Energy absorption of sandwich panels subjected to in-plane loads

The energy absorption mechanisms of sandwich panels subjected to in-plane compression are studied. Quasi-static experiments are performed and analysed in order to support the development of a modelling strategy for failure initiation and propagation in sandwich panels. The test specimens consist of balsa wood cores and glass-fibre reinforced polyester faces. During compression of a tested panel, the displacement field on one outer face is measured using a digital speckle photography (DSP) equipment. The absorbed energy is related to debonding, delamination and crushing of the face sheets and crushing of the core. At initial failure, the load drops dramatically and is then relatively constant during continued compression. The energy per unit length necessary for propagation of the damage is considerably lower than for damage initiation. Assuming that the damage propagation is uniform through the thickness of the panels a simple model of damage growth is developed. Calibration of the model is however dubious due to the large scatter in the experimental results. The studied material shows damage mechanisms favourable for efficient energy absorption but the behaviour is far from being optimal.