Failure of Carbon/Epoxy Lamina Under Combined Stress

Abstract

It is well known that matrix failure in carbon/epoxy composites is influenced by multiaxial states of stress. However most of the experimental work to measure this interaction has not focused exclusively on matrix failure, and a general multiaxial stress criterion for matrix failure has not been established. To examine this question experimentally we have carried out a series of tests involving torsional shear combined with axial tension or compression of unidirectional hoop wound cylinders, using AS4/55A carbon/ epoxy lamina. The matrix failure stresses are seen to be well correlated with the Tsai-Wu quadratic polynomial. There is also a strong interaction between the strains at failure, with small amounts of transverse tension giving a significant reduction in the shear strain at failure. The effect of σ 2 on the nonlinear shear stress-strain curves is also presented.

A Tow-Level Progressive Damage for Simulating Carbon-Fiber Textile Composites: Interim Report

“…The assumption that fiber-direction tensile failure is controlled by the fiber quantities is support by Swanson and co-workers (Swanson et al, 1987). They performed bi-axial testing on several carb0n-fiber uni-directional composites, and concluded that e~l/does not vary with physically achievable bi-axial loads -including shear.…”

Failure criteria for fibrous composites based on multiscale modeling

“…The criterion adequately accounts for this trend. The second example-not a part of the WWFE tasksapplied additional multi-axial loading to tubular specimens so as to determine failure data for AS4/55A (Swanson et al 1987) whose properties were similar to the AS4/3501-6 carbon fiber. The resin property needed to be adjusted to match the replacement resin.…”

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