Mechanical behaviors of 3D re-entrant honeycomb polyamide structure under compression

In this study, a total of five 3D re-entrant honeycomb (RH) specimens made of polyamide were fabricated with various configurations by using additive manufacturing (AM) technique. Uniaxial quasi-static compressive tests were conducted on the RH specimens. The damage modes, the stress-strain curves and Poisson's ratios were recorded and analysed. The five specimens exhibited negative Poisson's ratios between-0.105 and-0.193. The effects of geometric parameters on the mechanical properties were analysed and discussed. In addition, 3D finite element (FE) models were established by using a commercial finite element software (ANSYS), and verified by comparing the predicted stress-strain curves and deformation patterns with the experimental results. Furthermore, an analytical model of 3D RH unit cell under uniaxial compression was proposed based on Timoshenko beam theory and large deflection beam theory. The proposed analytical model can well predict the mechanical properties of 3D RH unit under compression.