A Finite Element Study of Crack Behavior for Carbon Na-notube Reinforced Bone Cement
A Finite Element Study of Crack Behavior for Carbon Na-notube Reinforced Bone Cement
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DOI：
10.4236/wjm.2013.35a003
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发表时间：
2013-08
期刊：
影响因子：
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通讯作者：
K. Saffar;A. Najafi;M. Moeinzadeh;Leszek Sudak
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文献类型：
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作者：
K. Saffar;A. Najafi;M. Moeinzadeh;Leszek Sudak
聚甲基丙烯酸甲酯（PMMA）骨水泥是一种广泛用作结构骨科材料的聚合物材料。然而，由于其易碎性，它不是理想的骨移植材料。碳纳米管（CNT）已经被引入以增强PMMA，从而产生表现出改善的拉伸性能、增加的抗疲劳性和断裂韧性的复合材料。这种改进可能是由于桥接和阻止裂纹以及能量吸收。在这项研究中，二维有限元模型的PMMA-CNT复合材料的断裂分析。与经典的单纤维模型不同，本工作考虑了与预先存在的裂纹相互作用的碳纳米管系综。Casca用于生成二维网格，并使用Franc 2D进行断裂分析。该模型进行单轴加载在横向平面和裂纹和碳纳米管之间的相互作用进行评估，通过确定在裂纹尖端附近的应力强度因子。研究了碳纳米管几何参数和材料结构非均匀性对裂纹扩展轨迹的影响。此外，研究了碳纳米管直径、壁厚以及基体与碳纳米管之间的弹性失配对裂纹扩展的影响。结果表明，碳纳米管排斥裂纹在加载过程中，因为它们作为裂纹生长的障碍。因此，将CNT并入PMMA中减少了裂纹生长，但更重要的是增加了骨水泥的抗断裂性。
Polymethylmethacrylate (PMMA) bone cement is a polymeric material that is widely used as a structural orthopedic material. However, it is not an ideal material for bone grafting due to its fragility. Carbon nanotubes (CNTs) have been introduced in order to reinforce PMMA resulting in a composite material which exhibits improved tensile properties, increased fatigue resistance and fracture toughness. This improvement is potentially due to bridging and arresting cracks as well as absorption of energy. In this study, a two-dimensional finite element model is presented for the fracture analysis of PMMA-CNT composite material. Instead of the classical single fiber model, the present work considers an ensemble of CNTs interacting with a pre-existing crack. Casca is used to produce a two dimensional mesh and the fracture analysis is performed using Franc 2D. The model is subjected to uni-axial loading in the transverse plane and the interaction between the crack and CNTs is evaluated by determining the stress intensity factor in the vicinity of the crack tips. The effects of geometric parameters of the CNTs and the material structural heterogeneity on crack propagation trajectory are investigated. Furthermore, the effects of CNT diameter, wall thickness and elastic mismatch between the matrix and the nanotubes on crack growth are studied. The results illustrate that the CNTs repel cracks during loading as they act as barriers to crack growth. As a result, the incorporation of CNTs into PMMA reduces crack growth but more importantly increases the fracture resistance of bone cement.