Compressive failure of carbon/epoxy laminate composites under high impact loading

The effect of strain rate on the dynamic compressive of carbon/epoxy composite materials was investigated via the split Hopkinson pressure bar (SHPB) technique. The specimens were tested in the thickness, as well as in the in-plane direction at different high strain rates. The macro- and micro-fracture morphology of the damaged laminated specimens was obtained utilizing the scanning electron microscope (SEM). The experimental results showed that the compressive properties could be significantly affected by the strain rates. The compressive strength and the ultimate strain in the in-plane direction were obviously lower than that in the thickness direction. As the strain rate increased, the laminate had not enough time to respond, the splitting failure of 0° ply of laminates loaded in-plane along 0° was firstly found, then interfacial crack and delamination were induced, the specimens were crushed to fragments at the highest strain rate. No obvious damage of laminates loaded through the thickness could be observed at strain rate below 2000 s ^-1. The main way of the dynamic compressive failures through the thickness was shear failure due to the brittle fracture of the fiber at 2260s^-1.