Damage evaluation of CFRP laminates due to iterative impact

Damage of CFRP (carbon-fiber-reinforced-plastic) laminates due to iterative impact is evaluated with the compliance responses of deflections. The instrumented drop-weight impact test system converts the strain histories in the drop weight into the impact loads and deflections according to one-dimensional wave equation. It is shown that the impact load histories of laminates include the signals having high frequencies due to generation of the damage. The compliance responses, which are considered as the rigidity of laminates, are computed from the yielded loads and the deflections. As the experimental result, it is shown that impact damage can be estimated with the compliance response. When the fiber breaks during the impact process, the rigidity of laminates reduces considerably. The reduction of the rigidity is not marked for the case of quasi-isotropic laminate or CF/PEEK.