Multi-parameter structural optimization to reconcile mechanical conflicts in nacre-like composites

Abstract

Natural nacre exhibits a remarkable combination of high stiffness, strength, and toughness, originating from its ingenious hierarchical staggered structure. However, the conflicts among different mechanical indicators usually have negative effects on improving the comprehensive performance of nacre-like composites. In this study, we develop an optimization approach to determining the optimum structural parameters of nacre-like composites to reconcile mechanical conflicts and achieve desired comprehensive properties by combining theoretical framework and finite element simulation. For regularly staggered model, exact explicit solutions for Young’s modulus, strength, and toughness under three different cases of deformation and failure modes are given through rigorous derivations based on brick-and-mortar (BM) microstructure. For randomly staggered model, the mechanical response and failure mechanism are identified through numerical simulation. Parametric studies are conducted to investigate the effects of platelet volume fraction, aspect ratio, and offset ratio on mechanical properties. Using the weighted equation, we achieve the structural optimization with a simultaneous requirement of various mechanical indicators and illustrate the optimum results by ternary diagram. The presented insights should pave the way for optimization design of biomimetic composites for desired mechanical properties.