In-plane compression response of foam filled re-entrant auxetic structure

The in-plane compression response and energy absorption capacity of a new foam filled re-entrant honeycomb (FFRH) with negative Poisson’s ratio were investigated in this paper. Polyurethane foam filled aluminum alloy re-entrant honeycomb structures were fabricated though 3D printing method and pressure foaming method. The in-plane compression process and energy absorption properties under compression loading were studied experimentally and numerically, and a good agreement was observed between experimental results and numerical results. The comparison of experimental results of FFRH and ERH (empty re-entrant honeycomb) shows that, FFRH has a higher plateau stress and energy absorption capacity, and the auxetic behavior of re-entrant honeycomb causes a biaxial compression of the foam to form an enhanced compression resistance. The influence of compression velocity and foam filling mode on energy absorption were explored in details. With the increase of the compression velocity, the dominant factor of energy absorption transfer from the filled foam to the honeycomb structure. And it was discovered that foam filling modes have direct influence on deformation modes. Foam filling mode with the rule that all the surroundings of the empty cell are filled cells shows a higher specific energy absorption capacity. Our research provides a new method for designing auxetic structures, and the FFRH with light weight and high energy absorption can be used in aerospace and vehicles.