Nested star-shaped auxetic metamaterials for high-efficiency energy dissipation

Mechanical metamaterials exhibiting a negative Poisson’s ratio (NPR) have attracted broad interest due to their anomalous mechanical responses. Conventional star-shaped structures with auxetic effect often suffer from inefficient energy absorption and structural instability under continuous deformation. To address these limitations, we propose a nested star-shaped architecture that is formed by nesting a star-shaped unit and a concave unit. By systematically varying geometric parameters, we derive theoretical relationships that govern the structure’s Young’s modulus and Poisson’s ratio. Through quasi-static compression experiments and finite element simulations, our findings demonstrate that the nested star-shaped design yields a stronger NPR behavior than the conventional star-shaped geometry at the same relative density. Furthermore, the nested geometry promotes a more uniform stress distribution, ensuring a highly stable deformation mode during compression. This mechanical stability translates to high energy dissipation, increasing the absorption efficiency to 1.3∼2.0 times that of traditional star-shaped structures. This work introduces a robust design paradigm for NPR metamaterials, offering substantial promise for applications ranging from architectural damping to biomedical devices.