Bio-inspired perturbated hierarchical mechanical metamaterial for energy absorption

Abstract

Mechanical metamaterials inspired by the disordered and hierarchical structure of natural materials show promising potential in enhancing stress dissipation, damage tolerance and energy absorption. However, translating these bio-inspired principles into tunable and manufacturable architectures remains a critical challenge, requiring advances in multiscale design and predictive modeling. To mimic nature’s ability to balance structural disorder with hierarchy, a computationally driven metamaterial design that integrates controlled random perturbations with periodic hierarchical unit cells is presented. This design exploits the sequential collapse behavior of hierarchical structures and perturbation-induced post-yielding hardening to improve energy absorption capacity under predefined allowable stress constraints, optimized through Bayesian methods. The optimized metamaterials achieve increases in energy absorption of up to 112.7% and 46.8% at different allowable stress levels, compared to a baseline structure. These results demonstrate that controlled disorder enhances mechanical performance and enables a new paradigm for tunable, non-periodic metamaterials under varied application conditions.