Effective Structural Parameters of Single-walled Carbon Nanotubes

A three-dimensional finite element (FE) model for the prediction of mechanical properties of defect-free carbon nanotubes (CNTs) is developed by incorporating the modified Morse potential energy and the universal force field (UFF) with an analytical molecular structural model. The concept of the model is based on the assumption that CNTs, when loaded, behave like space-frame structures. Based on the use of beam and nonlinear truss rod elements, the effects of nanotube diameter, length and tube chirality on the elastic properties are investigated. With increasing tube diameter, the elastic and shear modulus of both Armchair and Zigzag CNTs increase monotonically and approach the elastic properties of graphite, but the variation trend of Poisson’s ratio is reverse. Additionally, the effects of wall thickness and van der Waals (vdW) interactions on mechanical properties of SWCNTs were studied based on the LennardJones (LJ) model and also the effect of the potential function was investigated in details. The findings are in good agreements with the existing theoretical and experimental results.