Characterisation of impact damage in skin-stringer composite structures

In studies aimed at understanding the impact performance of structures made from carbon-fibre composites, effects of structural geometry, material type and impact location have been investigated in skin-stringer panels representative of aircraft structure. Effects were investigated for low-velocity impacts to the skin in the bay between stringers, over a stringer foot, and over a stringer centreline. Detailed studies of the impact damage at these locations were investigated using ultrasonic techniques, and optical and electron microscopy. The damage characteristics were explained in terms of the proportion of energy absorbed through damage, such as delamination, and elastic effects, such as structural response of the panel.