-03-01

    Isochronous stress-strain curves for Alloy 617 up to a temperature of 1000°C will be required to qualify the material for elevated temperature design in Section III, Division 1, Subsection NH of the ASME Boiler and Pressure Vessel Code. Several potential methods for developing these curves are reviewed in this report. It is shown that in general power-law creep is the rate controlling deformation mechanism for a wide range of alloy heats, test temperatures and stresses. Measurement of the strain rate sensitivity of Alloy 617 indicates that the material is highly strain rate sensitive in the tensile deformation range above about 750°C. This suggests that the concept of a hot tensile curve as a bounding case on the isochronous stress-strain diagrams is problematic. The impact of strain rate on the hot tensile curves is examined and it is concluded that incorporating such a curve is only meaningful if a single tensile strain rate (typically the ASTM standard rate of 0.5%/min) is arbitrarily defined. Current experimentally determined creep data are compared to isochronous stress-strain curves proposed previously by the German programs in the 1980s and by the 1990 draft ASME Code Case. Variability in how well the experimental data are represented by the proposed design curves that suggests further analysis is necessary prior to completing a new draft Code Case.

  3. Wind turbine blade fatigue tests: lessons learned and application to SHM system development

    SciTech Connect (OSTI)

    Taylor, Stuart G. [Los Alamos National Laboratory; Farinholt, Kevin M. [Los Alamos National Laboratory; Jeong, Hyomi [Chonbuk National University, Korea; Jang, JaeKyung [Chonbuk National University, Korea; Park, Gyu Hae [Los Alamos National Laboratory; Todd, Michael D. [Los Alamos National Laboratory; Farrar, Charles R. [Los Alamos National Laboratory; Ammerman, Curtt N. [Los Alamos National Laboratory

    2012-06-28

    This paper presents experimental results of several structural health monitoring (SHM) methods applied to a 9-meter CX-100 wind turbine blade that underwent fatigue loading. The blade was instrumented with piezoelectric transducers, accelerometers, acoustic emission sensors, and foil strain gauges. It underwent harmonic excitation at its first natural frequency using a hydraulically actuated resonant excitation system. The blade was initially excited at 25% of its design load, and then with steadily increasing loads until it failed. Various data were collected between and during fatigue loading sessions. The data were measured over multiple frequency ranges using a variety of acquisition equipment, including off-the-shelf systems and specially designed hardware developed by the authors. Modal response, diffuse wave-field transfer functions, and ultrasonic guided wave methods were applied to assess the condition of the wind turbine blade. The piezoelectric sensors themselves were also monitored using a sensor diagnostics procedure. This paper summarizes experimental procedures and results, focusing particularly on fatigue crack detection, and concludes with considerations for implementing such damage identification systems, which will be used as a guideline for future SHM system development for operating wind turbine blades.

  4. Dynamics and Fatigue Damage of Wind Turbine Rotors

    E-Print Network [OSTI]

    6 3 RiS0-Rr512 Dynamics and Fatigue Damage of Wind Turbine Rotors during Steady Operation Peter OF WIND TURBINE ROTORS DURING STEADY OPERATION Peter Hauge Madsen, Sten Frandsen, William E. Holley-carrying capacity of a wind turbine rotor with respect to short-term strength and material fatigue are presented

  5. ICAF Symposium Montral, 13 June 2011 FATIGUE LIFE ASSESSMENT

    E-Print Network [OSTI]

    Texas at Arlington, University of

    assessment of useful life for composite aircraft fatigue-critical, flight-critical components and structure process used to produce carbon/epoxy and glass/epoxy composite aircraft fatigue-critical, flight advances in the technologies which could enable accurate assessment of useful life for composite aircraft

  6. Caloric Curves and Nuclear Expansion

    E-Print Network [OSTI]

    J. B. Natowitz; K. Hagel; Y. Ma; M. Murray; L. Qin; S. Shlomo; R. Wada; J. Wang

    2002-08-08

    Nuclear caloric curves have been analyzed using an expanding Fermi gas hypothesis to extract average nuclear densities. In this approach the observed flattening of the caloric curves reflects progressively increasing expansion with increasing excitation energy. This expansion results in a corresponding decrease in the density and Fermi energy of the excited system. For nuclei of medium to heavy mass apparent densities ~ 0.4 rho_0 are reached at the higher excitation energies.

  7. April 10, 2014- “Workplace Disruptions, Reorganizations, and ‘Change Fatigue’: Can ADR Support Resilience?”

    Broader source: Energy.gov [DOE]

    April 10, 2014 - “Workplace Disruptions, Reorganizations, and ‘Change Fatigue’: Can ADR Support Resilience?”

  8. Fatigue Testing of 9 m Carbon Fiber Wind Turbine Research Blades

    SciTech Connect (OSTI)

    Paquette, J.; van Dam, J.; Hughes, S.; Johnson, J.

    2008-01-01

    Fatigue testing was conducted on Carbon Experimental and Twist-Bend Experimental (CX-100 and TX-100) 9-m wind turbine research blades. The CX-100 blade was designed to investigate the use of a carbon spar cap to reduce weight and increase stiffness while being incorporated using conventional manufacturing techniques. The TX-100 blade used carbon in the outboard portion of the skin to produce twist-bend coupling to passively alleviate aerodynamic loads. In the fatigue tests, the CX-100 blade was loaded by a single hydraulic cylinder while the TX-100 blade was loaded via a hydraulically-actuated resonant loading system called the Universal Resonant Exciter. The blades were outfitted with approximately 30 strain gages as well as displacement and load sensors. Both blades survived to cycle counts sufficient to demonstrate a 20-year operational life. The CX-100 blade failed at approximately 1.6 million cycles because of a buckle and crack that formed and grew just outboard of max-chord. The TX-100 blade failed because of a crack that grew from the termination point of the spar cap at the midspan of the blade. This paper covers the results of the fatigue tests.

  9. Thermomechanics of damage and fatigue by a phase field model

    E-Print Network [OSTI]

    Giovambattista Amendola; Mauro Fabrizio

    2014-10-26

    In the paper we present an isothermal model for describing damage and fatigue by the use of the Ginzburg-Landau (G-L) equation. Fatigue produces progressive damage, which is related with a variation of the internal structure of the material. The G-L equation studies the evolution of the order parameter, which describes the constitutive arrangement of the system and, in this framework, the evolution of damage. The thermodynamic coherence of the model is proved. In the last part of the work, we extend the results of the paper to a non-isothermal system, where fatigue contains thermal effects, which increase the damage of materials.

  10. 2004-01-0628 Fatigue Life Comparisons of Competing Manufacturing

    E-Print Network [OSTI]

    Fatemi, Ali

    knuckles. In light of the high volume of forged steel vehicle components, the forging process components. Lee(2) evaluated fatigue strength for truck axle housing, crankshaft, leaf spring, torque

  11. Fatigue Enhancement of a Carbon Fiber Reinforced Nanocomposite 

    E-Print Network [OSTI]

    Wilkerson, Justin W.

    2008-08-19

    The primary objective of the present investigation is to study the fatigue characteristics of a woven carbon fiber reinforced polymer which has been modified with either amine or fluorine functionalized carbon nanotubes ...

  12. The biological versus psychological basis of fatigue in depression 

    E-Print Network [OSTI]

    Coscio, Stacey Aileen

    1993-01-01

    The objective of this study was to attempt to determine if the symptom of fatigue represents a metabolically induced or a perceived component in depressed individuals. Dietary intake patterns were analyzed for 20 depressed ...

  13. Grain size effects on the fatigue response of nanocrystalline materials

    E-Print Network [OSTI]

    Hanlon, Timothy, 1977-

    2004-01-01

    The resistance of metals and alloys to fatigue crack initiation and propagation is known to be influenced significantly by grain size. Based on a wealth of experimental results obtained from microcrystalline metals, where ...

  14. Fatigue allowances as determined by pulse rate analysis 

    E-Print Network [OSTI]

    Street, Robert Lewis

    1965-01-01

    FATIGUE ALLOWANCES AS DETERMINED BY PULSE RATE ANALYSIS A Thesis By Robert Lewis Street Submitted to the Graduate College of the Texas. A&M University in Partial fdlfillment of the requirements for the degree of MASTER OF SCIENCE January... 1965 Major. Subject: Industrial Engineering FATIGUE ALLONANCES AS DETERMINED BY PULSE RATE ANALYSIS A Thesis By Robert Lewis Street Approved as to style and content by (C a rman of Committee) (Head of Departme and Member) (Member) January 1965...

  15. JAEA Fatigue Analysis of EBR-II Duplex Tubing

    SciTech Connect (OSTI)

    J. H. Jackson; D. L. Porter; W. R. Lloyd

    2009-07-01

    This work addresses questions brought up concerning the mechanisms associated with fatigue crack growth retardation and/or arrest within the nickel bond layer in duplex 2¼ Cr-1Mo steel superheater tubes. Previous work performed at the Idaho National Laboratory (INL) indicated that the nickel bond layer did not function as a crack arrestor during fatigue crack propagation with the exception of one, isolated case involving an exceptionally low fatigue load and a high temperature (400 0C) environment. Since it is atypical for a fatigue crack to propagate from a relatively soft material (the nickel bond layer) to a harder material (the 2¼ Cr-1Mo steel) there has been speculation that the nickel bond layer was hardened in service. Additionally, there are questions surrounding the nature of the fatigue crack propagation within the nickel bond layer; specifically with regard to the presence of voids seen on micrographs of the bond layer and oxidation within the steel along the edge of the nickel bond layer. There is uncertainty as to the effect of these voids and/or oxide barriers with respect to potential fatigue crack arrest.

  16. Comparison of fatigue analysis approaches for predicting fatigue lives of hot-mix asphalt concrete (HMAC) mixtures 

    E-Print Network [OSTI]

    Walubita, Lubinda F.

    2006-08-16

    -1 COMPARISON OF FATIGUE ANALYSIS APPROACHES FOR PREDICTING FATIGUE LIVES OF HOT-MIX ASPHALT CONCRETE (HMAC) MIXTURES A Dissertation by LUBINDA F. WALUBITA Submitted to the Office of Graduate Studies of Texas A&M University in partial... Dissertation by LUBINDA F. WALUBITA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved by: Chair of Committee, Amy Epps Martin...

  17. NEW BAINITIC STEELS BY DESIGN Displacive Phase Transformations and their Appli-

    E-Print Network [OSTI]

    Cambridge, University of

    are the days when industry could simply make a whole matrix of alloys, test them, and then hope for the best Stress corrosion Slow corrosion & cracking Creep strength High temperature service Creep ductility Safe design Creep­fatigue Fatigue at creep temperatures Elastic modulus Deflection, stored energy Thermal

  18. H. J. Sutherland, "Damage Estimates for European and U.S. Sites Using the U.S. High-Cycle Fatigue Data Base," Proceedings of the IEA Fourth Symposium of Wind Turbine

    E-Print Network [OSTI]

    Fatigue Data Base," Proceedings of the IEA Fourth Symposium of Wind Turbine Fatigue, IEA, Implementing

  19. Adventures in Structural Design Using Theoretical, Computational, and

    E-Print Network [OSTI]

    Ballarini, Roberto

    Design of anchor bolts Design guidelines for spur gears Fatigue of MEMS materials/structures Mechanical-rim gears compared to conventional gears. · Designed according to standards published by AGMA design guidelines to prevent rim fracture failure modesprevent rim fracture failure modes in gear tooth

  20. Analysis of Industrial Microgrid Power Curves Based on the Theory of Stochastic Variables for

    E-Print Network [OSTI]

    Noé, Reinhold

    Analysis of Industrial Microgrid Power Curves Based on the Theory of Stochastic Variables--Design and control of microgrids require a wide range of considerations and information. A main issue is the sizing, which help to assess power curves and to dimension components of microgrids. I. INTRODUCTION The energy

  1. Testing Controls to Mitigate Fatigue Loads in the Controls Advanced Research Turbine

    SciTech Connect (OSTI)

    Wright, A. D.; Fingersh, L. J.; Stol, K. A.

    2009-01-01

    Wind turbines are complex, nonlinear, dynamic systems forced by aerodynamic, gravitational, centrifugal, and gyroscopic loads. The aerodynamics of wind turbines is nonlinear, unsteady, and complex. Turbine rotors are subjected to a complicated three-dimensional (3D) turbulent wind inflow field with imbedded coherent vortices that drive fatigue loads and reduce lifetime. Design of control algorithms for wind turbines must account for multiple control objectives. Future large multi-megawatt turbines must be designed with lighter weight structures, using active controls to mitigate fatigue loads, maximize energy capture, and add active damping to maintain stability for these dynamically active structures operating in a complex environment. Researchers at the National Renewable Energy Laboratory are designing, implementing, and testing advanced controls to maximize energy extraction and reduce structural dynamic loads. These control designs are based on a linear model of the turbine that is generated by specialized modeling software. This paper describes testing of a control algorithm to mitigate blade, tower, and drivetrain loads using advanced state-space control methods. The controller uses independent blade pitch to regulate the turbine's speed in Region 3, mitigate the effects of shear across the rotor disk, and add active damping to the tower's first fore-aft bending mode. Additionally, a separate generator torque control loop is designed to add active damping to the tower's first side-side mode and the first drivetraintorsion mode. This paper discusses preliminary implementation and field tests of this controller in the Controls Advanced Research Turbine at the National Renewable Energy Laboratory. Also included are preliminary comparisons of the performance of this controller to results from a typical baseline Proportional-Integral-Derivative controller designed with just Region 3 speed regulation as the goal.

  2. Fatigue-Resistance Enhancements by Glass-Forming Metallic Films

    SciTech Connect (OSTI)

    Liu, F. X. [University of Tennessee, Knoxville (UTK); Liaw, Peter K [University of Tennessee, Knoxville (UTK); Jiang, W. H. [University of Tennessee, Knoxville (UTK); Chiang, C L [National Taiwan Ocean University; Gao, Yanfei [ORNL; Guan, Y F [University of Tennessee, Knoxville (UTK); Chu, J. P. [National Taiwan Ocean University; Rack, P. D. [University of Tennessee, Knoxville (UTK)

    2007-01-01

    Zr-based glass-forming metallic films were coated on a 316L stainless steel and a Ni-based alloy by the magnetron-sputter deposition. Four-point-bending fatigue tests were conducted on those coated materials with the film surface on the tensile side. Results showed that the fatigue life and fatigue-endurance limit of the materials could be considerably improved, and the enhancements vary with the maximum applied stress and the substrate material. Fractographs showed that the film remained well adhered to the substrate even after the severe plastic deformation. Surface-roughness measurements indicated the improvement of the surface finishes due to the deposition of the glass-forming film. Nanoindentation test results suggested that the thin film exhibited both high yield strength and good ductility. The reduction of the surface roughness, good adhesion between the film and the substrate, and the excellent strength and ductility of the glass-forming metallic film are the major factors for the fatigue-resistance enhancements of the coated material. A micromechanical model is developed to illustrate the mechanisms of fatigue-resistance enhancements through the interaction between the amorphous film and the substrate slip bands.

  3. Multiaxial plasticity and fatigue life prediction in coiled tubing

    SciTech Connect (OSTI)

    Tipton, S.M.

    1996-12-31

    Coiled tubing is being used increasingly in the oil well drilling and servicing industry. Continuous steel tubing of structural dimensions (up to 89 mm or 3.5 in. in diameter) is wound onto a large-diameter reel for repeated deployment into and out of a well bore. The bending strain range associated with each wrap-unwrap cycle can exceed 3% with lives well below 100 cycles. During constant internal pressure fatigue testing, tubing has been observed to grow in diameter by as much as 30%. This paper describes an analytical model to predict the fatigue behavior of coiled tubing subjected to variable pressure service conditions. The approach utilizes standard low-cycle fatigue data but requires additional experimental results from constant pressure fatigue testing. The algorithm is based on estimates of biaxial ratcheting from an incremental plasticity model using a hybrid associated flow rule, a modified kinematic hardening rule with multiple von Mises yield surfaces, and a specialized limit surface concept. An empirical damage parameter was formulated based on constant pressure fatigue data using mean and fluctuating von Mises equivalent strain components occurring throughout the life of a section of tubing. This parameters is used with the Palmgren-Miner definition of cumulative damage to track damage that is accumulating nonlinearly under constant or variable pressure histories. Modifications to standard incremental plasticity components and implementation assumptions used to apply the model are presented and discussed. The predictive capability of the model is demonstrated relative to data generated under constant and variable pressure histories.

  4. 18.783 Elliptic Curves, Spring 2013

    E-Print Network [OSTI]

    Sutherland, Andrew

    This graduate-level course is a computationally focused introduction to elliptic curves, with applications to number theory and cryptography.

  5. VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY

    E-Print Network [OSTI]

    Bradley, David

    VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY 1. Introduction Students tend to regard the elongated ``S­shaped'' [3, 6, 8] logistic curve of pop­ ulation dynamics (fig. 1) as somewhat exotic, 5, 6, 7, 8, 9, 10, 11]. My purpose here is to show how the logistic curve may be derived more

  6. VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY

    E-Print Network [OSTI]

    Bradley, David

    VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY 1. Introduction Students tend to regard the elongated "S-shaped" [3, 6, 8] logistic curve of pop- ulation dynamics (fig. 1) as somewhat exotic. It is typically, 8, 9, 10, 11]. My purpose here is to show how the logistic curve may be derived more directly

  7. VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY

    E-Print Network [OSTI]

    Bradley, David

    VERHULST'S LOGISTIC CURVE DAVID M. BRADLEY 1.Introduction Students tend to regard the elongated "S-shaped" [3, 6, 8] logistic curve here is to show how the logistic curve may be derived more directly as a simple consequence of the more

  8. The cognitive performance of patients with multiple sclerosis during periods of high and low fatigue.

    E-Print Network [OSTI]

    Parmenter, Brett A.; Denney, Douglas R.; Lynch, Sharon G.

    2003-03-01

    The objective of this study was to examine whether multiple sclerosis (MS)-related fatigue affects patients' cognitive performance. Thirty patients who had substantial fatigue in conjunction with MS and who reported marked diurnal variability...

  9. Use of CFRP Overlays to Repair Fatigue Damage in Steel Bridge Girders and Components

    E-Print Network [OSTI]

    Gangel, Regan Elisabeth

    2012-05-31

    Fatigue damage in steel girder bridges built prior to the mid-1980s is common due to distortion-induced fatigue. Different repair techniques have been developed and implemented to retrofit bridges of this era with existing ...

  10. Study of the Fatigue Life of Steel Catenary Risers in Interaction with the Seabed 

    E-Print Network [OSTI]

    Nakhaee, Ali

    2011-02-22

    The fatigue life of a Steel Catenary Riser (SCR) near its touch-down zone is substantially affected by its interaction with the seabed. Hence, accurate estimate of its fatigue life requires the understanding and realistic ...

  11. Thermal aspects in curved metrics

    E-Print Network [OSTI]

    Giovanni Acquaviva

    2013-01-15

    In this paper we describe two approaches that allow to calculate some thermal features as perceived by different observers in curved spacetimes: the tunnelling method and the Unruh-DeWitt detector. The tunnelling phenomenon is a semi-classical approach to the issue of Hawking radiation and allows a straightforward calculation of the horizon temperature in a plethora of scenarios; the Unruh-DeWitt model relies instead on a quantum field-theoretical approach and (whenever possible) gives a more exact answer in terms of transition rates between energy levels of an idealized detector.

  12. Driver mental workload requirements on horizontal curves based on occluded vision test measurements 

    E-Print Network [OSTI]

    Shafer, Mark Anthony

    1994-01-01

    This thesis documents an evaluation of driver mental workload requirements on horizontal curves based on occluded vision test measurements. Driver workload is an important concept in the design of highway systems. A ...

  13. STATIC AND FATIGUE PERFORMANCE OF 40 YEAR OLD PRESTRESSED CONCRETE GIRDERS STRENGTHENED WITH VARIOUS CFRP SYSTEMS

    E-Print Network [OSTI]

    STATIC AND FATIGUE PERFORMANCE OF 40 YEAR OLD PRESTRESSED CONCRETE GIRDERS STRENGTHENED program aimed at investigating the static and fatigue behavior of 40 year old prestressed concrete bridge girders were tested as control girders (one in static and one in fatigue), while the remaining ten girders

  14. FATIGUE OF 8630 CAST STEEL IN THE PRESENCE OF SHRINKAGE POROSITY

    E-Print Network [OSTI]

    Beckermann, Christoph

    FATIGUE OF 8630 CAST STEEL IN THE PRESENCE OF SHRINKAGE POROSITY K.M. Sigl1 , R.A. Hardin2 , R of shrinkage porosity on the mechanical performance of the cast steel. Axial fatigue tests were conducted under.I., and Beckermann, C., "Fatigue of 8630 Cast Steel in the Presence of Shrinkage Porosity," in Proceedings of the 57

  15. Viewpoint Paper Further considerations on the high-cycle fatigue of micron-scale

    E-Print Network [OSTI]

    Ritchie, Robert

    (polysilicon) MEMS comb-drive actuated fatigue resonators (Fig. 1), which are cycled at a constant disViewpoint Paper Further considerations on the high-cycle fatigue of micron-scale polycrystalline is not susceptible to high-cycle fatigue but micron-scale silicon films are. Using polysilicon resonators to deter

  16. Final Report on In-Reactor Creep-Fatigue Deformation Behaviour of a

    E-Print Network [OSTI]

    , in-reactor creep- fatigue tests have been performed at strain amplitudes of 0.25 and 0 temperatures of 326K and 323K. For comparison purposes corresponding out-of-reactor creep-fatigue tests were.2 Test module and irradiation rig 6 2.3 In-reactor creep-fatigue tests 7 2.4 Out-of-reactor creep

  17. Sex Differences in Long Bone Fatigue Using a Rat Model Luisa D. Moreno,1

    E-Print Network [OSTI]

    Waldman, Stephen D.

    response to fatigue, we also determined the creep that occurred during the fatigue test. From the creep progress (Fig. 1). Caler and Carter32 studied cortical bone creep behavior during fatigue testing. When adaptation. From these results, we hypothesized that creep was the underlying mechanism that accounted

  18. A Joint-level Model of Fatigue for the Postural Control of Virtual Humans

    E-Print Network [OSTI]

    Rodríguez, Inmaculada

    A Joint-level Model of Fatigue for the Postural Control of Virtual Humans Inmaculada Rodríguezb , e. Keywords: human body simulation, posture control, fatigue, computer animation. 1 Introduction Achieving specifically with humans should produce realistic animation in all the sense of the word, including fatigue

  19. Mechanisms for fatigue and wear of polysilicon structural thinfilms

    SciTech Connect (OSTI)

    Alsem, Daniel Henricus

    2006-12-01

    Fatigue and wear in micron-scale polysilicon structural films can severely impact the reliability of microelectromechanical systems (MEMS). Despite studies on fatigue and wear behavior of these films, there is still an on-going debate regarding the precise physical mechanisms for these two important failure modes. Although macro-scale silicon does not fatigue, this phenomenon is observed in micron-scale silicon. It is shown that for polysilicon devices fabricated in the MUMPs foundry and SUMMiT process stress-lifetime data exhibits similar trends in ambient air, shorter lifetimes in higher relative humidity environments and no fatigue failure at all in high vacuum. Transmission electron microscopy of the surface oxides of the samples show an approximate four-fold thickening of the oxide at stress concentrations after fatigue failure, but no thickening after fracture in air or after fatigue cycling in vacuo. It is found that such oxide thickening and fatigue failure (in air) occurs in devices with initial oxide thicknesses of {approx}4-20 nm. Such results are interpreted and explained by a reaction layer fatigue mechanism; specifically, moisture-assisted subcritical cracking within a cyclic stress-assisted thickened oxide layer occurs until the crack reaches a critical size to cause catastrophic failure. Polysilicon specimens from the SUMMiT process are used to study wear mechanisms in micron-scale silicon in ambient air. Worn parts are examined by analytical scanning and transmission electron microscopy, while temperature changes are monitored using infrared microscopy. These results are compared with the development of values of static coefficients of friction (COF) with number of wear cycles. Observations show amorphous debris particles ({approx}50-100 nm) created by fracture through the silicon grains ({approx}500 nm), which subsequently oxidize, agglomerate into clusters and create plowing tracks. A nano-crystalline layer ({approx}20-200 nm) forms at worn regions. No dislocations or extreme temperature increases are found, ruling out plasticity and temperature-assisted mechanisms. The COF reaches a steady-state value of {approx}0.20{+-}0.05 after a short time at an initial value of {approx}0.11{+-}0.01. Plowing tracks are found before the steady-state value of the COF is reached, suggesting only a short adhesive wear regime. This suggests a predominantly abrasive wear mechanism, controlled by fracture, which commences by the first particles created by adhesive wear.

  20. Does the Environmental Kuznets Curve Describe How Individual Countries Behave?

    E-Print Network [OSTI]

    Deacon, Robert; Norman, Catherine S

    2004-01-01

    for an Environmental Kuznets Curve. ” Review of EconomicsFactoring the Environmental Kuznets Curve: Evidence fromand Development: Is There a Kuznets Curve for Air Pollution

  1. Is the environmental Kuznets curve an empirical regularity?

    E-Print Network [OSTI]

    Deacon, Robert; Norman, Catherine S

    2004-01-01

    the Environmental Kuznets Curve: Turning a Black Box into aand Development: Is There a Kuznets Curve for Air Pollutionon the Environmental Kuznets Curve? ” Environment and

  2. Experience curves for power plant emission control technologies

    E-Print Network [OSTI]

    Rubin, Edward S.; Yeh, Sonia; Hounshell, David A; Taylor, Margaret R

    2007-01-01

    2004) ‘Experience curves for power plant emission controlLtd. Experience curves for power plant emission controlInc. Experience curves for power plant emission control

  3. Fatigue Life Prediction in Rapid Die Casting - Preliminary Work in View of Current Research

    SciTech Connect (OSTI)

    Chuan Huat Ng [Faculty of Mechanical and Manufacturing Engineering (FKMP), Kolej Universiti Teknologi Tun Hussein Onn (KUiTTHO), P.O.Box 101, 86400 Parit Raja, Batu Pahat, Johor (Malaysia); Grote, Karl-Heinrich [Institut fuer Maschinenkonstruktion, Lehrstuhl Konstruktionstechnik, Otto-von-Guericke University Magdeburg, Universitaetsplatz 2, 39106 Magdeburg (Germany); Baehr, Ruediger [Institut fuer Fertigungstechnik und Qualitaetssicherung, Ur und Umformtechnik, Otto-von-Guericke University Magdeburg, Universitaetsplatz 2, 39106 Magdeburg (Germany)

    2007-05-17

    Numerical simulation technique as a prediction tool is slowly adopted in metal casting industry for predicting design modelling solidification analysis. The reasons for this activity is found in the need to further enhance the geometrical design and mechanical properties of the tool design and the correct prediction methodology to fulfil industrial needs. The present state of numerical simulation capabilities in rapid die casting technologies is reviewed and the failure mode mechanisms of thermal fatigue, aimed at developing a numerical simulation with a systematic design guidance for predicting the thermal cyclic loading analysis and improvement is presented along with several other methods. The economic benefits of a numerical simulation technique in die casting are limited to tool life time, mechanical properties and design guidance. The extensive computer capabilities of a numerical simulation with a systematic design guidance methodology are exploited to provide a solution for flexible design, mechanical properties and mould life time. Related research carried out worldwide by different organisations and academic institutions are discussed.

  4. 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

  5. Fatigue evaluation in maintenance and assembly operations by digital human simulation

    E-Print Network [OSTI]

    Ma, Liang; Bennis, Fouad; Zhang, Wei; Hu, Bo; Guillaume, François; 10.1007/s10055-010-0156-8

    2010-01-01

    Virtual human techniques have been used a lot in industrial design in order to consider human factors and ergonomics as early as possible. The physical status (the physical capacity of virtual human) has been mostly treated as invariable in the current available human simulation tools, while indeed the physical capacity varies along time in an operation and the change of the physical capacity depends on the history of the work as well. Virtual Human Status is proposed in this paper in order to assess the difficulty of manual handling operations, especially from the physical perspective. The decrease of the physical capacity before and after an operation is used as an index to indicate the work difficulty. The reduction of physical strength is simulated in a theoretical approach on the basis of a fatigue model in which fatigue resistances of different muscle groups were regressed from 24 existing maximum endurance time (MET) models. A framework based on digital human modeling technique is established to realiz...

  6. Effects of LWR coolant environments on fatigue lives of austenitic stainless steels.

    SciTech Connect (OSTI)

    Chopra, O. K.

    1998-01-13

    Fatigue tests have been conducted on Types 304 and 316NG stainless steels to evaluate the effects of various material and loading variables, e.g., steel type, strain rate, dissolved oxygen (DO) in water, and strain range, on the fatigue lives of these steels. The results confirm significant decreases in fatigue life in water. Unlike the situation with ferritic steels, environmental effects on Types 304 and 316NG stainless steel are more pronounced in low-DO than in high-DO water. Experimental results have been compared with estimates of fatigue life based on a statistical model. The formation and growth of fatigue cracks in air and water environments are discussed.

  7. SPECTRUM FATIGUE LIFETIME AND RESIDUAL STRENGTH FOR FIBERGLASS LAMINATES

    E-Print Network [OSTI]

    fulfillment of the requirements for a doctoral degree at Montana State University, I agree that the Library shall make it available to borrowers under rules of Library. I further agree that copying of this thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Fatigue Trends of Fiberglass Laminates

  8. INFLOW AND THE FATIGUE OF THE LIST WIND TURBINE*

    E-Print Network [OSTI]

    1 INFLOW AND THE FATIGUE OF THE LIST WIND TURBINE* Herbert J. Sutherland Wind Energy Technology response data to characterize the spectrum of loads on wind turbines. A heavily instrumented Micon 65/13M turbine with SERI 8m blades is being used as the primary test turbine for this test. This turbine

  9. 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 ...

  10. Mechanical fatigue and fracture of Nitinol S. W. Robertson*1

    E-Print Network [OSTI]

    Ritchie, Robert

    Mechanical fatigue and fracture of Nitinol S. W. Robertson*1 , A. R. Pelton1 and R. O. Ritchie2 Nitinol, a near equiatomic intermetallic of nickel and titanium, is the most widely known and used shape transformation, Nitinol displays recoverable strains that are more than an order of magnitude greater than

  11. Modeling Creep-Fatigue-Environment Interactions in Steam Turbine Rotor Materials for Advanced Ultra-supercritical Coal Power Plants

    SciTech Connect (OSTI)

    Shen, Chen

    2014-01-20

    The goal of this project is to model creep-fatigue-environment interactions in steam turbine rotor materials for advanced ultra-supercritical (A-USC) coal power Alloy 282 plants, to develop and demonstrate computational algorithms for alloy property predictions, and to determine and model key mechanisms that contribute to the damages caused by creep-fatigue-environment interactions. The nickel based Alloy 282 is selected for this project because it is one of the leading candidate materials for the high temperature/pressure section of an A-USC steam turbine. The methods developed in the project are expected to be applicable to other metal alloys in similar steam/oxidation environments. The major developments are: ? failure mechanism and microstructural characterization ? atomistic and first principles modeling of crack tip oxygen embrittlement ? modeling of gamma prime microstructures and mesoscale microstructure-defect interactions ? microstructure and damage-based creep prediction ? multi-scale crack growth modeling considering oxidation, viscoplasticity and fatigue The technology developed in this project is expected to enable more accurate prediction of long service life of advanced alloys for A-USC power plants, and provide faster and more effective materials design, development, and implementation than current state-of-the-art computational and experimental methods. This document is a final technical report for the project, covering efforts conducted from January 2011 to January 2014.

  12. Advanced Tools For Characterizing HMA Fatigue Resistance 

    E-Print Network [OSTI]

    Lawrence, James Jefferies

    2011-02-22

    Accurately and efficiently characterizing the material properties of hot mix asphalt (HMA) is critical to the design and development of pavements that can experience repeated loading for long periods of time and resist ...

