Exploring biomimetic structures with multi-level mechanical properties to improve energy absorption

In this study, a class of bio-inspired three-layer twisted meta-units was proposed and systematically investigated. Parameterized models with different sequences and angles were systematically constructed through geometric twisting mapping formulas, forming multi-level mechanical response structures that combine periodicity and twisting coupling characteristics. The study focused on the effects of twisting angle, support rod diameter, and layer height sequence on mechanical properties. The results indicate that these meta-units exhibit distinct two-stage or even multi-stage plateau stresses during compression. The initial stage is primarily dominated by rotation–buckling instability induced by anti-chiral interfaces, while the later stage is governed by the curling–collapse of homo-chiral layers. In terms of sequence arrangement, the reverse–sequential arrangement mode maintains a lower first peak load while exhibiting a wider negative Poisson's ratio range and higher specific energy absorption. An increase in the twisting angle shortens the strain range of the first plateau stress but contributes to higher overall energy absorption. As the rod diameter increases, the plateau load-bearing capacity and energy absorption significantly improve, though excessively large diameters weaken the structure's negative Poisson's ratio effect. Notably, stress cloud diagrams reveal the evolutionary path of progressive hierarchical instability, explaining the coupling relationship between plateau stability and energy dissipation capacity. Overall, these twisted meta-units demonstrate significant parameter tunability and functional diversity, providing new design insights for lightweight structures in impact resistance and energy absorption applications.