On optimal hierarchy of load-bearing biological materials

• Published in: Proceedings of the Royal Society. B, Biological sciences Vol. 278; no. 1705; pp. 519 - 525
• Main Authors: Zhang, Zuoqi, Zhang, Yong-Wei, Gao, Huajian
• Format: Journal Article
• Language: English
• Published: England The Royal Society 22.02.2011
• Subjects: Animals; Aspect ratio; Biomaterials; Biomechanical Phenomena; Biomechanics; Biomimetic; Bone and Bones - chemistry; Bone and Bones - physiology; Bones; Collagens; Composite materials; Flaw Tolerance; Hierarchical Material; Materials; Minerals; Minerals - chemistry; Models, Biological; Multilevel models; Quasi-Self-Similar; Tendons; Tendons - chemistry; Tendons - physiology; Toughness; Weight-Bearing
• ISSN: 0962-8452; 1471-2945; 1471-2954
• DOI: 10.1098/rspb.2010.1093

Load-bearing biological materials such as shell, mineralized tendon and bone exhibit two to seven levels of structural hierarchy based on constituent materials (biominerals and proteins) of relatively poor mechanical properties. A key question that remains unanswered is what determines the number of hierarchical levels in these materials. Here we develop a quasi-self-similar hierarchical model to show that, depending on the mineral content, there exists an optimal level of structural hierarchy for maximal toughness of biocomposites. The predicted optimal levels of hierarchy and cooperative deformation across multiple structural levels are in excellent agreement with experimental observations.