Small object low-velocity impact damage on hybrid sandwich structures with CFRP face sheets and aluminum foam cores

An important, but insufficiently explored load case for sandwich composites is an impact by a small object. This contribution investigates sandwich panels exposed to such an impact event. The sandwich panels consist of carbon fiber reinforced face sheets and three different core structures, among them two types of aluminum foam and one Nomex honeycomb. The forces during the impact event were obtained by optically recording and analyzing the impactor trajectory. The impact deformation was evaluated using X-Ray computed tomography. An energy balance model, previously used for conventional low-velocity-impact cases, was applied to predict the peak force during impact dependent on the impact velocity, including the described data. The comparison to literature and the coherence of the model to the measured values demonstrated the suitability of the model for this load case. A systematic description of the influences of the sandwich composition on the impact behaviour was identified and qualitatively evaluated.