Constrained functionally graded gyroid structure for tunable energy absorption

Abstract

Gyroid metamaterials are promising for impact mitigation due to their high surface-to-volume ratio, smooth stress distribution, and tunable mechanical response. This study examined thirty thermoplastic polyurethane (TPU) gyroid structures produced by 3D printing, comprising equal numbers of simple gyroid (SG) and wall constrained gyroid (CG) structures. Three geometric refinements, defined by the number of unit cells per edge, and five relative density gradients from uniform (0%) to graded (40%) were implemented to enable systematic evaluation under quasi-static compression. Two performance scenarios were defined, a crash-absorption case to maximize absorbed energy and a force-limiting case to minimize transmitted peak load, relevant to applications such as automotive bumpers and wearable protective gear, respectively. Results showed that the best CG configuration achieved up to 145% higher energy absorption and 69% greater specific energy absorption than the corresponding SG structure. Performance maps identified the CG structure with two cells per edge and a relative density gradient of 30% as optimal for energy absorption efficiency, providing actionable design rules for next-generation impact-mitigation metamaterials.