Buckling and Growth of Delamination in Thermoset and Thermoplastic Composites

Abstract

Compression instability growth of through-width delaminations in composite laminates is investigated. A previously developed beam model that incorporates effects of elastic restraint at the ends of the delamination is combined with a finite element superposition model that yields the Mode I (GI ) and Mode II (GII ) components of the strain energy release rate. Experimental data were generated for near surface delaminations over a wide range of crack lengths in unidirectional graphite/epoxy and graphite/PEEK laminates. Good agreement between experimentally observed critical loads for crack propagation and analytical predictions was observed using a linear mixed-mode crack growth criterion.