  13. UV Light Curves of Thermonuclear Supernovae

    E-Print Network [OSTI]

    S. I. Blinnikov; E. I. Sorokina

    2000-03-17

    Ultraviolet light curves are calculated for several thermonuclear supernova models using a multifrequency radiation hydrodynamic code. It is found that Chandrasekhar-mass models produce very similar light curves both for detonation and deflagration. Sub-Chandrasekhar-mass models essentially differ from ``normal'' Chandrasekhar ones regarding behaviour of their UV fluxes. Differences in absolute brightness and in shape of light curves of thermonuclear supernovae could be detectable up to 300 Mpc with modern UV space telescopes.

  14. Reversible Bending Fatigue Test System for Investigating Vibration Integrity of Spent Nuclear Fuel during Transportation

    SciTech Connect (OSTI)

    Wang, Jy-An John; Wang, Hong; Bevard, Bruce Balkcom; Howard, Rob L; Flanagan, Michelle

    2013-01-01

    Transportation packages for spent nuclear fuel (SNF) must meet safety requirements under normal and accident conditions as specified by federal regulations. During transportation, SNF experiences unique conditions and challenges to cladding integrity due to the vibrational and impact loading during road or rail shipment. Oak Ridge National Laboratory (ORNL) has been developing testing capabilities that can be used to improve the understanding of the impacts on SNF integrity due to vibration loading, especially for high burn-up SNF in normal transportation operation conditions. This information can be used to meet the nuclear industry and U.S. Nuclear Regulatory Commission needs in the area of safety and security of spent nuclear fuel storage and transport operations. The ORNL developed test system can perform reversible-bending fatigue testing to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The testing apparatus is also designed to meet the challenges of hot-cell operation, including remote installation and detachment of the SNF test specimen, in-situ test specimen deformation measurement, and implementation of a driving system suitable for use in a hot cell. The system contains a U-frame set-up equipped with uniquely designed grip rigs, to protect SNF rod and to ensure valid test results, and use of 3 specially designed LVDTs to obtain the in-situ curvature measurement. A variety of surrogate test rods have been used to develop and calibrate the test system as well as in performing a series of systematic cyclic fatigue tests. The surrogate rods include stainless steel (SS) cladding, SS cladding with cast epoxy, and SS cladding with alumina pellets inserts simulating fuel pellets. Testing to date has shown that the interface bonding between the SS cladding and the alumina pellets has a significant impact on the bending response of the test rods as well as their fatigue strength. The failure behaviors observed from tested surrogate rods provides a fundamental understanding of the underlying failure mechanisms of the SNF surrogate rod under vibration which has not been achieved previously. The newly developed device is scheduled to be installed in the hot-cell in summer 2013 to test high burnup SNF.

  15. Design, prototyping and preliminary testing of an elastic-powered climbing exoskeleton

    E-Print Network [OSTI]

    Briner, Hazel (Hazel Linn)

    2011-01-01

    Human powered elastic mechanisms can be used to reduce work requirements of muscles, by storing and releasing energy to more evenly distribute work load. An exoskeleton was designed to delay human fatigue during rock ...

  16. Canonical correlation of shipping forward curves

    E-Print Network [OSTI]

    Hadjiyiannis, Nicholas

    2010-01-01

    The behavior and interrelations between the main shipping forward curves are analyzed using multivariate statistics after removing the volatility distortions dictated by the Samuelson hypothesis. Principal Components ...

  17. Refinements and Tests of an Advanced Controller to Mitigate Fatigue Loads in the Controls Advanced Research Turbine: Preprint

    SciTech Connect (OSTI)

    Wright, A.; Fleming, P.

    2010-12-01

    Wind turbines are complex, nonlinear, dynamic systems forced by aerodynamic, gravitational, centrifugal, and gyroscopic loads. The aerodynamics of wind turbines are nonlinear, unsteady, and complex. Turbine rotors are subjected to a complicated 3-D turbulent wind inflow field, with imbedded coherent vortices that drive fatigue loads and reduce lifetime. Design of control algorithms for wind turbines must account for multiple control objectives. Future large multi-megawatt turbines must be designed with lighter weight structures, using active controls to mitigate fatigue loads, while maximizing energy capture. Active damping should be added to these dynamic structures to maintain stability for operation in a complex environment. At the National Renewable Energy Laboratory (NREL), we have designed, implemented, and tested advanced controls to maximize energy extraction and reduce structural dynamic loads. These control designs are based on linear models of the turbine that are generated by specialized modeling software. In this paper, we present field test results of an advanced control algorithm to mitigate blade, tower, and drivetrain loads in Region 3.

  18. LIGHT CURVES OF 32 LARGE TRANSNEPTUNIAN OBJECTS

    SciTech Connect (OSTI)

    Benecchi, Susan D.; Sheppard, Scott S.

    2013-05-15

    We present observations of 32 primarily bright, newly discovered Transneptunian objects (TNOs) observable from the Southern Hemisphere during 39 nights of observation with the Irenee du Pont 2.5 m telescope at Las Campanas Observatory. Our dataset includes objects in all dynamical classes, but is weighted toward scattered objects. We find 15 objects for which we can fit periods and amplitudes to the data, and place light curve amplitude upper limits on the other 17 objects. Combining our sample with the larger light curve sample in the literature, we find a 3{sigma} correlation between light curve amplitude and absolute magnitude with fainter objects having larger light curve amplitudes. We looked for correlations between light curve and individual orbital properties, but did not find any statistically significant results. However, if we consider light curve properties with respect to object dynamical classification, we find statistically different distributions between the classical-scattered and classical-resonant populations at the 95.60% and 94.64% level, respectively, with the classical objects having larger amplitude light curves. The significance is 97.05% if the scattered and resonant populations are combined. The properties of binary light curves are largely consistent with the greater TNO population except in the case of tidally locked systems. All the Haumea family objects measured so far have light curve amplitudes and rotation periods {<=}10 hr, suggesting that they are not significantly different from the larger TNO population. We expect multiple factors are influencing object rotations: object size dominates light curve properties except in the case of tidal, or proportionally large collisional interactions with other TNOs, the influence of the latter being different for each TNO sub-population. We also present phase curves and colors for some of our objects.

  19. PAPILLON: Designing Curved Display Surfaces With Printed Optics

    E-Print Network [OSTI]

    Poupyrev, Ivan

    manufac- tured as arbitrary 3D shapes. Flexible displays, such as or- ganic light emitting displays (OLED. It is based on 3D printed optics, where the surface of the display is constructed as a bundle of printed light elements also direct light from the surface of the display back to the image sensor allowing for touch

  20. Digital Styling for Designers: in Prospective Automotive Design

    E-Print Network [OSTI]

    Toronto, University of

    design studios are introducing a high resolution large-display H/W, so called a power wallDigital Styling for Designers: in Prospective Automotive Design Seok-Hyung Bae and Ryugo Kijima) the digital design sketch, (b) real-size spline curve modification system, and (c) direct 3D shape creation

  1. SMOOTHING SPLINE GROWTH CURVES WITH COVARIATES

    E-Print Network [OSTI]

    #11;ect growth curves. Due to the repeated measurement structure of his model, he is able to determine adapt the interactive spline model of Wahba to growth curves with covariates. The smoothing spline smoothing spline models (Ch. 10, Wahba (1990)). In this brief article, we adapt interactive spline models

  2. Twisted Jacobi Intersections Curves Rongquan Feng1

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Twisted Jacobi Intersections Curves Rongquan Feng1 , Menglong Nie1 , Hongfeng Wu2 1LMAM, School, whfmath@gmail.com Abstract In this paper, the twisted Jacobi intersections which contains Ja- cobi points of order 2 is iso- morphic to a twisted Jacobi intersections curve. Some fast explicit for- mulae

  3. Assessing Fatigue and Ultimate Load Uncertainty in Floating Offshore Wind Turbines Due to Varying Simulation Length

    SciTech Connect (OSTI)

    Stewart, G.; Lackner, M.; Haid, L.; Matha, D.; Jonkman, J.; Robertson, A.

    2013-07-01

    With the push towards siting wind turbines farther offshore due to higher wind quality and less visibility, floating offshore wind turbines, which can be located in deep water, are becoming an economically attractive option. The International Electrotechnical Commission's (IEC) 61400-3 design standard covers fixed-bottom offshore wind turbines, but there are a number of new research questions that need to be answered to modify these standards so that they are applicable to floating wind turbines. One issue is the appropriate simulation length needed for floating turbines. This paper will discuss the results from a study assessing the impact of simulation length on the ultimate and fatigue loads of the structure, and will address uncertainties associated with changing the simulation length for the analyzed floating platform. Recommendations of required simulation length based on load uncertainty will be made and compared to current simulation length requirements.

  4. Learning Curve: Analysis of an Agent Pricing Strategy Under Varying Conditions

    E-Print Network [OSTI]

    Greenwald, Amy

    . This paper addresses these issues by presenting a market simulator designed for analyzing agent pricing the Learning Curve Simulator, is designed for testing agent pricing strategies under varied market conditions], we analyzed the effectiveness of two different pricing strategies within a specific market scenario

  5. Finding the Energy Efficient Curve: Gate Sizing for Minimum Power under Delay Constraints

    E-Print Network [OSTI]

    Kolodny, Avinoam

    Finding the Energy Efficient Curve: Gate Sizing for Minimum Power under Delay Constraints Yoni in a fast circuit by the same factor does not yield an energy-efficient design, and we characterize efficient. A design implementation is considered to be energy efficient when it has the highest performance

  6. Decline curve analysis for horizontal wells 

    E-Print Network [OSTI]

    Shih, Min-Yu

    1994-01-01

    Subject; Petroleum Engineering DECLINE CURVE ANALYSIS FOR HORIZONTAL WELLS A Thesis by MIN- YU SHIH Submitted to Texas A8tM University in partial fulfillment of the requirements for the degtee of MASTER OF SCIENCE Approved as to style and content... curves are given as log-log plots of MttdaLLattaad: Fetkovich Type Curve Radial Flow, Circular Reservoir Solutions 12 Transient "Stems" tTransient Flow) 8 001 160 000 x10 Depletion "Stems" (Boundary-Dominated Flow) r)04Arps Equations b 0 0...

  7. Final Report on In-Reactor Creep-Fatigue Deformation Behaviour of a

    E-Print Network [OSTI]

    .5% with holdtimes of 10 and 100s, respectively. For comparison purposes, similar creep-fatigue tests were performed Procedure 5 2.1 Materials 5 2.2 Test module and irradiation rig 5 2.3 In-reactor creep-fatigue tests 6 2Final Report on In-Reactor Creep- Fatigue Deformation Behaviour of a CuCrZr Alloy: COFAT 1 B

  8. Four-point-bending-fatigue behavior of the Zr-based Vitreloy 105 bulk metallic glass

    SciTech Connect (OSTI)

    Morrison, M. L. [University of Tennessee, Knoxville (UTK); Buchanan, R. A. [University of Tennessee, Knoxville (UTK); Liaw, Peter K [University of Tennessee, Knoxville (UTK); Green, B. A. [University of Tennessee, Knoxville (UTK); Wang, G Y [University of Tennessee, Knoxville (UTK); Liu, Chain T [ORNL; Horton Jr, Joe A [ORNL

    2007-01-01

    The purpose of this study was to make a direct comparison between four-point-bending and uniaxial fatigue tests with the Zr{sub 52.5}Cu{sub 17.9}Ni{sub 14.6}Al{sub 10.0}Ti{sub 5.0} (at.%) BMG alloy (Vitreloy 105). The fatigue lifetimes in four-point bending were found to be greater than those reported in uniaxial testing. However, the fatigue-endurance limit found in four-point bending was slightly less than that reported for uniaxial fatigue. Thus, the significant differences between fatigue studies in the literature are not likely due to this difference in testing geometry. On the contrary, the fatigue lifetimes were found to be highly dependent upon surface defects and material quality. The four-point-bending-fatigue performance of the Vit 105 alloy was found to be greater than most BMGs and similar to the 300 M high-strength steel and other crystalline alloys in spite of not being 'perfectly amorphous.' Due to the detrimental effects of these inhomogeneities and wear at the supporting pins, this fatigue behavior can be assumed to be a conservative estimate of the potential fatigue performance of a perfectly amorphous and homogeneous BMG.

  9. 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.

  10. Incorporating Experience Curves in Appliance Standards Analysis

    E-Print Network [OSTI]

    Desroches, Louis-Benoit

    2012-01-01

    appliance price trends. Energy Policy 37, 597-605. Day, G.learning hypothesis. Energy Policy 37, 2525-2535. Fusfeld,curves for wind farms. Energy Policy 33, 133-150. Klaassen,

  11. Stable Segmentation of 2D Curves 

    E-Print Network [OSTI]

    Fitzgibbon, Andrew WJ

    This thesis deals with the specific subproblem of converting sequences of two-dimensional data points into higher level descriptions in terms of curved shape primitives. This is an important member of the wider family ...

  12. Environmental bias and elastic curves on surfaces

    E-Print Network [OSTI]

    Jemal Guven; Dulce María Valencia; Pablo Vázquez-Montejo

    2014-08-15

    The behavior of an elastic curve bound to a surface will reflect the geometry of its environment. This may occur in an obvious way: the curve may deform freely along directions tangent to the surface, but not along the surface normal. However, even if the energy itself is symmetric in the curve's geodesic and normal curvatures, which control these modes, very distinct roles are played by the two. If the elastic curve binds preferentially on one side, or is itself assembled on the surface, not only would one expect the bending moduli associated with the two modes to differ, binding along specific directions, reflected in spontaneous values of these curvatures, may be favored. The shape equations describing the equilibrium states of a surface curve described by an elastic energy accommodating environmental factors will be identified by adapting the method of Lagrange multipliers to the Darboux frame associated with the curve. The forces transmitted to the surface along the surface normal will be determined. Features associated with a number of different energies, both of physical relevance and of mathematical interest, are described. The conservation laws associated with trajectories on surface geometries exhibiting continuous symmetries are also examined.

  13. 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 ...

  14. Creep-Fatigue Behavior of Alloy 617 at 850°C

    SciTech Connect (OSTI)

    Carroll, Laura

    2015-05-01

    Creep-fatigue deformation is expected to be a significant contributor to the potential factors that limit the useful life of the Intermediate Heat Exchanger (IHX) in the Very High Temperature Reactor (VHTR) nuclear system.[1] The IHX of a high temperature gas reactor will be subjected to a limited number of transient cycles due to start-up and shut-down operations imparting high local stresses on the component. This cycling introduces a creep-fatigue type of interaction as dwell times occur intermittently. The leading candidate alloy for the IHX is a nickel-base solid solution strengthened alloy, Alloy 617, which must safely operate near the expected reactor outlet temperature of up to 950 °C.[1] This solid solution strengthened nickel-base alloy provides an interesting creep-fatigue deformation case study because it has characteristics of two different alloy systems for which the cyclic behavior has been extensively investigated. Compositionally, it resembles nickel-base superalloys, such as Waspalloy, IN100, and IN718, with the exception of its lower levels of Al. At temperatures above 800 °C, the microstructure of Alloy 617, however, does not contain the ordered ?’ or ?’’ phases. Thus microstructurally, it is more similar to an austenitic stainless steel, such as 316 or 304, or Alloy 800H comprised of a predominantly solid solution strengthened matrix phase with a dispersion of inter- and intragranular carbides. Previous studies of the creep-fatigue behavior of Alloy 617 at 950 °C indicate that the fatigue life is reduced when a constant strain dwell is added at peak tensile strain.[2-5] This results from the combination of faster crack initiation occurring at surface-connected grain boundaries due to oxidation from the air environment along with faster, and intergranular, crack propagation resulting from the linking of extensive interior grain boundary cracking.[3] Saturation, defined as the point at which further increases in the strain-controlled hold time duration no longer decreases the cycle life, has been observed for Alloy 617 at 950 °C at least to the investigated hold times[2,3], as illustrated through a plot of cycles to failure v. hold time in Figure 1. The 950 °C creep-fatigue data set generated by Totemeier and Tian[5] at the 0.3% and 1.0% strain range is consistent in magnitude in terms of the cycles to failure data of that of Carroll et al., however, 0.3% strain range data did not exhibit saturation at hold times of up to 10 min. At 1.0% total strain, saturation in the number of cycles to failure was observed within the investigated peak tensile hold times of up to 10 min[5]. The data of Carroll et al.[2,3] in Figure 1 and Totemeier and Tian[5] is also consistent in magnitude with the data of Rao and coworkers[4] investigated at the 0.6% strain range. It should be noted that saturation in the number of cycles to failure is not present in the data published by Rao and coworkers[4] for tensile hold times of up to 120 min. The latter testing was in a simulated primary-circuit helium gas as opposed to air and a single data point is reported for the longer hold time conditions.

  15. MEASUREMENT OF THE SHOCK-HEATED MELT CURVE OF LEAD USING PYROMETRY AND REFLECTOMETRY

    SciTech Connect (OSTI)

    D. Partouche-Sebban and J. L. Pelissier, Commissariat a` l'Energie Atomique,; F. G. Abeyta, Los Alamos National Laboratory; W. W. Anderson, Los Alamos National Laboratory; M. E. Byers, Los Alamos National Laboratory; D. Dennis-Koller, Los Alamos National Laboratory; J. S. Esparza, Los Alamos National Laboratory; S. D. Borror, Bechtel Nevada; C. A. Kruschwitz, Bechtel Nevada

    2004-01-01

    Data on the high-pressure melting temperatures of metals is of great interest in several fields of physics including geophysics. Measuring melt curves is difficult but can be performed in static experiments (with laser-heated diamond-anvil cells for instance) or dynamically (i.e., using shock experiments). However, at the present time, both experimental and theoretical results for the melt curve of lead are at too much variance to be considered definitive. As a result, we decided to perform a series of shock experiments designed to provide a measurement of the melt curve of lead up to about 50 GPa in pressure. At the same time, we developed and fielded a new reflectivity diagnostic, using it to make measurements on tin. The results show that the melt curve of lead is somewhat higher than the one previously obtained with static compression and heating techniques.

  16. Spontaneously curving trajectory in Brownian motion of particle with broken symmetry

    E-Print Network [OSTI]

    Nan Sheng; YuSong Tu; ZuoWei Wang; HaiPing Fang

    2015-08-31

    By molecular dynamics simulations, we observe that the trajectory of Brownian particle with asymmetrical structure shows a systematic curving toward an orientation-dependent direction during the Brownian motion, rather than a simple random walk. This systematic curving indicates that there is a spontaneous breaking of equal probability in Brownian motion owing to the asymmetrical structure of the particle. We find that the characteristic time for this systematic curving is ~10 ps for a particle with a length of 0.37 nm. Furthermore, we find that as the degree of the particle asymmetry increases, the ensemble-averaged velocity along the initial orientation shows higher peak value and the characteristic time for the systematic curving of the trajectory becomes longer. The finding is expected to be of essential importance in the understanding of the dynamic behavior of many physical, chemical and bio-systems at nanoscale and even microscale. It also provides insights into the design of nano- and microscale devices.

  17. Mechanism of fatigue in micron-scale films of polycrystalline silicon for microelectromechanical applications

    SciTech Connect (OSTI)

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

    2001-08-02

    Reported nearly a decade ago, cyclic fatigue failure in silicon thin films has remained a mystery. Silicon does not display the room temperature plasticity or extrinsic toughening mechanisms necessary to cause fatigue in either ductile (e.g., metals) or brittle (e.g., ceramics and ordered mintermetallic) materials.

  18. Fatigue Analysis of Wind Turbines Issued by Sandia National Laboratories, operated for the United States

    E-Print Network [OSTI]

    On the Fatigue Analysis of Wind Turbines *"f~-9,a, ,.*,. ,^__.c #12;Issued by Sandia National-0089 Unlimited Release Printed June 1999 On the Fatigue Analysis of Wind Turbines by Herbert J. Sutherland Sandia National Laboratories P.O. Box 5800 Albuquerque, New Mexico 87185-0708 Abstract Modern wind turbines

  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. 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

  1. Abstract--Despite growing interest in the behavior of electromyographic signals during muscle fatigue, few studies

    E-Print Network [OSTI]

    Carvalho, João Luiz

    Abstract--Despite growing interest in the behavior of electromyographic signals during muscle fatigue, few studies investigate fatigue recovery. In this work, we use surface electromyographic signals for each experimental group: 1, 2, 4, 8, 24 and 48 hours. Surface electromyographic signals were acquired

  2. Mitigation of Fatigue Loads Using Individual Pitch Control of Wind Turbines Based on FAST

    E-Print Network [OSTI]

    Chen, Zhe

    Mitigation of Fatigue Loads Using Individual Pitch Control of Wind Turbines Based on FAST Yunqian University, China jiz@seu.edu.cn Abstract-With the increase of wind turbine dimension and capacity, the wind turbine structures are subjected to prominent loads and fatigue which would reduce the lifetime of wind

  3. Prediction of the Fatigue Life of Cast Steel Containing Shrinkage Porosity

    E-Print Network [OSTI]

    Beckermann, Christoph

    Prediction of the Fatigue Life of Cast Steel Containing Shrinkage Porosity RICHARD A. HARDIN and CHRISTOPH BECKERMANN A simulation methodology for predicting the fatigue life of cast steel components with shrinkage porosity is developed and validated through comparison with previously performed measure- ments

  4. 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

  5. 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

  6. 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

  7. 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.

  8. Damage mechanics characterization on fatigue behavior of a solder joint material

    SciTech Connect (OSTI)

    Chow, C.L.; Yang, F. [Univ. of Michigan, Dearborn, MI (United States). Dept. of Mechanical Engineering; Fang, H.E. [Sandia National Labs., Albuquerque, NM (United States). Computational Physics Dept.

    1998-08-01

    This paper presents the first part of a comprehensive mechanics approach capable of predicting the integrity and reliability of solder joint material under fatigue loading without viscoplastic damage considerations. A separate report will be made to present a comprehensive damage model describing life prediction of the solder material under thermomechanical fatigue loading. The method is based on a theory of damage mechanics which makes possible a macroscopic description of the successive material deterioration caused by the presence of microcracks/voids in engineering materials. A damage mechanics model based on the thermodynamic theory of irreversible processes with internal state variables is proposed and used to provide a unified approach in characterizing the cyclic behavior of a typical solder material. With the introduction of a damage effect tensor, the constitutive equations are derived to enable the formulation of a fatigue damage dissipative potential function and a fatigue damage criterion. The fatigue evolution is subsequently developed based on the hypothesis that the overall damage is induced by the accumulation of fatigue and plastic damage. This damage mechanics approach offers a systematic and versatile means that is effective in modeling the entire process of material failure ranging from damage initiation and propagation leading eventually to macro-crack initiation and growth. As the model takes into account the load history effect and the interaction between plasticity damage and fatigue damage, with the aid of a modified general purpose finite element program, the method can readily be applied to estimate the fatigue life of solder joints under different loading conditions.

  9. Updated U.S. Geothermal Supply Curve

    SciTech Connect (OSTI)

    Augustine, C.; Young, K. R.; Anderson, A.

    2010-02-01

    This paper documents the approach used to update the U.S. geothermal supply curve. The analysis undertaken in this study estimates the supply of electricity generation potential from geothermal resources in the United States and the levelized cost of electricity (LCOE), capital costs, and operating and maintenance costs associated with developing these geothermal resources. Supply curves were developed for four categories of geothermal resources: identified hydrothermal (6.4 GWe), undiscovered hydrothermal (30.0 GWe), near-hydrothermal field enhanced geothermal systems (EGS) (7.0 GWe) and deep EGS (15,900 GWe). Two cases were considered: a base case and a target case. Supply curves were generated for each of the four geothermal resource categories for both cases. For both cases, hydrothermal resources dominate the lower cost range of the combined geothermal supply curve. The supply curves indicate that the reservoir performance improvements assumed in the target case could significantly lower EGS costs and greatly increase EGS deployment over the base case.

  10. Freedom from Pollution? The State, the People, and the Environmental Kuznets Curve

    E-Print Network [OSTI]

    Bond, Craig A.; Farzin, Y. Hossein

    2004-01-01

    and the environmental Kuznets curve for deforestation: aand the environmental Kuznets curve. Ecological Economicsbias in environmental Kuznets curves. Ecological Economics

  11. A new muscle fatigue and recovery model and its ergonomics application in human simulation

    E-Print Network [OSTI]

    Ma, Liang; Bennis, Fouad; Zhang, Wei; Guillaume, François

    2009-01-01

    Although automatic techniques have been employed in manufacturing industries to increase productivity and efficiency, there are still lots of manual handling jobs, especially for assembly and maintenance jobs. In these jobs, musculoskeletal disorders (MSDs) are one of the major health problems due to overload and cumulative physical fatigue. With combination of conventional posture analysis techniques, digital human modelling and simulation (DHM) techniques have been developed and commercialized to evaluate the potential physical exposures. However, those ergonomics analysis tools are mainly based on posture analysis techniques, and until now there is still no fatigue index available in the commercial software to evaluate the physical fatigue easily and quickly. In this paper, a new muscle fatigue and recovery model is proposed and extended to evaluate joint fatigue level in manual handling jobs. A special application case is described and analyzed by digital human simulation technique.

  12. A new muscle fatigue and recovery model and its ergonomics application in human simulation

    E-Print Network [OSTI]

    Ma, Liang; Bennis, Fouad; Zhang, Wei; Guillaume, François; 10.1080/17452759.2010.504056

    2010-01-01

    Although automatic techniques have been employed in manufacturing industries to increase productivity and efficiency, there are still lots of manual handling jobs, especially for assembly and maintenance jobs. In these jobs, musculoskeletal disorders (MSDs) are one of the major health problems due to overload and cumulative physical fatigue. With combination of conventional posture analysis techniques, digital human modelling and simulation (DHM) techniques have been developed and commercialized to evaluate the potential physical exposures. However, those ergonomics analysis tools are mainly based on posture analysis techniques, and until now there is still no fatigue index available in the commercial software to evaluate the physical fatigue easily and quickly. In this paper, a new muscle fatigue and recovery model is proposed and extended to evaluate joint fatigue level in manual handling jobs. A special application case is described and analyzed by digital human simulation technique.

  13. Experimental Simulation of Closed Timelike Curves

    E-Print Network [OSTI]

    Martin Ringbauer; Matthew A. Broome; Casey R. Myers; Andrew G. White; Timothy C. Ralph

    2015-01-20

    Closed timelike curves are among the most controversial features of modern physics. As legitimate solutions to Einstein's field equations, they allow for time travel, which instinctively seems paradoxical. However, in the quantum regime these paradoxes can be resolved leaving closed timelike curves consistent with relativity. The study of these systems therefore provides valuable insight into non-linearities and the emergence of causal structures in quantum mechanics-essential for any formulation of a quantum theory of gravity. Here we experimentally simulate the non-linear behaviour of a qubit interacting unitarily with an older version of itself, addressing some of the fascinating effects that arise in systems traversing a closed timelike curve. These include perfect discrimination of non-orthogonal states and, most intriguingly, the ability to distinguish nominally equivalent ways of preparing pure quantum states. Finally, we examine the dependence of these effects on the initial qubit state, the form of the unitary interaction, and the influence of decoherence.

  14. 13/2 ways to count curves

    E-Print Network [OSTI]

    Pandharipande, R

    2011-01-01

    In the past 20 years, compactifications of the families of curves in algebraic varieties X have been studied via stable maps, Hilbert schemes, stable pairs, unramified maps, and stable quotients. Each path leads to a different enumeration of curves. A common thread is the use of a 2-term deformation/obstruction theory to define a virtual fundamental class. The richest geometry occurs when X is a nonsingular projective variety of dimension 3. We survey here the 13/2 principal ways to count curves with special attention to the 3-fold case. The different theories are linked by a web of conjectural relationships which we highlight. Our goal is to provide a guide for graduate students looking for an elementary route into the subject.

  15. Chiral gap effect in curved space

    E-Print Network [OSTI]

    Antonino Flachi; Kenji Fukushima

    2015-05-29

    We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum, a mass-gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass-gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition.

  16. Deformation and fatigue behavior of hot dip galvanized coatings

    SciTech Connect (OSTI)

    Camurri, Carlos P. [University of Concepcion, Department of Materials Engineering, Edmundo Larenas 270, Casilla 160-C, Correo 3, Concepcion (Chile)]. E-mail: ccamurri@udec.cl; Benavente, Raul G. [University of Concepcion, Department of Materials Engineering, Edmundo Larenas 270, Casilla 160-C, Correo 3, Concepcion (Chile); Roa, Isidoro S. [University of Concepcion, Department of Materials Engineering, Edmundo Larenas 270, Casilla 160-C, Correo 3, Concepcion (Chile); Carrasco, Claudia C. [University of Concepcion, Department of Materials Engineering, Edmundo Larenas 270, Casilla 160-C, Correo 3, Concepcion (Chile)

    2005-09-15

    This paper reports on the results of a study of the effect of static and dynamic stresses on hot dip galvanized coatings on SAE 1020 steel substrates. Galvanizing was performed using baths maintained at 450 deg. C, the zinc containing 0.16% Ti and 0.02% Fe and with Al and Ni in the ranges 0-0.20% and 0-0.30%, respectively. Static three-point bend tests were conducted with applied stresses in the range 428-790 MPa. Dynamic bend-fatigue tests involved stresses in the range 228-578 MPa at a cyclic frequency of 0.25 Hz for up to 700 cycles. The total crack density in the coatings was measured before and after the tests using light optical and electron microscopy. The results showed that the crack density increased as the applied stress increased and crack propagation was promoted perpendicular to the substrate. The number of cycles had no effect on the crack density and propagation at stresses lower than 386 MPa. At higher stresses the number of applied cycles contributed only to crack propagation. It was concluded that the best bath composition for preventing fatigue crack propagation is one that minimized the formation of thinner brittle layers in the galvanized coatings.

  17. 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.

  18. Human performance modeling for system of systems analytics :soldier fatigue.

    SciTech Connect (OSTI)

    Lawton, Craig R.; Campbell, James E.; Miller, Dwight Peter

    2005-10-01

    The military has identified Human Performance Modeling (HPM) as a significant requirement and challenge of future systems modeling and analysis initiatives as can be seen in the Department of Defense's (DoD) Defense Modeling and Simulation Office's (DMSO) Master Plan (DoD 5000.59-P 1995). To this goal, the military is currently spending millions of dollars on programs devoted to HPM in various military contexts. Examples include the Human Performance Modeling Integration (HPMI) program within the Air Force Research Laboratory, which focuses on integrating HPMs with constructive models of systems (e.g. cockpit simulations) and the Navy's Human Performance Center (HPC) established in September 2003. Nearly all of these initiatives focus on the interface between humans and a single system. This is insufficient in the era of highly complex network centric SoS. This report presents research and development in the area of HPM in a system-of-systems (SoS). Specifically, this report addresses modeling soldier fatigue and the potential impacts soldier fatigue can have on SoS performance.

