Finite element models of single-walled and multi-walled carbon nanotubes in their perfect and fundamental forms (zig-zag and armchair) were constructed. After obtaining the mechanical properties of perfect carbon nanotubes, three types of imperfection, i.e., doping with Si atoms, carbon vacancies and perturbation of the ideal location of the carbon atom were introduced in different numbers to the perfect models in order to make them imperfect. Finally, the mechanical properties of the imperfect carbon nanotubes were numerically simulated and compared with those of perfect ones. Simple relationships which predicted the change in Young’s modulus as a function of the imperfection percentage were derived. The results showed that the existence of any kind of imperfection in the perfect models led to lower stiffness values. This study permitted realistic judgement of any simulation based upon perfect structures and, for the first time, furnished a good estimate of the extent to which values based upon perfect structures had to be lowered in order to account for common imperfections and to predict the mechanical properties of carbon nanotubes.

A Numerical Evaluation of the Influence of Defects on the Elastic Modulus of Single and Multi-Walled Carbon Nanotubes. A.Ghavamian, M.Rahmandoust, A.Öchsner: Computational Materials Science, 2012, 62, 110-6