单壁碳纳米管受压屈曲行为的数值模拟

Numerical Simulation on Buckling Behavior of Single-Wall Carbon Nanotubes under Compression

采用以Tersoff Brenner势函数来描述碳纳米管中碳原子间的相互作用的分子动力学方法,模拟了单壁 碳纳米管(SWCNTs)的受压屈曲行为.计算结果表明,单壁碳纳米管的杨氏模量随着管径的增大而减小;碳纳米 管屈曲的临界应力和临界应变与碳纳米管细长比有关,不同的细长比决定了碳纳米管结构不同的屈曲模态;碳纳 米管的受压屈曲机理和连续介质力学中柱体壳的受压屈曲理论随细长比的不同而存在一些异同.

The buckling behavior of single-wall carbon nanotubes(SWCNTs) under compression is simulated by using the molecular dynamics method with Tersoff-Brenner potential to describe the interactions between atoms in SWCNT. The results show that the Young's modulus of SWCNTs decreases as the radius of SWCNTs increases, and critical stress and critical strain when the buckling of SWCNTs occurs are related to the slender ratio of SWCNTs. The difference of slender ratio determines two different buckling modes. The global buckling first happens for SWCNTs with the smaller slender ratio, while the local buckling first occurs for those with the larger slender ratio. The critical stress in the global buckling is proportional to the inverse of length of SWCNTs, while the critical stress in the local buckling is inversely proportional to the radius and the square of length of SWCNTs, which shows that the buckling theory of circular cylindrical shell in continuum mechanics can not be directly applied to the buckling of SWCNTs.