  19. Reversible vectorisation of 3D digital planar curves and applications

    E-Print Network [OSTI]

    Sivignon, Isabelle

    Reversible vectorisation of 3D digital planar curves and applications Isabelle Sivignon a,, Florent the problem of the computation of a planar polygonal curve from a digital planar curve, such that the digital data can be exactly retrieved from the polygonal curve. The proposed transformation also provides

  20. Monitoring microstructural evolution of alloy 617 with non-linear acoustics for remaining useful life prediction; multiaxial creep-fatigue and creep-ratcheting

    SciTech Connect (OSTI)

    Lissenden, Cliff; Hassan, Tasnin; Rangari, Vijaya

    2014-10-30

    The research built upon a prior investigation to develop a unified constitutive model for design-­by-­analysis of the intermediate heat exchanger (IHX) for a very high temperature reactor (VHTR) design of next generation nuclear plants (NGNPs). Model development requires a set of failure data from complex mechanical experiments to characterize the material behavior. Therefore uniaxial and multiaxial creep-­fatigue and creep-­ratcheting tests were conducted on the nickel-­base Alloy 617 at 850 and 950°C. The time dependence of material behavior, and the interaction of time dependent behavior (e.g., creep) with ratcheting, which is an increase in the cyclic mean strain under load-­controlled cycling, are major concerns for NGNP design. This research project aimed at characterizing the microstructure evolution mechanisms activated in Alloy 617 by mechanical loading and dwell times at elevated temperature. The acoustic harmonic generation method was researched for microstructural characterization. It is a nonlinear acoustics method with excellent potential for nondestructive evaluation, and even online continuous monitoring once high temperature sensors become available. It is unique because it has the ability to quantitatively characterize microstructural features well before macroscale defects (e.g., cracks) form. The nonlinear acoustics beta parameter was shown to correlate with microstructural evolution using a systematic approach to handle the complexity of multiaxial creep-­fatigue and creep-­ratcheting deformation. Mechanical testing was conducted to provide a full spectrum of data for: thermal aging, tensile creep, uniaxial fatigue, uniaxial creep-­fatigue, uniaxial creep-ratcheting, multiaxial creep-fatigue, and multiaxial creep-­ratcheting. Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Optical Microscopy were conducted to correlate the beta parameter with individual microstructure mechanisms. We researched application of the harmonic generation method to tubular mechanical test specimens and pipes for nondestructive evaluation. Tubular specimens and pipes act as waveguides, thus we applied the acoustic harmonic generation method to guided waves in both plates and shells. Magnetostrictive transducers were used to generate and receive guided wave modes in the shell sample and the received signals were processed to show the sensitivity of higher harmonic generation to microstructure evolution. Modeling was initiated to correlate higher harmonic generation with the microstructure that will lead to development of a life prediction model that is informed by the nonlinear acoustics measurements.

  1. Curving Dynamics in High Speed PUBLIC VERSION

    E-Print Network [OSTI]

    Curving Dynamics in High Speed Trains PUBLIC VERSION Daniele Bigoni Kongens Lyngby 2011 IMM forces on the dynamics, due to the high speed spinning of the wheel sets, has been highlighted. The wheel-rail interaction is modeled using the Hertz's static contact theory, corrected with the Kalker

  2. Cryptographic Schemes based on Elliptic Curve Pairings

    E-Print Network [OSTI]

    Paterson, Kenny

    on Elliptic Curve Pairings: Contributions to Public Key Cryptography and Key Agreement Protocols This thesis are then used to make concrete CL-PKC schemes and are also used to make other efficient key agreement protocols. It does rely on the use of a trusted authority (TA) who is in possession of a master key. In this respect

  3. Closed timelike curves in general relativity

    E-Print Network [OSTI]

    W. B. Bonnor

    2002-11-13

    Many solutions of Einstein's field equations contain closed timelike curves (CTC). Some of these solutions refer to ordinary materials in situations which might occur in the laboratory, or in astrophysics. It is argued that, in default of a reasonable interpretation of CTC, general relativity does not give a satisfactory account of all phenomena within its terms of reference.

  4. Research Summary Estimating Woodfuel Resource Cost Curves

    E-Print Network [OSTI]

    and extraction methods. Background Just under half of the final energy consumed in the UK (49%) is in the formResearch Summary Estimating Woodfuel Resource Cost Curves As a renewable energy source, woodfuel. The woodfuel strategy adopted by Forestry Commission England supports delivery of these. It aims to sustainably

  5. Updated Hubbert curves analyze world oil supply

    SciTech Connect (OSTI)

    Ivanhoe, L.F.

    1996-11-01

    The question is not whether, but when, world crude oil production will start to decline, ushering in the permanent oil shock era. While global information for predicting this event is not so straightforward as the data M. King Hubbert used in creating his famous Hubbert Curve that predicted the US (Lower 48 states, or US/48) 1970 oil production peak, there are strong indications that most of the world`s large exploration targets have now been found. Meanwhile, the earth`s population is exploding along with the oil needs of Asia`s developing nations. This article reviews Hubbert`s original analyses on oil discovery and production curves for the US/48 and projects his proven methodology onto global oil discoveries and production as of 1992. The world`s oil discovery curve peaked in 1962, and thence declined, as a Hubbert Curve predicts. However, global production was restricted after the 1973 Arab oil embargo. Otherwise, world production would have peaked in the mid-1990s. Two graphs show alternate versions of future global oil production.

  6. Fractionalization of Interstitials in Curved Colloidal Crystals

    E-Print Network [OSTI]

    William T. M. Irvine; Mark J. Bowick; Paul M. Chaikin

    2013-10-11

    Understanding the out-of equilibrium behaviour of point defects in crystals, yields insights into the nature and fragility of the ordered state, as well as being of great practical importance. In some rare cases defects are spontaneously healed - a one-dimensional crystal formed by a line of identical charged particles, for example, can accommodate an interstitial (extra particle) by a re-adjusting all particle positions to even out the spacing. In sharp contrast, particles organized into a perfect hexagonal crystal in the plane cannot accommodate an interstitial by a simple re-adjustment of the particle spacing - the interstitial remains instead trapped between lattice sites and diffuses by hopping, leaving the crystal permanently defected. Here we report on the behavior of interstitials in colloidal crystals on curved surfaces. Using optical tweezers operated independently of three dimensional imaging, we insert a colloidal interstitial in a lattice of similar particles on flat and curved (positively and negatively) oil-glycerol interfaces and image the ensuing dynamics. We find that, unlike in flat space, the curved crystals self-heal through a collective rearrangement that re-distributes the increased density associated with the interstitial. The self-healing process can be interpreted in terms of an out of equilibrium interaction of topological defects with each other and with the underlying curvature. Our observations suggest the existence of "particle fractionalization" on curved surface crystals.

  7. Beauty waves: an artistic representation of ocean waves using Bezier curves 

    E-Print Network [OSTI]

    Faulkner, Jay Allen

    2007-04-25

    In this thesis, we present a method for computing an artistic representation of ocean waves using Bezier curves. Wave forms are loosely based on procedural wave models and are designed to emulate those found in both art and nature. The wave forms...

  8. 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.

  9. High-temperature low cycle fatigue behavior of a gray cast iron

    SciTech Connect (OSTI)

    Fan, K.L. He, G.Q.; She, M.; Liu, X.S.; Lu, Q.; Yang, Y.; Tian, D.D.; Shen, Y.

    2014-12-15

    The strain controlled low cycle fatigue properties of the studied gray cast iron for engine cylinder blocks were investigated. At the same total strain amplitude, the low cycle fatigue life of the studied material at 523 K was higher than that at 423 K. The fatigue behavior of the studied material was characterized as cyclic softening at any given total strain amplitude (0.12%–0.24%), which was attributed to fatigue crack initiation and propagation. Moreover, this material exhibited asymmetric hysteresis loops due to the presence of the graphite lamellas. Transmission electron microscopy analysis suggested that cyclic softening was also caused by the interactions of dislocations at 423 K, such as cell structure in ferrite, whereas cyclic softening was related to subgrain boundaries and dislocation climbing at 523 K. Micro-analysis of specimen fracture appearance was conducted in order to obtain the fracture characteristics and crack paths for different strain amplitudes. It showed that the higher the temperature, the rougher the crack face of the examined gray cast iron at the same total strain amplitude. Additionally, the microcracks were readily blunted during growth inside the pearlite matrix at 423 K, whereas the microcracks could easily pass through pearlite matrix along with deflection at 523 K. The results of fatigue experiments consistently showed that fatigue damage for the studied material at 423 K was lower than that at 523 K under any given total strain amplitude. - Highlights: • The low cycle fatigue behavior of the HT250 for engine cylinder blocks was investigated. • TEM investigations were conducted to explain the cyclic deformation response. • The low cycle fatigue cracks of HT250 GCI were studied by SEM. • The fatigue life of the examined material at 523 K is higher than that at 423 K.

  10. Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies

    SciTech Connect (OSTI)

    Yang, Z.; Dong, P.; Liu, S.; Babu, S.; Olson, G.; DebRoy, T.

    2005-04-15

    The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high strength steels. In order to achieve high fatigue strength in a welded-joint it is necessary to manage the weld bead shape for lower stress concentration, produce preferable residual stress distribution, and obtain the desired microstructure for improved material toughness and strength. This is a systems challenge that requires the optimization of the welding process, the welding consumable, the base material, as well as the structure design. The concept of virtual welded-joint design has been proposed and established in this project. The goal of virtual welded-joint design is to develop a thorough procedure to predict the relationship of welding process, microstructure, property, residual stress, and the ultimate weld fatigue strength by a systematic modeling approach. The systematic approach combines five sub-models: weld thermal-fluid model, weld microstructure model, weld material property model, weld residual stress model, and weld fatigue model. The systematic approach is thus based on interdisciplinary applied sciences including heat transfer, computational fluid dynamics, materials science, engineering mechanics, and material fracture mechanics. The sub-models are based on existing models with further development. The results from modeling have been validated with critical experiments. The systematic modeling approach has been used to design high fatigue resistant welds considering the combined effects of weld bead geometry, residual stress, microstructure, and material property. In particular, a special welding wire has been developed in this project to introduce compressive residual stress at weld toe for weld fatigue resistance.

  11. Parametric System Curves: Correlations Between Fan Pressure Rise and Flow for Large Commercial Buildings

    SciTech Connect (OSTI)

    Sherman, Max; Wray, Craig

    2010-05-19

    A substantial fraction of HVAC energy use in large commercial buildings is due to fan operation. Fan energy use depends in part on the relationship between system pressure drop and flow through the fan, which is commonly called a "system curve." As a step toward enabling better selections of air-handling system components and analyses of common energy efficiency measures such as duct static pressure reset and duct leakage sealing, this paper shows that a simple four-parameter physical model can be used to define system curves. Our model depends on the square of the fan flow, as is commonly considered. It also includes terms that account for linear-like flow resistances such as filters and coils, and for supply duct leakage when damper positions are fixed or are changed independently of static pressure or fan flow. Only two parameters are needed for systems with variable-position supply dampers (e.g., VAV box dampers modulating to control flow). For these systems, reducing or eliminating supply duct leakage does not change the system curve. The parametric system curve may be most useful when applied to field data. Non-linear techniques could be used to fit the curve to fan pressure rise and flow measurements over a range of operating conditions. During design, when measurements are unavailable, one could use duct design calculation tools instead to determine the coefficients.

  12. The marine biodiversity curve is an icon of paleobiology. The familiar curve shows

    E-Print Network [OSTI]

    Waxman, David

    the Mesozoic and Cenozoic. The curve also gives us often quoted magnitudes of mass extinctions and the relay owing to an increase in habitable area. To test this possibility, they compared the degree

  13. Design and Development of a High Temperature Radiatively Cooled

    E-Print Network [OSTI]

    McDonald, Kirk

    Experiment Beam kinetic energy 8 GeV Beam spot shape Gaussian Beam spot size x = y = 1 mm Main Injector cycle attack? · Beam-induced Thermal Cycling - Can we rule out failure by fatigue? · Support Structure - Can we / manufacturing options are available? #12;Target conceptual design Titanium mounting ring Refractory metal spokes

  14. INTEGRATED DESIGN OF STEEL CASTINGS FOR SERVICE PERFORMANCE

    E-Print Network [OSTI]

    Beckermann, Christoph

    Bellet TMS (The Minerals, Metals & Materials Society), 2006 #12;Casting Simulation (Shrinkage PredictionINTEGRATED DESIGN OF STEEL CASTINGS FOR SERVICE PERFORMANCE Richard. A. Hardin1 , Richard K. Huff2, USA 2 Caterpillar Inc., Champaign, IL 61820, USA Keywords: steel casting, porosity, fatigue life

  15. Geometrically controlled snapping transitions in shells with curved creases

    E-Print Network [OSTI]

    Nakul P. Bende; Arthur A. Evans; Sarah Innes-Gold; Luis A. Marin; Itai Cohen; Ryan C. Hayward; Christian D. Santangelo

    2014-10-26

    Curvature and mechanics are intimately connected for thin materials, and this coupling between geometry and physical properties is readily seen in folded structures from intestinal villi and pollen grains, to wrinkled membranes and programmable metamaterials. While the well-known rules and mechanisms behind folding a flat surface have been used to create deployable structures and shape transformable materials, folding of curved shells is still not fundamentally understood. Curved shells naturally deform by simultaneously bending and stretching, and while this coupling gives them great stability for engineering applications, it makes folding a surface of arbitrary curvature a non-trivial task. Here we discuss the geometry of folding a creased shell, and demonstrate theoretically the conditions under which it may fold continuously. When these conditions are violated we show, using experiments and simulations, that shells undergo rapid snapping motion to fold from one stable configuration to another. Although material asymmetry is a proven mechanism for creating this bifurcation of stability, for the case of a creased shell, the inherent geometry itself serves as a barrier to folding. We discuss here how two fundamental geometric concepts, creases and curvature, combine to allow rapid transitions from one stable state to another. Independent of material system and length scale, the design rule that we introduce here explains how to generate snapping transitions in arbitrary surfaces, thus facilitating the creation of programmable multi-stable materials with fast actuation capabilities.

  16. Centrifugally driven relativistic dynamics on curved trajectories

    E-Print Network [OSTI]

    Andria Rogava; George Dalakishvili; Zaza Osmanov

    2003-03-27

    Motion of test particles along rotating curved trajectories is considered. The problem is studied both in the laboratory and the rotating frames of reference. It is assumed that the system rotates with the constant angular velocity $\\omega = const$. The solutions are found and analyzed for the case when the form of the trajectory is given by an Archimedes spiral. It is found that particles can reach infinity while they move along these trajectories and the physical interpretation of their behaviour is given. The analogy of this idealized study with the motion of particles along the curved rotating magnetic field lines in the pulsar magnetosphere is pointed out. We discuss further physical development (the conserved total energy case, when $\\omega \

  17. Quantum Mechanics and Closed Timelike Curves

    E-Print Network [OSTI]

    Florin Moldoveanu

    2007-04-23

    General relativity allows solutions exhibiting closed timelike curves. Time travel generates paradoxes and quantum mechanics generalizations were proposed to solve those paradoxes. The implications of self-consistent interactions on acausal region of space-time are investigated. If the correspondence principle is true, then all generalizations of quantum mechanics on acausal manifolds are not renormalizable. Therefore quantum mechanics can only be defined on global hyperbolic manifolds and all general relativity solutions exhibiting time travel are unphysical.

  18. Galaxy rotation curves in de Sitter space

    E-Print Network [OSTI]

    Maurice H. P. M. van Putten

    2015-01-27

    Dark energy inferred from the observed negative deceleration parameter introduces a small mass of the graviton, that satisfies the Higuchi stability condition. It implies an infra-red modification of gravitation that produces Milgrom's inverse distance law of gravitational attraction in excellent agreement with the observed galaxy rotation curves. We conclude that dark matter is present cosmologically with no need for local clustering in galaxies.

  19. Light Curves of Swift Gamma Ray Bursts

    E-Print Network [OSTI]

    Paolo Cea

    2006-09-22

    Recent observations from the Swift gamma-ray burst mission indicate that a fraction of gamma ray bursts are characterized by a canonical behaviour of the X-ray afterglows. We present an effective theory which allows us to account for X-ray light curves of both (short - long) gamma ray bursts and X-ray rich flashes. We propose that gamma ray bursts originate from massive magnetic powered pulsars.

  20. 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.

  1. Incorporating Experience Curves in Appliance Standards Analysis

    SciTech Connect (OSTI)

    Garbesi, Karina; Chan, Peter; Greenblatt, Jeffery; Kantner, Colleen; Lekov, Alex; Meyers, Stephen; Rosenquist, Gregory; Buskirk, Robert Van; Yang, Hung-Chia; Desroches, Louis-Benoit

    2011-10-31

    The technical analyses in support of U.S. energy conservation standards for residential appliances and commercial equipment have typically assumed that manufacturing costs and retail prices remain constant during the projected 30-year analysis period. There is, however, considerable evidence that this assumption does not reflect real market prices. Costs and prices generally fall in relation to cumulative production, a phenomenon known as experience and modeled by a fairly robust empirical experience curve. Using price data from the Bureau of Labor Statistics, and shipment data obtained as part of the standards analysis process, we present U.S. experience curves for room air conditioners, clothes dryers, central air conditioners, furnaces, and refrigerators and freezers. These allow us to develop more representative appliance price projections than the assumption-based approach of constant prices. These experience curves were incorporated into recent energy conservation standards for these products. The impact on the national modeling can be significant, often increasing the net present value of potential standard levels in the analysis. In some cases a previously cost-negative potential standard level demonstrates a benefit when incorporating experience. These results imply that past energy conservation standards analyses may have undervalued the economic benefits of potential standard levels.

  2. Capillary migration of microdisks on curved interfaces

    E-Print Network [OSTI]

    Lu Yao; Nima Sharifi-Mood; Iris B. Liu; Kathleen J. Stebe

    2014-12-23

    The capillary energy landscape for particles on curved fluid interfaces is strongly influenced by the particle wetting conditions. Contact line pinning has now been widely reported for colloidal particles, but its implications in capillary interactions have not been addressed. Here, we present experiment and analysis for disks with pinned contact lines on curved fluid interfaces. In experiment, we study microdisk migration on a host interface with zero mean curvature; the microdisks have contact lines pinned at their sharp edges and are sufficiently small that gravitational effects are negligible. The disks migrate away from planar regions toward regions of steep curvature with capillary energies inferred from the dissipation along particle trajectories which are linear in the deviatoric curvature. We derive the curvature capillary energy for an interface with arbitrary curvature, and discuss each contribution to the expression. By adsorbing to a curved interface, a particle eliminates a patch of fluid interface and perturbs the surrounding interface shape. Analysis predicts that perfectly smooth, circular disks do not migrate, and that nanometric deviations from a planar circular, contact line, like those around a weakly roughened planar disk, will drive migration with linear dependence on deviatoric curvature, in agreement with experiment.

  3. Residual stress relief due to fatigue in tetragonal lead zirconate titanate ceramics

    SciTech Connect (OSTI)

    Hall, D. A.; Mori, T. [School of Materials, University of Manchester, Grosvenor St., Manchester M1 7HS (United Kingdom); Comyn, T. P. [Institute for Materials Research, Woodhouse Lane, University of Leeds, LS2 9JT (United Kingdom); Ringgaard, E. [Meggitt Sensing Systems, Hejreskovvej 18A, 3490 Kvistgaard (Denmark); Wright, J. P. [ESRF, 6 Rue Jules Horowitz, BP-220, 38043 Grenoble Cedex (France)

    2013-07-14

    High energy synchrotron XRD was employed to determine the lattice strain {epsilon}{l_brace}111{r_brace}and diffraction peak intensity ratio R{l_brace}200{r_brace}in tetragonal PZT ceramics, both in the virgin poled state and after a bipolar fatigue experiment. It was shown that the occurrence of microstructural damage during fatigue was accompanied by a reduction in the gradient of the {epsilon}{l_brace}111{r_brace}-cos{sup 2} {psi} plot, indicating a reduction in the level of residual stress due to poling. In contrast, the fraction of oriented 90 Degree-Sign ferroelectric domains, quantified in terms of R{l_brace}200{r_brace}, was not affected significantly by fatigue. The change in residual stress due to fatigue is interpreted in terms of a change in the average elastic stiffness of the polycrystalline matrix due to the presence of inter-granular microcracks.

  4. Fatigue Enhancement of Category E' Detailsin Steel Bridge Girders Using CFRP Materials

    E-Print Network [OSTI]

    Kaan, Benjamin Nicolaas

    2008-01-01

    Carbon Fiber Reinforced Polymer (CFRP) composite overlay elements were developed to improve the fatigue performance of Category E' steel details. By increasing the stiffness of the detail with the CFRP overlay, the stress demand at the weld...

  5. Mechanisms of bioprosthetic heart valve failure: Fatigue causes collagen denaturation and glycosaminoglycan loss

    E-Print Network [OSTI]

    Zand, Robert

    Mechanisms of bioprosthetic heart valve failure: Fatigue causes collagen denaturation heart valve (BPHV) degeneration, characterized by extracellular matrix deterioration, remod- eling) with glutaraldehyde fixed porcine aortic valve bioprostheses, that the mechanical function of cardiac valve cusps

  6. Rolling contact fatigue in martensitic 100Cr6: Subsurface hardening and crack formation

    E-Print Network [OSTI]

    Kang, Jee-Hyun; Vegter, R. H.; Rivera-Díaz-del-Castillo, Pedro E. J.

    2014-04-13

    Rolling contact fatigue tests on 100Cr6 steel were carried out with a ball-on-rod tester. Microstructural damage was manifested by gradual hardness changes under the subsurface, and microcracks formed adjacent to inclusions; both being evidence...

  7. Mitigating Wind-Induced Fatigue in Steel Traffic Signal Support Structures 

    E-Print Network [OSTI]

    Wieghaus, Kyle T

    2015-05-26

    Traffic signal structures undergo wind-induced vibrations that result in fatigue damage accumulation and reduced service life. Mast arms have failed and required removal while in service. A dual experimental and analytical modeling approach is taken...

  8. The high cycle fatigue and fracture behavior of aluminum alloy 7055

    SciTech Connect (OSTI)

    Srivatsan, T.S.; Anand, S.; Sriram, S.; Narendra, N. [Univ. of Akron, OH (United States). Dept. of Mechanical Engineering

    1997-12-31

    In this paper, the results of a recent study on the high-cycle fatigue and fracture behavior of aluminum alloy 7055 is presented and discussed. Specimens of the alloy, in the T7751 temper, were cyclically deformed over a range of stress amplitudes at both ambient and elevated temperatures. Increase in test temperature was found to have a detrimental influence on cyclic fatigue life of the specimens machined in the transverse orientation. Temperature was found to have little influence on fatigue life of the longitudinal specimens. No major change in macroscopic fracture mode was observed with direction of testing. Cyclic fracture, on a microscopic scale, revealed features reminiscent of both ductile and brittle mechanisms. The microscopic fracture behavior was a function of test temperature. The mechanisms governing cyclic fatigue response are discussed in light of the mutually interactive influences of microstructural effects, matrix deformation characteristics and test temperature.

  9. Reliability-based framework for fatigue damage prognosis of bonded structural elements in aerospace composite structures

    E-Print Network [OSTI]

    Gobbato, Maurizio

    2011-01-01

    and J.D. Achenbach, Structural health monitoring and damagein fatigue, Structural Health Monitoring, 7(1), 37-49, 2008.and J.D. Achenbach, Structural health monitoring and damage

  10. Stochastic Damage Evolution under Static and Fatigue Loading in Composites with Manufacturing Defects 

    E-Print Network [OSTI]

    Huang, Yongxin

    2012-07-16

    In this dissertation, experimental investigations and theoretical studies on the stochastic matrix cracking evolution under static and fatigue loading in composite laminates with defects are presented. The presented work ...

  11. The Impact of Cognitive Fatigue on Age-Related Differences in Neuromuscular Function 

    E-Print Network [OSTI]

    Shortz, Ashley

    2015-07-27

    As the population of adults aged 65 and above is rapidly growing, it is crucial to identify physical and cognitive limitations pertaining to daily living. The aim of the study was to examine the impact of cognitive fatigue ...

  12. Fatigue behavior of full-size soild-sawn timber railroad stringers 

    E-Print Network [OSTI]

    Maingot, Martin Rex

    1999-01-01

    As part of the Timber Bridge Life Extension Program sponsored by the Association of American Railroads (AAR), the objective of this thesis is to investigate the fatigue behavior of large solid-sawn timber beams. Specifically, ...

  13. The effects of asphalt binder oxidation on hot mix asphalt concrete mixture rheology and fatigue performance 

    E-Print Network [OSTI]

    Jung, Sung Hoon

    2009-06-02

    Asphalt oxidation causes major changes to binder properties and is hypothesized to be a major contributor to age-related pavement failure such as fatigue cracking. Extensive laboratory aging research has been done to assess ...

  14. The effectiveness of floor mats as an intervention for standing fatigue of light fabrication workers 

    E-Print Network [OSTI]

    O'Brien, Michael Shannon

    1996-01-01

    A field study was conducted in a light fabrication plant to determine the effectiveness of floor mats on reducing the symptoms of standing fatigue. Specific physiological variables measured include skin temperature of the ...

  15. Characterization and Modeling of Transformation Induced Fatigue of Shape Memory Alloy Actuators 

    E-Print Network [OSTI]

    Bertacchini, Olivier Walter

    2011-02-22

    The main focus of this research is the transformation induced fatigue behavior of shape memory alloy (SMA) actuators undergoing thermally induced martensitic phase transformation. The recent development of aerospace ...

  16. The effect of SAS shoes on standing fatigue in light fabrication workers 

    E-Print Network [OSTI]

    Bradley, Lee Norman

    1996-01-01

    A field study was conducted on light fabrication workers who worked 12-hour shifts to determine the effect of a high quality shoe, such as a SAS shoe, on standing fatigue. Nine participants (five male, four female) were ...

  17. Transformation Induced Fatigue of Ni-Rich NiTi Shape Memory Alloy Actuators 

    E-Print Network [OSTI]

    Schick, Justin Ryan

    2011-02-22

    In this work the transformation induced fatigue of Ni-rich NiTi shape memory alloys (SMAs) was investigated. The aerospace industry is currently considering implementing SMA actuators into new applications. However, before ...

  18. ‘A Weariness of the Flesh’: Towards a Theology of Boredom and Fatigue 

    E-Print Network [OSTI]

    Wardley, Kenneth Jason

    2012-01-01

    This essay follows two impulses: Jean-Yves Lacoste’s suggestion that philosophy and theology should speak about boredom and about fatigue, just as they do about anguish or joy, and the Swiss theologian Karl Barth’s contention ...

  19. REPAIR OF BRIDGE STEEL GIRDERS DAMAGED BY DISTORTION-INDUCED FATIGUE

    E-Print Network [OSTI]

    Alemdar, Fatih

    2011-12-31

    This study investigates the repair of steel bridge girders damaged by distortion-induced fatigue. The study is presented in three parts. The first part describes finite element modeling techniques used to evaluate the ...

  20. Repair of Steel Bridge Girders Damaged by Distortion-Induced Fatigue

    E-Print Network [OSTI]

    Nagati, Amr Daniel

    2012-08-31

    Several studies have identified distortion-induced fatigue as the leading cause of cracks in steel bridges built prior to the mid-1980s. Experimental and computer simulations of 914-mm (36-in.) deep girder-cross frame ...

  1. Mechanisms of microstructural damage during rolling contact fatigue of bearing steels

    E-Print Network [OSTI]

    Kang, JeeHyun

    2014-04-08

    Bearings are employed in a number of applications under extremely demanding conditions. During long operation times, the material undergoes rolling contact fatigue where microstructural damage manifests as dark-etching regions and white...

  2. Neuroimaging abnormalities, neurocognitive function, and fatigue in patients with hepatitis C.

    E-Print Network [OSTI]

    2015-01-01

    fatigue in patients with hepatitis C April D. Thames, PhDamong a sample of adults with hepatitis C virus (HCV). WeControl and Prevention: Hepatitis C Information for Health

  3. SUBSPACE-BASED DETECTION OF FATIGUE DAMAGE ON JACKET SUPPORT STRUCTURES OF OFFSHORE WIND TURBINES

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    SUBSPACE-BASED DETECTION OF FATIGUE DAMAGE ON JACKET SUPPORT STRUCTURES OF OFFSHORE WIND TURBINES damage in real size structural components of offshore wind turbines. KEYWORDS : Damage detection, Offshore wind turbines, Numerical response simulation. INTRODUCTION Offshore wind turbines are exposed

  4. Effect of nano-scale twinning on the fracture, fatigue and wear properties of copper

    E-Print Network [OSTI]

    Singh, Aparna, Ph.D. Massachusetts Institute of Technology

    2011-01-01

    Grain refinement in materials has been one of the most common strategies for improving the strength of materials. However this comes at the price of reduced ductility, fracture toughness and stable fatigue crack propagation ...

  5. Analytical and Experimental Investigation for Distortion-Induced Fatigue in Steel Bridges

    E-Print Network [OSTI]

    Hartman, Amanda

    2013-08-31

    Distortion-induced fatigue has been extensively studied; however, retrofit techniques currently used are expensive and/or time consuming to implement. These retrofit techniques primarily fall into two categories--stiffening or softening the weak web...

  6. 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...

  7. 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.

  8. Creep-fatigue of High Temperature Materials for VHTR: Effect of Cyclic Loading and Environment

    SciTech Connect (OSTI)

    Celine Cabet; L. Carroll; R. Wright; R. Madland

    2011-05-01

    Alloy 617 is the one of the leading candidate materials for Intermediate Heat eXchangers (IHX) of a Very High Temperature Reactor (VHTR). System start-ups and shut-downs as well as power transients will produce low cycle fatigue (LCF) loadings of components. Furthermore, the anticipated IHX operating temperature, up to 950°C, is in the range of creep so that creep-fatigue interaction, which can significantly increase the fatigue crack growth, may be one of the primary IHX damage modes. To address the needs for Alloy 617 codification and licensing, a significant creep-fatigue testing program is underway at Idaho National Laboratory. Strain controlled LCF tests including hold times up to 1800s at maximum tensile strain were conducted at total strain range of 0.3% and 0.6% in air at 950°C. Creep-fatigue testing was also performed in a simulated VHTR impure helium coolant for selected experimental conditions. The creep-fatigue tests resulted in failure times up to 1000 hrs. Fatigue resistance was significantly decreased when a hold time was added at peak stress and when the total strain was increased. The fracture mode also changed from transgranular to intergranular with introduction of a tensile hold. Changes in the microstructure were methodically characterized. A combined effect of temperature, cyclic and static loading and environment was evidenced in the targeted operating conditions of the IHX. This paper This paper reviews the data previously published by Carroll and co-workers in references 10 and 11 focusing on the role of inelastic strain accumulation and of oxidation in the initiation and propagation of surface fatigue cracks.

  9. Experience curves for power plant emission control technologies

    E-Print Network [OSTI]

    Rubin, Edward S.; Yeh, Sonia; Hounshell, David A

    2007-01-01

    1/2, 2004 Experience curves for power plant emission controlcoal-fired electric power plants. In particular, we focus on2004) ‘Experience curves for power plant emission control

  10. Visual Attention and Driver Performance at Horizontal Curves 

    E-Print Network [OSTI]

    Brimley, Bradford K.

    2014-12-02

    at any location and on any facility. Traffic control devices (TCDs) can be installed at curves to provide drivers the information necessary for safe navigation. The research in this dissertation examines the theory that TCDs at curves are not only...

  11. Fatigue and strain hardening of simulated case microstructure in carburized steels

    SciTech Connect (OSTI)

    Zaccone, M.A.; Krauss, G.

    1988-01-01

    Tension, compression, and cyclic stress-strain testing were used to evaluate the effect of retained austenite on high and low cycle fatigue of Cr-Mo-Ni alloy steels containing 0.8 pct C to simulate the high carbon case of carburized steels. In low cycle fatigue, cracks develop at austenite grain boundaries early during tensile and cyclic loading. Propagation of these cracks is stabilized in specimens which contain large amounts of retained austenite which dynamically forms martensite by strain-induced transformation. Without sufficient austenite, incipient cracks are not effectively stabilized, and low cycle fatigue life is reduced. In high cycle fatigue, insufficient strain accumulates for the activation of strain-induced martensite, and large amounts of retained austenite are not as beneficial as in low cycle fatigue. Microstructures with 30--35 volume percent retained austenite and fine mixtures of martensite and austenite which contribute to high elastic limits appear to be the most satisfactory for good high and low cycle fatigue resistance. 18 refs., 6 figs., 4 tabs.

  12. Towards a renaissance of curved spanning structures

    E-Print Network [OSTI]

    Hartshorne, Thomas Hunter

    1983-01-01

    Today, as always, there is a great need for expressiveness in design. There are a multitude of forms which, over the years, have been stripped from the designer's repertoire in the name of economics. There exists a sub-group ...

