Modelling of Crushing Due to Impact in Honeycomb Sandwiches

Because of high stiffness and strength to weight ratios, composite sandwiches are being used increasingly, especially in aerospace applications. The main drawback of sandwich components is their relatively low resistance to impact damage and the extent to which their strength is reduced under compressive loading after impact. As part of a wider study aimed at increasing the impact resistance of sandwich panels, a continuum damage model is proposed. The model developed describes the compressive behaviour of honeycombs made from materials that are prone to elastic buckling. The material behaviour in compression is described by a combination of three distinct constitutive models, namely elastic, elastic continuum damage and an inelastic strain accumulation model. This has been interfaced with a commercial finite element package to model soft body impacts onto a minimum gauge honeycomb core sandwich. Results from analysis are compared to experimental data and the correlation is found to be very good.