Dynamic axial crush response of circular cell honeycombs

The dynamic axial crush response of circular cell polycarbonate honeycombs was studied for 3-cell and 7-cell specimens experimentally and through finite-element (FE) simulation. The experiments were conducted using two loading methods: (i) the wave loading device (WLD) method and (ii) the direct impact method (DIM). The specimens were subjected to crush velocities of about 12 000 mms(-1) in the WLD method and 5000 mms(-1) in the DIM. The two methods were used to obtain a fairly wide range of input velocities. The collapse sequence and displacement information of the specimens were captured using a high-speed camera. The mode of collapse was through progressive concertina-diamond fold formation over a fairly constant state of load, which is referred to as the crush load. The crushing was simulated using an explicit FE analysis using ABAQUS, with geometrically imperfect 3-cell and 7-cell honeycomb models that incorporated the rate-dependent properties of polycarbonate. The FE results were found to agree well with the experimental results in terms of overall force-displacement plots, thus providing a basis to extract energy absorption estimates from the models and to draw comparisons between the 3-cell and 7-cell response behaviour. Moreover, the dynamic crush results were compared against a quasi-static axial crush response to demonstrate the presence of rate effects.