  13. Local Orthogonal Cutting Method for Computing Medial Curves and...

    Office of Scientific and Technical Information (OSTI)

    BLOOD VESSELS; COMPUTERS; DIFFERENTIAL GEOMETRY; EFFICIENCY; EIGENVALUES; LUNGS; MINIMIZATION; RELIABILITY; SHAPE; SIMULATION; STABILITY; SURGERY curves and surfaces;...

  14. Length and Energy of Quadratic Bezier Curves and Applications

    E-Print Network [OSTI]

    Hoffmann, Christoph M.

    Length and Energy of Quadratic B´ezier Curves and Applications Young Joon Ahn a , Christoph for the arc length and the bending energy of quadratic B´ezier curves. The formulae are in terms control point is analyzed for curves of fixed arc length or bending energy. In the case of arc length

  15. Oil production models with normal rate curves Dudley Stark

    E-Print Network [OSTI]

    Stark, Dudley

    Oil production models with normal rate curves Dudley Stark School of Mathematical Sciences Queen;Abstract The normal curve has been used to fit the rate of both world and U.S.A. oil production. In this paper we give the first theoretical basis for these curve fittings. It is well known that oil field

  16. Number of Jacobi quartic curves over finite Rongquan Feng1

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Number of Jacobi quartic curves over finite fields Rongquan Feng1 , Hongfeng Wu2 1 LMAM, School@gmail.com Abstract In this paper the number of Fq-isomorphism classes of Jacobi quar- tic curves, i.e., the number of Jacobi quartic curves with distinct j- invariants, over finite field Fq is enumerated. Keywords: Elliptic

  17. High-cycle fatigue behavior of Ti-5Al-2.5Sn ELI alloy forging at low temperatures

    SciTech Connect (OSTI)

    Ono, Yoshinori; Yuri, Tetsumi; Ogata, Toshio; Demura, Masahiko; Matsuoka, Saburo; Sunakawa, Hideo

    2014-01-27

    High-cycle fatigue properties of Ti-5Al-2.5Sn Extra Low Interstitial (ELI) alloy forging were investigated at low temperatures. The high-cycle fatigue strength at low temperatures of this alloy was relatively low compared with that at ambient temperature. The crystallographic orientation of a facet formed at a fatigue crack initiation site was determined by electron backscatter diffraction (EBSD) method in scanning electron microscope (SEM) to understand the fatigue crack initiation mechanism and discuss on the low fatigue strength at low temperature. Furthermore, in terms of the practical use of this alloy, the effect of the stress ratio (or mean stress) on the high-cycle fatigue properties was evaluated using the modified Goodman diagram.

  18. Application of Hybrid Geo-Spatially Granular Fragility Curves to Improve Power Outage Predictions

    SciTech Connect (OSTI)

    Fernandez, Steven J; Allen, Melissa R; Omitaomu, Olufemi A; Walker, Kimberly A

    2014-01-01

    Fragility curves depict the relationship between a weather variable (wind speed, gust speed, ice accumulation, precipitation rate) and the observed outages for a targeted infrastructure network. This paper describes an empirical study of the county by county distribution of power outages and one minute weather variables during Hurricane Irene with the objective of comparing 1) as built fragility curves (statistical approach) to engineering as designed (bottom up) fragility curves for skill in forecasting outages during future hurricanes; 2) county specific fragility curves to find examples of significant deviation from average behavior; and 3) the engineering practices of outlier counties to suggest future engineering studies of robustness. Outages in more than 90% of the impacted counties could be anticipated through an average or generic fragility curve. The remaining counties could be identified and handled as exceptions through geographic data sets. The counties with increased or decreased robustness were characterized by terrain more or less susceptible to persistent flooding in areas where above ground poles located their foundations. Land use characteristics of the area served by the power distribution system can suggest trends in the as built power grid vulnerabilities to extreme weather events that would be subjects for site specific studies.

  19. Calibrating Curved Crystals Used for Plasma Spectroscopy

    SciTech Connect (OSTI)

    Haugh, M. J., Jacoby, K. D., Ross, P. W., Rochau, G. Wu, M., Regan, S. P., Barrios, M. A.

    2012-10-29

    The throughput and resolving power of an X-ray spectrometer that uses a curved crystal as the diffraction element is determined primarily by the crystal X-ray reflectivity properties. This poster presents a measurement technique for these crystal parameters using a simple diode source to produce a narrow spectral band. The results from measurements on concave elliptical polyethylene terephthalate (PET) crystals and convex potassium acid phthalate (KAP) crystals show large variations in the key parameters compared to those from the flat crystal.

  20. Modeling the Phillips curve with unobserved components

    E-Print Network [OSTI]

    Harvey, Andrew C

    is then nonstationary. However, writing the equation as #1;#25;t = #12;xt+"t makes it clear that what we have is not really a Phillips curve (though adding lags of xt and incorporating a unit root could retrieve the situation). On the other hand, a stationary model... -looking. The conditions under which a model with an expectational term reverts to (10) are derived below. The fact that the forecast function for a random walk component is constant simpli?es matters considerably. The reduced form of (10) is an ARMAX model in which #1;#25...

  1. Spherical nanoindentation stress–strain curves

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

    Pathak, Siddhartha; Kalidindi, Surya R.

    2015-03-24

    Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength inmore »the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.« less

  2. Light curves from rapidly rotating neutron stars

    E-Print Network [OSTI]

    Numata, Kazutoshi

    2010-01-01

    We calculate light curves produced by a hot spot of a rapidly rotating neutron star, assuming that the spot is perturbed by a core $r$-mode, which is destabilized by emitting gravitational waves. To calculate light curves, we take account of relativistic effects such as the Doppler boost due to the rapid rotation and light bending assuming the Schwarzschild metric around the neutron star. We assume that the core $r$-modes penetrate to the surface fluid ocean to have sufficiently large amplitudes to disturb the spot. For a $l'=m$ core $r$-mode, the oscillation frequency $\\omega\\approx2m\\Omega/[l'(l'+1)]$ defined in the co-rotating frame of the star will be detected by a distant observer, where $l'$ and $m$ are respectively the spherical harmonic degree and the azimuthal wave number of the mode, and $\\Omega$ is the spin frequency of the star. In a linear theory of oscillation, using a parameter $A$ we parametrize the mode amplitudes such that ${\\rm max}\\left(|\\xi_\\theta|,|\\xi_\\phi|\\right)/R=A$ at the surface, w...

  3. Spherical nanoindentation stress–strain curves

    SciTech Connect (OSTI)

    Pathak, Siddhartha; Kalidindi, Surya R.

    2015-03-24

    Although indentation experiments have long been used to measure the hardness and Young's modulus, the utility of this technique in analyzing the complete elastic–plastic response of materials under contact loading has only been realized in the past few years – mostly due to recent advances in testing equipment and analysis protocols. This paper provides a timely review of the recent progress made in this respect in extracting meaningful indentation stress–strain curves from the raw datasets measured in instrumented spherical nanoindentation experiments. These indentation stress–strain curves have produced highly reliable estimates of the indentation modulus and the indentation yield strength in the sample, as well as certain aspects of their post-yield behavior, and have been critically validated through numerical simulations using finite element models as well as direct in situ scanning electron microscopy (SEM) measurements on micro-pillars. Much of this recent progress was made possible through the introduction of a new measure of indentation strain and the development of new protocols to locate the effective zero-point of initial contact between the indenter and the sample in the measured datasets. As a result, this has led to an important key advance in this field where it is now possible to reliably identify and analyze the initial loading segment in the indentation experiments.

  4. Fabrication procedure effects on fatigue resistance of rib -to-deck welded joints of steel orthotropic bridge decks

    E-Print Network [OSTI]

    Sim, Hyoung-Bo

    2010-01-01

    International Orthotropic Bridge Conference (CD-ROM),fatigue evaluation of steel bridges. ” International Journalfor the Bronx-Whitestone Bridge rehabilitation. ” Journal of

  5. 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.

  6. Design Editorial Design Innovation

    E-Print Network [OSTI]

    Papalambros, Panos

    juxtaposition of innovation versus invention: "Invention is the first occurrence of an idea for a new product such as innovation strategies, product design, service inno- vation, cutting-edge designers, design awards, and green design. Much of that perspective on innovation is then tied to industrial or product design, often

  7. Curved Spacetimes and Curved Graphene: a status report of the Weyl-symmetry approach

    E-Print Network [OSTI]

    Alfredo Iorio

    2014-12-15

    This is a status report about the ongoing work on the realization of quantum field theory on curved graphene spacetimes that uses Weyl symmetry. The programme is actively pursued from many different perspectives. Here we point to what has been done, and to what needs to be done.

  8. Essays on the Economics of Environmental Issues: The Environmental Kuznets Curve to Optimal Energy Portfolios

    E-Print Network [OSTI]

    Meininger, Aaron G.

    2012-01-01

    Issues: The Environmental Kuznets Curve to Optimal EnergyE. (2005), “An environmental kuznets curve analysis of u.s.proach to environmental kuznets curves using the ecological

  9. Searching for Empirical Regularity and Theoretical Structure: The Environmental Kuznets Curve

    E-Print Network [OSTI]

    Carson, Richard T

    2009-01-01

    of the environmental Kuznets curve. Journal of Publicof the environmental Kuznets curve studies. Agriculture andhypothesis and environmental Kuznets Curve: examining the

  10. DEVELOPING FLOW AND HEAT TRANSFER IN STRONGLY CURVED DUCTS OF RECTANGULAR CROSS-SECTION

    E-Print Network [OSTI]

    Yee, G.

    2010-01-01

    DEVELOpiNG FLOW AND HEAT TRANSFER IN STRONGLY CURVED DUCTS9092 Developing Flow and Heat Transfer in Strongly CurvedForced Convection Heat Transfer in Curved Rectangular

  11. Force-extension curves of bacterial flagella

    E-Print Network [OSTI]

    Reinhard Vogel; Holger Stark

    2010-11-10

    Bacterial flagella assume different helical shapes during the tumbling phase of a bacterium but also in response to varying environmental conditions. Force-extension measurements by Darnton and Berg explicitly demonstrate a transformation from the coiled to the normal helical state [N.C. Darnton and H.C. Berg, Biophys. J. {92}, 2230 (2007)]. We here develop an elastic model for the flagellum based on Kirchhoff's theory of an elastic rod that describes such a polymorphic transformation and use resistive force theory to couple the flagellum to the aqueous environment. We present Brownian dynamics simulations that quantitatively reproduce the force-extension curves and study how the ratio $\\Gamma$ of torsional to bending rigidity and the extensional rate influence the response of the flagellum. An upper bound for $\\Gamma$ is given. Using clamped flagella, we show in an adiabatic approximation that the mean extension, where a local coiled-to-normal transition occurs first, depends on the logarithm of the extensional rate.

  12. Hydrogen atom on curved noncommutative space

    E-Print Network [OSTI]

    V. G. Kupriyanov

    2013-06-05

    We have calculated the hydrogen atom spectrum on curved noncommutative space defined by the commutation relations $\\left[ \\hat {x}^{i},\\hat{x}^{j}\\right] =i\\theta\\hat{\\omega}^{ij}\\left( \\hat {x}\\right) $, where $\\theta$ is the parameter of noncommutativity. The external antisymmetric field which determines the noncommutativity is chosen as $\\omega^{ij}(x) =\\varepsilon^{ijk}{x}_{k}f\\left( {x_i}x^{i}\\right) $. In this case the rotational symmetry of the system is conserved, preserving the degeneracy of the energy spectrum. The contribution of the noncommutativity appears as a correction to the fine structure. The corresponding nonlocality is calculated: $\\Delta x\\Delta y \\geq \\frac{\\theta^2}{4} |m\\langle f^2\\rangle| $, where $m$ is a magnetic quantum number.

  13. Novel Experiments to Characterize Creep-Fatigue Degradation in VHTR Alloys

    SciTech Connect (OSTI)

    J. K. Wright; J. A. Simpson; L. J. Carroll; R. N. Wright; T.-L. Sham

    2013-10-01

    It is well known in energy systems that the creep lifetime of high temperature alloys is significantly degraded when a cyclic load is superimposed on components operating in the creep regime. A test method has been developed in an attempt to characterize creep-fatigue behavior of alloys at high temperature. The test imposes a hold time during the tensile phase of a fully reversed strain-controlled low cycle fatigue test. Stress relaxation occurs during the strain-controlled hold period. This type of fatigue stress relaxation test tends to emphasize the fatigue portion of the total damage and does not necessarily represent the behavior of a component in-service well. Several different approaches to laboratory testing of creep-fatigue at 950°C have been investigated for Alloy 617, the primary candidate for application in VHTR heat exchangers. The potential for mode switching in a cyclic test from strain control to load control, to allow specimen extension by creep, has been investigated to further emphasize the creep damage. In addition, tests with a lower strain rate during loading have been conducted to examine the influence of creep damage occurring during loading. Very short constant strain hold time tests have also been conducted to examine the influence of the rapid stress relaxation that occurs at the beginning of strain holds.

  14. Engineering Predictions in Industrial and Power Flows Using the Retrograde Condensation Curve. Part I-Methodology

    E-Print Network [OSTI]

    Labinov, Mark S

    2014-01-01

    Industrial and power systems rely on engineering predictions of the flow properties of working fluids. The paper proposes a way of the utilization of the vapor quality values along the new retrograde condensation curve in the generation of the void fraction design guidelines and reliable prediction of the saturated liquid specific volumes/densities. The new procedure eliminates the involvement of semi-empirical relationships like rectilinear diameter and other similar models.

  15. Design of Wind Turbines in an Area with Tropical Cyclones Niels-Erik Clausen, niels-erik.clausen@risoe.dk, Sren Ott, Niels-Jacob Tarp-Johansen, Per Nrgrd and

    E-Print Network [OSTI]

    Design of Wind Turbines in an Area with Tropical Cyclones Niels-Erik Clausen, niels and cost of wind turbines is influenced by a combination of fatigue and extreme loads and the applied design codes. In general wind turbines are designed for 20 years of operation using design standards

  16. Design Editorial Design Intent

    E-Print Network [OSTI]

    Papalambros, Panos

    Journal of Mechanical Design Editorial Design Intent Is this paper suitable for JMD of criteria to answer the question. As editor of JMD, apart from the obvious criteria of quality and research assumed my editorial duties is the paper's design intent. It was in that spirit that I wrote the Design

  17. Atmospheric and Wake Turbulence Impacts on Wind Turbine Fatigue Loading: Preprint

    SciTech Connect (OSTI)

    Lee, S.; Churchfield, M.; Moriarty, P.; Jonkman, J.; Michalakes, J.

    2011-12-01

    Large-eddy simulations of atmospheric boundary layers under various stability and surface roughness conditions are performed to investigate the turbulence impact on wind turbines. In particular, the aeroelastic responses of the turbines are studied to characterize the fatigue loading of the turbulence present in the boundary layer and in the wake of the turbines. Two utility-scale 5 MW turbines that are separated by seven rotor diameters are placed in a 3 km by 3 km by 1 km domain. They are subjected to atmospheric turbulent boundary layer flow and data is collected on the structural response of the turbine components. The surface roughness was found to increase the fatigue loads while the atmospheric instability had a small influence. Furthermore, the downstream turbines yielded higher fatigue loads indicating that the turbulent wakes generated from the upstream turbines have significant impact.

  18. Oxidation, Creep And Fatigue Properties of Bare and Coated 31V alloy

    SciTech Connect (OSTI)

    Dryepondt, Sebastien N.; Jones, Samuel J.; Zhang, Ying; Maziasz, Philip J.; Pint, Bruce A.

    2014-12-06

    Increasing the efficiency of natural gas reciprocating engines will require materials with better mechanical and corrosion resistance at high temperatures. One solution to increase the lifetime of exhaust valves is to apply an aluminide coating to prevent corrosion assisted fatigue cracking, but the impact of the coating on the valve material mechanical properties needs to be assessed. Creep and high cycle fatigue (HCF) testing were conducted at 816°C on bare and slurry or pack-coated 31V alloy. After annealing according to the 31V standard heat treatment, the coated and bare creep specimens exhibited very similar creep rupture lives. The HCF behavior of the pack-coated alloy was close to the behavior of the bar alloy, but fatigue lifetimes of slurry-coated 31V specimens had higher variability. Aluminide coatings have the potential to improve the valve performance at high temperature, but the coating deposition process needs to be tailored for the substrate standard heat treatment.

  19. Effect of Loading Mode and Coating on Dynamic Fatigue of Optical Fiber in Two-Point Bending

    E-Print Network [OSTI]

    Matthewson, M. John

    and hence on the reliability of the bending technique. This paper presents dynamic fatigue results usingEffect of Loading Mode and Coating on Dynamic Fatigue of Optical Fiber in Two-Point Bending Science and Engineering, Rutgers University, Piscataway, New Jersey 08855-0909 Tho-point bending

  20. Proceeding of Energy Week 1996, ASME APPLICATION OF THE U.S. HIGH CYCLE FATIGUE DATA BASE

    E-Print Network [OSTI]

    Proceeding of Energy Week 1996, ASME APPLICATION OF THE U.S. HIGH CYCLE FATIGUE DATA BASE TO WIND the service lifetime of wind turbine blades using the high-cycle fatigue data base for typical U.S. blade materials developed by Mandell, et al. (1995). The first step in the analysis is to normalize the data base

  1. 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

  2. Role of Microstructure in Promoting Fracture and Fatigue Resistance in Mo-Si-B Alloys J. J. Kruzic*

    E-Print Network [OSTI]

    Ritchie, Robert

    -Si-B based alloys is presented. Fracture toughness and fatigue-crack growth properties are measured at 25º to impart some ductility and fracture resistance to a three phase microstructure also containing Mo3SiRole of Microstructure in Promoting Fracture and Fatigue Resistance in Mo-Si-B Alloys J. J. Kruzic

  3. 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

  4. A numerical method for predicting the bending fatigue life of NiTi and stainless steel root canal

    E-Print Network [OSTI]

    Zheng, Yufeng

    A numerical method for predicting the bending fatigue life of NiTi and stainless steel root canal. A numerical method for predicting the bending fatigue life of NiTi and stainless steel root canal instruments­titanium alloy (NiTi) and stainless steel (SS) endodontic files using finite element analysis. Methodology

  5. Multigroup Radiation Transport in Supernova Light Curve Calculations...

    Office of Scientific and Technical Information (OSTI)

    Multigroup Radiation Transport in Supernova Light Curve Calculations Even, Wesley P. Los Alamos National Laboratory; Frey, Lucille H. Los Alamos National Laboratory; Fryer,...

  6. Multigroup Radiation Transport in Supernova Light Curve Calculations...

    Office of Scientific and Technical Information (OSTI)

    Technical Report: Multigroup Radiation Transport in Supernova Light Curve Calculations Citation Details In-Document Search Title: Multigroup Radiation Transport in Supernova Light...

  7. THE CENTRAL CURVE IN LINEAR PROGRAMMING 1. Introduction ...

    E-Print Network [OSTI]

    2010-12-17

    Section 2 offers an analysis of central curves in the plane, with emphasis on the dual ...... path is generated by the circuit polynomials (21) and the d linear ...

  8. N=2 Supersymmetric Kinks and real algebraic curves

    E-Print Network [OSTI]

    A. Alonso Izquierdo; M. A. Gonzalez Leon; J. Mateos Guilarte

    2000-02-17

    The kinks of the (1+1)-dimensional Wess-Zumino model with polynomic superpotential are investigated and shown to be related to real algebraic curves.

  9. Integrated X-Ray Reflectivity Measurements for Elliptically Curved...

    Office of Scientific and Technical Information (OSTI)

    provides valuable information about the temperature and density of a compressed pellet in a plasma. Elliptically curved pentaerythritol (PET) crystals are used as components...

  10. Normal holomorphic curves from parabolic regions to projective ...

    E-Print Network [OSTI]

    For a given curve f its reduced homogeneous rep-. resentation is defined up to multiplication of all coordinates by the same. holomorphic function without zeros.

  11. Fatigue of 8630 cast steel in the presence of K. M. Sigl{, R. A. Hardin, R. I. Stephens and C. Beckermann*

    E-Print Network [OSTI]

    Beckermann, Christoph

    Fatigue of 8630 cast steel in the presence of porosity K. M. Sigl{, R. A. Hardin, R. I. Stephens- to macroscopic levels were cast from 8630 steel. Monotonic and fatigue properties were obtained to determine the effect of porosity on the mechanical performance of the cast steel. Axial fatigue tests were conducted

  12. Mixed-mode, high-cycle fatigue-crack growth thresholds in I. A comparison of large-and short-crack behavior

    E-Print Network [OSTI]

    Ritchie, Robert

    of turbine engine components to failure from high-cycle fatigue (HCF), i.e., the rapid propagation of fatigue are known to exist at speci®c fatigue-critical locations within the turbine engine com- ponents Engineering, University of California, 463 Evans Hall, Berkeley, CA 94720-1760, USA Received 27 December 1999

  13. Effects of microstructure on mixed-mode, high-cycle fatigue crack-growth thresholds in Ti-6Al-4V alloy

    E-Print Network [OSTI]

    Ritchie, Robert

    O D U C T IO N The control of failures owing to high-cycle fatigue (HCF) in turbine-engine for such HCF failures. Indeed, there are many fatigue-critical locations within the turbine engine where- ing HCF failures in turbine engines, it is critical that fatigue crack-growth thresholds are well

  14. 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

  15. Simulation and Experiment of Thermal Fatigue in the CPV Die Attach: Preprint

    SciTech Connect (OSTI)

    Bosco, N.; Silverman, T.; Kurtz, S.

    2012-05-01

    FEM simulation and accelerated thermal cycling have been performed for the CPV die attach. Trends in fatigue damage accumulation and equivalent test time are explored and found to be most sensitive to temperature ramp rate. Die attach crack growth is measured through cycling and found to be in excellent agreement with simulations of the inelastic strain energy accumulated. Simulations of an entire year of weather data provides for the relative ranking of fatigue damage between four cites as well as their equivalent accelerated test time.

  16. Failure by fracture and fatigue in 'NANO' and 'BIO'materials

    SciTech Connect (OSTI)

    Ritchie, R.O.; Muhlstein, C.L.; Nalla, R.K.

    2003-12-19

    The behavior of nanostructured materials/small-volumestructures and biologi-cal/bio-implantable materials, so-called "nano"and "bio" materials, is currently much in vogue in materials science. Oneaspect of this field, which to date has received only limited attention,is their fracture and fatigue properties. In this paper, we examine twotopics in this area, namely the premature fatigue failure ofsilicon-based micron-scale structures for microelectromechanical systems(MEMS), and the fracture properties of mineralized tissue, specificallyhuman bone.

  17. Analysis of the effect of matrix degradation on fatigue behavior of a graphite/epoxy laminate 

    E-Print Network [OSTI]

    Arenburg, Robert Thomas

    1982-01-01

    ANALYSIS OF THE EFFECT OF MATRIX DEGRADATION ON FATIGUE BEHAVIOR OF A GRAPHITE/EPOXY LAMINATE A Thesis by ROBERT THOMAS ARENBURG Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE May 1982 Major Subject: Civil Engineering ANALYSiS OF THE EFFECT OF MATRIX DEGRAOATION ON FATIGUE BEHAVIOR OF A GRAPHITE/EPOXY LAMINATE A Thesis by ROBERT THOMAS ARENBURG Approved as to style and content by: (Chairman...

  18. Effect of composition and processing on the thermal fatigue and toughness of high performance die steels. Final report

    SciTech Connect (OSTI)

    Wallace, J.F.; Wang, Y.; Schwam, D.

    1997-06-01

    The objective of this study was to improve average die life by optimizing die steel composition and the die processing. Four different steels, K,Q,C and Premium Grade H-13 have been investigated for thermal fatigue resistance and toughness. Optimum heat treatment processing has been determined for each steel with respect to austenitizing temperature and tempering conditions. The effect of the quenching rate on the thermal fatigue resistance and toughness of the die steels and the effect of Electro-Discharge Machining (EDM) on the thermal fatigue resistance were also determined. The immersion thermal fatigue specimen developed at CWRU was used to determine the thermal fatigue resistance as characterized by the two parameters of average maximum crack length and total crack area. The Charpy V-notch impact test was used over a -100{degrees}F to 450{degrees}F testing temperature range to evaluate the toughness and the brittle-ductile transition behavior. K steel has been identified as superior in performance compared to Premium Grade H-13. Q and C provide lower toughness and thermal fatigue resistance than H-13. Faster cooling rates provide higher thermal fatigue resistance and toughness. Higher austenitizing temperatures such as 1925{degrees}F compared to 1875{degrees}F provide better thermal fatigue resistance, but lower austenitizing temperatures of 1875{degrees}F provide better toughness. Higher hardness improves thermal fatigue resistance, but reduces toughness. A minimum of Rc 46 hardness is desired for aluminum die casting dies. EDM reduces the thermal fatigue resistance compared to conventional machining operations. When the EDM process of multiple small steps of decreasing energy and post-EDM treatments are employed, the effect can be reduced to a very slight amount. Preliminary evidence of the superior performance of the K steel has been provided by ongoing field testing of inserts in multiple cavity dies.

  19. Supersymmetric branes on curved spaces and fluxes

    E-Print Network [OSTI]

    Triendl, Hagen

    2015-01-01

    We discuss general supersymmetric brane configurations in flux backgrounds of string and M-theory and derive a necessary condition for the worldvolume theory to be supersymmetric on a given curved manifold. This condition resembles very much the conditions found from coupling a supersymmetric field theory to off-shell supergravity but can be derived in any dimension and for up to sixteen supercharges. Apart from the topological twist, all couplings appearing in the supersymmetry condition are linked to fluxes in the bulk. We explicitly derive the condition for D3-, M2- and M5-branes, in which case the results are also useful for constructing holographic duals to the corresponding field theories. In $N=1$ setups we compare the supersymmetry conditions to those that arise by coupling the field theory to off-shell supergravity. We find that the couplings of both old and new minimal supergravity are simultaneously realized, indicating that off-shell supergravity should be coupled via the S-multiplet of 16/16 supe...

  20. Aerodynamics of a rigid curved kite wing

    E-Print Network [OSTI]

    Maneia, Gianmauro; Tordella, Daniela; Iovieno, Michele

    2013-01-01

    A preliminary numerical study on the aerodynamics of a kite wing for high altitude wind power generators is proposed. Tethered kites are a key element of an innovative wind energy technology, which aims to capture energy from the wind at higher altitudes than conventional wind towers. We present the results obtained from three-dimensional finite volume numerical simulations of the steady air flow past a three-dimensional curved rectangular kite wing (aspect ratio equal to 3.2, Reynolds number equal to 3x10^6). Two angles of incidence -- a standard incidence for the flight of a tethered airfoil (6{\\deg}) and an incidence close to the stall (18{\\deg}) -- were considered. The simulations were performed by solving the Reynolds Averaged Navier-Stokes flow model using the industrial STAR-CCM+ code. The overall aerodynamic characteristics of the kite wing were determined and compared to the aerodynamic characteristics of the flat rectangular non twisted wing with an identical aspect ratio and section (Clark Y profil...

  1. Calibration curves for some standard Gap Tests

    SciTech Connect (OSTI)

    Bowman, A.L.; Sommer, S.C.

    1989-01-01

    The relative shock sensitivities of explosive compositions are commonly assessed using a family of experiments that can be described by the generic term ''Gap Test.'' Gap tests include a donor charge, a test sample, and a spacer, or gap, between two explosives charges. The donor charge, gap material, and test dimensions are held constant within each different version of the gap test. The thickness of the gap is then varied to find the value at which 50% of the test samples will detonate. The gap tests measure the ease with a high-order detonation can be established in the test explosive, or the ''detonability,'' of the explosive. Test results are best reported in terms of the gap thickness at the 50% point. It is also useful to define the shock pressure transmitted into the test sample at the detonation threshold. This requires calibrating the gap test in terms of shock pressure in the gap as a function of the gap thickness. It also requires a knowledge of the shock Hugoniot of the sample explosive. We used the 2DE reactive hydrodynamic code with Forest Fire burn rates for the donor explosives to calculate calibration curves for several gap tests. The model calculations give pressure and particle velocity on the centerline of the experimental set-up and provide information about the curvature and pulse width of the shock wave. 10 refs., 1 fig.

  2. Determining worst-case fatigue thresholds for grain-bridging ceramics

    E-Print Network [OSTI]

    Kruzic, J.J.; Yuan, R.; Cannon, R.M.; Ritchie, R.O.

    2002-01-01

    bridging silicon carbide ceramic," Acta Mater. , 46 (2) 17.of R-curve behavior in ceramic/metal composites," Actastresses and R-curves in ceramic/metal composites," J. Eur.

  3. AIAA-2001-0025 SPECTRUM FATIGUE LIFETIME AND RESIDUAL STRENGTH

    E-Print Network [OSTI]

    on a typical fiberglass laminate configuration turbine blade fiberglass material has been undertaken under a variety of load sequences. Repeated block loading for the development of refined design tools. Present at two or more load levels as well as a modified standard design tools for estimating lifetimes

  4. A bottom-up method to develop pollution abatement cost curves for coal-fired utility boilers

    E-Print Network [OSTI]

    Barlaz, Morton A.

    costs depend, in part, on a complex combination of coal type, coal composition, boiler design, plantA bottom-up method to develop pollution abatement cost curves for coal-fired utility boilers. The Coal Utility Environmental Cost (CUECost) model is used to estimate retrofit costs for five different

  5. Design for manufacturability Design verification

    E-Print Network [OSTI]

    Patel, Chintan

    ITRS Design #12;Design · Design for manufacturability · Design verification #12;Design for Manufacturability · Architecture challenges · Logic and circuit challenges · Layout and physical design challenges · Expected to be the source of multiple DFM challenges · Invest in variability reduction or design

  6. Atomistic modeling of nanowires, small-scale fatigue damage in cast magnesium, and materials for MEMS.

    SciTech Connect (OSTI)

    Dunn, Martin L.; Talmage, Mellisa J.; McDowell, David L., 1956- (,-Georgia Institute of Technology, Atlanta, GA); West, Neil (University of Colorado, Boulder, CO); Gullett, Philip Michael (Mississippi State University , MS); Miller, David C. (University of Colorado, Boulder, CO); Spark, Kevin (University of Colorado, Boulder, CO); Diao, Jiankuai (University of Colorado, Boulder, CO); Horstemeyer, Mark F. (Mississippi State University , MS); Zimmerman, Jonathan A.; Gall, K

    2006-10-01

    Lightweight and miniaturized weapon systems are driving the use of new materials in design such as microscale materials and ultra low-density metallic materials. Reliable design of future weapon components and systems demands a thorough understanding of the deformation modes in these materials that comprise the components and a robust methodology to predict their performance during service or storage. Traditional continuum models of material deformation and failure are not easily extended to these new materials unless microstructural characteristics are included in the formulation. For example, in LIGA Ni and Al-Si thin films, the physical size is on the order of microns, a scale approaching key microstructural features. For a new potential structural material, cast Mg offers a high stiffness-to-weight ratio, but the microstructural heterogeneity at various scales requires a structure-property continuum model. Processes occurring at the nanoscale and microscale develop certain structures that drive material behavior. The objective of the work presented in this report was to understand material characteristics in relation to mechanical properties at the nanoscale and microscale in these promising new material systems. Research was conducted primarily at the University of Colorado at Boulder to employ tightly coupled experimentation and simulation to study damage at various material size scales under monotonic and cyclic loading conditions. Experimental characterization of nano/micro damage will be accomplished by novel techniques such as in-situ environmental scanning electron microscopy (ESEM), 1 MeV transmission electron microscopy (TEM), and atomic force microscopy (AFM). New simulations to support experimental efforts will include modified embedded atom method (MEAM) atomistic simulations at the nanoscale and single crystal micromechanical finite element simulations. This report summarizes the major research and development accomplishments for the LDRD project titled 'Atomistic Modeling of Nanowires, Small-scale Fatigue Damage in Cast Magnesium, and Materials for MEMS'. This project supported a strategic partnership between Sandia National Laboratories and the University of Colorado at Boulder by providing funding for the lead author, Ken Gall, and his students, while he was a member of the University of Colorado faculty.

