Conch shells, characterized by a highly mineralized hierarchical crossed-lamellar structure that represents the pinnacle of molluscan evolution, exhibit exceptional crack resistance to protect their soft bodies from predatorial attacks. In this paper, we present a three-dimensional fracture mechanics model to establish a correlation between fracture toughness and the crossed-lamellar structure, elucidating the hierarchical crack bridging mechanism of aragonite lamellae. We find that increased fracture toughness is achieved through the energy dissipation contributed by the interfacial debonding of both first-order and second-order lamellae. The conch shells demonstrate outstanding resistance to cracking in two principal directions, featuring a locally stacked structure of flat plates that effectively withstand complex loads. The vertically alternating stacking structure of macroscopic layers of equal thickness inspires a biomimetic design with more balanced mechanical properties, accompanied by enhanced crack resistance observed as the lamellae become thinner. The theoretical results are in good agreement with relevant experimental measurements. This work not only sheds light on the physical mechanisms responsible for the remarkable fracture toughness of crossed-lamellar structures but also provides guidelines for designing high-performance biomimetic structural materials.

中文翻译：

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具有分层交叉层状结构的海螺壳的三维断裂力学模型


海螺壳的特点是高度矿化的分层交叉层状结构，代表了软体动物进化的巅峰之作，表现出非凡的抗裂性，以保护它们的软体免受捕食性的攻击。在本文中，我们提出了一个三维断裂力学模型，以建立断裂韧性与交叉层状结构之间的相关性，阐明了文石薄片的分层裂纹桥接机制。我们发现，通过一级和二级薄片的界面剥离贡献的能量耗散，可以提高断裂韧性。海螺壳在两个主要方向上表现出出色的抗裂性，采用局部堆叠的平板结构，可有效承受复杂的负载。等厚宏观层的垂直交替堆叠结构激发了具有更平衡机械性能的仿生设计，同时随着薄片变薄，观察到的抗裂性增强。理论结果与相关实验测量结果吻合较好。这项工作不仅阐明了导致交叉层状结构显着断裂韧性的物理机制，还为设计高性能仿生结构材料提供了指导。