Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China; State Key Laboratory for Powder Metallurgy, School of Materials Science and Engineering, Central South University, Changsha, China.
University of California, San Diego, La Jolla, CA, USA.
J Mech Behav Biomed Mater. 2017 Dec;76:4-20. doi: 10.1016/j.jmbbm.2017.05.015. Epub 2017 May 8.
Keratinous materials, omnipresent as the hard and durable epidermal appendages of animals, are among the toughest biological materials. They exhibit diverse morphologies and structures that serve a variety of amazing and inspiring mechanical functions. In this work, we provide a review of representative terrestrial, aerial and aquatic keratinous materials, pangolin scales, feather shafts and baleen plates, and correlate their hierarchical structures to respective functions of dermal armor, flight material and undersea filter. The overlapping pattern of pangolin scales provides effective body coverage, and the solid scales show transverse isotropy and strain-rate sensitivity, both important for armor function. The feather shaft displays a distinct shape factor, hierarchical fibrous structure within the cortex, and a solid shell-over-foam design, which enables synergistic stiffening and toughening with exceptional lightness to fulfill flight. Baleen plates exhibit a sandwich-tubular structure that features anisotropic flexural properties to sustain forces from water flow and remarkable fracture toughness that ensures reliable undersea functioning. The latest findings regarding the structural design principles and mechanical properties are presented in order to advance current understanding of keratinous materials and to stimulate the development of new bioinspired materials.
角蛋白材料作为动物坚硬而持久的表皮附属物无处不在，是最坚韧的生物材料之一。它们具有多种形态和结构，具有各种令人惊叹和鼓舞人心的机械功能。在这项工作中，我们综述了有代表性的陆生、空生和水生角蛋白材料，如穿山甲鳞片、羽毛轴和鲸须板，并将它们的层次结构与皮肤盔甲、飞行材料和海底过滤器的各自功能相关联。穿山甲鳞片的重叠模式提供了有效的身体覆盖，实心鳞片表现出横向各向同性和应变速率敏感性，这对盔甲功能都很重要。羽毛轴具有独特的形状因子、皮质内的分层纤维结构以及实心壳-泡沫设计，使协同增强和增韧具有非凡的轻盈性，以实现飞行。鲸须板呈现出三明治管状结构，具有各向异性的弯曲性能，能够承受水流的力，并且具有出色的断裂韧性，确保可靠的海底功能。本文介绍了最新的结构设计原则和机械性能的研究结果，以期推进对角蛋白材料的现有认识，并激发新的仿生材料的发展。