  7. Low Cost Security: Explicit Formulae for Genus 4 Hyperelliptic Curves

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    1 Low Cost Security: Explicit Formulae for Genus 4 Hyperelliptic Curves Jan Pelzl, Thomas Wollinger. Our contribution shows that for low cost security applications genus-4 hyperellip- tic curves (HEC surprising results are: 1) for low cost security application, namely considering an underlying group of order

  8. Stochastic Analysis of Wind Turbine Power Curves Edgar Anahua

    E-Print Network [OSTI]

    Peinke, Joachim

    Stochastic Analysis of Wind Turbine Power Curves Edgar Anahua Oldenburg 2007 Zur Homepage der Dissertation #12;#12;Stochastic Analysis of Wind Turbine Power Curves Edgar Anahua Von der Fakult¨at f the wind turbine's power per- formance directly from high frequency fluctuating measurements. In particular

  9. Fast Quadrupling of a Point on Elliptic Curves Cryptography

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Fast Quadrupling of a Point on Elliptic Curves Cryptography Duc-Phong Le Temasek Laboratories of Weierstrass form. In this paper we extend their method and present a fast algorithm for computing 4P with only algorithm gains better results. Keywords: Elliptic curve cryptography, fast arithmetic, affine co- ordinates

  10. Fast Multipole Representation of Diffusion Curves and Points Timothy Sun

    E-Print Network [OSTI]

    Columbia University

    Fast Multipole Representation of Diffusion Curves and Points Timothy Sun Papoj Thamjaroenporn performed on the fast multipole representation. Abstract We propose a new algorithm for random-access evaluation of diffu- sion curve images (DCIs) using the fast multipole method. Unlike all previous methods

  11. COMPLETE BOUNDED NULL CURVES IMMERSED IN C3

    E-Print Network [OSTI]

    Martín, Francisco

    COMPLETE BOUNDED NULL CURVES IMMERSED IN C3 AND SL(2, C) FRANCISCO MARTIN, MASAAKI UMEHARA, AND KOTARO YAMADA ABSTRACT. We construct a simply connected complete bounded Bryant surface in the hyperbolic 3-space H3. Such a surface in H3 can be lifted as a complete bounded null curve in SL(2, C). Using

  12. Embeddings of Surfaces, Curves, and Moving Points in Euclidean Space

    E-Print Network [OSTI]

    Agarwal, Pankaj K.

    generally between low-dimensional flats, polynomial curves, curves with low winding degree, and polynomial such as text and image data [Kle97, IM98, KOR00]. Dimensionality reduction is a powerful tool in tackling. Department of Computer Science, Duke University, Durham, NC 27708, USA; pankaj@cs.duke.edu Department

  13. Dark halo properties from rotation curves

    E-Print Network [OSTI]

    Raul Jimenez; Licia Verde; S. Peng Oh

    2002-01-21

    We study a large set of high spatial resolution optical rotation curves of galaxies with the goal of determining the model parameters for a disk embedded within a CDM halo that we model either with a NFW profile or pseudo-isothermal profile. We show that parameter degeneracies present in lower resolution data are lifted at these higher resolutions. 34% of the galaxies do not have a meaningful fit when using the NFW profile and 32% when using the pseudoisothermal profile, however only 14% do not have a meaningful fit in either model. In both models we find correlations between the disk baryon fraction $f_d$ and the spin parameter of the halo $\\lambda'$, between $f_d$ and the dark halo mass $M_{200}$, and between $M_{200}$ and the concentration parameter $c$. We show that the distribution of the concentration parameters $c$, for a NFW halo, is in good agreement with CDM predictions; no significant galaxy population is found with very low values of $c$. The overall distribution of $\\lambda'$ is in good agreement with theoretical predictions from hierarchical tidal torque theory. The whole sample is also well fitted by a pseudo-isothermal dark halo with a core, but the size of the core is rather small (for 70% of the sample the core size is less than 2 kpc). Thus we conclude that the profile of dark matter is steep ($r^{-1}$ or steeper) down to this radius; large dark matter cores (and therefore very low dark matter central densities) seem to be excluded. LSBs tend to have higher values of $\\lambda'$ for a given $f_d$ and lower values of $c$ for a given mass than HSBs. In an appendix we give some useful formula for pseudo-isothermal profile halos and discuss in detail the issue of parameter degeneracies.

  14. Cosmological Applications of Algebraic Quantum Field Theory in Curved Spacetimes

    E-Print Network [OSTI]

    Hack, Thomas-Paul

    2015-01-01

    This monograph provides a largely self--contained and broadly accessible exposition of two cosmological applications of algebraic quantum field theory (QFT) in curved spacetime: a fundamental analysis of the cosmological evolution according to the Standard Model of Cosmology and a fundamental study of the perturbations in Inflation. The two central sections of the book dealing with these applications are preceded by sections containing a pedagogical introduction to the subject as well as introductory material on the construction of linear QFTs on general curved spacetimes with and without gauge symmetry in the algebraic approach, physically meaningful quantum states on general curved spacetimes, and the backreaction of quantum fields in curved spacetimes via the semiclassical Einstein equation. The target reader should have a basic understanding of General Relativity and QFT on Minkowski spacetime, but does not need to have a background in QFT on curved spacetimes or the algebraic approach to QFT. In particul...

  15. Influence of Hold Time on Creep-Fatigue Behavior of an Advanced Austenitic Alloy

    SciTech Connect (OSTI)

    Mark Carroll; Laura Carroll

    2011-09-01

    An advanced austenitic alloy, HT-UPS (high temperature-ultrafine precipitate strengthened), is a candidate material for the structural components of fast reactors and energy-conversion systems. HT-UPS provides improved creep resistance through a composition based on 316 stainless steel (SS) with additions of Ti and Nb to form nano-scale MC precipitates in the austenitic matrix. The low cycle fatigue and creep-fatigue behavior of a HT-UPS alloy has been investigated at 650 C, 1.0% total strain, and an R ratio of -1 with hold times as long as 9000 sec at peak tensile strain. The cyclic deformation response of HT-UPS is compared to that of 316 SS. The cycles to failure are similar, despite differences in peak stress profiles and the deformed microstructures. Cracking in both alloys is transgranular (initiation and propagation) in the case of continuous cycle fatigue, while the primary cracks also propagate transgranularly during creep-fatigue cycling. Internal grain boundary damage as a result of the tensile hold is present in the form of fine cracks for hold times of 3600 sec and longer and substantially more internal cracks are visible in 316 SS than HT-UPS. The dislocation substructures observed in the deformed material are different. An equiaxed cellular structure is observed in 316 SS, whereas tangles of dislocations are present at the nanoscale MC precipitates in HT-UPS and no cellular substructure is observed.

  16. Modeling cyclic ratcheting based fatigue life of HSLA steels using crystal plasticity FEM simulations and experiments

    E-Print Network [OSTI]

    Ghosh, Somnath

    Modeling cyclic ratcheting based fatigue life of HSLA steels using crystal plasticity FEM of results from experiments and finite element simulations using crystal plasticity constitutive relations the simulated results with experiments. A crystal plasticity based FEM (CPFEM) model is used in this paper

  17. High-cycle fatigue and durability of polycrystalline silicon thin lms in ambient air

    E-Print Network [OSTI]

    Ritchie, Robert

    High-cycle fatigue and durability of polycrystalline silicon thin ®lms in ambient air C. First, silicon-based ®lms are still the dominant structural material for micromachines. Second of MEMS components are critical in this maturing ®eld. The silicon-based ®lms commonly used in micromecha

  18. Time-domain Fatigue Response and Reliability Analysis of Offshore Wind Turbines with

    E-Print Network [OSTI]

    Nørvåg, Kjetil

    Time-domain Fatigue Response and Reliability Analysis of Offshore Wind Turbines with Emphasis of offshore wind turbines Defense: 09.12.2012 2012 - : Structural Engineer in Det Norske Veritas (DNV) 2007 sector. Wind is one of the most rapidly growing renewable energy sources, as it is clean

  19. Influence of Nonlinear Irregular Waves on the Fatigue Loads of an Offshore Wind Turbine

    E-Print Network [OSTI]

    Papalambros, Panos

    Influence of Nonlinear Irregular Waves on the Fatigue Loads of an Offshore Wind Turbine Michiel B-mail: michiel van.der.meulen@siemens.com Abstract. In order to make offshore wind power a cost effective load calculations by using a more advanced model for wave kinematics. As offshore wind turbines

  20. Graphene coating makes carbon nanotube aerogels superelastic and resistant to fatigue

    E-Print Network [OSTI]

    McGaughey, Alan

    Graphene coating makes carbon nanotube aerogels superelastic and resistant to fatigue Kyu Hun Kim one and five layers of graphene nanoplates. The graphene-coated aerogel exhibits no change , but collapse under stress15 . We fabricated graphene-coated single-walled carbon nanotube aerogels by coating

  1. CONTINUOUS FATIGUE ASSESSMENT OF AN OFFSHORE WIND TURBINE USING A LIMITED NUMBER OF VIBRATION SENSORS

    E-Print Network [OSTI]

    Boyer, Edmond

    CONTINUOUS FATIGUE ASSESSMENT OF AN OFFSHORE WIND TURBINE USING A LIMITED NUMBER OF VIBRATION Wind turbines are exposed to continuous wind and wave excitation that leads to high periodic stresses initiations and propagations. The continuous monitoring of the Wind Turbine is of utmost importance in order

  2. 2009 ASME WIND ENERGY SYMPOSIUM Static and Fatigue Testing of Thick Adhesive Joints for

    E-Print Network [OSTI]

    1 2009 ASME WIND ENERGY SYMPOSIUM Static and Fatigue Testing of Thick Adhesive Joints for Wind as wind blade size has increased. Typical blade joints use paste adhesives several millimeters thick aircraft, which are also of relevance to wind blades in many instances. The strengths of lap-shear and many

  3. Static and fatigue bending behavior of pultruded GFRP sandwich panels with through-thickness fiber insertions

    E-Print Network [OSTI]

    Static and fatigue bending behavior of pultruded GFRP sandwich panels with through-thickness fiber testing a b s t r a c t This paper presents the findings of a research program that was undertaken to evaluate the effective elastic modulus, shear modulus and degree of composite interaction of the panels

  4. BAYESIAN UPDATING OF PROBABILISTIC TIME-DEPENDENT FATIGUE MODEL: APPLICATION TO JACKET FOUNDATIONS OF WIND TURBINES

    E-Print Network [OSTI]

    Boyer, Edmond

    OF WIND TURBINES Benjamin Rocher1,2 , Franck Schoefs1 , Marc François1 , Arnaud Salou2 1 LUNAM Université.rocher@univ-nantes.fr ABSTRACT Due to both wave and wind fluctuation, the metal foundations of offshore wind turbines are highly algorithm. KEYWORDS: Fatigue, Damage, Reliability, Bayesian updating. INTRODUCTION In offshore wind turbines

  5. November 1998 NREL/SR-500-24379 Fatigue of Composite Material Beam

    E-Print Network [OSTI]

    November 1998 · NREL/SR-500-24379 Fatigue of Composite Material Beam Elements Representative Blade Substructure NREL Technical Monitors: Richard Osgood and Walt Musial John F. Mandell, Daniel D University (MSU) under National Renewable Energy Laboratory (NREL) sponsorship from August 1991 through

  6. Stress dependent activation entropy for dynamic fatigue of pristine silica optical fibers

    E-Print Network [OSTI]

    Matthewson, M. John

    Stress dependent activation entropy for dynamic fatigue of pristine silica optical fibers Y. S Subcritical crack growth in fused silica is treated as a stress assisted chemical reaction between water the stress reduces the energy barrier of the activated complex by affecting both the activation enthalpy

  7. 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

  8. Biomaterials 27 (2006) 19882000 Fatigue and life prediction for cobalt-chromium stents

    E-Print Network [OSTI]

    Ritchie, Robert

    2006-01-01

    Biomaterials 27 (2006) 1988­2000 Fatigue and life prediction for cobalt-chromium stents: A fracture of testing to failure. This is typically achieved using one of two ARTICLE IN PRESS www.elsevier.com/locate/biomaterials 0142-9612/$ - see front matter r 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials

  9. 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

  10. Author's personal copy An equivalent strain/CoffineManson approach to multiaxial fatigue

    E-Print Network [OSTI]

    Ritchie, Robert

    prediction in superelastic Nitinol medical devices Amanda Runciman a,b , David Xu a,b , Alan R. Pelton c, Berkeley, CA, USA b Materials Sciences Division, Lawrence Berkeley National Laboratory, CA, USA c Nitinol Accepted 24 March 2011 Available online 30 April 2011 Keywords: Medical devices Nitinol Fatigue Life

  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. Fatigue-Life Computational Analysis for the Self-Expanding Endovascular Nitinol Stents

    E-Print Network [OSTI]

    Grujicic, Mica

    Fatigue-Life Computational Analysis for the Self-Expanding Endovascular Nitinol Stents M. Grujicic-expanding endovascular stents made of Nitinol (a Ni-Ti intermetallic compound possessing superelastic and shape, Nitinol, stents 1. Introduction The main objective of the present study is to investigate computationally

  13. Mechanism of fatigue in micron-scale films of polycrystalline silicon for microelectromechanical systems

    E-Print Network [OSTI]

    Ritchie, Robert

    the past decade, microelectromechanical systems MEMS and the enabling technologies of surface micromaMechanism of fatigue in micron-scale films of polycrystalline silicon for microelectromechanical. During this pe- riod of rapid innovation, a vast array of MEMS applications have emerged and many

  14. Slow-Time Changes in Human EMG Muscle Fatigue States Are Fully Represented in Movement Kinematics

    E-Print Network [OSTI]

    Chelidze, David

    from the kinematic data. Nonlinear analysis of kinematic features was shown to be essential nonlinear PSW-based analysis of kinematic data was shown to adequately predict all EMG-based individual-based analysis of strictly kinematic time series data directly predicted all of the local muscle fatigue trends

  15. Torsion Property and Cyclic Fatigue Fracture Behavior of Nickel-Titanium Endodontic Instruments

    E-Print Network [OSTI]

    Zheng, Yufeng

    -Titanium rotary instruments. In 1999, HaïKel[2] studied engine-driven rotary NiTi endodontic instruments and Engineering Science, Peking University, Beijing 100871, China 2 School of Materials Science and Engineering Abstract. The torsion property and rotary fatigue fracture behavior of Smart® K file and R reamer made

  16. 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

  17. A Model to Assess Fatigue at Joint-Level Using the Half-Joint Concept

    E-Print Network [OSTI]

    Rodríguez, Inmaculada

    and simulations generated by our animation environment. 1. Introduction The human body is continuously under b Virtual Reality Laboratory. Swiss Federal Institute of Technology Lausanne, Switzerland In this paper we focus on the modeling and evaluation of performance factors as human fatigue at joint level. We

  18. Analysis and detection of driver fatigue caused by sleep deprivation

    E-Print Network [OSTI]

    Yang, Ji Hyun, 1978-

    2007-01-01

    Human errors in attention and vigilance are among the most common causes of transportation accidents. Thus, effective countermeasures are crucial for enhancing road safety. By pursuing a practical and reliable design of ...

  19. Analysis of SNL/MSU/DOE fatigue database trends for wind turbine blade materials.

    SciTech Connect (OSTI)

    Mandell, John F. (Montana State University, Bozeman, MT); Ashwill, Thomas D.; Wilson, Timothy J. (Montana State University, Bozeman, MT); Sears, Aaron T. (Montana State University, Bozeman, MT); Agastra, Pancasatya (Montana State University, Bozeman, MT); Laird, Daniel L.; Samborsky, Daniel D. (Montana State University, Bozeman, MT)

    2010-12-01

    This report presents an analysis of trends in fatigue results from the Montana State University program on the fatigue of composite materials for wind turbine blades for the period 2005-2009. Test data can be found in the SNL/MSU/DOE Fatigue of Composite Materials Database which is updated annually. This is the fifth report in this series, which summarizes progress of the overall program since its inception in 1989. The primary thrust of this program has been research and testing of a broad range of structural laminate materials of interest to blade structures. The report is focused on current types of infused and prepreg blade materials, either processed in-house or by industry partners. Trends in static and fatigue performance are analyzed for a range of materials, geometries and loading conditions. Materials include: sixteen resins of three general types, five epoxy based paste adhesives, fifteen reinforcing fabrics including three fiber types, three prepregs, many laminate lay-ups and process variations. Significant differences in static and fatigue performance and delamination resistance are quantified for particular materials and process conditions. When blades do fail, the likely cause is fatigue in the structural detail areas or at major flaws. The program is focused strongly on these issues in addition to standard laminates. Structural detail tests allow evaluation of various blade materials options in the context of more realistic representations of blade structure than do the standard test methods. Types of structural details addressed in this report include ply drops used in thickness tapering, and adhesive joints, each tested over a range of fatigue loading conditions. Ply drop studies were in two areas: (1) a combined experimental and finite element study of basic ply drop delamination parameters for glass and carbon prepreg laminates, and (2) the development of a complex structured resin-infused coupon including ply drops, for comparison studies of various resins, fabrics and pry drop thicknesses. Adhesive joint tests using typical blade adhesives included both generic testing of materials parameters using a notched-lap-shear test geometry developed in this study, and also a series of simulated blade web joint geometries fabricated by an industry partner.

  20. 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.

  1. Multifrequency Eddy Current Inspection of Corrosion in Clad Aluminum Riveted Lap Joints and Its Effect on Fatigue Life

    SciTech Connect (OSTI)

    Okafor, A. C.; Natarajan, S. [Nondestructive Evaluation and Structural Health Monitoring Laboratory, Department of Mechanical and Aerospace Engineering, University of Missouri - Rolla, 1870 Miner Circle, Rolla, MO 65409-0050 (United States)

    2007-03-21

    Aging aircraft are prone to corrosion damage and fatigue cracks in riveted lap joints of fuselage skin panels. This can cause catastrophic failure if not detected and repaired. Hence detection of corrosion damage and monitoring its effect on structural integrity are essential. This paper presents multifrequency eddy current (EC) inspection of corrosion damage and machined material loss defect in clad A1 2024-T3 riveted lap joints and its effect on fatigue life. Results of eddy current inspection, corrosion product removal and fatigue testing are presented.

  2. Bolometric and UV light curves of core-collapse supernovae

    SciTech Connect (OSTI)

    Pritchard, T. A.; Roming, P. W. A. [Department of Astronomy and Astrophysics, Penn State University, 525 Davey Lab, University Park, PA 16802 (United States); Brown, Peter J. [Department of Physics and Astronomy, George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, 4242 TAMU, College Station, TX 77843 (United States); Bayless, Amanda J. [Southwest Research Institute, Department of Space Science, 6220 Culebra Road, San Antonio, TX 78238 (United States); Frey, Lucille H. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2014-06-01

    The Swift UV-Optical Telescope (UVOT) has been observing core-collapse supernovae (CCSNe) of all subtypes in the UV and optical since 2005. Here we present 50 CCSNe observed with the Swift UVOT, analyzing their UV properties and behavior. Where we have multiple UV detections in all three UV filters (? {sub c} = 1928-2600 Å), we generate early time bolometric light curves, analyze the properties of these light curves and the UV contribution to them, and derive empirical corrections for the UV-flux contribution to optical-IR based bolometric light curves.

  3. Exhaustive search system and method using space-filling curves

    DOE Patents [OSTI]

    Spires, Shannon V.

    2003-10-21

    A search system and method for one agent or for multiple agents using a space-filling curve provides a way to control one or more agents to cover an area of any space of any dimensionality using an exhaustive search pattern. An example of the space-filling curve is a Hilbert curve. The search area can be a physical geography, a cyberspace search area, or an area searchable by computing resources. The search agent can be one or more physical agents, such as a robot, and can be software agents for searching cyberspace.

  4. Developments in coiled tubing BOP ram design

    SciTech Connect (OSTI)

    Palmer, R.; Newman, K.; Reaper, A.

    1995-12-31

    Significant technical improvements have been made recently in the design of coiled tubing (CT) blowout preventer (BOP) shear and slip rams. This technology is constantly being enhanced and refined as the CT service industry continues to mature and new operational demands are placed on the CT pressure control equipment. Larger CT sizes require better BOP shearing capabilities. Advancements in the understanding of CT fatigue life have caused the life reducing affects of the slip ram markings on the pipe to be examined. This paper explores the circumstances that have precipitated these improvements, and the research and development methods involved in developing better BOP rams.

  5. The roles of the binodal curve and the spinodal curve in expansions from the supercritical state with flashing

    SciTech Connect (OSTI)

    Knuth, Eldon L.; Miller, David R.; Even, Uzi

    2014-12-09

    Data extracted from time-of-flight (TOF) measurements made on steady-state He free jets at Göttingen already in 1986 and for pulsed Ne free jets investigated recently at Tel Aviv have been added to an earlier plot of terminal condensed-phase mass fraction x{sub 2?} as a function of the dimensionless scaling parameter ?. ? characterizes the source (fluid species, temperature, pressure and throat diameter); values of x{sub 2?} are extracted from TOF measurements using conservation of energy in the free-jet expansion. For nozzles consisting of an orifice in a thin plate; the extracted data yield 22 data points which are correlated satisfactorily by a single curve. The Ne free jets were expanded from a conical nozzle with a 20° half angle; the three extracted data points stand together but apart from the aforementioned curve, indicating that the presence of the conical wall influences significantly the expansion and hence the condensation. The 22 data points for the expansions via an orifice consist of 15 measurements with expansions from the gas-phase side of the binodal curve which crossed the binodal curve downstream from the sonic point and 7 measurements with expansions of the gas-phase product of the flashing which occurred after an expansion from the liquid-phase side of the binodal curve crossed the binodal curve upstream from the sonic point. The association of these 22 points with a single curve supports the alternating-phase model for flows with flashing upstream from the sonic point proposed earlier. In order to assess the role of the spinodal curve in such expansions, the spinodal curves for He and Ne were computed using general multi-parameter Helmholtz-free-energy equation-of-state formulations. Then, for the several sets of source-chamber conditions used in the free-jet measurements, thermodynamic states at key locations in the free-jet expansions (binodal curve, sonic point and spinodal curve) were evaluated, with the expansion presumed to be metastable from the binodal curve to the spinodal curve. TOF distributions with more than two peaks (interpreted earlier as superimposed alternating-state TOF distributions) indicated flashing of the metastable flow downstream from the binodal curve but upstream from the sonic point. This relatively early flashing is due apparently to destabilizing interactions with the walls of the source. If the expansion crosses the binodal curve downstream from the nozzle, the metastable fluid does not interact with surfaces and flashing might be delayed until the expansion reaches the spinodal curve. It is concluded that, if the expansion crosses the binodal curve before reaching the sonic point, the resulting metastable fluid downstream from the binodal curve interacts with the adjacent surfaces and flashes into liquid and vapor phases which expand alternately through the nozzle; the two associated alternating TOF distributions are superposed by the chopping process so that the result has the appearance of a single distribution with three peaks.

  6. GENETICS, BREEDING, AND MODELING Use of Lactation Curves for Analysis

    E-Print Network [OSTI]

    Yandell, Brian S.

    Department of Agricultural Economics. 4Department of Dairy Science. plot model, LHG = lactation within a herd lactation within a herd group (LHG) (10, 22, 23). Primiparous cows are more persistent, and lactation curves

  7. Convex hulls of a curve in control theory

    SciTech Connect (OSTI)

    Kurbatskii, Aleksei N [Moscow School of Economics of Lomonosov MSU, Moscow (Russian Federation)

    2012-03-31

    A classification is obtained for typical singularities of the local transitivity sets of control systems on three-dimensional manifolds with nonconvex indicatrices that are closed smooth spatial curves. Bibliography: 8 titles.

  8. Galaxy rotation curves with log-normal density distribution

    E-Print Network [OSTI]

    Marr, John H

    2015-01-01

    The log-normal distribution represents the probability of finding randomly distributed particles in a micro canonical ensemble with high entropy. To a first approximation, a modified form of this distribution with a truncated termination may represent an isolated galactic disk, and this disk density distribution model was therefore run to give the best fit to the observational rotation curves for 37 representative galaxies. The resultant curves closely matched the observational data for a wide range of velocity profiles and galaxy types with rising, flat or descending curves in agreement with Verheijen's classification of 'R', 'F' and 'D' type curves, and the corresponding theoretical total disk masses could be fitted to a baryonic Tully Fisher relation (bTFR). Nine of the galaxies were matched to galaxies with previously published masses, suggesting a mean excess dynamic disk mass of dex0.61+/-0.26 over the baryonic masses. Although questionable with regard to other measurements of the shape of disk galaxy g...

  9. NATURE OF SINGULARITIES FOR ANALYTICITY DOMAINS OF INVARIANT CURVES 1

    E-Print Network [OSTI]

    preprint archive. Send mail to mp arc@math.utexas.edu for details. 2 Supported by NSF grants. 3 e of physics, ranging from plasma to solid state physics. To study invariant curves we will find it more

  10. Perspective+Detail a visualization technique for vertically curved displays

    E-Print Network [OSTI]

    on the vertical display segment and (3) a head-up display (HUD) in the connecting curved segment (see Figure 1 display connection. The detail view and the HUD are seamlessly integrated with this extended overview

  11. Constructing Pairing-Friendly Elliptic Curves with Embedding Degree 10.

    E-Print Network [OSTI]

    on the application. In order to vary the security level or adapt to future improvements in discrete log technology with k = 12. There is a gen- eral construction, originally due to Cocks and Pinch [8], for curves

  12. A New 24 ?m Phase Curve for ? Andromedae b

    E-Print Network [OSTI]

    Crossfield, Ian J.

    We report the detection of 24 ?m variations from the planet-hosting ? Andromedae system consistent with the orbital periodicity of the system's innermost planet, ? And b. We find a peak-to-valley phase curve amplitude of ...

  13. Proceedings of WindPower 95, AWEA, Washington, D.C., 1995. FATIGUE DAMAGE ESTIMATE COMPARISONS FOR

    E-Print Network [OSTI]

    Proceedings of WindPower 95, AWEA, Washington, D.C., 1995. FATIGUE DAMAGE ESTIMATE COMPARISONS," Proceedings of WindPower `95, AWEA, Washington, DC, March, 1995, pp. 177-186. * This work is supported

  14. Fatigue failure in thin-film polycrystalline silicon is due to subcritical cracking within the oxide layer

    E-Print Network [OSTI]

    Ritchie, Robert

    the oxide layer D. H. Alsem Department of Materials Science and Engineering, University of California SiO2 oxide layer "reaction-layer" fatigue .1,7,8,18 The mechanism of oxide thickening is as yet

  15. The effects of laser trimming on the tensile strength and fatigue resistance properties of titanium - 6Al-4V 

    E-Print Network [OSTI]

    Whitesel, Dean Adam

    1994-01-01

    The effect of laser trimming on the tensile strength and fatigue resistance of titanium-6% aluminum-4% vanadium specimens was investigated. Due to the nature of laser processing, the microstructure of the titanium alloy ...

  16. Fatigue resistance of hot-mix asphalt concrete (HMAC) mixtures using the calibrated mechanistic with surface energy (CMSE) measurements approach 

    E-Print Network [OSTI]

    Ofori-Abebresse, Edward Kwame

    2006-10-30

    Fatigue cracking is one of the fundamental distresses that occur in the life of a Hot Mix Asphalt Concrete (HMAC) pavement. This load induced distress leads to structural collapse of the entire pavement ultimately and can ...

  17. FATIGUE RESISTANT FIBERGLASS LAMINATES FOR WIND TURBINE BLADES (published for Wind Energy 1996, ASME, pp. 46-51)

    E-Print Network [OSTI]

    FATIGUE RESISTANT FIBERGLASS LAMINATES FOR WIND TURBINE BLADES (published for Wind Energy 1996/MSU database to lifetime prediction as described in Ref. [1]. INTRODUCTION Most U.S. fiberglass wind turbine

  18. The effect of environment, chemistry, and microstructure on the corrosion fatigue behavior of austenitic stainless steels in high temperature water

    E-Print Network [OSTI]

    O'Brien, Lindsay Beth

    2014-01-01

    The effect of sulfur on the corrosion fatigue crack growth of austenitic stainless steel was evaluated under Light Water Reactor (LWR) conditions of 288°C deaerated (less than 5ppb O?) water, to shed light on the accelerating ...

  19. The influence of high harmonic force on fatigue life and its prediction via coupled inline-crossflow VIV modeling

    E-Print Network [OSTI]

    Zheng, Haining

    2014-01-01

    Vortex Induced Vibrations (VIV) of a flexibly mounted rigid cylinder placed in a flow is a canonical problem of fluid-structure interactions and the study of VIV and the resulting material fatigue is particularly important ...

  20. UTILIZING ON-CHIP TESTING AND ELECTRON MICROSCOPY TO STUDY FATIGUE AND WEAR IN POLYSILICON STRUCTURAL FILMS

    E-Print Network [OSTI]

    Ritchie, Robert

    and fatigue are important factors in determining the reliability of microelectromechanical systems (MEMS properties of the material. The main reliability issues for microelectromechanical systems (MEMS). While the reliability of MEMS has received extensive attention, the physical mechanisms responsible

  1. Fatigue analysis of stringer to floor beam connections in through plate girder and through truss railroad bridges 

    E-Print Network [OSTI]

    Evans, Leslie Virginia

    1999-01-01

    The objective of this thesis is to determine fatigue stresses in the stringer to floor beam connections of through plate girder (TPG) and through truss (TT) bridges in order to predict failure. Field observations by the Association of American...

  2. Shifting the cost curve for subsea developments

    SciTech Connect (OSTI)

    Solheim, B.J.; Hestad, E.

    1995-12-31

    A steadily increasing challenge in offshore oil and gas field developments in the Norwegian part of the North Sea is to design, construct, and install offshore installations that give an acceptable return of investment Deeper water, limited reservoirs and a low, fluctuating oil price make the task even more demanding. Saga Petroleum has recently faced this challenge with its last field development project. Attention in this paper is focused on the Vigdis subsea production system. However, the considerations and cost reduction elements are valid for offshore field developments in general. The main cost reductions are obtained by: Maximum use of industry capability; Application of new organization principles; Focus on functional requirements; Shortened project execution time; Technological development. In addition this paper presents thoughts on further cost reduction possibilities for future subsea field developments.

  3. Application of the decline curve method to aquifers 

    E-Print Network [OSTI]

    Potnis, Girish Vijay

    1992-01-01

    on p/z plot. . . 7. Hypothetical semi-log decline curve for an aquifer . 19 20 20 21 8. Hypothetical exponential decline on log-log plot for an aquifer . . 9. Normalized influx rate curves for aquifer with different radii, . . . 10. Decline.... Hurst modified steady-state method~, 3. van Everdingen and Hurst pseudosteady state methods, 4. Carter - Tracy method, 5. Influence or resistance function methods 6. Fetkovich methodt 1 The most basic model of these methods is the Schilthuis steady...

  4. Automatic classification of eclipsing binaries light curves using neural networks

    E-Print Network [OSTI]

    L. M. Sarro; C. Sánchez-Fernández; A. Giménez

    2005-11-11

    In this work we present a system for the automatic classification of the light curves of eclipsing binaries. This system is based on a classification scheme that aims to separate eclipsing binary sistems according to their geometrical configuration in a modified version of the traditional classification scheme. The classification is performed by a Bayesian ensemble of neural networks trained with {\\em Hipparcos} data of seven different categories including eccentric binary systems and two types of pulsating light curve morphologies.

  5. Seiberg-Witten curve via generalized matrix model

    E-Print Network [OSTI]

    Kazunobu Maruyoshi; Futoshi Yagi

    2010-12-27

    We study the generalized matrix model which corresponds to the n-point toric Virasoro conformal block. This describes four-dimensional N=2 SU(2)^n gauge theory with circular quiver diagram by the AGT relation. We first verify that it is obtained from the perturbative calculation of the Liouville correlation function. We derive the Seiberg-Witten curve for N=2 gauge theory as a spectral curve of the generalized matrix model.

