Dynamic Performance of a 3D Re-entrant Structure

In this study, the mechanical performance of a three-dimensional (3D) re-entrant structure subjected to dynamic compression was experimentally investigated using a high-speed Instron machine. Quasi-static tests were conducted for comparison. All samples were fabricated by multi-jet fusion technology. A finite element (FE) model was developed using ABAQUS/Explicit and validated against the dynamic test results in terms of deformation mode, plateau stress, and Poisson's ratio. The validated FE model was subsequently employed to study the effects of the number of unit cells, geometrical parameters (aspect ratio, H/L, and re-entrant angle, θ) of the re-entrant unit cell, and compressive velocity. The results showed that the structure with H/L = 1 and θ = 45° had the highest specific energy absorption (SEA) when compressed in the Z direction and the structure with H/L = 1.1 and θ = 75° had the highest SEA when compressed in the X direction. Moreover, the performance of the 3D re-entrant structure was compared with that of a 2D re-entrant structure with the same geometrical parameters. The energy absorption of the 3D re-entrant structure was also compared with other popular cellular structures using an Ashby chart.