单壁碳纳米管屈曲的原子/连续介质混合模型

BUCKLING OF SINGLE-WALLED CARBON NANOTUBES VIA A HYBRID ATOMIC/CONTINUUM APPROACH

提供了一种运用原子/连续介质混合(hybrid atomic/continuum,HAC)方法解决纳米力学问题的思路.通过在连续介质力学模型中引入利用分子力学方法获得物性参数,建立了预测单壁碳纳米管临界屈曲参数的HAC模型.结果表明,HAC模型具有与连续介质力学模型可比拟的简洁性,同时可表征纳米管微观结构特征对屈曲参数的影响.计算结果表明,Zigzag纳米管的抗屈曲性能优于Armchair纳米管.基于Tersoff-Brenner作用势的分子动力学结果证实了这一结论.

Mechanical behaviors and properties of carbon nanotubes are drawing increasing attention from the mechanics community. Both the 'Bottom Up' approach based on quantum mechanics and the 'Top Down' approach based on continuum mechanics are frequently used to model mechanical behaviors and properties of nanotubes. For some problems, a nanotube can be well described as a continuum solid cylindrical beam or shell. For some other problems, nanotubes show unique properties which cannot be described by continuum methods alone and require atomic or quantum descriptions of the phenomena involved. Buckling of carbon nanotubes has been extensively studied theoretically since such a phenomenon was observed experimentally. However, no analytical solution is so far available to investigate the effect of tube chirality on the buckling behavior of CNTs, although the effect has been shown by some molecular dynamics simulations. Hybrid Atomic/Continuum (HAC) approach has been recognized to be a potential useful tool to describe the effect of atomic details on the macro properties and behaviors of nano-structures and materials. In this paper, buckling of single-walled carbon nanotubes is modeled via a HAC approach. The model shows that zigzag nanotubes are stiffer than armchair tubes. The conclusion is validated by Tersoff-Brenner molecular dynamics simulation.