Strengthening and toughening behaviors of conch-like composite structures with hierarchical cross-lamellar architecture.

Abstract

Many biological bodies have evolved sophisticated architecture that simultaneously exhibits superior strength and toughness to withstand predatory attacks, which provides valuable insights for addressing the trade-off between strength and toughness in brittle materials. Inspired by hierarchical crossed-lamellar microstructure in conch shell, this study proposes a kind of novel 3-level crossed-lamellar composite architecture featuring serration structure. Quasi-static three-point bending experiments combined with finite element method (FEM) are employed to investigate the mechanical performance and deformation mechanism. The results show that the 3-level crossed-lamellar architectures have higher stiffness and strength but lower toughness than typical 2-level crossed-lamellar architecture with inclined structure. Further, as the serration number increases, the stiffness and strength gradually decrease while the toughness increases. The effect of hybrid design exhibits significant location dependence. It is crucial to retain a high-toughness structure at the bottom, as this configuration effectively avoids the formation of high-stress regions, thereby preventing early failure. Incorporating serration structure at the top composite layer and inclined structure at the bottom composite layer not only maintains high toughness but also improves stiffness and strength. This positive hybrid design provides a promising strategy to overcome the strength-toughness trade-off and holds considerable potential for engineering applications.