Energy Absorption Performance of 3D Printed Lattice–Polyurethane Foam Composites Inspired by the Human Skeletal Architecture

Abstract

Lightweight energy-absorbing structures are critical for aerospace and automotive crashworthiness, yet traditional auxetic honeycombs often suffer from global buckling and limited crushing stability. To address these limitations, this study proposes a bioinspired structural design featuring a functional member hierarchy inspired by the “trunk–bifurcation–constraint” load-transfer mechanism of the human shoulder girdle system (sternum–clavicle–scapula). Unlike conventional lattices, the proposed design integrates polyurethane (PU) foam to construct a series of lattice–foam hybrid composites that effectively mitigate localized instability and enhance energy dissipation. Four representative three-dimensional bioinspired honeycomb lattice structures (including baseline, high-energy-absorption, centrally-regulated, and high-stiffness variants) were fabricated using fused deposition modeling (FDM). In these architectures, the main struts mimic the load-bearing backbone, while the re-entrant inclined ribs induce a negative Poisson’s ratio (NPR) effect to facilitate material densification. Quasi-static compression tests were conducted to investigate the deformation modes and energy absorption characteristics. The results indicate that the in-situ foaming process discernibly improves the interfacial bonding and constrains the lateral deformation of the lattice struts. Specifically, the synergistic effect between the bioinspired topology and the foam core enhances the Specific Energy Absorption (SEA) and delays the onset of densification. This study demonstrates that the proposed bioinspired strategy offers a promising route for developing lightweight, high-performance crashworthiness components.