Simulation of static and dynamic mechanical characteristics of carbon nanotubes and carbon nano-peapods with defects

Abstract

The static and dynamic mechanical characteristics of carbon nanotubes with double and multiple vacancy defects are simulated by the molecular dynamics method. Firstly, the effects of diatomic and polyatomic vacancy defects on the quasi-static mechanical properties of carbon nanotubes are discussed. Then, the effects of defects and axial pre-stress on the dynamics of C60 molecular oscillation in carbon nano-peapods are discussed. The results show that the ultimate stress, ultimate strain and elastic modulus of carbon nanotube containing different types of diatomic vacancies are significantly reduced as compared with those of non-defective carbon nanotubes. When the carbon nanotubes have many defective atoms and the defects are connected together to form a crack, the axial compressive properties of the carbon nanotubes are greatly reduced. Compared with the circumferential development of cracks, the cracks along the axis greatly reduce the compressive capacity of carbon nanotubes, which is similar to that of shell models with cracks. The oscillation frequency of C60 molecular in defective carbon nano-peapods is affected by the number of missing atoms. The single vacancy defect increases the oscillation frequency of C60 molecule, while with the further increase of vacancy number, the oscillation frequency of C60 molecule decreases gradually. When the defective carbon nano-peapod has axial tensile or compressive pre-stress, the oscillation of the C60 molecule is affected not only by the defects, but also by the axial pre-stress, which makes the oscillation of C60 molecule more complicated.