A static compressive strength model for damaged composite laminates

An analytical model for the prediction of compressive strength of composite structures with barelyvisible impact damage (BVID) is presented. The model represents the complex damage morphologyusing one of two simple methods based on circular approximations of the damage area and determinesa critical interface for propagation of BVID. The finite strip program VICONOPT is used to calculatethe strain at which thin-film buckling of the circular delaminated region occurs. The threshold strain isdefined as the strain at which the strain energy release rate for the fracture of post-buckled delaminatedplies along the delamination is equal to the critical Mode I value ( C G1 ) for the resin. Results obtainedusing the model are compared with experimental values for static strength of a variety of coupons andstiffened panels reported in the literature. For impacts on the skin under a stiffener the model isaccurate to within 5% of the reported experimental result.