提出了碳碳键的断裂准则,建立了含空位缺陷碳纳米管的有限元模型,基于此断裂准则采用有限元方法对单壁碳纳米管的断裂行为进行了模拟研究,计算得到了碳纳米管的抗拉强度和极限应变,并研究了单原子空位缺陷对碳纳米管抗拉强度和极限应变的影响。结果表明理想单壁碳纳米管的抗拉强度约为100 GPa,极限应变约为20%。单原子空位缺陷显著降低了碳纳米管的抗拉强度和极限应变,使抗拉强度降低了20%~30%,极限应变降低了12%~18%,这也正是碳纳米管极限强度的实验结果远低于理论预测结果的原因。
A finite element model of single-walled carbon nanotubes ( SWCNTs) was established using ANSYS parametric design language, by which their fracture behavior was simulated on the platform of ANSYS using the criterion of the fracture of a carbon-carbon bond based on the Morse potential. The influence of a single atomic vacancy on the tensile strength and ultimate strain of SWCNTs was investigated. Results showed that the tensile strength and ultimate strain of perfect SWCNTs are about 120 GPa and 22%, respectively. Values for SWCNTs with the single vacancy are 20-30% and 12-18% less than those of the perfect ones. This is why the experimental tensile strengths of SWCNTs are far less than the theoretical predicted values. In addition, the tensile strengths of SWCNTs are anisotropic at large deformations, which agrees well with the simulation results obtained using molecular mechanics.
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