Abstarct: In the present thesis a structural mechanics model is employed for the investigation of the buckling behavior of CNT bundles of three SWCNTs under axial compressive, bending and torsional loading in the CAE space of ABAQUS. A nonlinear connector is considered for modeling of stretching and torsional interactions, and a nonlinear spring is used for modeling of the angle variation interaction. A Morse potential is employed for stretching and bending potentials, and a periodic type of bond torsion is used for torsion interactions. To evaluate the buckling loads of carbon nanotube bundles, the effects of van der Waals forces are further modeled using a nonlinear spring element. The effects of different types of boundary conditions (Fixed–Fixed, Simple–Simple and Fixed-Free) are studied for armchair nanotubes with various aspect ratios (length/diameter) and also the bending and torsional buckling behaviors of carbon nanotube bundle are investigated. Apart from the above, structural simulations were performed at different interspatial gaps. This is to determine the size effect of the interspatial gaps on the buckling properties of CNT bundles. In this work, a total of three interspatial gaps were used, i.e. 0.22, 0.34 and 0.51 nm. The structural mechanics simulations reveal that CNT bundles comprising longer SWCNTs will exhibit lower critical buckling load. Results indicate that for Fixed- Free boundary condition the rate of critical buckling load’s reduction is highest and lowest critical buckling load occurs. In addition, the average buckling load of each SWCNT was computed and compared with buckling loads for individual SWCNTs. Finally, the results of the present structural model are compared with results of molecular dynamics (MD). Simulation show good agreement between our model and the MD model.