Experimental and numerical studies on the repeated low-velocity impact response and damage accumulation in woven S2-glass fibre/epoxy composites

In this paper, the repeated low-velocity impact response of woven S2-glass/epoxy composites is studied. The impacts were performed with energies from 18.4 to 59.2 J using a drop-tower apparatus, and a post-mortem analysis after each impact was employed to assess the impact response. A damage index was used to describe the changes in impact response due to repeated impacts. Finite element simulations considering both interlaminar and intralaminar failure modes were performed. The results showed that the impact force and bending stiffness decreased with the number of impacts, while impact duration and maximum central displacement increased. The shape of the damaged area was also affected. The numerical results showed that interlaminar damage initiated at most interfaces during the first impact, followed by in-plane propagation in the next impacts. Also, intralaminar damage initiated at the backside of the laminate, and then in-plane and through-thickness propagations followed until penetration occurred.