A first-principles study on the elastic properties of single-walled carbon nanotubesg

Abstract

A first-principles study is carried out to investigate the effects of structure and size on the elastic properties of single-walled carbon nanotubes (SWNTs). Ten zigzag-type and seven armchair-type SWNTs with diameters between 0.551 and 1.358nm are systematically studied. The linear elastic behaviour of the SWNTs when subjected to small deformations is studied by four virtual mechanical experiments: uniaxial strain, uniaxial stress, in-plane pure shear, and in-plane biaxial tension tests. Assuming that a SWNT should be transversely isotropic, a strain energy approach is used to calculate the Young's moduli in axial and transverse directions, major Posson's ratio, plain strain bulk, and in-plane shear moduli of the carbon nanotubes. It is found that the elastic constants are insensitive to the tube size, but show a slight dependence on the helicity. The differences in all the elastic moduli between zigzag and armchair nanotubes are within 10 per cent.