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Multi-scale modeling and mechanical performance characterization of stingray skeleton-inspired tessellations
Journal of the Mechanics and Physics of Solids ( IF 5.3 ) Pub Date : 2020-02-17 , DOI: 10.1016/j.jmps.2020.103906
A.K. Jayasankar , R. Seidel , A. Hosny , J.C. Weaver , P. Fratzl , J. Chen , M.N. Dean

Sharks and rays have distinctive skeletons among vertebrate animals, consisting primarily of unmineralized cartilage wrapped in a surface tessellation of minute polygonal tiles called tesserae, linked by unmineralized collagenous fibers. The discrete combination of hard and soft tissues is hypothesized to enhance the mechanical performance of tessellated cartilage (which performs many of the same functional roles as bone) by providing either rigidity or flexibility, depending on the nature of the applied load. These mechanisms and the effect of tesserae ultrastructure on cartilage mechanics, however, have never been demonstrated in the actual tissue, nor in bio-accurate models. Here, we develop bio-inspired three-dimensional tesserae computer models, incorporating material properties and ultrastructural features from natural tessellated cartilage. The geometries of ultrastructural features were varied parametrically, and the effective modulus of whole tesserae was evaluated using finite element analysis to determine the roles of ultrastructural features in mechanics. Whereas altering some structural features had no effect on the macroscopic in-plane modulus of tesserae, a three-fold increase in the contact surface area between two adjacent tesserae increased the effective modulus of tesserae by 6%. Modeled stress distributions suggest that tesseral ‘spokes’ (distinct hypermineralized features in tesserae) bear maximum stresses in the skeleton and serve to funnel stresses to particular populations of cells in tesserae, while spokes’ lamellated structure likely helps dissipate crack energy, making tesserae more damage-tolerant. Simulations of multi-tesseral arrays showed that maximum stresses in tension and compression are borne by different tissues, supporting hypotheses of multi-functional properties of tessellated cartilage. Further, tesseral array models showed that minor alterations to tesserae/joint shape and/or material properties can be used to tune the mechanical behavior of the whole tiled composite. Our models provide the first functional understanding of the distinct morphologies of spokes and of ‘stellate’ tesserae (a tesseral shape observed first over 150 years ago), while also being useful drivers for hypotheses of growth, mechanics, load management, and the prevention and ‘directing’ of cracks in tessellated cartilage, as well as other biological composites. Additionally, these results establish guidelines and design principles for bio-inspired, tunable tiled materials.



中文翻译:

黄貂鱼骨架启发的棋盘格的多尺度建模和力学性能表征

鲨鱼和射线在脊椎动物中具有独特的骨骼,主要由未矿化的软骨包裹,该软骨被包裹在未镶嵌矿物质的胶原纤维连接的细小多边形瓷砖的表面镶嵌中,称为tesserae。假设硬组织和软组织的离散组合可通过提供刚性或柔韧性来增强棋盘状软骨的机械性能(该棋盘状软骨具有许多与骨骼相同的功能),具体取决于所施加载荷的性质。但是,尚未在实际组织或生物精确模型中证明这些机制以及tesserae超微结构对软骨力学的影响。在这里,我们开发了受生物启发的三维镶嵌计算机模型,该模型融合了天然镶嵌软骨的材料特性和超微结构特征。参数化地改变了超微结构特征的几何形状,并使用有限元分析来评估整个镶嵌的有效模量,以确定超微结构特征在力学中的作用。改变某些结构特征对镶嵌的宏观面内模量没有影响,而两个相邻镶嵌之间的接触表面积增加三倍,则使镶嵌的有效模量增加了6%。建模的应力分布表明,齿骨“辐条”(齿骨中明显的超矿化特征)在骨骼中承受最大应力,并有助于将应力集中到齿骨中的特定细胞群体上,而辐条的层状结构可能有助于消散裂纹能量,使齿骨更易受损-宽容。多镶嵌阵列的仿真表明,拉伸和压缩过程中的最大应力由不同组织承担,这支持了镶嵌软骨多功能特性的假设。此外,镶嵌阵列模型显示,对镶嵌/关节形状和/或材料特性的微小更改可用于调整整个平铺复合材料的机械性能。我们的模型提供了对辐条和“星状”齿的独特形态(对150年前首次观察到的齿形)的不同形态的初步功能理解,同时也为假设增长,力学,负载管理以及预防和预防提供了有用的驱动力。 “引导”棋盘状软骨以及其他生物复合材料中的裂缝。此外,这些结果为生物启发,

更新日期:2020-02-17
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