  6. Bandgap properties of diamond structure photonic crystal heterostructures with inclined and curved interfaces

    SciTech Connect (OSTI)

    Lei, Haitao; Li, Yong; Wang, Hong, E-mail: hwang@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education and International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049 (China)

    2014-06-14

    The 3D (dimensional) diamond structure photonic crystal heterostructures with different lattice constants were prepared using rapid prototyping and gel casting with alumina. In this paper, heterostructures with inclined and curved interfaces were designed and its bandgap properties were studied. The normalized resonant intensity of electromagnetic wave in heterostructure with inclined and curved interface is stronger than that in the ordinary heterostructure without modified interface. The influence of curved interface on transmission properties of electromagnetic wave was investigated with the radius of curvature ranging from 17?mm to 37?mm at 5?mm interval. The results show that two resonant modes appear in the photonic band gap, being similar to the band gap characteristics of the photonic crystals with two defects inside. With the increasing of the radius of curvature, the resonant mode shift to higher frequency. In the structure with a radius of curvature of 32?mm, a guiding band appears in the photonic band gap. Further increase in the radius of curvature, the guiding band will split into two resonant modes again and the two resonant modes shift to lower frequencies.

  7. Progress Letter Report on Bending Fatigue Test System Development for Spent Nuclear Fuel Vibration Integrity Study (Out-of-cell fatigue testing development - Task 2.4)

    SciTech Connect (OSTI)

    Wang, Jy-An John [ORNL; Wang, Hong [ORNL; Cox, Thomas S [ORNL; Baldwin, Charles A [ORNL; Bevard, Bruce Balkcom [ORNL

    2013-08-01

    Vibration integrity of high burn-up spent nuclear fuel in transportation remains to be a critical component of US nuclear waste management system. The structural evaluation of package for spent fuel transportation eventually will need to see if the content or spent fuel is in a subcritical condition. However, a system for testing and characterizing such spent fuel is still lacking mainly due to the complication involved with dealing radioactive specimens in a hot cell environment. Apparently, the current state-of-the-art in spent fuel research and development is quite far away from the delivery of reliable mechanical property data for the assessment of spent fuels in the transport package evaluation. Under the sponsorship of US NRC, ORNL has taken the challenge in developing a robust testing system for spent fuel in hot cell. An extensive literature survey was carried out and unique requirements of such testing system were identified. The U-frame setup has come to the top among various designs examined for reverse bending fatigue test of spent fuel rod. The U-frame has many features that deserve mentioned here: Easy to install spent fuel rod in test; Less linkages than in conventional bending test setup such as three-point or four-point bending; Target the failure mode relevant to the fracture of spent fuel rod in transportation by focusing on pure bending; The continuous calibrations and modifications resulted in the third generation (3G) U-frame testing setup. Rigid arms are split along the LBB axis at rod sample ends. For each arm, this results in a large arm body and an end piece. Mating halves of bushings were modified into two V-shaped surfaces on which linear roller bearings (LRB) are embedded. The rod specimen is installed into the test fixture through opening and closing slide end-pieces. The 3G apparently has addressed major issues of setup identified in the previous stage and been proven to be eligible to be further pursued in this project. On the other hand, the purchase of universal testing machine or Bose dual LM2 TB was completed and the testing system was delivered to ORNL in August 2012. The preliminary confirmation of the system and on-site training were given by Bose field engineer and regional manager on 8/1-8/2/2012. The calibration of Bose testing system has been performed by ORNL because the integration of ORNL setup into the Bose TestBench occurred after the installation. Major challenge with this process arose from two aspects: 1) the load control involves two load cells, and 2) U-frame setup itself is a non-standard specimen. ORNL has been able to implement the load control through Cycle Indirect along with pinning the U-frame setup. Two meetings with ORNL hot-cell group (November 2012 and January 2013) were held to discuss the potential issues with both epoxy mounting of rigid sleeve and U-frame setup. Many suggestions were provided to make the procedure friendlier to the manipulator in hot cell. Addressing of these suggestions resulted in another cycle of modifications of both vise mold and setup. The initial meeting with ORNL I&C group occurred in November 2012 with regard to the Bose cable modification and design of central panel to integrate the cables and wires. The first round of cable modification and central panel fabrication was completed in February 2012. The testing with the modified cables exhibited substantial noises and the testing system was not shown to be stable. It was believed the cross talk was responsible to the noise, and a central panel with a better grounding and shielding was highly recommended. The central panel has been re-designed and fabricated in March 2013. In the subsequent period, the ORNL made substantial effort to debug the noises with the load cell channel, and to resolve the noises and nonlinearity with RDP LVDTs related to the integration of RDP LVDTs to Bose system. At the same time, ORNL has completed the verification tests of Bose test system, including cycle tests under reversal bending in load control, bending tests under monotonic load, and cycle test

  8. Environmental Kuznets Curve for carbon dioxide emissions: lack of robustness to heterogeneity?

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    1 Environmental Kuznets Curve for carbon dioxide emissions: lack of robustness to heterogeneity applying the iterative Bayesian shrinkage procedure. The environmental Kuznets curve (EKC) hypothesis. Keywords: Environmental Kuznets curve; Bayesian shrinkage estimator; Heterogeneity JEL classification: O13

  9. Surface Studies of Ultra Strength Drilling Steel after Corrosion Fatigue in Simulated Sour Environment

    SciTech Connect (OSTI)

    M. Ziomek-Moroz; J.A. Hawk; R. Thodla; F. Gui

    2012-05-06

    The Unites States predicted 60% growth in energy demand by 2030 makes oil and natural gas primary target fuels for energy generation. The fact that the peak of oil production from shallow wells (< 5000 m) is about to be reached, thereby pushing the oil and natural gas industry into deeper wells. However, drilling to depths greater than 5000 m requires increasing the strength-to weight ratio of the drill pipe materials. Grade UD-165 is one of the ultra- high yield strength carbon steels developed for ultra deep drilling (UDD) activities. Drilling UDD wells exposes the drill pipes to Cl{sup -}, HCO{sub 3}{sup -}/CO{sub 3}{sup 2-}, and H{sub 2}S-containig corrosive environments (i.e., sour environments) at higher pressures and temperatures compared to those found in conventional wells. Because of the lack of synergism within the service environment, operational stresses can result in catastrophic brittle failures characteristic for environmentally assisted cracking (EAC). Approximately 75% of all drill string failures are caused by fatigue or corrosion fatigue. Since there is no literature data on the corrosion fatigue performance of UD-165 in sour environments, research was initiated to better clarify the fatigue crack growth (FCGR) behavior of this alloy in UDD environments. The FCGR behavior of ultra-strength carbon steel, grade UD-165, was investigated by monitoring crack growth rate in deaerated 5%NaCl solution buffered with NaHCO{sub 3}/Na{sub 2}CO{sub 3} and in contact with H{sub 2}S. The partial pressure of H{sub 2}S (p{sub H2S}) was 0.83 kPa and pH of the solution was adjusted by NaOH to 12. The fatigue experiments were performed at 20 and 85 C in an autoclave with surface investigations augmented by scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy. In this study, research focused on surface analyses supported by the fatigue crack growth rate measurements. Fig. 1 shows an SEM micrograph of the crack that propagated from the notch in the solution at 20 C. Accumulation of the corrosion products is visible along the crack. The EDX chemical analysis near the crack tip found iron, sulfur and oxygen in the passive layer. The surface of the sample after the fatigue test in the sour environment at 85{sup o}, Fig. 2, C looks different from that fatigued surface at 20 C. The crack propagates across the passive film that covers the surface fairly uniformly. Some spallation of the passive film is observed near the notch. The EDX chemical analysis of the passive film near the crack tip identified mainly iron, carbon and oxygen. It appears that temperature plays a very important role in formation of the passive film. This may be associated with different solubility of H{sub 2}S in the solution, which will be further studied.

  10. Implementation of a Biaxial Resonant Fatigue Test Method on a Large Wind Turbine Blade

    SciTech Connect (OSTI)

    Snowberg, D.; Dana, S.; Hughes, S.; Berling, P.

    2014-09-01

    A biaxial resonant test method was utilized to simultaneously fatigue test a wind turbine blade in the flap and edge (lead-lag) direction. Biaxial resonant blade fatigue testing is an accelerated life test method utilizing oscillating masses on the blade; each mass is independently oscillated at the respective flap and edge blade resonant frequency. The flap and edge resonant frequency were not controlled, nor were they constant for this demonstrated test method. This biaxial resonant test method presented surmountable challenges in test setup simulation, control and data processing. Biaxial resonant testing has the potential to complete test projects faster than single-axis testing. The load modulation during a biaxial resonant test may necessitate periodic load application above targets or higher applied test cycles.

  11. Multi-objective optimal design of steel trusses in unstructured design domains 

    E-Print Network [OSTI]

    Paik, Sangwook

    2006-04-12

    allows a Pareto-optimal set to be identified within a single trial. These truss designs reflect the tradeoffs that occur between the multiple objectives optimized. Finally, the obtained Pareto-optimal curve will be used to provide design engineers with a...

  12. 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.

  13. Stress-relaxation and fatigue behaviour of synthetic brow-suspension materials

    E-Print Network [OSTI]

    Kwon, Kyung-Ah; Shipley, Rebecca J.; Edirisinghe, Mohan; Rayment, Andrew W.; Best, Serena M.; Cameron, Ruth E.; Salam, Tahrina; Rose, Geoffrey E.; Ezra, Daniel G.

    2014-11-12

    Salamc, Geoffrey E. Rosec, Daniel G. Ezrac aDepartment of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, UK bDepartment of Materials Science and Metallurgy, Cambridge Centre for Medical Materials, University... increasing strain rate has been reported to result in increasing peak force (Ching et al. 2000; Nilsson 1982). Each sample was stretched at ×6 faster rate for fatigue tests than for stress-relaxation or preconditioning tests, thereby resulting...

  14. Initiation mechanisms and fatigue growth of internal delaminations in graphite/epoxy cross-ply laminates 

    E-Print Network [OSTI]

    Georgiou, Ioannis Theodorou

    1986-01-01

    . . . . . . . . . . 10 3. Photograph of the test station. . 12 4, Photograph of the MTS biaxial extensometer mounted on a uniaxial laminate specimen. . 13 5. (a) Cross, (b) Longitudinal, and (c) Slant sections subjected to microscopic observation. . 15 6. A... and Research Obgective. . . . CHAPTER II. TENSION-TENSION UNIAXIAL FATIGUE TEST. . . 2. 1 Laminate Fabrication & Specimen Preparation. . 2. 2 Test Station Description. 2. 3 Damage Documentation in the Specimen Interior. . . 2. 4 Testing Procedure...

  15. Fatigue failure of regenerator screens in a high frequency Stirling engine

    SciTech Connect (OSTI)

    Hull, D.R.; Alger, D.L.; Moore, T.J.; Sheuermann, C.M.

    1987-03-01

    Failure of Stirling Space Power Demonstrator Engine (SPDE) regenerator screens was investigated. After several hours of operation the SPDE was shut down for inspection and upon removal of the regenerator screens, debris of an unknown origin was discovered along with considerable cracking of the screens in localized areas. Metallurgical analysis of the debris determined it to be cracked-off-deformed pieces of the 41 pm thickness Type 304 stainless steel wire screen. Scanning electron microscopy of the cracked screens revealed failures occurring at wire crossovers and fatigue striations on the fracture surface of the wires. Thus, the screen failure can be characterized as a fatigue failure of the wires. The crossovers were determined to contain a 30 percent reduction in wire thickness and a highly worked microstructure occurring from the manufacturing process of the wire screens. Later it was found that reduction in wire thickness occurred because the screen fabricator had subjected the screen to a light cold-roll process after weaving. Installation of this screen left a clearance in the regenerator allowing the screens to move. The combined effects of the reduction in wire thickness, stress concentration (caused by screen movement), and highly worked microstructure at the wire crossovers led to the fatigue failure of the screens.

  16. Control of corrosion-fatigue in NGV fuel cylinders. Topical report, January 1987-August 1989

    SciTech Connect (OSTI)

    Hudak, S.J.; Birring, A.S.; Bartlett, M.L.; Hanley, J.J.

    1990-02-01

    Natural gas vehicle (NGV) fuel cylinders are periodically recertified using hydrostatic testing. However, the procedure is costly, and of questionable value for the detection of corrosion-fatigue cracking, the most serious form of cylinder degradation. The present program examines the feasibility of an improved recertification procedure based on in-service acoustic emissions (AE) monitoring of cracks during cylinder refueling, combined with fracture mechanics testing and analysis to determine the optimum inspection period, the level of detectability required, and the cylinder retirement criteria. Laboratory experiments were used to measure the corrosion-fatigue and fracture resistance of several cylinder steels, as well as to provide basic information on AE sources. A comparison of the latter information with the background noise obtained during cylinder refueling was used to demonstrate the feasibility of the AE procedure. An analytical fracture mechanics model for corrosion-fatigue crack growth in the cylinders was also developed and used, together with the measured materials' properties, to predict cylinder life as a function of crack size, operating pressure, and environment. Conditions for leak-before-break of the cylinder were also examined. Areas requiring additional work are defined, including the important task of determining the minimum AE-detectable crack size in actual cylinders.

  17. Oxidation, Creep And Fatigue Properties of Bare and Coated 31V alloy

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

    Dryepondt, Sebastien N.; Jones, Samuel J.; Zhang, Ying; Maziasz, Philip J.; Pint, Bruce A.

    2014-12-06

    Increasing the efficiency of natural gas reciprocating engines will require materials with better mechanical and corrosion resistance at high temperatures. One solution to increase the lifetime of exhaust valves is to apply an aluminide coating to prevent corrosion assisted fatigue cracking, but the impact of the coating on the valve material mechanical properties needs to be assessed. Creep and high cycle fatigue (HCF) testing were conducted at 816°C on bare and slurry or pack-coated 31V alloy. After annealing according to the 31V standard heat treatment, the coated and bare creep specimens exhibited very similar creep rupture lives. The HCF behaviormore »of the pack-coated alloy was close to the behavior of the bar alloy, but fatigue lifetimes of slurry-coated 31V specimens had higher variability. Aluminide coatings have the potential to improve the valve performance at high temperature, but the coating deposition process needs to be tailored for the substrate standard heat treatment.« less

  18. Scalar potential model of spiral galaxy HI rotation curves and rotation curve asymmetry

    E-Print Network [OSTI]

    John C. Hodge

    2006-11-22

    A scalar potential model (SPM) was developed from considerations of galaxy clusters and of redshift. The SPM is applied to HI rotation curves (RCs) and RC asymmetry of spiral galaxies. The resulting model adds the force of a scalar potential of the host galaxy and of neighboring galaxies to the Newtonian rotation velocity equation. The RC is partitioned radially into regions. The form of the equation for each parameter of each region is the same with differing proportionality constants. Integer values of each equation are determined empirically for each galaxy. Among the sample galaxies, the global properties of galaxies of B band luminosity, of position, and of orientation determine the RC and RC asymmetry. The Source of the scalar field acts as a monopole at distances of a few kpc from the centre of spiral galaxies. The scalar potential field causes Newtonian mechanics to considerably underestimate the mass in galaxies, which is the ``missing mass problem''. The SPM is consistent with RC and RC asymmetry observations of the sample spiral galaxies.

  19. The hidden X-ray breaks in afterglow light curves

    SciTech Connect (OSTI)

    Curran, P. A.; Wijers, R. A. M. J.; Horst, A. J. van der; Starling, R. L. C.

    2008-05-22

    Gamma-Ray Burst (GRB) afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared to the BeppoSAX, or pre-Swift era. Specifically, relatively few breaks, consistent with jet breaks, are observed in the X-ray light curves of these bursts. If these breaks are truly missing, it has serious consequences for the interpretation of GRB jet collimation and energy requirements, and the use of GRBs as standard candles.Here we address the issue of X-ray breaks which are possibly 'hidden' and hence the light curves are misinterpreted as being single power-laws. We show how a number of precedents, including GRB 990510 and GRB 060206, exist for such hidden breaks and how, even with the well sampled light curves of the Swift era, these breaks may be left misidentified. We do so by synthesising X-ray light curves and finding general trends via Monte Carlo analysis. Furthermore, in light of these simulations, we discuss how to best identify achromatic breaks in afterglow light curves via multi-wavelength analysis.

  20. A reaction-layer mechanism for the delayed failure of micron-scale polycrystalline silicon structural films subjected to high-cycle fatigue loading

    SciTech Connect (OSTI)

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

    2001-11-01

    A study has been made of high-cycle fatigue in 2um thick structural films of n+- type, polycrystalline silicon for MEMS applications.

  1. H. J. Sutherland, "Frequency Domain Analysis of the Fatigue Loads on Typical Wind Turbine Blades," J. of Solar Energy Engineering, Transactions of ASME, Vol. 118, November, 1996,

    E-Print Network [OSTI]

    ," J. of Solar Energy Engineering, Transactions of ASME, Vol. 118, November, 1996, pp. 204 Energy Technology Sandia National Laboratories Albuquerque, NM 87107 ABSTRACT The fatigue analysis

  2. Visualization of Growth Curve Data from Phenotype MicroarrayExperiments

    SciTech Connect (OSTI)

    Jacobsen, Janet S.; Joyner, Dominique C.; Borglin, Sharon E.; Hazen, Terry C.; Arkin, Adam P.; Bethel, E. Wes

    2007-04-19

    Phenotype microarrays provide a technology to simultaneouslysurvey the response of an organism to nearly 2,000 substrates, includingcarbon, nitrogen and potassium sources; varying pH; varying saltconcentrations; and antibiotics. In order to more quickly and easily viewand compare the large number of growth curves produced by phenotypemicroarray experiments, we have developed software to produce and displaycolor images, each of which corresponds to a set of 96 growth curves.Using color images to represent growth curves data has proven to be avaluable way to assess experiment quality, compare replicates, facilitatecomparison of the responses of different organisms, and identifysignificant phenotypes. The color images are linked to traditional plotsof growth versus time, as well as to information about the experiment,organism, and substrate. In order to share and view information and dataproject-wide, all information, plots, and data are accessible using onlya Web browser.

  3. An extinction curve template for intrinsically reddened quasars

    E-Print Network [OSTI]

    Zafar, Tayyaba; Watson, Darach; Fynbo, Johan P U; Krogager, Jens-Kristian; Zafar, Nosheen; Saturni, Francesci G; Geier5, Stefan; Venemans, Bram P

    2015-01-01

    We analyze the near-infrared to UV data of 16 quasars with redshifts ranging from 0.71 $New Technology Telescope (NTT). To study dust extinction curves intrinsic to the quasars, from the HAQ survey we selected 16 cases where the Small Magellanic Cloud (SMC) law could not provide a good solution to the spectral energy distributions (SEDs). We derived the extinction curves using Fitzpatrick & Massa 1986 (FM) law by comparing the observed SEDs to the combined quasar template from Vanden Berk et al. 2001 and Glikman et al. 2006. The derived extinction, $A_V$, ranges from 0.2-1.0 mag. All the individual extinction curves of our quasars are steeper ($...

  4. Combined Solar System and rotation curve constraints on MOND

    E-Print Network [OSTI]

    A. Hees; B. Famaey; G. W. Angus; G. Gentile

    2015-10-05

    The Modified Newtonian Dynamics (MOND) paradigm generically predicts that the external gravitational field in which a system is embedded can produce effects on its internal dynamics. In this communication, we first show that this External Field Effect can significantly improve some galactic rotation curves fits by decreasing the predicted velocities of the external part of the rotation curves. In modified gravity versions of MOND, this External Field Effect also appears in the Solar System and leads to a very good way to constrain the transition function of the theory. A combined analysis of the galactic rotation curves and Solar System constraints (provided by the Cassini spacecraft) rules out several classes of popular MOND transition functions, but leaves others viable. Moreover, we show that LISA Pathfinder will not be able to improve the current constraints on these still viable transition functions.

  5. Electromagnetic field limits set by the V-Curve.

    SciTech Connect (OSTI)

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Hudson, Howard Gerald

    2014-07-01

    When emitters of electromagnetic energy are operated in the vicinity of sensitive components, the electric field at the component location must be kept below a certain level in order to prevent the component from being damaged, or in the case of electro-explosive devices, initiating. The V-Curve is a convenient way to set the electric field limit because it requires minimal information about the problem configuration. In this report we will discuss the basis for the V-Curve. We also consider deviations from the original V-Curve resulting from inductive versus capacitive antennas, increases in directivity gain for long antennas, decreases in input impedance when operating in a bounded region, and mismatches dictated by transmission line losses. In addition, we consider mitigating effects resulting from limited antenna sizes.

  6. Fast identification of transits from light-curves

    E-Print Network [OSTI]

    Pavlos Protopapas; Raul Jimenez; Charles Alcock

    2005-02-15

    We present an algorithm that allows fast and efficient detection of transits, including planetary transits, from light-curves. The method is based on building an ensemble of fiducial models and compressing the data using the MOPED algorithm. We describe the method and demonstrate its efficiency by finding planet-like transits in simulated Pan-STARRS light-curves. We show that that our method is independent of the size of the search space of transit parameters. In large sets of light-curves, we achieve speed up factors of order of $10^{8}$ times over the full $\\chi2$ search. We discuss how the algorithm can be used in forthcoming large surveys like Pan-STARRS and LSST and how it may be optimized for future space missions like Kepler and COROT where most of the processing must be done on board.

  7. Automatic generation and analysis of solar cell IV curves

    SciTech Connect (OSTI)

    Kraft, Steven M.; Jones, Jason C.

    2014-06-03

    A photovoltaic system includes multiple strings of solar panels and a device presenting a DC load to the strings of solar panels. Output currents of the strings of solar panels may be sensed and provided to a computer that generates current-voltage (IV) curves of the strings of solar panels. Output voltages of the string of solar panels may be sensed at the string or at the device presenting the DC load. The DC load may be varied. Output currents of the strings of solar panels responsive to the variation of the DC load are sensed to generate IV curves of the strings of solar panels. IV curves may be compared and analyzed to evaluate performance of and detect problems with a string of solar panels.

  8. The Hardy inequality and the heat flow in curved wedges

    E-Print Network [OSTI]

    David Krejcirik

    2015-07-13

    We show that the polynomial decay rate of the heat semigroup of the Dirichlet Laplacian in curved planar wedges equals the sum of the usual dimensional decay rate and a multiple of the reciprocal value of the opening angle. To prove the result, we develop the method of self-similar variables for the associated heat equation and study the asymptotic behaviour of the transformed non-autonomous parabolic problem for large times. We also establish an improved Hardy inequality for the Dirichlet Laplacian in non-trivially curved wedges and state a conjecture about an improved decay rate in this case.

  9. Curved Herbig-Haro Jets: Simulations and Experiments

    E-Print Network [OSTI]

    A. Ciardi; D. J. Ampleford; S. V. Lebedev; C. Stehle

    2007-12-28

    Herbig-Haro jets often show some degree of curvature along their path, in many cases produced by the ram pressure of a side-wind. We present simulations of both laboratory and astrophysical curved jets and experimental results from laboratory experiments. We discuss the properties and similarities of the laboratory and astrophysical flow, which show the formation of internal shocks and working surfaces. In particular the results illustrate how the break-up of the bow-shock and clumps in the flow are produced without invoking jet variability; we also discuss how jet rotation reduces the growth of the Rayleigh-Taylor instability in curved jets.

  10. A Comparison of Vehicle Speed at Day and Night Rural Horizontal Curves 

    E-Print Network [OSTI]

    Quaium, Ridwan B.

    2010-07-14

    This thesis documents the linear mixed model developed for vehicle speed along two-lane two-way rural horizontal curves in the outside lane. Speed data at each curve was collected at four points along the curve including the midpoint of the curve...

  11. Fast and compact elliptic-curve cryptography Mike Hamburg

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    relatively compact. For example, on Intel Sandy Bridge, a curve with about 2250 points produces a signa- ture a difficult choice for less powerful systems such as embedded devices and smart phones. Cryptography Research Bridge microarchitecture. While RSA-2048 is still con- siderably faster at approximately 98k (even

  12. A Construction for Computer Visualization Certain Complex Curves

    E-Print Network [OSTI]

    Indiana University

    A Construction for Computer Visualization of Certain Complex Curves Andrew J. Hanson Computer representation of a manifold's geometry. Driven by this motivation, we found an extremely use- ful construction variables. Our construction is ideally suited for interactive computer graphics systems; in addition

  13. CURVES, K3 SURFACES, FANO THREEFOLDS PAUL HACKING

    E-Print Network [OSTI]

    Hacking, Paul

    CURVES, K3 SURFACES, FANO THREEFOLDS PAUL HACKING (Notes by Anna Kazanova) No Fano 3-fold in fact )) P(n r)-1 . Dimension dim G(r, n) = r(n - r). Date: 03/02/2012. 1 #12;2 PAUL HACKING · g = 6. Take

  14. Tracking stochastic resonance curves using an assisted reference model

    SciTech Connect (OSTI)

    Calderón Ramírez, Mario; Rico Martínez, Ramiro; Parmananda, P.

    2015-06-15

    The optimal noise amplitude for Stochastic Resonance (SR) is located employing an Artificial Neural Network (ANN) reference model with a nonlinear predictive capability. A modified Kalman Filter (KF) was coupled to this reference model in order to compensate for semi-quantitative forecast errors. Three manifestations of stochastic resonance, namely, Periodic Stochastic Resonance (PSR), Aperiodic Stochastic Resonance (ASR), and finally Coherence Resonance (CR) were considered. Using noise amplitude as the control parameter, for the case of PSR and ASR, the cross-correlation curve between the sub-threshold input signal and the system response is tracked. However, using the same parameter the Normalized Variance curve is tracked for the case of CR. The goal of the present work is to track these curves and converge to their respective extremal points. The ANN reference model strategy captures and subsequently predicts the nonlinear features of the model system while the KF compensates for the perturbations inherent to the superimposed noise. This technique, implemented in the FitzHugh-Nagumo model, enabled us to track the resonance curves and eventually locate their optimal (extremal) values. This would yield the optimal value of noise for the three manifestations of the SR phenomena.

  15. Wind Energy Learning Curves for Reference in Expert Elicitations

    E-Print Network [OSTI]

    Mountziaris, T. J.

    Wind Energy Learning Curves for Reference in Expert Elicitations Sarah Mangels, Erin Baker. Abstract: This study presents future projections of wind energy capacity and cost based on historical data. The study will be used during wind- energy expert elicitations (formal interviews aimed to quantify

  16. The Orbital Light Curve of Aquila X-1

    E-Print Network [OSTI]

    William F. Welsh; Edward L. Robinson; Patrick Young

    2000-04-25

    We obtained R- and I-band CCD photometry of the soft X-ray transient/neutron- star binary Aql X-1 in 1998 June while it was at quiescence. We find that its light curve is dominated by ellipsoidal variations, although the ellipsoidal variations are severely distorted and have unequal maxima. After we correct for the contaminating flux from a field star located only 0.46" away, the peak-to-peak amplitude of the modulation is ~0.25 mag in the R band, which requires the orbital inclination to be greater than 36 degrees. The orbital period we measure is consistent with the 18.95 h period measured by Chevalier & Ilovaisky (1998). During its outbursts the light curve of Aql X-1 becomes single humped. The outburst light curve observed by Garcia et al. (1999) agrees in phase with our quiescent light curve. We show that the single humped variation is caused by a ``reflection effect,'' that is, by heating of the side of the secondary star facing towards the neutron star.

  17. Late Time Tail of Wave Propagation on Curved Spacetime

    E-Print Network [OSTI]

    E. S. C. Ching; P. T. Leung; W. M. Suen; K. Young

    1994-10-30

    The late time behavior of waves propagating on a general curved spacetime is studied. The late time tail is not necessarily an inverse power of time. Our work extends, places in context, and provides understanding for the known results for the Schwarzschild spacetime. Analytic and numerical results are in excellent agreement.

  18. Supplemental Material Generalized Streak Lines Advected Tangent Curves

    E-Print Network [OSTI]

    of advected tangent curves. It turns out that generalized streak lines [WTS+ 07] can be described using. Generalized Streak Lines w = v, ¯f = FFF Wiebel et al. [WTS+ 07] introduced a generalization of streak lines. In Data Visualization 2003. Proc. VisSym 03, pages 141­148, 2003. [WTS+ 07] Alexander Wiebel, Xavier

  19. Compiler Assisted Elliptic Curve Cryptography M. Barbosa1

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Compiler Assisted Elliptic Curve Cryptography M. Barbosa1 , A. Moss2 and D. Page2 1 Departamento de and compilation techniques for cryptographic software, focusing on ECC in particular. Specifically, we describe and optimisation of ECC point arithmetic using a cryptography-aware lan- guage and compiler. Our main results show

  20. RIEMANN SURFACES, PLANE ALGEBRAIC CURVES AND THEIR PERIOD MATRICES

    E-Print Network [OSTI]

    numerically the canonical map. Therefore symmetric 1991 Mathematics Subject Classification. 14Q05, 14H55, 14P for computing a representation of a compact Riemann surface as an algebraic plane curve and to compute a numerical approximation for its period matrix. We will describe a program Cars ([3]) that can be used

  1. Monomial Embeddings of the Klein Curve \\Lambda Iwan M. Duursma

    E-Print Network [OSTI]

    Duursma, Iwan M.

    of the automor­ phism group. The curve has 24 flexpoints, i.e. points where the tangent intersects]. For the case N = 25, we first consider a configuration in PG(2; 8). Starting point are the seven points and seven lines of the Fano plane. Through the seven points pass 42 lines not in the Fano plane

  2. Symmetries for Galileons and DBI scalars on curved space

    SciTech Connect (OSTI)

    Goon, Garrett; Hinterbichler, Kurt; Trodden, Mark

    2011-07-08

    We introduced a general class of four-dimensional effective field theories which include curved space Galileons and DBI theories possessing nonlinear shift-like symmetries. These effective theories arise from purely gravitational actions and may prove relevant to the cosmology of both the early and late universe.

  3. Testing MONDian dark matter with galactic rotation curves

    SciTech Connect (OSTI)

    Edmonds, Doug [Department of Physics, Emory and Henry College, Emory, VA 24327 (United States); Farrah, Duncan; Minic, Djordje; Takeuchi, Tatsu [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Ho, Chiu Man [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Ng, Y. Jack, E-mail: dedmonds@ehc.edu, E-mail: farrah@vt.edu, E-mail: dminic@vt.edu, E-mail: takeuchi@vt.edu, E-mail: chiuman.ho@vanderbilt.edu, E-mail: yjng@physics.unc.edu [Institute of Field Physics, Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States)

    2014-09-20

    MONDian dark matter (MDM) is a new form of dark matter quantum that naturally accounts for Milgrom's scaling, usually associated with modified Newtonian dynamics (MOND), and theoretically behaves like cold dark matter (CDM) at cluster and cosmic scales. In this paper, we provide the first observational test of MDM by fitting rotation curves to a sample of 30 local spiral galaxies (z ? 0.003). For comparison, we also fit the galactic rotation curves using MOND and CDM. We find that all three models fit the data well. The rotation curves predicted by MDM and MOND are virtually indistinguishable over the range of observed radii (?1 to 30 kpc). The best-fit MDM and CDM density profiles are compared. We also compare with MDM the dark matter density profiles arising from MOND if Milgrom's formula is interpreted as Newtonian gravity with an extra source term instead of as a modification of inertia. We find that discrepancies between MDM and MOND will occur near the center of a typical spiral galaxy. In these regions, instead of continuing to rise sharply, the MDM mass density turns over and drops as we approach the center of the galaxy. Our results show that MDM, which restricts the nature of the dark matter quantum by accounting for Milgrom's scaling, accurately reproduces observed rotation curves.

