Novel lightweight high-energy absorbing auxetic structures guided by topology optimisation

Abstract

This paper aims to develop lightweight high-performance auxetic structures for protective applications such as blast and impact energy absorption. In this study, novel auxetic topologies were computed with an objective of energy absorption maximisation through the topology optimisation method. Analytical design formulations with the consideration of fabrication practicality were derived for the novel auxetic structures; named as the hourglass structure (HGS), braced cross-petal structure (BCPS) and cross-petal structure (CPS). Based on the formulated design parameters, rectangular scaffolds of each structure were designed to investigate bulk mechanical properties and energy absorption under a compressive load. Validated nonlinear finite element (FE) models developed in LS-DYNA FE code were used to examine the mechanical performance of the novel structures. The FE simulations revealed the deformation mechanism, negative Poisson's ratio, stress-strain behaviour and energy absorption. The protective performances of the developed auxetic structure were evaluated with respect to the peak elastic stress, plateau stress, onset of the densification strain and energy absorption capacity. The HGS outperformed the other structures in term of the protective performance. In addition, comparison of specific energy absorption at the onset of densification showed that the HGS, BCPS and CPS possessed superior energy absorption capacities than the conventional auxetic structures.