Effect of impact speed on high-speed impact damage in CFRP unidirectional and cross-ply laminates

This paper aims at characterizing the effect of impact velocity on high-speed impact damage behavior in carbon fiber reinforced plastic (CFRP) unidirectional (UD) and cross-ply (CP) laminates. First, The surface and internal damages of CFRP plates impacted at a velocity ranging from 150 to 500 m/s were observed by using optical microscopy together with radiography. Next, dynamic finite element analysis was performed to simulate the damage process. Cohesive elements were introduced to express the delamination and splitting cracks while the maximum stress fracture criteria were employed to express the intralaminar failure. Finally, the simulation was compared with the experiment results to understand the damage evolution for two impact velocities. The damage process in both laminates was as follows: 1. A crater accompanied by splitting cracks is generated at the impact point on the front surface while splitting cracks due to bending are observed on the back surface. 2. Cone-shaped matrix cracking is observed in the UD laminate while few matrix cracking is generated in the CP laminate. 3. The shape of the delamination in the UD and CP laminate is a diamond and a spiral, respectively. Although these damage processes were not greatly affected by impact velocity, the degree of damage strongly depended on impact velocity in both laminates. In addition, it was found that a critical impact velocity for perforation in the CP laminate is slightly larger than that in the UD laminate.