Energy Absorption Characteristics of Coupled Auxetic Metamaterials with Enhanced Local Stiffness

Mechanical metamaterials have attracted significant attention in energy absorption due to their structural designability and superior performance tunability. In this work, a novel re‐entrant chiral coupled structure (RCCS) is proposed inspired by the bionic design of the bamboo joint and shell structure. The coupled metamaterials integrate the auxetic effect of re‐entrant elements with the buckling resistance of chiral configurations to enhance energy absorption capability. Various array configurations with variable‐thickness designs are constructed and analyzed through simulation, theoretical, and experimental validation. Results show that the RCCS arranged with an alternating arrangement enhances plateau stress and specific energy absorption (SEA) by ≈2.5 and 2.2 times, respectively, compared to the traditional re‐entrant structure. To further optimize energy dissipation performance, this study systematically investigates the thickness effects of the RCCS units and their gradient distribution on their mechanical behavior. The results show that these optimized designs significantly enhance plateau stress and improve energy absorption capacity. The periodic meta‐unit with internal thickness modulation and discrete uniform‐thickness unit with gradient alternation structure exhibit the highest average plateau stress and the largest SEA value due to the improved local stiffness. A new approach is provided to design and optimize high‐performance metamaterials with improved local stiffness.