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Nature serves as an inexhaustible reservoir of inspiration for engineering breakthroughs in material design. Inspired by natural composite materials found in various species, new mechanics can be distilled from analytical analyses, systematic finite element (FE) simulations, together with mechanical experiments on additively manufactured specimens. The knowledge discovered provides design guidelines for designing new mechanical metamaterials. Specifically, inspired by sutural tessellations found in woodpecker beak and seedcoats of plants, various new mechanical metamaterials are designed. The new designs show various unique mechanical properties including auxeticity[1-3], high resilience and hysteresis[2], on-demand stiffness[1]. Based on the mechanisms explored via analytical models, FE models of various designs are developed. Effective mechanical properties including the effective stiffness, effective Poisson’s ratio, and mechanical hysteresis under cyclical loading are quantified systematically. In order to study the on-demand stiffness, new adaptive FE algorithms are also developed. Prototypes of the new designs are fabricated via multi-material polymer jetting. Both quasi-static and dynamic impact experiments are conducted to verify the new mechanisms and design concepts. The new methodology developed will not only create new artificial materials, such as Frictional Mechanical Metamaterials, and Adaptive Mechanical Metamaterials, but also provide a new perspective in design approaches in this field. References: [1] Richard Nash and Yaning Li, 2024. On-Demand Auxeticity and Co-existing Pre-tension Induced Compression Stage in a Sandwich Design with Kinematically Constrained 3D Suture Tiles, Nature Communications 15, 6994. https://doi.org/10.1038/s41467-024-50664-8 [2] Tiantian Li and Yaning Li, 2024. 3D Tiled Auxetic Metamaterial: A New Family of Mechanical Metamaterial with High Resilience and Mechanical Hysteresis (Frontispiece). Advanced Materials. https://doi.org/10.1002/adma.202309604 [3] Yanzhang, Xu, Richard Nash, Ammar Batwa, and Yaning Li, 2024. Auxetic Two-Phase Chevron Mechanical Metamaterial. Advanced Engineering Materials 2400691. https://doi.org/10.1002/adem.202400691