Impact and high strain rate delamination characteristics of carbon fibre epoxy composites

Delamination mechanisms and energy dissipation of carbon fibre epoxy composites under impact and high strain rate conditions are studied in terms of a new experimental set-up. The test set-up is designed to separate the Mode-I, -II and mixed mode delamination resistance so that relevant mechanisms can be studied in greater detail. The impact specimens consist of 18x18 mm laminated composite pieces bonded to steel bars to form the impact specimens with the normal Charpy and Izod specimen geometry. The impact energy dissipation is recorded and taken as a dynamic delamination toughness measurement, and the transition from the pure Mode-I to Mode-II through the mixed mode delamination is measured. Detailed delamination surface examinations by scanning electron microscopy (SERI) show that different failure mechanisms are involved in the dynamic and usual quasi-static delamination processes. The influence of chopped Kevlar fibres used as low cost interlaminar reinforcement on the energy dissipation is also studied.