Temperature and size-dependent modeling for predicting mechanical properties of carbon nanotubes

Abstract

In this paper, a temperature and size-dependent molecular model is proposed to calculate the mechanical properties of carbon nanotubes. The cross section of carbon nanotubes is regarded as a hexagonal ring structure, and the covalent bond between carbon atoms is regarded as a beam of nonlinear spring structure, that is, the molecular structure system is regarded as a "beam-helical spring" structure. For considering the wall thickness of carbon nanotube, the influence of force constant on the molecular structure model is analyzed. On this basis, according to the principle of molecular mechanics, the expressions of calculating surface Young's modulus, Poisson's ratio, shear modulus and bulk modulus are obtained. It is found that due to the wall thickness, the Young's modulus, shear modulus, and bulk modulus of carbon nanotubes decrease with the increase of radius size.