Shear failure and impact resistance in graphite fiber laminates

The multispan beam (MSB) test was evaluated as a predictor of damage resistance and damage tolerance in quasi-isotropic graphite laminates. Materials studied were five commercial prepreg systems using high-strain and intermediate-modulus carbon fibers, as well as an amorphous thermoplastic system prepared in-house. Failure loads and displacements in the MSB tests showed little rate dependence. Values of compressive strength after a standard low-velocity impact (compression after impact [CAI]) correlated fairly well with the MSB results.