Effect of defects and boundary conditions on the vibrational behavior of carbon nanotube and graphene: A molecular dynamics perspective

The presence of defects has a significant effect on the mechanical and vibrational properties of carbon nanotubes (CNTs) and graphene. The vibrational properties of single-layered graphene sheets (SLGS) and single-wall carbon nanotubes (SWCNT) have been investigated in this research. Molecular dynamics simulations have been conducted on pristine and defective zigzag and armchair CNTs, with clamped-free (C-F) boundary conditions as well as pristine and defective armchair graphene sheets with different boundary conditions to investigate the effect of various parameters such as chirality, aspect ratio, boundary conditions, and types and number of defects on the longitudinal and transverse vibrational behavior of CNTs and graphene sheets. It was observed that for the cantilever boundary condition, shorter tubes give better vibrational sensitivity as compared to the larger ones for a constant diameter of the tube. The chirality has not a considerable effect on the natural frequency of CNTs. Regarding graphene sheets, it was observed that increasing the size of the graphene sheet decreased the fundamental natural frequency of SLGS. As compared to Stone-Wales defects, the vacancy defects were found to have more impact on the degradation of the natural frequency of CNTs and GS. • An inverse relationship between the natural frequency and length size • Natural frequency of SLGS decreases with increase of length and size of graphene sheets. • The effect of vacancy defect is more prominent as compared to Stone-Wales defects.