Plastic analyses of thin-walled steel honeycombs with re-entrant deformation style

To get an ideal energy absorbing structure, which has low initial peak force but high energy absorbing efficiency, non-entrant and re-entrant honeycombs have re-entrant deformation styles were designed and fabricated. In-plane compression experiments and numerical simulations were carried out to reveal the progressive crushing process and the energy absorption level. In the crushing, the re-entrant honeycomb contracts laterally and has the potential to turn to a triangular lattice structure. The initial yield force of these honeycombs is not high but the stress after yield keeps high level and the plateau in stable. It is found to get a stable deformation curve the vertical wall must be thicker. Based on the crushing modes, plastic models were built to predict the mean crushing force (MCF) and they fit the test data very well. It is found that the re-entrant honeycomb has better energy absorption than the non-entrant honeycomb. Adopting re-entrant design, the MCF is even greater than the peak force, which benefits engineering design for energy absorbing structures in devices which requires smaller peak force but greater energy absorption.