Torsional Buckling Analysis of Carbon Nanotubes by Molecular Structural Mechanics Approach

In this article, torsional of two kinds of single wall carbon nanotubes (SWCNT) are studied. An exact relation for nanotubes’ diameter is introduced. Also, all of internal loads in each element are considered. Results are shown as diagrams stating critical buckling forces with respect to aspect ratios for several kinds of nanotubes. This study shows that bending buckling force decreases by increasing nanotube's length and decreasing its diameter.Nanotubes were discovered by Ijima at 1991. Carbon nanotubes are used in several fields such as medicine, automotive industries, etc[3].Buckling of CNTs is very important in micro electro mechanical systems(MEMS) and nano electro mechanical systems(NEMS)[3]. Unique mechanical properties of CNTs are high strength, high resilience and high Young and shear moduluses[1]. For example, their yield strength is 100 times greater than that of steel[4]. In this article, two types of zigzag CNTs, three types of armchair CNTs with free-fix end condition are studied. In torsional buckling analysis, external torque is applied to the top of nanotube