  4. Fast Software Implementation of Binary Elliptic Curve Cryptography

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Fast Software Implementation of Binary Elliptic Curve Cryptography Manuel Bluhm1 and Shay Gueron2 protected software implementation of point multiplication for the standard NIST and SECG binary elliptic of their relatively short keys. Thus, software implementations of ECC for the high end server platforms become

  5. Twisted Ate Pairing on Hyperelliptic Curves and Applications

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    of Information Science and Technology, Sun Yat­Sen University, Guangzhou 510275, P.R.China isszhfg@mail.sysu.edu.cn 2 Guangdong Key Laboratory of Information Security Technology Guangzhou 510275, P.R.China Abstract hyperelliptic curves over prime fields with ordinary Jacobians by modeling on the Cocks­Pinch method

  6. Twisted Ate Pairing on Hyperelliptic Curves and Applications

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    of Information Science and Technology, Sun Yat-Sen University, Guangzhou 510275, P.R.China isszhfg@mail.sysu.edu.cn 2 Guangdong Key Laboratory of Information Security Technology Guangzhou 510275, P.R.China Abstract hyperelliptic curves over prime fields with ordinary Jacobians by modeling on the Cocks-Pinch method

  7. Guideline for bolted joint design and analysis : version 1.0.

    SciTech Connect (OSTI)

    Brown, Kevin H.; Morrow, Charles W.; Durbin, Samuel; Baca, Allen

    2008-01-01

    This document provides general guidance for the design and analysis of bolted joint connections. An overview of the current methods used to analyze bolted joint connections is given. Several methods for the design and analysis of bolted joint connections are presented. Guidance is provided for general bolted joint design, computation of preload uncertainty and preload loss, and the calculation of the bolted joint factor of safety. Axial loads, shear loads, thermal loads, and thread tear out are used in factor of safety calculations. Additionally, limited guidance is provided for fatigue considerations. An overview of an associated Mathcad{copyright} Worksheet containing all bolted joint design formulae presented is also provided.

  8. Regulatory Design for RES-E Support Mechanisms: Learning Curves, Market Structure, and Burden-Sharing

    E-Print Network [OSTI]

    Batlle, Carlos

    Drawing from relevant experiences in power systems around the world, this paper offers a critical review of existing policy support mechanisms for RES-E (renewable energy sources for electricity), with a detailed analysis ...

  9. The impact of modern headlamps on the design of sag vertical curves 

    E-Print Network [OSTI]

    Gogula, Madhuri

    2006-08-16

    in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, H. Gene Hawkins Committee Members, Dominique Lord Rodger J. Koppa Paul J. Carlson Head of Department, David V... will always remember his willingness to guide and support me during my graduate studies at Texas A&M University. I would like to thank my committee members, Dr. Dominique Lord, Dr. Rodger Koppa, and Dr. Paul Carlson for their valuable suggestions...

  10. Evaluation of design and operating speeds for crest vertical curves with limited sight distance 

    E-Print Network [OSTI]

    Russell, Charles William

    1994-01-01

    are also being considered. A integrated reservoir characterization technique is used to integrate the geological, engineering, and reservoir performance data to describe the reservoir and to develop an appropriate reservoir management plan. We have...

  11. Historical overview on Vacuum suitable Welding and fatigue resistance in Research Devices

    E-Print Network [OSTI]

    Wolf, Martin

    2015-01-01

    New inventions change the approach of vacuum suitable welding for research purpose. With orbital welding, laser welding and robot welding the possibilities increase to fabricate larger vessels more accurately. Despite this development there is still no perfect understanding on how to avoid virtual leaks and how to make such joints suitable for dynamic stress. By recalling its historical development, it is apparent how welding mistakes began occurring systematically and how to avoid them. With ASDEX-Upgrade as an example, it is shown how the attempt to conduct vacuum suitable welding has decreased the fatigue strength. ITER could repeat the mistakes of ASDEX-Upgrade even for unwanted welding (accidental fusing of joints).

  12. A Strategically Timed Verbal Task Improves Performance and Neurophysiological Alertness During Fatiguing Drives

    E-Print Network [OSTI]

    Atchley, Paul; Chan, Mark; Gregersen, Sabrina

    2013-08-06

    , fatigue inducing, drives which are more typical for motor carrier operators, military operations, or long-distance recreational drives. Second, improved performance was measured primarily by lateral vehicle control. While maintaining a stable lane... sounded if driving speed exceeded 125.53 km/h. Data collection began at the 0.600 km mark and ended at the 177.600 km mark. Data was divided into 9 blocks of 19.733 km. Braking events occurred in the first, fourth, seventh and ninth block of the drive...

  13. Fatigue fracture of thin plates under tensile and transverse shear stresses

    SciTech Connect (OSTI)

    Viz, M.J.; Zehnder, A.T.; Bamford, J.D.

    1995-12-31

    Crack growth in thin sheets loaded under tension and transverse shear is studied experimentally and the mechanics of such problems are reviewed. A small scale yielding approach is adopted that describes the crack tip fields using a combination if Kirchhoff plate theory and plane stress elasticity. Techniques for calculating the relevant stress intensity factors are presented and validated with results from six test cases. Fatigue crack growth rates are measured using a double-edge notch test specimen configuration loaded in tension and torsion. A geometrically nonlinear finite element computation is used to determine the stress intensity factors as functions of axial load, torque, and crack length.

  14. Effects of creatine loading on electromyographic fatigue threshold during cycle ergometry in college-aged women

    E-Print Network [OSTI]

    Smith, Abbie E.; Herda, Ashley A.; Herda, Trent J.; Ryan, Eric D.; Moon, Jordan R.; Cramer, Joel T.; Stout, Jeffrey R.

    2007-01-01

    @ou.edu; Joel T Cramer - jcramer@ou.edu; Jeffrey R Stout* - jrstout@ou.edu * Corresponding author Abstract The purpose of this study was to examine the effects of 5 days of Creatine (Cr) loading on the electromyographic fatigue threshold (EMGFT) in college...-aged women. Fifteen healthy college-aged women (mean ± SD = 22.3 ± 1.7 yrs) volunteered to participate in this double-blind, placebo- controlled study and were randomly placed into either placebo (PL – 10 g of flavored dextrose powder; n = 8) or creatine (Cr...

  15. Tensile creep of soil-cement and its relationship to fatigue 

    E-Print Network [OSTI]

    Kim, Youngsoo

    1985-01-01

    , D(t) = De + Dz x t . As a result, he was able to exPress the crack velocity explicitly and show the crack growth parameters, A and n in Paris' law, in terms of the creep parameters and material properties. A more detailed review of his theory...TENSILE CREEP OF SOIL-CEMENT AND ITS RELATIONSHIP TO FATIGUE A Thesis YOUNGSOO KIM Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1985 Major...

  16. Low-Cycle-Fatigue Behavior of Copper Materials and Their Use

    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 Administration would likeUniverseIMPACTThousand CubicResourcelogoFeet)LowCycle-Fatigue Behavior of Copper

  17. High temperature fracture and fatigue of ceramics. Annual technical progress report No. 6, August 15, 1994--August 14, 1995

    SciTech Connect (OSTI)

    Cox, B.

    1996-04-01

    This report covers work done in the first year of our new contract {open_quotes}High Temperature Fracture and Fatigue of Ceramics,{close_quotes} which commenced in August, 1995 as a follow-on from our prior contract {open_quotes}Mechanisms of Mechanical Fatigue in Ceramics.{close_quotes} Our activities have consisted mainly of studies of the failure of fibrous ceramic matrix composites (CMCs) at high temperature; with a little fundamental work on the role of stress redistribution in the statistics of fracture and cracking in the presence of viscous fluids.

  18. A COST BASED APPROACH TO DESIGN OF RESIDENTIAL STEEL ROOF SYSTEMS

    E-Print Network [OSTI]

    Mobasher, Barzin

    A COST BASED APPROACH TO DESIGN OF RESIDENTIAL STEEL ROOF SYSTEMS B. Mobasher1 , S-Y.Chen2 , C-5306 Abstract A comprehensive system for the design of residential steel roof truss systems is presented automatically design a roof truss given minimal input and using the design curves as the performance constraints

  19. Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction

    SciTech Connect (OSTI)

    Huang, Xianjun, E-mail: xianjun.huang@manchester.ac.uk [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Hu, Zhirun [School of Electrical and Electronic Engineering, University of Manchester, Manchester M13 9PL (United Kingdom); Liu, Peiguo [College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-11-15

    This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of the screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS) reduction applications.

  20. Driven Around the Bend: Novel Use of a Curved Steerable Needle

    SciTech Connect (OSTI)

    Murphy, Darra T. Korzan, Jeffrey R.; Ouellette, Hugue A.; Liu, David M.; Clarkson, Paul W.; Munk, Peter L.

    2013-04-15

    This technical note describes the novel use of a curved, steerable needle to access symptomatic osseous lesions in the pelvis and sacrum for palliative percutaneous treatment that would otherwise be difficult to treat using conventional straight needles. Seven patients with lytic bone lesions were treated. One patient had multiple myeloma; the remaining had metastatic disease: breast carcinoma (n = 2), colorectal carcinoma (n = 1), renal cell carcinoma (n = 1), squamous cell carcinoma (n = 1), and leiomyosarcoma (n = 1). Five of the seven patients had lesions in the posterior acetabulum, and the two other patients had lesions in the sacrum. Four of the seven patients received radiofrequency ablation followed by cementoplasty; three patients received cementation alone. We used a novel needle designed for vertebroplasty, which has an articulating tip allowing it to be guided into lytic bone lesions located in difficult-to-access regions of the pelvis and sacrum. All patients were successfully treated with cementoplasty either with or without thermal ablation. No serious adverse events were reported. The needle was difficult to withdraw in two patients. Steerable curved needles can be successfully used to treat lytic osseous metastases with cementoplasty when lesions are located in sites that may be difficult to reach using conventional straight needles.

  1. 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.

  2. Fatigue Testing of Metallurgically-Bonded EBR-II Superheater Tubes

    SciTech Connect (OSTI)

    T.C. Totemeier; D.M. Wachs; D.L. Porter

    2008-05-01

    Fatigue crack growth and impact tests were performed on 2¼Cr-1Mo steel specimens machined from ex-service Experimental Breeder Reactor – II (EBR-II) superheater duplex tubes. The tubes had been metallurgically bonded with a 100 µm thick Ni layer; the specimens incorporated this bond layer. Impact tests were performed at temperatures from –50 to 400°C; cracks propagating from the V-notch were arrested by delamination at the bond layer for all tests with one exception at –50°C. Fatigue crack growth tests were performed at room temperature in air and at 400°C in air and humid Ar; cracks were grown at varied levels of constant ?K. In all conditions the presence of the Ni bond layer was found to result in a net retardation of growth as the crack passed through the layer. The mechanism of retardation was identified as a disruption of crack planarity and uniformity after passing through the porous bond layer. Full crack arrest was only observed in a single test performed at near-threshold ?K level (12 MPa?m) at 400°C. In this case the crack tip was blunted by oxidation of the base steel at the steel-nickel interface.

  3. 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.

  4. Dissipative dark matter and the rotation curves of dwarf galaxies

    E-Print Network [OSTI]

    Foot, R

    2015-01-01

    There is ample evidence from rotation curves that dark matter halo's around disk galaxies have nontrivial dynamics. Of particular significance are: a) the cored dark matter profile of disk galaxies, b) correlations of the shape of rotation curves with baryonic properties, and c) the Tully-Fisher relation. Dark matter halo's around disk galaxies may have nontrivial dynamics if dark matter is strongly self interacting and dissipative. Multicomponent hidden sector dark matter featuring a massless `dark photon' (from an unbroken dark $U(1)$ gauge interaction) which kinetically mixes with the ordinary photon provides a concrete example of such dark matter. The kinetic mixing interaction facilitates halo heating by enabling ordinary supernovae to be a source of these `dark photons'. Dark matter halo's can expand and contract in response to the heating and cooling processes, but for a sufficiently isolated halo should have evolved to a steady state or `equilibrium' configuration where heating and cooling rates local...

  5. Sagittal focusing of synchrotron x radiation with curved crystals

    SciTech Connect (OSTI)

    Sparks, C.J. Jr.; Ice, G.E.; Wong, J.; Batterman, B.W.

    1981-01-01

    We describe the sagittal focusing of x rays with singly bent crystals that accept the meridian plane divergence from a similar but flat crystal to form a pair in a nondispersive two-crystal Bragg monochromator. Curved crystals can intercept from 5 to 20 times the sagittal divergence of curved mirrors at x-ray energies above 10 keV. Anticlastic (transverse) bending of the crystal is made negligible in the meridian plane with reinforcing ribs cut parallel to the plane of scattering. Results show that at energies of 10, 20, and 30 keV the bent crystal performs efficiently and images the source size at the Cornell High Energy Synchrotron Source.

  6. Curve fitting methods for solar radiation data modeling

    SciTech Connect (OSTI)

    Karim, Samsul Ariffin Abdul, E-mail: samsul-ariffin@petronas.com.my, E-mail: balbir@petronas.com.my; Singh, Balbir Singh Mahinder, E-mail: samsul-ariffin@petronas.com.my, E-mail: balbir@petronas.com.my [Department of Fundamental and Applied Sciences, Faculty of Sciences and Information Technology, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak Darul Ridzuan (Malaysia)

    2014-10-24

    This paper studies the use of several type of curve fitting method to smooth the global solar radiation data. After the data have been fitted by using curve fitting method, the mathematical model of global solar radiation will be developed. The error measurement was calculated by using goodness-fit statistics such as root mean square error (RMSE) and the value of R{sup 2}. The best fitting methods will be used as a starting point for the construction of mathematical modeling of solar radiation received in Universiti Teknologi PETRONAS (UTP) Malaysia. Numerical results indicated that Gaussian fitting and sine fitting (both with two terms) gives better results as compare with the other fitting methods.

  7. Trapping and guiding surface plasmons in curved graphene landscapes

    E-Print Network [OSTI]

    Smirnova, Daria; Wang, Zheng; Kivshar, Yuri S; Khanikaev, Alexander B

    2015-01-01

    We demonstrate that graphene placed on top of structured substrates offers a novel approach for trapping and guiding surface plasmons. A monolayer graphene with a spatially varying curvature exhibits an effective trapping potential for graphene plasmons near curved areas such as bumps, humps and wells. We derive the governing equation for describing such localized channel plasmons guided by curved graphene and validate our theory by the first-principle numerical simulations. The proposed confinement mechanism enables plasmon guiding by the regions of maximal curvature, and it offers a versatile platform for manipulating light in planar landscapes. In addition, isolated deformations of graphene such as bumps are shown to support localized surface modes and resonances suggesting a new way to engineer plasmonic metasurfaces.

  8. A consideration of a micro-Phillips' Curve 

    E-Print Network [OSTI]

    Paczkowski, Walter Richard

    1973-01-01

    Micro-Phillips' Curve (August 1973) j Walter Richard Paczkowski, A. B. , Rutgers College of Rutgers University; Directed by: Dr. Arthur S. De Vany The notion of a Phillips' Curve has been in the forefront of economic literature for over a decade... al Alt 0014 tQ W 0 Ql '0 Ql 40 g Q! 5 5~ Cl OA N 5 44 tU~ 44 '0 0 Ql 0 5 44 5 ttt 0 C 44 O 5 40 Ql 5 W Ql 5 0, 44 QU cd td 5 0! 5 Ql 5 5 5 B NC 5 Ql 5 44 ~ 44 5 5 Ql 5 ~ 0! B 'cl 04 44 0 Ql 44 40 0 cQ Ql 0 ~ 44 0 44 td 5 0 0 0 B...

  9. Generation of Closed Timelike Curves with Rotating Superconductors

    E-Print Network [OSTI]

    Clovis Jacinto de Matos

    2007-01-19

    The spacetime metric around a rotating SuperConductive Ring (SCR) is deduced from the gravitomagnetic London moment in rotating superconductors. It is shown that theoretically it is possible to generate Closed Timelike Curves (CTC) with rotating SCRs. The possibility to use these CTC's to travel in time as initially idealized by G\\"{o}del is investigated. It is shown however, that from a technology and experimental point of view these ideas are impossible to implement in the present context.

  10. Discontinuous quantum evolutions in the presence of closed timelike curves

    E-Print Network [OSTI]

    Richard DeJonghe; Kimberly Frey; Tom Imbo

    2010-05-06

    We consider Deutsch's computational model of a quantum system evolving in a spacetime containing closed timelike curves. Although it is known that this model predicts non-linear and non-unitary evolutions of the system, we demonstrate that it also gives rise to evolutions which are a discontinuous function of the input state. These discontinuities persist for the most natural modifications of Deutsch's approach.

  11. Design and optimization of polymer electrolyte membrane (PEM) fuel cells

    E-Print Network [OSTI]

    Grujicic, Mica

    Design and optimization of polymer electrolyte membrane (PEM) fuel cells M. Grujicic* , K optimization algorithm to determine an optimum design of the fuel cell with respect to the operation difference has the largest effect on the predicted polarization curve of the fuel cell. However, the optimal

  12. TPX: Contractor preliminary design review. Volume 3, Design and analysis

    SciTech Connect (OSTI)

    NONE

    1995-06-30

    Several models have been formed for investigating the maximum electromagnetic loading and magnetic field levels associated with the Tokamak Physics eXperiment (TPX) superconducting Poloidal Field (PF) coils. The analyses have been performed to support the design of the individual fourteen hoop coils forming the PF system. The coils have been sub-divided into three coil systems consisting of the central solenoid (CS), PF5 coils, and the larger radius PF6 and PF7 coils. Various electromagnetic analyses have been performed to determine the electromagnetic loadings that the coils will experience during normal operating conditions, plasma disruptions, and fault conditions. The loadings are presented as net body forces acting individual coils, spatial variations throughout the coil cross section, and force variations along the path of the conductor due to interactions with the TF coils. Three refined electromagnetic models of the PF coil system that include a turn-by-turn description of the fields and forces during a worst case event are presented in this report. A global model including both the TF and PF system was formed to obtain the force variations along the path of the PF conductors resulting from interactions with the TF currents. In addition to spatial variations, the loadings are further subdivided into time-varying and steady components so that structural fatigue issues can be addressed by designers and analysts. Other electromagnetic design issues such as the impact of the detailed coil designs on field errors are addressed in this report. Coil features that are analyzed include radial transitions via short jogs vs. spiral type windings and the effects of layer-to-layer rotations (i.e clocking) on the field errors.

  13. Proceedings of WindPower 95, AWEA, Washington, D.C., 1995. FATIGUE DAMAGE ESTIMATE COMPARISONS FOR

    E-Print Network [OSTI]

    Sandia National Laboratories Albuquerque, New Mexico N.D. Kelley Wind Technology Division NationalProceedings of WindPower 95, AWEA, Washington, D.C., 1995. FATIGUE DAMAGE ESTIMATE COMPARISONS FOR NORTHERN EUROPEAN AND U.S. WIND FARM LOADING ENVIRONMENTS H.J. Sutherland Wind Energy Technology Department

  14. Static and Fatigue Analysis of Wind Turbine Blades Subject to Cold Weather Conditions Using Finite Element Analysis

    E-Print Network [OSTI]

    Victoria, University of

    Static and Fatigue Analysis of Wind Turbine Blades Subject to Cold Weather Conditions Using Finite Turbine Blades Subject to Cold Weather Conditions Using Finite Element Analysis by Patricio Andres Lillo experienced in candi- date Canadian wind turbine deployment locations. The thesis then narrows its focus

  15. Staring at a computer screen for hours at a time can result in fatigue, eyestrain, headaches and other problems.

    E-Print Network [OSTI]

    Slatton, Clint

    and clarity. The computer should be placed at right angles to any windows. Light from windows either aheadStaring at a computer screen for hours at a time can result in fatigue, eyestrain, headaches make computer use more comfortable for your eyes. These are signs of eye problems that can be caused

  16. Int. Symposium on Mechanics and Materials, May 9-14, 2010, Greece Fatigue Investigation of Ultrasonic Impact Treatment

    E-Print Network [OSTI]

    Aristomenis, Antoniadis

    31st Int. Symposium on Mechanics and Materials, May 9-14, 2010, Greece Fatigue Investigation Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece 2 School of Pedagogical and Technological Education, 14121 N. Heraklion, Athens, Greece 3 Technological Educational Institution of Serres, 62124

  17. Fracture and Fatigue Behavior at Ambient and Elevated Temperatures of Alumina Bonded with Copper/Niobium/Copper Interlayers

    E-Print Network [OSTI]

    Ritchie, Robert

    Fracture and Fatigue Behavior at Ambient and Elevated Temperatures of Alumina Bonded with Copper and Engineering, University of California, Berkeley, California 94720 Interfacial fracture toughness and cyclic temperatures, and assessed in terms of interfacial chemistry and microstructure. The mean interfacial fracture

  18. High-Frequency Fatigue Behavior of Woven-Fiber-Fabric-Reinforced Polymer-Derived Ceramic-Matrix Composites

    E-Print Network [OSTI]

    Barber, James R.

    heat exchangers, continuous-fiber-reinforced ceramic- matrix composites (CFCMCs) will encounter cyclic glass-matrix composite showed that, unlike monolithic ceramics, fatigue life of this composite decreased. The emphasis of processing research in the ceramic-matrix composite (CMC) area has increasingly shifted from

  19. 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

  20. HIGH-TEMPERATURE FRACTURE AND FATIGUE RESISTANCE OF A DUCTILE b-TiNb REINFORCED g-TiAl

    E-Print Network [OSTI]

    Ritchie, Robert

    are in part aimed at improving their low room-temperature ten- sile ductility and fracture toughness, bothHIGH-TEMPERATURE FRACTURE AND FATIGUE RESISTANCE OF A DUCTILE b-TiNb REINFORCED g the fracture toughness of g-TiAl, even at high temperatures, from about 12 to H40 MPa m1/2 , although

  1. Effects of plastic constraint on the cyclic and static fatigue behavior of metal/ceramic layered structures

    E-Print Network [OSTI]

    Ritchie, Robert

    Effects of plastic constraint on the cyclic and static fatigue behavior of metal/ceramic layered of metal/ceramic layered structures is examined under cyclic and static loading conditions. Crack-crack growth; Stress-corrosion cracking; Plastic constraint; Alumina; Aluminum 1. Introduction Metal/ceramic

  2. High-cycle fatigue of nickel-base superalloy Rene 104 (ME3): Interaction of microstructurally small cracks with

    E-Print Network [OSTI]

    Ritchie, Robert

    of turbine engine failures in aircraft. In this work, we consider the feasibility of using grain-cycle fatigue (HCF) in turbine engine components represents a problem of considerable importance for civilian. In conventional gas-turbine engines, the highest temperature components are invariably made of nickel

  3. 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

  4. High-Cycle Fatigue of Nickel-Based Superalloy ME3 at Ambient and Elevated Temperatures: Role of

    E-Print Network [OSTI]

    Ritchie, Robert O.

    periods, possibly within a single flight segment. Conse- quently, HCF-critical turbine-engine components of Grain-Boundary Engineering YONG GAO, MUKUL KUMAR, R.K. NALLA, and R.O. RITCHIE High-cycle fatigue (HCF-frequency cyclic loading, remains a principal cause of failures in gas-turbine propul- sion systems. In this work

  5. Materials and design bases issues in ASME Code Case N-47

    SciTech Connect (OSTI)

    Huddleston, R.L.; Swindeman, R.W. [Oak Ridge National Lab., TN (United States)

    1993-04-01

    A preliminary evaluation of the design bases (principally ASME Code Case N-47) was conducted for design and operation of reactors at elevated temperatures where the time-dependent effects of creep, creep-fatigue, and creep ratcheting are significant. Areas where Code rules or regulatory guides may be lacking or inadequate to ensure the operation over the expected life cycles for the next-generation advanced high-temperature reactor systems, with designs to be certified by the US Nuclear Regulatory Commission, have been identified as unresolved issues. Twenty-two unresolved issues were identified and brief scoping plans developed for resolving these issues.

  6. 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.

  7. On estimating functional average breakthrough curve using time-warping technique and perturbation approach

    E-Print Network [OSTI]

    Lu, Zhiming

    March 2012; published 22 May 2012. [1] Simulated contaminant breakthrough curves (BTC) are often used directly. In this study, we consider each BTC as a random curve, and use time-warping techniques to align

  8. On the Computation of Integral Curves in Adaptive Mesh Refinement Vector Fields

    E-Print Network [OSTI]

    Deines, Eduard

    2012-01-01

    Gen- eration of accurate integral surfaces in time-dependent2002. On the Computation of Integral Curves in Adaptive MeshOn the Computation of Integral Curves in Adaptive Mesh Re?

  9. Conjectured Security of the ANSI-NIST Elliptic Curve RNG Daniel R. L. Brown

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Conjectured Security of the ANSI-NIST Elliptic Curve RNG Daniel R. L. Brown March 29, 2006 Abstract An elliptic curve random number generator (ECRNG) has been proposed in ANSI and NIST draft standards

  10. Engitectural Design 

    E-Print Network [OSTI]

    Gagliardi, D. R.

    1996-01-01

    to the mechanical systems of building, and in a hot and humid climate the issues are magnified. Therefore, this paper will discuss the concepts and merits of a new design process called: Engitectural Design. Engitectural Design is the concept of blending the many...

  11. On-line monitoring of power curves Andrew Kusiak*, Haiyang Zheng, Zhe Song

    E-Print Network [OSTI]

    Kusiak, Andrew

    are constructed using historical wind turbine data. Three power curve models are developed, one by the least by the control system. To analyze the performance of wind turbines, the SCADA data collected at a wind farm has of wind turbines is presented. Turbine performance is captured with a power curve. The power curves

  12. Potential energy curves for NO+ D. L. Albritton and A. L. Schmeltekopf

    E-Print Network [OSTI]

    ' potential energy curves that are based on the best current experimental and theo- retical knowledgePotential energy curves for NO+ D. L. Albritton and A. L. Schmeltekopf Aeronomy Laboratory. NOAA of the electronic structure of the NO+ ion. Based on these results. new potential energy curves for the electronic

  13. Ris-R-Report Multi-MW wind turbine power curve

    E-Print Network [OSTI]

    Risø-R-Report Multi-MW wind turbine power curve measurements using remote sensing instruments Wagner, Michael Courtney Title: Multi-MW wind turbine power curve measurements using remote sensing (max. 2000 char.): Power curve measurement for large wind turbines requires taking into account more

  14. Building curves with arbitrary small MOV degree over nite prime elds

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Building curves with arbitrary small MOV degree over #12;nite prime #12;elds R. Dupont, A. Enge, F for building ordinary elliptic curves over #12;nite prime #12;elds having arbitrary small MOV degree. The el and Shacham leave it as an open problem to build curves with k = 10). In [22] Miyaji, Nakabayashi and Takano

  15. WORKING PAPER N 2007 -12 Education inequalities and the Kuznets curves

    E-Print Network [OSTI]

    Boyer, Edmond

    WORKING PAPER N° 2007 - 12 Education inequalities and the Kuznets curves: a global perspective, human capital, economic history, Kuznets curve. PARIS-JOURDAN SCIENCES ECONOMIQUES LABORATOIRE D2011 #12;Education Inequalities and the Kuznets Curves: A Global Perspective Since 1870 Christian

  16. Bolometric Light Curves of Type Ia Supernovae G. Contardo 1;2 , B. Leibundgut 1

    E-Print Network [OSTI]

    Leibundgut, Bruno

    Bolometric Light Curves of Type Ia Supernovae G. Contardo 1;2 , B. Leibundgut 1 1 European Southern, Karl­Schwarzschild­Straße 1, D­85748 Garch­ ing, Germany 1.1 Light Curves of Type Ia Supernovae Substantial information about the processes in supernovae is contained in their light curves. They track

  17. Jacobi Quartic Curves Revisited Huseyin Hisil, Kenneth Koon-Ho Wong, Gary Carter, Ed Dawson

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Jacobi Quartic Curves Revisited Huseyin Hisil, Kenneth Koon-Ho Wong, Gary Carter, Ed Dawson. Abstract This paper provides new results about efficient arithmetic on (extended) Jacobi quartic form elliptic curves y2 = dx4 + 2ax2 + 1. Recent works have shown that arithmetic on an elliptic curve in Jacobi

  18. Number of Jacobi quartic curves over finite Rongquan Feng 1 , Hongfeng Wu 2

    E-Print Network [OSTI]

    International Association for Cryptologic Research (IACR)

    Number of Jacobi quartic curves over finite fields #3; Rongquan Feng 1 , Hongfeng Wu 2 1 LMAM@gmail.com Abstract In this paper the number of F q ­isomorphism classes of Jacobi quar­ tic curves, i.e., the number of Jacobi quartic curves with distinct j­ invariants, over finite field F q is enumerated. Keywords

  19. The Geometric Invariants of Null Cartan Curves Under The Similarity Transformations

    E-Print Network [OSTI]

    Hakan Simsek; Mustafa Özdemir

    2015-04-07

    In this paper, we study the differential geometry of null Cartan curves under the similarity transformations in the Minkowski space-time. Besides, we extend the fundamental theorem for a null Cartan curve according to a similarity motion. We find the equations of all self-similar null curves which is given its shape Cartan curvatures.

  20. Transit light curves with finite integration time: Fisher information analysis

    SciTech Connect (OSTI)

    Price, Ellen M.; Rogers, Leslie A.

    2014-10-10

    Kepler has revolutionized the study of transiting planets with its unprecedented photometric precision on more than 150,000 target stars. Most of the transiting planet candidates detected by Kepler have been observed as long-cadence targets with 30 minute integration times, and the upcoming Transiting Exoplanet Survey Satellite will record full frame images with a similar integration time. Integrations of 30 minutes affect the transit shape, particularly for small planets and in cases of low signal to noise. Using the Fisher information matrix technique, we derive analytic approximations for the variances and covariances on the transit parameters obtained from fitting light curve photometry collected with a finite integration time. We find that binning the light curve can significantly increase the uncertainties and covariances on the inferred parameters when comparing scenarios with constant total signal to noise (constant total integration time in the absence of read noise). Uncertainties on the transit ingress/egress time increase by a factor of 34 for Earth-size planets and 3.4 for Jupiter-size planets around Sun-like stars for integration times of 30 minutes compared to instantaneously sampled light curves. Similarly, uncertainties on the mid-transit time for Earth and Jupiter-size planets increase by factors of 3.9 and 1.4. Uncertainties on the transit depth are largely unaffected by finite integration times. While correlations among the transit depth, ingress duration, and transit duration all increase in magnitude with longer integration times, the mid-transit time remains uncorrelated with the other parameters. We provide code in Python and Mathematica for predicting the variances and covariances at www.its.caltech.edu/?eprice.

  1. How current loops and solenoids curve space-time

    E-Print Network [OSTI]

    A. Füzfa

    2015-04-01

    The curved space-time around current loops and solenoids carrying arbitrarily large steady electric currents is obtained from the numerical resolution of the coupled Einstein-Maxwell equations in cylindrical symmetry. The artificial gravitational field associated to the generation of a magnetic field produces gravitational redshift of photons and gravitational acceleration of neutral massive particles. The strength of the generated gravitational field is extremely weak from what can be obtained through present technology, although it might be detectable with high-precision measurements such as atom interferometry.

  2. Validity of the Hadronic Freeze-Out Curve

    E-Print Network [OSTI]

    F. Becattini; M. Bleicher; T. Kollegger; M. Mitrovski; T. Schuster; R. Stock

    2011-07-08

    We analyze hadro-chemical freeze-out in central Pb+Pb collisions at CERN SPS energies, employing the hybrid version of UrQMD which models hadronization by the Cooper-Frye mechanism, and matches to a final hadron-resonance cascade. We fit the results both before and after the cascade stage using the Statistical Hadronization Model, to assess the effect of the cascade phase. We observe a strong effect on antibaryon yields except anti-{\\Omega}, resulting in a shift in T and {\\mu}_B. We discuss the implications for the freeze-out curve.

