Fatigue life prediction of composites based on microstress analysis.

摘要

A multiaxial microstress model has been proposed for fatigue life prediction of long fibre reinforced composites. The fatigue lives of off-axially loaded laminae, angle ply laminates and notched composites were correlated using a parameter consisting of matrix shear and normal strain amplitudes on the critical plane which is parallel to the fibre axis. By using these crack behaviour related, actual strain components a better generalization of composite fatigue data than the traditional macrostress models has been achieved.;Predictions using the critical plane model were compared to the experimental fatigue data for boron/aluminum, glass/epoxy, graphite/epoxy and silicon-carbide/titanium composites. The model was verified by unifying fatigue data of unidirectional laminae cycled with different fibre/load angles, also be unifying the fatigue data for tensile and shear cycled composites with notches and for accurately predicting the fatigue crack initiation sites.