Multi-scale design of the chela of the hermit crab Coenobita brevimanus
Multi-scale design of the chela of the hermit crab Coenobita brevimanus
复制标题
寄居蟹 Coenobita brevimanus 螯的多尺度设计
DOI：
10.1016/j.actbio.2021.04.012
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发表时间：
2021
影响因子：
9.7
通讯作者：
Luo Tianzhi
中科院分区：
文献类型：
--
作者：
Lin Weiqin;Liu Pan;Li Shan;Tian Jie;Cai Wenran;Zhang Xiao;Peng Jinlan;Miao Chunguang;Zhang Hong;Gu Ping;Wang Zhengzhi;Zhang Zuoqi;Luo Tianzhi
寄居蟹的螯保护它的身体免受捕食者的攻击。然而，我们仍然缺乏对这种机械防御的深刻理解。本文以寄居蟹螯螯为研究对象，建立了寄居蟹螯螯的微观结构、化学成分和力学性能之间的关系，以期对寄居蟹螯螯的生物力学功能有更深入的了解。我们发现螯合是一个由五层不同的层组成的多层壳，具有不同的微观结构和化学成分特征，赋予不同的力学性能。特别是，与许多甲壳类动物外骨骼的化学梯度不同，碳酸钙含量向离外部最远的层增加，提供了强大的抗变形能力。纳米压痕测量表明，弹性模量和硬度在横截面上的整体梯度呈三明治状，即。这是一个由两层坚硬的表层夹住的软核。进一步的力学建模表明，高曲率和刚性的最内层亚层增强了螯合物的结构刚度。结合实验观察，动态有限元分析绘制了主应力的时空分布，并指出纤维桥接可能是微尺度下裂纹扩展的主要机制。从这种多相生物复合材料的研究中获得的经验教训可以为结构应用的生物启发材料的设计和制造提供重要的见解。在多种外骨骼中发现了多重层次结构。它们的自然设计是为了保持结构的完整性，并作为动物的保护层。然而，每一种层次结构都有其独特的拓扑结构、化学梯度和力学性能。我们发现螯合是由五层不同的层组成的多层壳，具有不同的微观结构和化学成分特征，赋予不同的力学性能。特别是在最内层，大量螺旋形有机原纤维形成高度有序的三维编织基质，提供了强大的机械阻力，避免了灾难性的破坏。截面上弹性模量和硬度的整体梯度呈三明治状，有效地减小了应力集中和变形。从螯合的多尺度设计策略中获得的经验教训为生物灵感材料的设计和制造提供了重要的见解。
The chela of the hermit crab protects its body against the attack from predators. Yet, a deep understanding of this mechanical defense is still lacking. Here, we investigate the chela of hermit crab,Coenobita brevimanus, and establish the relationships between the microstructures, chemical compositions and mechanical properties to gain insights into its biomechanical functions. We find that the chela is a multi-layered shell composed of five different layers with distinct features of the microstructures and chemical compositions, conferring different mechanical properties. Especially, an increase of the calcium carbonate content towards the layer furthest from the exterior, unlike the chemical gradients of many crustacean exoskeletons, provides a strong resistance to deformation. Nanoindentation measurements reveal that the overall gradient of the elastic modulus and hardness in the cross-section displays a sandwich profile,i.e., a soft core clamped by two stiff surface layers. Further mechanics modeling demonstrates that the high curvature and stiff innermost sublayer enhance the structural rigidity of the chela. In conjunction with the experimental observations, dynamic finite element analysis maps the time-spatial distribution of principal stress and indicates that fiber bridging might be the major mechanism against crack propagation at microscale. The lessons gained from the study of this multiphase biological composite could provide important insights into the design and fabrication of bioinspired materials for structural applications.Statement of significanceMultiple hierarchical structures have been discovered in a variety of exoskeletons. They are naturally designed to maintain the structural integrity and act as a protective layer for the animals. However, each kind of the hierarchical structures has its unique topology, chemical gradients as well as mechanical properties. We find that the chela is multi-layered shell composed of five different layers with distinct features of the microstructures and chemical compositions, conferring different mechanical properties. Especially, a large amount of helicoidal organic fibrils form highly organized 3D woven matrix in the innermost layer, providing a strong mechanical resistance to avoid catastrophic failure. The overall gradient of the elastic modulus and hardness in the cross-section display a sandwich profile, effectively minimizing the stress concentration and deformation. The lessons gained from the multiscale design strategy of the chela provide important insights into the design and fabrication of bioinspired materials.