CRITICAL STRAIN-ENERGY RELEASE RATE OF BROKEN PLY COMPOSITE LAMINATES

Ply breakage in laminated composites may be caused by impact load. Del amination usually precedes the failure of such broken ply laminates an d it occurs at the interface of the broken and continuous plies. In th e present work, an attempt has been made to find out the delamination initiation stress as well as critical strain energy release rate (G(c) ) for unidirectional [0 degrees] GL/E and GR/E laminates having one or more central ply/plies broken. Prediction of delamination initiation stress was attempted using ''Quadratic Stress Criterion'' and critical energy release for delamination has been assessed using LEFM in conju nction with a 3-D FE analysis.