Strain gages are still the most reliable shear strain transducers for use with this test method.Īcoustic emission monitoring of damage in ceramic matrix composites: Effects of weaves and feature While preliminary results are encouraging, several design iterations failed to produce a reliable shear transducer prototype. A conventional strain gage extensometer is modified to measure shear strains for use with the Iosipescu shear test. The auxiliary warp material is significantly weaker and less stiff in interlaminar shear parallel to its fill direction. Overall, little difference in shear properties attributable to the fabric weave pattern is observed.
In-plane and interlaminar shear properties are obtained for laminates of all four fabric types. Both orthogonal and quasi-isotropic layup laminates were tested. Different weave geometries tested include an Oxford weave, a 5- harness satin weave, an 8- harness satin weave, and a plain weave with auxiliary warp yarns. The Iosipescu shear test method is used to measure the in-plane and interlaminar shear properties of four T300 graphite fabric/934 epoxy composite materials. Iosipescu shear properties of graphite fabric/epoxy composite laminates Room temperature mechanical tests only were performed by Hitco the results are presented. The panels were fabricated for testing on NASA/Ames Research Center's Composites Modification Program. The current state-of-the-art resin system selected was Fiberite's 934 Epoxy the advanced resin systems evaluated were Phenolic, Phenolic/Novolac, Benzyl and Bismaleimide. Three weaves were evaluated a balanced plain weave, a balanced 8- harness satin weave, and a semiunidirectional crowfoot satin weave. A detailed examination of the Young's modulus and stress distributions near the crack tip is carried out which provides insight into material behavior at cryogenic temperatures.įabrication and physical testing of graphite composite panels utilizing woven graphite fabric with current and advanced state-of-the-art resin systems Two-dimentional generalized plane strain finite element models are developed to study the effects of residual thermal stresses and cracks on the mechanical behavior of CFRP woven laminates. Cracks are considered to occur in the transverse fiber bundles and extend through the entire thickness of the fiber bundles. This paper examines the thermal-mechanical response of satin weave carbon fiber reinforced polymer (CFRP) laminates with internal and/or edge cracks subjected to uniaxial tension load at cryogenic temperatures. Thermal-Mechanical Response of Cracked Satin Weave CFRP Composites at Cryogenic Temperatures
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