Damage mechanism of laminates delamination and bondline for scarf repaired CFRP under impact and parameter study

First, on account of the shortcoming of relative low ability of resistance to the impact load for scarf repaired CFRP, surface based cohesive model(SCZM) and element based cohesive zone model (ECZM) were used to simulate laminates delamination and bondline damage, respectively. The impact response of CFRP and the evolution of two failures were investigated. Then, the influences of the impact energy, scarf angle and pre-tension were studied. Results indicate that the laminates delamination initiates prior to the bondline damage, which is independent of the applied impact energy. The bondline damage area increases much obviously than the laminates delamination with the increasing of impact energy. The scarf angle will significantly influence the bondline damage, while has almost no effect on the laminates delamination area. The pre-tension has negative effect on these two failures. At last, the effect of laminates delamination on bondline damage was further discussed by comparing with the situation that only considered bondline damage. The laminates delamination will reduce the damage area of bondline and delay the catastrophic failure of bondline.