Compressive Failure of Fiber Composites: The Roles of Multiaxial Loading and Creep

The roles of multiaxial loading and creep in compressive failure of aligned fiber composites are considered. Analytical models are developed based on the model given by Budiansky and Fleck (1992). The critical microbuckling stress in multiaxial loading is calculated for a rigid-perfectly plastic solid and an elastic-plastic strain hardening solid. The rigid-perfectly plastic results predict a plane compressive failure surface in stress space. The rigid-perfectly plastic results are sufficiently accurate, when compared to the strain hardening results, so long as the remote shear stress and stress normal to the fiber direction are not too large relative to the remote stress in the fiber direction. The model given for creep microbuckling is suitable for power law viscous composite behavior. Deformation within a localized kink band is computed as a function of time. A creep life is predicted, based on a critical strain failure criterion.