Micro-scale modelling of bovine cortical bone fracture: Analysis of crack propagation and microstructure using X-FEM
Micro-scale modelling of bovine cortical bone fracture: Analysis of crack propagation and microstructure using X-FEM
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DOI：
10.1016/j.commatsci.2011.01.021
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发表时间：
2012-02-01
影响因子：
3.3
通讯作者：
Silberschmidt, Vadim V.
中科院分区：
文献类型：
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作者：
Abdel-Wahab, Adel A.;Maligno, Angelo R.;Silberschmidt, Vadim V.
骨折易感性增加的因素包括骨质流失、微观结构变化和材料性能的变化。因此，在宏观尺度上研究骨的微观结构和材料特性对裂纹扩展及其整体响应的影响具有重要意义。骨在皮质骨组织中的不均匀分布导致变形过程的局部化。这种定位会影响骨在外部载荷下的表现，引发骨折或协助其扩展。一旦发生断裂，这种分布在微观尺度上对裂纹扩展过程起着重要作用；随后，宏观层面的全球应对也可能受到影响。本研究采用扩展有限元法（X-FEM）建立了牛骨皮质骨的二维数值（有限元）断裂模型，并考虑了其微观结构。使用光学显微镜捕获了牛皮质骨的横向径向横截面的拓扑结构。利用纳米压痕技术获得了骨横截面微观结构特征的力学性能。将拓扑结构和纳米压痕数据作为Abaqus有限元软件构建模型的输入。该区域直接反映了微观尺度的信息，被嵌入到具有皮质骨均匀特性的区域中。数值模拟提供了拉伸载荷条件下三种不同拓扑结构（均质、三相复合和四相复合）的宏观整体响应、裂纹扩展路径和微观最大主应力分布。由于有限元模型中微观结构特征的实现，不同拓扑情况下的计算应力场呈现出不同的模式，证实了微观结构在裂纹扩展场景中的重要作用。建议的方法强调微观结构特征的重要性，特别是水泥线，在骨衰竭的发展。(C) 2011 Elsevier B.V.版权所有
Bone-fracture susceptibility is increased by factors such as bone loss, microstructure changes, and variations in material properties. Therefore, investigation of the effect of microstructure and material properties of bone on crack propagation in it and of its global response at macro-scale is important. A non-uniform distribution of osteons in a cortical bone tissue results in a localization of deformation processes. Such localization can affect bone's performance under external loads and initiate fracture or assist its propagation. Once the fracture initiates, that distribution can play an important role in the crack propagation process at micro-scale; subsequently, the global response at macro-scale could also be affected. In this study, a two-dimensional numerical (finite-element) fracture model for osteonal bovine cortical bone was developed with account for its microstructure using extended finite element method (X-FEM). The topology of a transverse-radial cross section of a bovine cortical bone was captured using optical microscopy. Mechanical properties for the bone's micro-structural features in the cross section were obtained with a use of the nanoindentation technique. Both the topology and nanoindentation data were used as input to the model formulated with the Abaqus finite-element software. The area, directly reflecting micro-scale information, was embedded into the region with homogenised properties of the cortical bone. Numerical simulations provide the macro-scale global response, crack propagation paths and distribution of maximum principal stress at the microscopic level for three different topologies - homogeneous, three-phase composite and four-phase composite model under tensile loading conditions.The calculated stress fields for various cases of topologies demonstrate different patterns due to implementation of micro-structural features in the finite-element models, confirming an important role of the microstructure in the crack propagation scenarios. The suggested approach emphasizes the importance of micro-structural features, especially cement lines, in development of bone failure. (C) 2011 Elsevier B.V. All rights reserved.