Finite Element Modeling of Microcrack Growth in Cortical Bone
Finite Element Modeling of Microcrack Growth in Cortical Bone
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DOI：
10.1115/1.4003754
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发表时间：
2011-07
期刊：
影响因子：
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通讯作者：
Susan Mischinski;A. Ural
中科院分区：
文献类型：
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作者：
Susan Mischinski;A. Ural
骨类似于由不同相组成的纤维增强复合材料，如骨（纤维）、骨间质（基质）和水泥线（基质-纤维界面）。骨骨和骨水泥线等微观结构特征在骨皮质裂纹扩展行为中起着重要的决定作用。本研究的目的是利用基于断裂力学的有限元模型来阐明影响裂纹渗入骨或挠曲进入水泥线的可能机制。采用内聚有限元模拟方法对被水泥线界面包围的单个骨元和间隙骨的二维模型进行了模拟，以确定裂纹是扩展成骨元还是偏转成水泥线。模拟研究了(i)裂缝方向相对于载荷的影响，（ii）水泥线的断裂韧性和强度，（iii）裂缝长度，以及（iv）骨单元相对于间隙骨的弹性模量和断裂特性。有限元模拟结果表明，无论水泥线的断裂韧性如何，较低的水泥线强度都有利于裂缝的偏转。但在水泥线强度较高的情况下，较低的水泥线断裂韧性并不能保证裂缝挠度。与短裂缝相比，长裂缝需要较低的水泥线强度和断裂韧性来挠曲成水泥线。裂纹的取向影响裂纹的扩展轨迹。改变骨元的断裂特性会影响裂纹扩展路径，而改变骨元的弹性模量对裂纹扩展轨迹几乎没有影响。本研究的发现提供了一种计算力学方法来评估骨的微尺度断裂机制，并为骨微观结构在控制微裂纹生长轨迹中的作用提供了额外的见解。
Bone is similar to fiber-reinforced composite materials made up of distinct phases such as osteons (fiber), interstitial bone (matrix), and cement lines (matrix-fiber interface). Microstructural features including osteons and cement lines are considered to play an important role in determining the crack growth behavior in cortical bone. The aim of this study is to elucidate possible mechanisms that affect crack penetration into osteons or deflection into cement lines using fracture mechanics-based finite element modeling. Cohesive finite element simulations were performed on two-dimensional models of a single osteon surrounded by a cement line interface and interstitial bone to determine whether the crack propagated into osteons or deflected into cement lines. The simulations investigated the effect of (i) crack orientation with respect to the loading, (ii) fracture toughness and strength of the cement line, (iii) crack length, and (iv) elastic modulus and fracture properties of the osteon with respect to the interstitial bone. The results of the finite element simulations showed that low cement line strength facilitated crack deflection irrespective of the fracture toughness of the cement line. However, low cement line fracture toughness did not guarantee crack deflection if the cement line had high strength. Long cracks required lower cement line strength and fracture toughness to be deflected into cement lines compared with short cracks. The orientation of the crack affected the crack growth trajectory. Changing the fracture properties of the osteon influenced the crack propagation path whereas varying the elastic modulus of the osteon had almost no effect on crack trajectory. The findings of this study present a computational mechanics approach for evaluating microscale fracture mechanisms in bone and provide additional insight into the role of bone microstructure in controlling the microcrack growth trajectory.