Influence of Lay-up Angles on the Delamination Characteristics of Composites

This work studies the behavior of multidirectional composite laminate under mode I & II loading. The material used is a Carbone/Epoxy composite and the staking sequences allowed studying the characteristics of delamination for the 22.5°/-22.5°, 45°/-45° and 67.5°/-67.5° interfaces. The DCB test and the ENF test was chosen to produce the experiments with a specific preparation of the specimens according to respectively the ESIS standard and the AITM standard. Despite the fibers bridging and the crack jumping phenomena, it was noticed the critical strain energy release rate is higher for multidirectional laminates than for the unidirectional laminates. It influences the damage of the cohesive elements layers of an impact load model.