3D curved-walled same-phase chiral honeycombs with controllable compression-torsion coupling effect via variable cross-section design

Abstract

Honeycombs are widely-used protective structures with exceptional properties. However, the performance improvement relying on regular configuration optimization and parametric study are relatively limited, because main plastic deformation only concentrates in folding line regions under progressive folding mode. To address this issue, 3D curved-walled same-phase chiral strategy is designed for honeycombs, and their crash performance is studied by experiments, numerical simulations, and theoretical analysis. The proposed honeycombs exhibit approximate progressive folding mode with controllable local compression-torsion coupling effect under out-of-plane loads. Therefore, the shearing energy is obviously increased, and the plastic hinge lines have been prolonged to increase bending energy. According to experimental results, the proposed honeycombs can achieve specific energy absorption SEA and energy absorption efficiency η respectively of 30.92J/g and 73.7 %, which are 14.6 % and 24.9 % larger than traditional honeycomb with same thickness. Moreover, their mean stress is effectively estimated based on plastic hinge analysis, and the contribution of coupling effect on crashworthiness is demonstrated. Furthermore, out-of-plane thickness gradient design can be implemented to further promote the crashworthiness. The proposed honeycomb with thickness gradient of Δt/tave=1.5 displays SEA and η respectively 10.9 % and 23.1 % larger than the non-gradient model under same equivalent density. This study for the first time introduces compression-torsion coupling mechanism into honeycombs, and provides a reference for developing high-performance honeycombs and expanding their potentials.