Finite Element Modeling of Shear Instability under Compression in Unidirectional Carbon-Fiber Composites*

ABSTRACT: Compressive failure of many carbon-fiber composites is generally believed to occur as a result of shear instability. Finite element analysis of this failure mechanism is presented, which includes the effects of non-linear geometry and non-linear shear stress-strain response. The influence of fiber misalignment and waviness on the maximum compressive stress is shown. Constraint from the test fixture, non-uniform waviness, and stress gradients are all shown to have a large effect on the maximum compressive stress. 1