WITHDRWAN 11/27/2023 SF01.03.29 Heterostructured Mechanical Metamaterials Inspired by the Shell of Strombus Gigas

The shells of molluscs have been shown to be strong and tough as a result of various types of architectural design that effectively control the evolution of shear bands and cracks during deformation. The crossed-lamellar design of the shell of <i>Strombus gigas</i>, whose hierarchy consists of four distinct lamellar-shaped features, represents the toughest of all seashells. A mechanical metamaterial that replicates the natural structure of this queen conch is anticipated to circumvent the renowned trade-off between strength-conductivity and strength-density. Here we introduce the architectural concepts of dimensional discreteness and interactive discreteness, inspired by the crossed-lamellar design, to instruct the design of bio-inspired metamaterials. The shear bands formed by the newly created metamaterial are effectively discrete and confined within an individual plank-like zone during compression. The mechanical properties are shown to be linearly proportional to the level of architectural discreteness, resulting in a progressive deformation with cross-layer hysteresis. A spring-based model is proposed that is in excellent qualitative agreement with experimental observation, that validates the superiority of the architectural discreteness-based paradigm, and that is capable of translating abstract designs into vivid layouts of spring systems with broad generality. The results have far-reaching implications for the design of strong mechanical metamaterials from a brand-new perspective.