Dynamic crushing behaviour of three-dimensional assembled auxetic metamaterials

Abstract Assembled auxetic metamaterials (AAMs) offer advantages of low fabrication cost, easy transportation, and reconfigurability but often suffer from inferior mechanical performance compared to monolithic structures. This study proposes a novel three-dimensional AAM (3D AAM) derived from re-entrant hexagonal unit cells, overcoming the performance limitation of conventional assembled structures. Its dynamic crushing behaviour is systematically investigated through finite element simulation, with the model accuracy validated against numerical and experimental results in the literature. Parametric analysis is conducted to explore the effects of impact velocity, cell-wall thickness, cell-wall angle, and out-of-plane thickness on the dynamic response and energy absorption (EA). Additionally, the 3D AAM is compared with its monolithic counterpart, and functionally graded designs based on cell-wall thickness and angle are introduced for dynamic performance optimization. Results show the 3D AAM matches its monolithic counterpart in load-bearing capacity and EA, which are enhanced by increasing the cell-wall thickness and angle. Furthermore, the graded designs effectively reduce the 3D AAM’s initial peak load while improving EA and material efficiency. This work deepens understanding of dynamic behaviour of 3D AAMs and provides design guidance for advanced protective and energy-absorbing structures.