  3. Learning Curves For Energy Technology: A Critical Assessment

    E-Print Network [OSTI]

    Jamasb, Tooraj; Kohler, Jonathan

    hydro 0.48% 2.8% 8 Waste to electricity 41.5% 57.9% 9 Nuclear light water reactor 37.6% 53.2% 10 Wind - onshore 13.1% 15.7% 11 Solar thermal power 2.2% 22.5% 12 Wind – offshore 1.0% 8.3% Table 1: Learning by doing rates using single-factor curves... Farms, Energy Policy, Vol. 33, 133-150. Klassen, G., Miketa, A., Larsen, K., and Sundqvist, T. (2002). The Impact of R&D on Innovation for Wind Energy in Denmark, Germany, and the United Kingdom, paper presented at the International Energy Workshop...

  4. Tyre curve estimation in slip-controlled braking

    E-Print Network [OSTI]

    Miller, Jonathan I.; Cebon, David

    2015-06-09

    identifying a Kalman filter observer for vehicle handling dynamics. IMECHE Part D – J. of Auto. Eng. 2006; 220: 1063–1072. 27. Yi J et al. Emergency braking control with an observer-based dynamic tire/road friction model and wheel angular velocity... also used by Shim et al.15, and Hong et al.16 Unsal and Kachroo17 compared an EKF with a sliding mode observer to estimate vehicle velocity, using this estimated velocity with a nominal slip-friction curve to determine the braking force. The authors...

  5. Broadband turbulent spectra in gamma-ray burst light curves

    SciTech Connect (OSTI)

    Van Putten, Maurice H. P. M.; Guidorzi, Cristiano; Frontera, Filippo

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  6. Light curves from supernova shock breakout through an extended wind

    SciTech Connect (OSTI)

    Ginzburg, Sivan; Balberg, Shmuel [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel)

    2014-01-01

    Recent observations suggest that some supernovae may be the result of an explosion into an optically thick circumstellar material, the product of pre-explosion mass loss (wind) by the progenitor star. This scenario has been studied previously both analytically and numerically. However, many previous studies base their analysis on the diffusion approximation for radiation transfer, which is inappropriate in the optically thin outer layers of the wind. Here we study the deviations from diffusion and calculate light curves more accurately using a Monte Carlo approach to photon transfer. We distinguish between 'compact' winds, for which the diffusion approximation is appropriate, and 'extended' winds, which require a more delicate treatment of the radiation. We show that this effect is more significant than that of the light-travel time difference to a distant observer, which has a secondary influence on the light curves of extended-wind systems. We also comment on the applicability of the widely used flux-limited diffusion approximation in this context: we find that it generally does not reproduce the Monte Carlo results. The flux-limited diffusion approximation leads to results that are not only quantitatively but also qualitatively wrong in the extended-wind regime.

  7. On the Nuclear Rotation Curve of M31

    E-Print Network [OSTI]

    Thomas S. Statler

    1999-05-08

    The nuclear rotation curve of M31, as observed by the Hubble Space Telescope Faint Object Camera Spectrograph, shows a significant disturbance coinciding with the off-center brightness peak, P1. This +/- 60 km/s feature is distinguished by a local velocity maximum centered on P1 and a local minimum approxmately 0.08" closer to P2. If the M31 double nucleus is an eccentric disk with an off-center density concentration, as suggested by Tremaine, then the self-gravity of the disk can produce just such a disturbance. The expected kinematic signature is calculated approximately by examining sequences of closed periodic orbits in a Kepler potential perturbed by a model disk potential that precesses at constant frequency. The perturbation forces a steep negative eccentricity gradient in the sequence of closed orbits through the densest part of the disk, which reverses the arrangement of periapsis and apoapsis with respect to the central mass. Stars making up the inner part of the density concentration are at apoapsis, while stars making up the outer part are at periapsis, producing a steep local velocity gradient. This result is independent of the details of the mass distribution. The projected rotation curve of the model is shown to closely resemble that of M31, giving strong support to the eccentric disk picture.

  8. Averaged null energy condition and quantum inequalities in curved spacetime

    E-Print Network [OSTI]

    Eleni-Alexandra Kontou

    2015-07-22

    The Averaged Null Energy Condition (ANEC) states that the integral along a complete null geodesic of the projection of the stress-energy tensor onto the tangent vector to the geodesic cannot be negative. ANEC can be used to rule out spacetimes with exotic phenomena, such as closed timelike curves, superluminal travel and wormholes. We prove that ANEC is obeyed by a minimally-coupled, free quantum scalar field on any achronal null geodesic (not two points can be connected with a timelike curve) surrounded by a tubular neighborhood whose curvature is produced by a classical source. To prove ANEC we use a null-projected quantum inequality, which provides constraints on how negative the weighted average of the renormalized stress-energy tensor of a quantum field can be. Starting with a general result of Fewster and Smith, we first derive a timelike projected quantum inequality for a minimally-coupled scalar field on flat spacetime with a background potential. Using that result we proceed to find the bound of a quantum inequality on a geodesic in a spacetime with small curvature, working to first order in the Ricci tensor and its derivatives. The last step is to derive a bound for the null-projected quantum inequality on a general timelike path. Finally we use that result to prove achronal ANEC in spacetimes with small curvature.

  9. Averaged null energy condition and quantum inequalities in curved spacetime

    E-Print Network [OSTI]

    Kontou, Eleni-Alexandra

    2015-01-01

    The Averaged Null Energy Condition (ANEC) states that the integral along a complete null geodesic of the projection of the stress-energy tensor onto the tangent vector to the geodesic cannot be negative. ANEC can be used to rule out spacetimes with exotic phenomena, such as closed timelike curves, superluminal travel and wormholes. We prove that ANEC is obeyed by a minimally-coupled, free quantum scalar field on any achronal null geodesic (not two points can be connected with a timelike curve) surrounded by a tubular neighborhood whose curvature is produced by a classical source. To prove ANEC we use a null-projected quantum inequality, which provides constraints on how negative the weighted average of the renormalized stress-energy tensor of a quantum field can be. Starting with a general result of Fewster and Smith, we first derive a timelike projected quantum inequality for a minimally-coupled scalar field on flat spacetime with a background potential. Using that result we proceed to find the bound of a qu...

  10. Incorporation of learning curve costs in acquisition strategy optimization

    SciTech Connect (OSTI)

    Loerch, A.

    1994-12-31

    Each year, the United States Army procures billions of dollars worth of weapons and equipment so that it can accomplish its worldwide mission of deterrence. The process of deciding what to buy, in what quantities, and when to best respond to the threat posed by potential adversaries, is extremely complex, requiring extensive analysis. Two techniques commonly used in this analysis are mathematical programming and cost estimation. Although they are related through constraints on available procurement funds, the use of nonlinear cost learning curves, which more accurately represent system costs as a function of quantity produced, have not been incorporated into mathematical programming formulations that compute the quantities of items to be procured. As a result, the solutions obtained could be either suboptimal, or even infeasible with respect to budgetary limitations. We present a mixed integer programming formulation that uses a piecewise linear approximation of the learning curve costs for a more accurate portrayal of budgetary constraints. In addition, implementation issues are discussed, and performance results are given.

  11. Fields and fluids on curved non-relativistic spacetimes

    E-Print Network [OSTI]

    Michael Geracie; Kartik Prabhu; Matthew M. Roberts

    2015-09-23

    We consider non-relativistic curved geometries and argue that the background structure should be generalized from that considered in previous works. In this approach the derivative operator is defined by a Galilean spin connection valued in the Lie algebra of the Galilean group. This includes the usual spin connection plus an additional "boost connection" which parameterizes the freedom in the derivative operator not fixed by torsion or metric compatibility. As an example we write down the most general theory of dissipative fluids consistent with the second law in curved non-relativistic geometries and find significant differences in the allowed transport coefficients from those found previously. Kubo formulas for all response coefficients are presented. Our approach also immediately generalizes to systems with independent mass and charge currents as would arise in multicomponent fluids. Along the way we also discuss how to write general locally Galilean invariant non-relativistic actions for multiple particle species at any order in derivatives. A detailed review of the geometry and its relation to non-relativistic limits may be found in a companion paper [arXiv:1503.02682].

  12. Magnetar Driven Shock Breakout and Double Peaked Supernova Light Curves

    E-Print Network [OSTI]

    Kasen, Daniel; Bildsten, Lars

    2015-01-01

    The light curves of some luminous supernovae are suspected to be powered by the spindown energy of a rapidly rotating magnetar. Here we describe a possible signature of the central engine: a burst of shock breakout emission occurring several days after the supernova explosion. The energy input from the magnetar inflates a high-pressure bubble that drives a shock through the pre-exploded supernova ejecta. If the magnetar is powerful enough, that shock will near the ejecta surface and become radiative. At the time of shock breakout, the ejecta will have expanded to a large radius (~10^{14} cm) so that the radiation released is at optical/ultraviolet wavelengths (T ~ 20,000 K) and lasts for several days. The luminosity and timescale of this magnetar driven shock breakout are similar to the first peak observed recently in the double-peaked light curve of SN-LSQ14BDQ. However, for a large region of model parameter space, the breakout emission is predicted to be dimmer than the diffusive luminosity from direct magn...

  13. Linearly resummed hydrodynamics in a weakly curved spacetime

    E-Print Network [OSTI]

    Yanyan Bu; Michael Lublinsky

    2015-02-27

    We extend our study of all-order linearly resummed hydrodynamics in a flat space~\\cite{1406.7222,1409.3095} to fluids in weakly curved spaces. The underlying microscopic theory is a finite temperature $\\mathcal{N}=4$ super-Yang-Mills theory at strong coupling. The AdS/CFT correspondence relates black brane solutions of the Einstein gravity in asymptotically \\emph{locally} $\\textrm{AdS}_5$ geometry to relativistic conformal fluids in a weakly curved 4D background. To linear order in the amplitude of hydrodynamic variables and metric perturbations, the fluid's energy-momentum tensor is computed with derivatives of both the fluid velocity and background metric resummed to all orders. We extensively discuss the meaning of all order hydrodynamics by expressing it in terms of the memory function formalism, which is also suitable for practical simulations. In addition to two viscosity functions discussed at length in refs.~\\cite{1406.7222,1409.3095}, we find four curvature induced structures coupled to the fluid via new transport coefficient functions. In ref.~\\cite{0905.4069}, the latter were referred to as gravitational susceptibilities of the fluid. We analytically compute these coefficients in the hydrodynamic limit, and then numerically up to large values of momenta.

  14. Adsorption of annealed branched polymers on curved surfaces

    E-Print Network [OSTI]

    Wagner, Jef; Zandi, Roya

    2015-01-01

    The behavior of annealed branched polymers near adsorbing surfaces plays a fundamental role in many biological and industrial processes. Most importantly single stranded RNA in solution tends to fold up and self-bind to form a highly branched structure. Using a mean field theory, we both perturbatively and numerically examine the adsorption of branched polymers on surfaces of several different geometries in a good solvent. Independent of the geometry of the wall, we observe that as branching density increases, surface tension decreases. However, we find a coupling between the branching density and curvature in that a further lowering of surface tension occurs when the wall curves towards the polymer, but the amount of lowering of surface tension decreases when the wall curves away from the polymer. We find that for branched polymers confined into spherical cavities, most of branch-points are located in the vicinity of the interior wall and the surface tension is minimized for a critical cavity radius. For bra...

  15. Design and Analysis of the ITER Vertical Stability Coils

    SciTech Connect (OSTI)

    Peter H. Titus, et. al.

    2012-09-06

    The ITER vertical stability (VS) coils have been developed through the preliminary design phase by Princeton Plasma Physics Laboratory (PPPL). Final design, prototyping and construction will be carried out by the Chinese Participant Team contributing lab, Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). The VS coils are a part of the in-vessel coil systems which include edge localized mode (ELM) coils as well as the VS coils. An overview of the ELM coils is provided in another paper at this conference. 15 The VS design employs four turns of stainless steel jacketed mineral insulated copper (SSMIC) conductors The mineral insulation is Magnesium Oxide (MgO). Joule and nuclear heat is removed by water flowing at 3 m/s through the hollow copper conductor. A key element in the design is that slightly elevated temperatures in the conductor and its support spine during operation impose compressive stresses that mitigate fatigue damage. Away from joints, and break-outs, conductor thermal stresses are low because of the axisymmetry of the winding (there are no corner bends as in the ELM coils).The 120 degree segment joint, and break-out or terminal regions are designed with similar but imperfect constraint compared with the ring coil portion of the VS. The support for the break-out region is made from a high strength copper alloy, CuCrZr. This is needed to conduct nuclear heat to the actively cooled conductor and to the vessel wall. The support "spine" for the ring coil portion of the VS is 316 stainless steel, held to the vessel with preloaded 718 bolts. Lorentz loads resulting from normal operating loads, disruption loads and loads from disruption currents in the support spine shared with vessel, are applied to the VS coil. The transmission of the Lorentz and thermal expansion loads from the "spine" to the vessel rails is via friction augmented with a restraining "lip" to ensure the coil frictional slip is minimal and acceptable. Stresses in the coil, joints, and break-outs are presented. These are compared with static and fatigue allowables. Design for fatigue is much less demanding than for the ELM coils. A total of 30,000 cycles is required for VS design. Loads on the vessel due to the thermal expansion of the coil and spine are significant. Efforts to reduce these by reducing the cross section of the spine have been made but the vessel still must support loads resulting from restraint of thermal expansion.

  16. On the influence of mechanical surface treatments*/deep rolling and laser shock peening*/on the fatigue behavior of Ti/6Al/4V at

    E-Print Network [OSTI]

    Ritchie, Robert

    corrosion, and in particular to enhance the fatigue strength of highly-stressed metallic components used aircraft components, deep rolling (DR) offers several attractive advantages due to the generation

  17. A Parameter Study of Type II Supernova Light Curves Using 6 M_odot He Cores

    E-Print Network [OSTI]

    Timothy R. Young

    2004-09-13

    Results of numerical calculations of Type II supernova light curves are presented. The model progenitor stars have 6 $M{_\\odot}$ cores and various envelopes, originating from a numerically evolved 20 $M{_\\odot}$ star. Five parameters that affect the light curves are examined: the ejected mass, the progenitor radius, the explosion energy, the $^{56}$Ni mass, and the extent of $^{56}$Ni mixing. The following affects have been found: 1) the larger the progenitor radius the brighter the early--time light curve, with little affect on the late--time light curve, 2) the larger the envelope mass the fainter the early light curve and the flatter the slope of the late light curve, 3) the larger the explosion energy the brighter the early light curve and the steeper the slope of the late light curve, 4) the larger the $^{56}$Ni mass the brighter the overall light curve after 20 to 50 days, with no affect on the early light curve, 5) the more extensive the $^{56}$Ni mixing the brighter the early light curve and the steeper the late light curve. The primary parameters affecting the light curve shape are the progenitor radius and the ejected mass. The secondary parameters are the explosion energy, $^{56}$Ni mass and $^{56}$Ni mixing. I find that while in principle the general shape and absolute magnitude of a light curve indicate a unique set of parameters, in practice it is difficult to avoid some ambiguity in the parameters. I find that the nickel--powered diffusion wave and the recombination of helium produce a prominent secondary peak in all our calculations. The feature is less prominent when compositional mixing, both $^{56}$Ni mixing and mixing between the hydrogen and helium layers, occurs. The model photospheric temperatures and velocities are presented, for comparison to observation.

  18. Generating Smooth Parting Lines for Mold Design for Meshes Ralph R. Martin

    E-Print Network [OSTI]

    Martin, Ralph R.

    Generating Smooth Parting Lines for Mold Design for Meshes Weishi Li Ralph R. Martin Frank C; (d) chosen cycle; (e) final parting line. Abstract This paper considers the mold design problem.C.Langbein@cs.cf.ac.uk Keywords: parting line, mesh, mold design 1 Introduction A parting line is a curve on the surface

  19. Experimental Study on Shear Fatigue Behavior and Stiffness Performance of Warm Mix Asphalt by adding Synthetic Wax

    E-Print Network [OSTI]

    Petit, Christophe; Canestrari, Francesco; Pannunzio, Valter; Virgili, Amadeo

    2012-01-01

    Synthetic waxes produced by standard and registered processes may be used to manufacture Warm Mix Asphalt (WMA), which is a modified asphalt concrete produced, applied and compacted at temperatures below those typically required. This feature leads to environmental benefits, such as reduced energy consumption, gas and fume emissions, as well as to economic/operational advantages, such as lower production costs and greater hauling distances for extended construction seasons with tighter schedules. The present article serves to compare the mechanical performance of a WMA produced by adding synthetic wax with a traditional Hot Mix Asphalt (HMA) specimen, in terms of shear fatigue response and both complex and stiffness moduli. The experimental results and related modeling work demonstrate that adding synthetic wax into the WMA composition does not hinder either the destructive or non-destructive performance of an HMA, and this finding is corroborated by respectively measuring fatigue life and stiffness.

  20. Experimental Study on Shear Fatigue Behavior and Stiffness Performance of Warm Mix Asphalt by adding Synthetic Wax

    E-Print Network [OSTI]

    Christophe Petit; Anne Millien; Francesco Canestrari; Valter Pannunzio; Amadeo Virgili

    2012-03-13

    Synthetic waxes produced by standard and registered processes may be used to manufacture Warm Mix Asphalt (WMA), which is a modified asphalt concrete produced, applied and compacted at temperatures below those typically required. This feature leads to environmental benefits, such as reduced energy consumption, gas and fume emissions, as well as to economic/operational advantages, such as lower production costs and greater hauling distances for extended construction seasons with tighter schedules. The present article serves to compare the mechanical performance of a WMA produced by adding synthetic wax with a traditional Hot Mix Asphalt (HMA) specimen, in terms of shear fatigue response and both complex and stiffness moduli. The experimental results and related modeling work demonstrate that adding synthetic wax into the WMA composition does not hinder either the destructive or non-destructive performance of an HMA, and this finding is corroborated by respectively measuring fatigue life and stiffness.

  1. Theory manual for FAROW version 1.1: A numerical analysis of the Fatigue And Reliability Of Wind turbine components

    SciTech Connect (OSTI)

    WUBTERSTEUBMSTEVEB R.; VEERS,PAUL S.

    2000-01-01

    Because the fatigue lifetime of wind turbine components depends on several factors that are highly variable, a numerical analysis tool called FAROW has been created to cast the problem of component fatigue life in a probabilistic framework. The probabilistic analysis is accomplished using methods of structural reliability (FORM/SORM). While the workings of the FAROW software package are defined in the user's manual, this theory manual outlines the mathematical basis. A deterministic solution for the time to failure is made possible by assuming analytical forms for the basic inputs of wind speed, stress response, and material resistance. Each parameter of the assumed forms for the inputs can be defined to be a random variable. The analytical framework is described and the solution for time to failure is derived.

  2. The Shape of M Dwarf Flares in Kepler Light Curves

    E-Print Network [OSTI]

    Davenport, James R A

    2015-01-01

    Ultra-precise light curves from Kepler provide the best opportunity to determine rates and statistical properties of stellar flares. From 11 months of data on the active M4 dwarf, GJ 1243, we have built the largest catalog of flares for a single star: over 6100 events. Combining 885 of our most pristine flares, we generated an empirical white-light flare template. This high-fidelity template shows a rapid initial rise, and two distinct exponential cooling phases. This template is useful in constraining flare energies and for improved flare detection in many surveys. Complex, multi-peaked events are more common for higher energy flares in this sample. Using our flare template we characterize the structure of complex events. In this contributed talk, I presented results from our boutique study of GJ 1243, and described an expanded investigation of the structure of complex flares and their connection to solar events.

  3. Fractal Diffusion in Smooth Dynamical Systems with Virtual Invariant Curves

    E-Print Network [OSTI]

    B. V. Chirikov; V. V. Vecheslavov

    2002-02-06

    Preliminary results of extensive numerical experiments on a simple model specified by the smooth canonical strongly chaotic 2D-map with global virtual invariant curves (VICs) are presented and discussed. We focus on the statistics of the diffusion rate of individual trajectories in dependence on the model parameters. Our previous conjecture about the fractal statistics determined by the critical structure of both the phase space and the motion is confirmed and studied in some detail. Particularly, we have found specific characteristics of what we termed the VIC diffusion suppression which is related to a new type of the critical structure. An example of ergodic motion with a surprising "hidden" critical structure strongly affecting the diffusion rate was also encountered and discussed.

  4. Fields and fluids on curved non-relativistic spacetimes

    E-Print Network [OSTI]

    Geracie, Michael; Roberts, Matthew M

    2015-01-01

    We consider non-relativistic curved geometries and argue that the background structure should be generalized from that considered in previous works. In this approach the derivative operator is defined by a Galilean spin connection valued in the Lie algebra of the Galilean group. This includes the usual spin connection plus an additional "boost connection" which parameterizes the freedom in the derivative operator not fixed by torsion or metric compatibility. As an example of this approach we develop the theory of non-relativistic dissipative fluids and find significant differences in both equations of motion and allowed transport coefficients from those found previously. Our approach also immediately generalizes to systems with independent mass and charge currents as would arise in multicomponent fluids. Along the way we also discuss how to write general locally Galilean invariant non-relativistic actions for multiple particle species at any order in derivatives. A detailed review of the geometry and its rela...

  5. Static spherically symmetric solutions in mimetic gravity: rotation curves & wormholes

    E-Print Network [OSTI]

    Myrzakulov, Ratbay; Vagnozzi, Sunny; Zerbini, Sergio

    2015-01-01

    In this work, we analyse static spherically symmetric solutions in the framework of mimetic gravity, an extension of general relativity where the conformal degree of freedom of gravity is isolated in a covariant fashion. Here we extend previous works by considering in addition a potential for the mimetic field. An appropriate choice of such potential allows for the reconstruction of a number of interesting cosmological and astrophysical scenarios. We explicitly show how to reconstruct such a potential for a general static spherically symmetric space-time. A number of applications and scenarios are then explored, among which traversable wormholes. Finally, we analytically reconstruct potentials which leads to solutions to the equations of motion featuring polynomial corrections to the Schwarzschild spacetime. Accurate choices for such corrections could provide an explanation for the inferred flat rotation curves of spiral galaxies within the mimetic gravity framework, without the need for particle dark matter.

  6. Curved track segment finding using Tiny Triplet Finder (TTF)

    SciTech Connect (OSTI)

    Wu, Jin-Yuan; Wang, M.; Gottschalk, E.; Shi, Z.; /Fermilab

    2006-11-01

    We describe the applications of a track segment recognition scheme called the Tiny Triplet Finder (TTF) that involves the grouping of three hits satisfying a constraint forming of a track segment. The TTF was originally developed solving straight track segment finding problem, however, it is also suitable in many curved track segment finding problems. The examples discussed in this document are among popular detector layouts in high-energy/nuclear physics experiments. Although it is not practical to find a universal recipe for arbitrary detector layouts, the method of the TTF application is illustrated via the discussion of the examples. Generally speaking, whenever the data item to be found in a pattern recognition problem contains two free parameters, and if the constraint connecting the measurements and the two free parameters has an approximate shift invariant property, the Tiny Triplet Finder can be used.

  7. Quantum fields and entanglement on a curved lightfront

    E-Print Network [OSTI]

    Illan Halpern; Yasha Neiman

    2015-07-15

    We consider field quantization on an arbitrary null hypersurface in curved spacetime. We discuss the de Sitter horizon as the simplest example, relating the horizon quantization to the standard Fock space in the cosmological patch. We stress the universality of null-hypersurface kinematics, using it to generalize the Unruh effect to vacuum or thermal states with respect to null "time translations" on arbitrary (e.g. non-stationary) horizons. Finally, we consider a general pure state on a null hypersurface, which is divided into past and future halves, as when a bifurcation surface divides an event horizon. We present a closed-form recipe for reducing such a pure state into a mixed state on each half-hypersurface. This provides a framework for describing entanglement between spacetime regions directly in terms of their causal horizons. To illustrate our state-reduction recipe, we use it to derive the Unruh effect.

  8. Quantum fields and entanglement on a curved lightfront

    E-Print Network [OSTI]

    Halpern, Illan

    2015-01-01

    We consider field quantization on an arbitrary null hypersurface in curved spacetime. We discuss the de Sitter horizon as the simplest example, relating the horizon quantization to the standard Fock space in the cosmological patch. We stress the universality of null-hypersurface kinematics, using it to generalize the Unruh effect to vacuum or thermal states with respect to null "time translations" on arbitrary (e.g. non-stationary) horizons. Finally, we consider a general pure state on a null hypersurface, which is divided into past and future halves, as when a bifurcation surface divides an event horizon. We present a closed-form recipe for reducing such a pure state into a mixed state on each half-hypersurface. This provides a framework for describing entanglement between spacetime regions directly in terms of their causal horizons. To illustrate our state-reduction recipe, we use it to derive the Unruh effect.

  9. General Relativistic Rotation Curves in a Post-Newtonian Light

    E-Print Network [OSTI]

    Aleksandar Rakic; Dominik J. Schwarz

    2008-11-10

    The missing of a Keplerian fall-off in the observed galaxy rotation curves represents classical evidence for the existence of dark matter on galactic scales. There has been some recent activity concerning the potential of modelling galactic systems with the help of general relativity. This was motivated by claims that by the use of full general relativity dark matter could be made superfluous. Here we focus on possible axisymmetric and stationary solutions of Einstein's equations with rotating dust. After a short review of the current debate we pursue the idea of approaching such relativistic models in a Newtonian language. We analyse rigidly as well as differentially rotating Newtonian and Post-Newtonian spacetimes and find that it is necessary to incorporate a Post-Newtonian term in order to make physical sense.

  10. Spinless Aharonov-Bohm problem in curved space

    E-Print Network [OSTI]

    Edilberto O. Silva; Sérgio C. Ulhoa; Fabiano M. Andrade; Cleverson Filgueiras; R. G. G. Amorin

    2015-02-25

    The dynamics of a spinless charged particle under the influence of a magnetic field in curved space is considered. We chose the surface as being a cone defined by a line element in polar coordinates. The geometry of this line element establishes that the motion of the particle can occur on the surface of a cone or an anti-cone. As a consequence of the nontrivial topology of the cone and also because of two-dimensional confinement, the geometric potential should be taken into account. At first, we establish the conditions for the particle describing a circular path in such a context. Because of the presence of the geometric potential, which contains a singular term, we use the self-adjoint extension method in order to describe the dynamics in all space including the singularity. Expressions are obtained for the bound state energies and wave functions.

  11. Graphene: QFT in curved spacetimes close to experiments

    E-Print Network [OSTI]

    Alfredo Iorio

    2013-04-09

    A recently proposed step-by-step procedure, to merge the low-energy physics of the $\\pi$-bonds electrons of graphene, and quantum field theory on curved spacetimes, is recalled. The last step there is the proposal of an experiment to test a Hawking-Unruh effect, emerging from the model, that manifests itself as an exact (within the model) prediction for the electronic local density of states, in the ideal case of the graphene membrane shaped as a Beltrami pseudosphere. A discussion about one particular attempt to experimentally test the model on molecular graphene is presented, and it is taken as an excuse to solve some basic issues that will help future experiments. In particular, it is stated that the effect should be visible on generic surfaces of constant negative Gaussian curvature, that are infinite in number.

  12. Mechanizing Exploratory Game Design

    E-Print Network [OSTI]

    Smith, Adam Marshall

    2012-01-01

    Game Design . . . . . . . . . . . . . . . . . . . . . . . .1.4.1 Designlevel Design Spaces . . . . . . . . . . . . . . . . . . . .

  13. Design Tool for Liquid-Nitrogen Gaps in Superconducting Apparatus

    SciTech Connect (OSTI)

    Pace, Marshall O [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Tuncer, Enis [ORNL; Polyzos, Georgios [ORNL

    2011-01-01

    For designers of high temperature superconducting equipment with liquid nitrogen as a dielectric, an expedient universal curve is sought that provides breakdown strength for a specified class of electrode shapes, with any practical sizes of electrodes and gap; thus the universal curve fills in missing experimental data. Universal breakdown strength curves at pressures of or slightly above 100 kPa, are being developed for AC, DC or impulse stress for the class with sphere-sphere, plane-plane and sphere-plane gaps, with three independent parameters: the size of each electrode and gap. A user can normalize his parameters and find the corresponding breakdown strength, even though no data were available for his exact dimensions. For AC and DC stresses the geometrical effects of stressed area/volume are incorporated from most published AC and DC experimental data of the last 50 years, by plotting breakdown field versus new geometrical quantities, such that all data fall approximately on or near one normalized universal curve. This avoids the usual difficult task of calculating stressed area and volume effects on the breakdown values for the graph ordinate. For impulse stress a more traditional plot suffices to produce a universal curve. This suggests that area/volume effects might not be so important with impulse stress. If the method proves reliable, it may be possible to determine design parameters for a broad range of geometries, help unify seemingly disparate breakdown data in the literature, and provide easily used, practical guidance for designers.

  14. 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

    been established that microelectromechanical systems (MEMS)in the design of microelectromechanical systems (MEMS) have

  15. On the effect of deep-rolling and laser-peening on the stress-controlled low- and high-cycle fatigue behavior of Ti-6Al-4V at elevated temperatures up to 550?C

    E-Print Network [OSTI]

    Ritchie, IAltenberger, RKNalla, YSano LWagner, RO

    2013-01-01

    high-cycle fatigue in a turbine engine Ti–6Al–4V alloy. Int.surface treatment in the turbine engine industry, although

  16. Fatigue Testing of Metallurgically-Bonded EBR-II Superheater Tubes

    SciTech Connect (OSTI)

    Terry C. Totemeier

    2006-12-01

    Fatigue crack growth tests were performed on 2¼Cr-1Mo steel specimens machined from ex-service Experimental Breeder Reactor – II (EBR-II) superheater duplex tubes. The tubes had been metallurgically bonded with a 100 µm thick Ni interlayer; the specimens incorporated this bond layer. Tests were performed at room temperature in air and at 400°C in air and humid Ar; cracks were grown at varied levels of constant ?K. Crack growth tests at a range of ?K were also performed on specimens machined from the shell of the superheater. In all conditions the presence of the Ni interlayer was found to result in a net retardation of growth as the crack passed through the interlayer. The mechanism of retardation was identified as a disruption of crack planarity and uniformity after passing through the porous interlayer. Full crack arrest was only observed in a single test performed at near-threshold ?K level (12 MPa?m) at 400°C. In this case the crack tip was blunted by oxidation of the base steel at the steel-interlayer interface.

  17. Rolling contact fatigue in high vacuum using ion plated nickel-copper-silver solid lubrication

    SciTech Connect (OSTI)

    Danyluk, Mike; Dhingra, Anoop

    2011-01-15

    Ion plated, nickel-copper-silver coated steel ball bearings that were tested in rolling contact fatigue (RCF) experiments in high vacuum are presented in this article. ANSI T5 ball bearings were coated with approximately 10 nm of nickel-copper followed by 100 nm of silver using a dc ion plating process. The balls were then tested for RCF in vacuum in the 10{sup -7} Torr range at 130 Hz rotational speed and at 4.1 GPa Hertzian contact stress. The significance of this work is in the extension of RCF testing to an ultrahigh vacuum (UHV) application using silver as a lubricant instead of oil. The effects of pressure and voltage on the ion plating process were also investigated using scanning electron microscopy and RCF life testing in UHV. Test results with a ball size of 5/16 in. in UHV show that deposition at voltages greater than 2.5 kV shortens the RCF life and introduces a unique failure mode. Voltage and pressure fluctuations during the deposition process result in significant thickness monitor measurement errors as well. A regulator control scheme that minimizes the process pressure overshoot is also simulated.

  18. 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.

  19. 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.

  20. Autonomous Ground Vehicle Path Planning for Autocross Tracks: Optimal vs an Efficient Bézier Curve Path

    E-Print Network [OSTI]

    Ash, John Patrick

    2015-01-01

    to Computationally Efficient Method . . . . . Minimizing theTracks: Optimal vs an Efficient B´ ezier Curve Path MASTERproposes a computationally efficient path planning algorithm