This study proposes a novel bio-inspired round auxetic metamaterial with tunable mechanical performance, designed for advanced protective applications. Inspired by the overlapping and rotational deformation mechanisms of fish scales, the structure exhibits pronounced negative Poisson’s ratio behavior, high stiffness, and enhanced energy absorption under compressive loading. Specimens were fabricated using Digital Light Processing (DLP) and investigated through quasi-static compression experiments and validated Abaqus finite element simulations. A parametric study was conducted to evaluate the influence of unit-cell curvature radius and thickness on the mechanical response, including stiffness, buckling behavior, Poisson’s ratio, and energy absorption capacity. The numerical model showed excellent agreement with experimental results, with deviations below 5% in load–displacement response and buckling force. Results indicate that increasing the curvature radius enhances stiffness and buckling resistance by up to 6% while reducing Poisson’s ratio by nearly 50%. In contrast, increasing the unit-cell thickness by only 0.2 mm leads to a substantial improvement in mechanical performance, raising the buckling force by approximately 70% and stiffness by about 45%, identifying thickness as the dominant design parameter. The combination of strong auxetic behavior, tunable stiffness, and high energy dissipation highlights the proposed metamaterial as a promising candidate for protective components such as blow hammer systems requiring controlled load transfer and mechanical durability.
Li et al. (Fri,) studied this question.