Effect of ply-thickness on impact damage morphology in CFRP laminates

In this article, the effects of ply thickness on the impact damage mechanisms in CFRP laminates are discussed based on the experimental observations. Quasi-isotropic CFRP laminates were manufactured using 38 mm thick thin-ply prepregs. Impact damage inside the laminates was evaluated by using ultrasonic scanning and sectional fractography. Compression after impact strength was also evaluated. Thin-ply laminates showed 23% higher strength than standard-ply laminates. Transverse cracks decreased drastically in thin-ply laminates, and localized delamination was largely extended. Based on the discussions in our previous study and the literature, the specific ply thickness without drastic crack propagation appears to be less than or equal to 40 mu m. Therefore, the thin laminates showed few and localized transverse cracks and delamination was largely propagated in the midplane.