skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Stressed Kevlar strand test

Abstract

Kevlar is a polyaramid fiber used in fiber composites. In order to characterize this material, we determined the effect of time, temperature, and chemical environment on the strength retention of stressed Kevlar strands. In this work, we applied a stress load of 20% of the ultimate tensile strength (UTS). Strands were hung with a suitable weight in a closed container. Each container was then provided with its own heater and chemical environment. No significant loss of strength retention was found on these stressed strands. 4 figures, 5 tables.

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (USA); Geneticon, Berkeley, CA (USA)
OSTI Identifier:
6232999
Report Number(s):
UCRL-86034; CONF-810953-3
ON: DE81030769
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: JOWOG-12 conference, Aldermaston, UK, 21 Sep 1981
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ARAMIDS; TENSILE PROPERTIES; COMPOSITE MATERIALS; ACETONE; ATMOSPHERES; EPOXIDES; EXPERIMENTAL DATA; FIBERS; FREONS; HYDROGEN; NITROGEN; PROPANOLS; STRESSES; TEMPERATURE DEPENDENCE; ALCOHOLS; DATA; ELEMENTS; HALOGENATED ALIPHATIC HYDROCARBONS; HYDROXY COMPOUNDS; INFORMATION; KETONES; MATERIALS; MECHANICAL PROPERTIES; NONMETALS; NUMERICAL DATA; ORGANIC COMPOUNDS; ORGANIC HALOGEN COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; PETROCHEMICALS; PETROLEUM PRODUCTS; PLASTICS; SYNTHETIC MATERIALS; 360403* - Materials- Polymers & Plastics- Mechanical Properties- (-1987)

Citation Formats

Golopol, H., Clarkson, J., Moore, R., and Hetherington, N.. Stressed Kevlar strand test. United States: N. p., 1981. Web.
Golopol, H., Clarkson, J., Moore, R., & Hetherington, N.. Stressed Kevlar strand test. United States.
Golopol, H., Clarkson, J., Moore, R., and Hetherington, N.. 1981. "Stressed Kevlar strand test". United States. doi:.
@article{osti_6232999,
title = {Stressed Kevlar strand test},
author = {Golopol, H. and Clarkson, J. and Moore, R. and Hetherington, N.},
abstractNote = {Kevlar is a polyaramid fiber used in fiber composites. In order to characterize this material, we determined the effect of time, temperature, and chemical environment on the strength retention of stressed Kevlar strands. In this work, we applied a stress load of 20% of the ultimate tensile strength (UTS). Strands were hung with a suitable weight in a closed container. Each container was then provided with its own heater and chemical environment. No significant loss of strength retention was found on these stressed strands. 4 figures, 5 tables.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1981,
month = 9
}

Conference:
Other availability
Please see Document Availability for additional information on obtaining the full-text document. Library patrons may search WorldCat to identify libraries that hold this conference proceeding.

Save / Share:
  • The highly crosslinked epoxy resins gave rise to isotropic scattering patterns and applying tensile stresses resulted in very little scattering changes. The dynamic scattering studies on the epoxy resins indicate the failure process as a catastrophic dynamic process with fractures initiating from surface or internal flaws. The crack propagates across the whole sample in a very short time to complete failure. The Kevlar fibers are microporous giving rise to equatorially elongated anisotropic scattering patterns. These microvoids can be partially filled by liquid epoxy. Based on comparisons of the volume fraction of the microvoids obtained by SAXS absolute intensity measurements andmore » by the density measurements, two sizes of microvoids are present in the Kevlar 49 fibers - one in the range of 10 to 20 nm and the other much larger. Applying tensile stresses results in an increase in the scattering intensities and in the volume fraction of smaller microvoids. The average radius of gyration of these microvoids remained constant, and hence the number of these smaller microvoids must have increased in order to account for increased scattering intensities. It is thus concluded that the failure of Kevlar 49 fibers is accompanied by the increase in number of smaller microvoids and the enlargement of the larger microvoids along the fiber axis direction. The reinforced epoxy composites of low volume fraction unidirectional Kevlar 49 fiber gave rise to anisotropic scattering patterns perpendicular to the fiber axis direction, and it is believed this scattering is due to voids within the fibers and voids entrapped along the fiber matrix interface during processing. The dynamic scattering studies on the composites indicate the failure as a catastrophic dynamic process, fracture initiating in the epoxy matrix and the fibers not being able to carry the load, thus failing catastrophically as well. The failure is thus instantaneous once incipient failure occurs.« less
  • Interfacial delamination is often the critical failure mode limiting the performance of polymer/metal interfaces. Consequently methods that measure the toughness of such interfaces are of considerable interest. One approach for measuring the toughness of a polymer/metal interface is to use the stressed-overlayer test. In this test a metal substrate is coated with a sub-micron thick polymer film to create the interface of interest. An overlayer, typically a few tenths of a micron of sputtered tungsten, is then deposited on top of the polymer in such a way as to generate a very high residual compressive stress within the sputtered layermore » ({approx} 1-2 GPa). This highly stressed overlayer induces delamination and blister formation. The measured buckle heights and widths are then used in conjunction with a fracture mechanics analysis to infer interfacial toughness. Here we use a finite element, cohesive-zone-based, fracture analysis to perform the required interfacial crack growth simulation. This analysis shows that calculated crack growth is sensitive to the polymer layer thickness even when the layer is only 10's of nanometers thick. The inward displacement of the overlayer at the buckle edge, which is enabled by the relatively low polymer compliance, is the primary cause of differences from a rigid substrate idealization.« less
  • One of the most challenging aspects of ion beam driven inertial fusion energy is the reliable and efficient generation of low emittance, high current ion beams. The primary ion source requirements include a rise time of order 1-{micro}sec, a pulse width of at least 20-{micro}sec, a flattop ripple of less than 0.1% and a repetition rate of at least 5-HZ. Naturally, at such a repetition rate, the duty cycle of the source must be greater than 10{sup 8} pulses. Although these specifications do not appear to exceed the state-of-the-art for pulsed power, considerable effort remains to develop a suitable highmore » current ion source. Therefore, we are constructing a 500-kV test stand specifically for studying various ion source concepts including surface, plasma and metal vapor arc. This paper will describe the test stand design specifications as well as the details of the various subsystems and components.« less
  • Fermilab is collaborating with LBNL and BNL (US-LARP collaboration) to develop a large-aperture Nb{sub 3}Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. Several two-layer quadrupole models of the 1-meter and 3.4-meter length with 90mm apertures have been fabricated and tested by the US-LARP collaboration. High-Jc RRP-54/61 strand was used for nearly all models. Large flux jumps typical for this strand due to the large sub-element diameter limited magnet quench performance at temperatures below 2.5-3K. This paper summarizes the fabrication and test by Fermilab of LQM01, a long quadrupole coil test structure (quadrupole mirror) with the first 3.4mmore » quadrupole coil made of more stable RRP-114/127 strand. The coil and structure are fully instrumented with voltage taps, full bridge strain gauges and strip heaters to monitor preload, thermal properties and quench behavior. Measurements during fabrication are reported, including preload during the yoke welding process. Testing is done at 4.5K, 1.9K and a range of intermediate temperatures. The test results include magnet strain and quench performance during training, as well as quench studies of current ramp rate and temperature dependence from 1.9K to 4.5K.« less
  • An EBIS program was initiated at Lawrence Berkeley Laboratory in late 1979. This first stage, construction of an EBIS research and development test-stand is described, along with results of the bare beam experiments.