Investigation of Crashworthiness Characteristics of Sandwich Panels Inspired by the Mantis Shrimp Dactyl Club

The growing demand for lightweight, crashworthy structures in aerospace, automotive, and protective engineering has motivated the development of sandwich panels with high stiffness-to-weight ratios and strong energy absorption. This study investigates the crashworthiness of additively manufactured polylactic acid (PLA) sandwich panels with biomimetics-based helicoidal cores. Rather than reproducing the Bouligand architecture of the mantis shrimp dactyl club as a fiber laminate, the progressive rotational principle was abstracted and applied to the walls of three-dimensional cellular cores. Square, octagonal, and circular unit-cell topologies were combined with gradual angular (10°) and orthogonal (90°) rotational arrangements, yielding six core configurations manufactured by fused deposition modeling (FDM). Drop-weight impact tests were conducted at 50 J, complemented by nonlinear explicit finite element analyses that were first validated against experiments and then extended to 100 J, including a mesh convergence study and sequence-angle variants (20° and 45°). Results show that the angular arrangement generally yields higher crash force efficiency, with the octagonal-angular core reaching the highest CFE (70.77% at 50 J), while orthogonal arrangements provide higher mean crash forces for cylindrical and octagonal cores. Increasing the layer-sequence angle from 20° to 45° raised the mean crash force by up to 15% and markedly improved resistance to face-sheet perforation, with the square-angular 45° configuration offering the best balance of efficiency and mean resistance. The findings demonstrate that sequential wall rotation is an effective multi-metric design parameter whose benefits depend on the underlying cell topology.