An energy-equivalent model is employed to develop the mechanical properties of singled-walled carbon nanotube (SWCNTs). This method is based on the equivalence of both the system potential energy as well as the strain energy of SWCNT. In fact, the energy-equivalent model is a link between molecular mechanics and continuum mechanics. In this research, Young’s and shear modulus as well as Poisson’s ratio are obtained for both armchair and zigzag SWCNTs. The effects of nanotube diameter and wall-thickness are investigated on the mechanical behavior of these types of nanotubes. It is seen that Young’s and shear modulus decrease significantly as the thickness of the SWCNT increases. Furthermore, elastic moduli of both armchair and zigzag carbon nanotubes increase monotonically and approach elastic moduli of graphite when the tube diameter is increased but the variation of Poisson’s ratio is vice versa. Also, the stress-strain curve for the armchair SWCNT predicted. The results show that armchair nanotube exhibit slightly higher values of Young’s modulus than zigzag ones for small values of radius, but their shear modulus are identical based on the present study. The developed results from a very simple approach, exhibit good agreement with the available solutions in the literature

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