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Title: MODELING AND TESTING OF THE INTERFACIAL STRESS STATE OF A TUNGSTEN-CLAD COMPOSITE USING PUSH-OUT TESTING

Abstract

No abstract prepared.

Authors:
;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
768790
Report Number(s):
LA-UR-00-5726
TRN: AH200105%%41
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Nov 2000
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MATERIALS TESTING; TUNGSTEN; CLADDING; STRESS ANALYSIS; MATHEMATICAL MODELS; COMPOSITE MATERIALS; INTERFACES

Citation Formats

R. RUTHERFORD, and ET AL. MODELING AND TESTING OF THE INTERFACIAL STRESS STATE OF A TUNGSTEN-CLAD COMPOSITE USING PUSH-OUT TESTING. United States: N. p., 2000. Web.
R. RUTHERFORD, & ET AL. MODELING AND TESTING OF THE INTERFACIAL STRESS STATE OF A TUNGSTEN-CLAD COMPOSITE USING PUSH-OUT TESTING. United States.
R. RUTHERFORD, and ET AL. 2000. "MODELING AND TESTING OF THE INTERFACIAL STRESS STATE OF A TUNGSTEN-CLAD COMPOSITE USING PUSH-OUT TESTING". United States. doi:. https://www.osti.gov/servlets/purl/768790.
@article{osti_768790,
title = {MODELING AND TESTING OF THE INTERFACIAL STRESS STATE OF A TUNGSTEN-CLAD COMPOSITE USING PUSH-OUT TESTING},
author = {R. RUTHERFORD and ET AL},
abstractNote = {No abstract prepared.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2000,
month =
}

Conference:
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  • No abstract prepared.
  • Analytical and experimental investigations were performed to determine the stress components responsible for interfacial debonding during pushout testing. The stress distributions along the fiber/matrix interface were modeled using finite element methods. Both thermal residual stresses as well as mechanical stresses were accounted for in the analysis. The analysis was performed for two SCS-6/Ti-based composite systems. The analytical results were calculated based on experimentally determined fiber debonding loads obtained at different specimen thicknesses and testing temperatures. The results of the analysis were consistent with the experimentally observed initiation failure sites. At room temperature, due to large thermal residual shear stresses, themore » maximum shear stress during thin-specimen pushout was located at the bottom face away from the indenter and was found to control the initiation of interfacial debonding. However, in very thin specimens, the bending stresses control interfacial debonding by causing radial opening at the bottom face. With an increase in temperature the analytical modeling shows that the maximum shear stress moves to the top face, due to the relaxation of the residual shear stresses. However, at high temperature the bending stresses result in failure initiation on the bottom face due to the softening of the matrix and the relaxation of the radial clamping stresses.« less
  • There is a wide range of values reported for the interfacial frictional shear stress {tau}, in the CAS/Nicalon glass ceramic matrix composite. Depending on the test method used, {tau} can vary from less than 10MPa to over 30MPa. The fibre push-down test generally gives values in the higher portion of this range, typically {tau} {ge} 25MPa. Two models describing the push-down test, that both assume a constant {tau} along the interface, are compared with data obtained using a Nanoindentation system. One ignores any residual stresses that may be present and the other includes axial residual stresses in the fibre. Themore » interface fracture surface energy G{sub I} was significantly lower when residual stresses were considered. The {tau} was observed to depend on the radius of fibre that was pushed, increasing as radius decreased. The effect of Poisson expansion was therefore investigated and found to contribute significantly to the {tau} recorded in these tests. It is possible that the contribution to {tau} from Poisson expansion can be more than 50% of its measured value.« less
  • Cyclic fiber push-in testing is used to examine the stability of interfacial frictional sliding stresses and fiber debond lengths with continued push-in load/unload cycles. The measured response to applying load cycling to a single fiber reveals the susceptibility of the fiber/matrix interface to degrade under cyclic loading conditions, and thus, helps evaluate the contribution of the interface to the cyclic fatigue behavior of the composite after the occurrence of matrix cracks. From cyclic push-in testing in room temperature air, decreasing interfacial sliding stresses and increasing debond lengths are observed with continued load cycling for SCS-6 SiC fiber reinforced reaction-bonded siliconmore » nitride (SCS-6/RBSN), whereas stable interfacial sliding stresses and no increase in debond lengths are observed with continued load cycling for SCS-6 SiC fiber reinforced strontium aluminosilicate (SCS-6/SAS). These results indicate that fiber-bridged matrix cracks should be stable under cyclic fatigue loading conditions in SCS-6/SAS, but should exhibit increasing crack opening displacements and fiber pull-out with continued cycling in SCS-6/RBSN. In addition, changing the test environment from room air to nitrogen significantly affects the cyclic push-in test results for SCS-6/RBSN, but not for SCS-6/SAS. The different responses to this change in test environment are attributed to different locations of interfacial failure.« less