Strength and failure mechanisms of composite laminates subject to localised transverse loading

Abstract The behaviour of composite laminates subject to transverse load introduction has been investigated experimentally and numerically. The effect of the specimen size, stacking sequence and material system on the failure load was determined experimentally and the failure modes examined through fractographic analysis. Damage was found to initiate at low load levels, typically 20–30% of the failure load. The dominant initial failure mode was matrix intralaminar shear failure which occurred in sub-surface plies. The damage developed into a network of intralaminar and interlaminar shear cracks. Two different macromechanical failure modes were identified, fastener pull-through failure and global collapse of the laminate. The internal damage and ultimate failure mode were found to depend upon the laminate stacking sequence and resin system. A three-dimensional finite element model was developed to analyse the stress distribution within the laminate and predict first-ply failure. The results from the finite element model were found to be in general agreement with the experimental observations.