A Novel 3D ‐Printed Modified Re‐Entrant Auxetic Metamaterial With Exceptional Energy Absorption and Stiffness for High‐Performance Running Sport

ABSTRACT In this study, a novel circular modified auxetic metamaterial is introduced, achieved by periodically arranging a re‐entrant unit cell along the circumferential direction to form a stable, tubular architecture. The proposed architecture was fabricated using digital light processing, and its mechanical behavior was systematically investigated through a combined experimental and finite element method. Excellent agreement between experiments and simulations validates the numerical model and confirms its capability to capture the deformation mechanisms. A comprehensive parametric study was conducted to elucidate the influence of cell thickness and curvature on stiffness, peak load, stress–strain distribution, and specific energy absorption. The results reveal that increasing thickness markedly enhances load‐bearing capacity and stiffness by promoting a more uniform stress distribution and mitigating localized deformation. Curvature plays a critical role in governing deformation modes, enabling higher stiffness and peak load through improved engagement of vertical struts, while also introducing curvature‐driven instability at higher values. The interplay between thickness and curvature enables precise tailoring of mechanical performance, revealing a clear transition between stable auxetic deformation and curvature‐induced softening behavior. Owing to its lightweight nature, tunable stiffness, efficient energy absorption, and controlled deformation, the proposed circular auxetic metamaterial demonstrates strong potential for high‐performance running footwear applications.