In-plane crushing behavior and energy absorption of sponge-inspired lattice structures

Novel energy-absorbing structures were a crucial requirement for the structural crashworthiness design in the automotive and aerospace industries. Inspired by the unique double-diagonal reinforced configuration of deep-sea glass sponge, we proposed a bionic lattice structure (BLS) fabricated by additive manufacturing (AM). In-plane quasi-static compression tests and numerical simulations were conducted on BLS with varying wall thicknesses (t), and two distinct deformation modes were observed: layer-by-layer mode with zero Poisson's ratio (ZPR) and uniform deformation mode with negative Poisson's ratio (NPR). The effects of structural parameters on the crushing behavior of BLS were investigated by numerical method. It was found that BLS with wall thickness (t) of 1.2 mm exhibited better energy absorption performance than 0.45 mm, with the energy absorption (EA), specific energy absorption (SEA), and mean crushing force (Pm) increased by 745.0%, 216.5%, and 744.3%, respectively. The change in crushing mode was caused by the '+' shaped joints changing from buckling to rotation, and the crushing behaviors of BLS could be effectively controlled by adjusting unit size and unit number. Finally, theoretical prediction models were developed using simplified super folding element (SSFE) theory to gain deeper insights into crushing behavior and performance of BLS. The present study provided valuable insights into the in-plane crushing and energy absorption capabilities of BLS. Moreover, it highlighted the potential of the double-diagonal reinforcement design in developing innovative energy-absorbing structures.