Parametric Optimization of 3D‐Printed Reentrant Metamaterials for Energy Absorption in Protective Sport Devices

This study introduces a novel auxetic metamaterial structure specifically engineered for protective sports equipment through a parametric design and additive manufacturing approach. Drawing inspiration from the intricate patterns of traditional Persian Lori rugs, a reentrant tubular lattice is conceived as a three‐dimensional metamaterial capable of exhibiting a tunable negative Poisson's ratio. The structure is fabricated using high‐resolution digital light processing (DLP) 3D printing with an ABS‐like photopolymer, enabling precise reproduction of the complex geometry. Systematic variation of two key geometric parameters, wall thickness (0.8, 1.0, 1.2 mm) and cell width (2.75, 4.0, 5.25 mm), allowed rigorous parametric control of mechanical behavior. Combined finite‐element analysis and experimental compression testing verified exceptional tunability in stiffness, energy absorption, and Poisson's ratio, which ranged from −1.09 to −2.3. The configuration with 1.2 mm thickness and 5.25 mm width demonstrated the highest stiffness and impact‐energy absorption, highlighting its potential for helmets, elbow pads, and similar high‐impact gear. The integration of culturally inspired geometry, metamaterial design principles, and precision DLP 3D printing establishes a unique pathway for next‐generation protective equipment, showcasing how parametric control of auxetic metamaterials can simultaneously achieve lightweight construction, superior energy dissipation, and enhanced user comfort.