Buckling of defective carbon nanotube

Carbon nanotube (CNT) has attracted enormous attention from researchers since its discovery in 1991. Due to their remarkable mechanical properties, carbon nanotubes have been employed in many diverse areas of applications including biological probes, atomic force microscopy and also in nanocomposites. However, similar to any of the many man-made construction materials used today such as steel and concrete, carbon nanotubes (CNTs) are also susceptible to various kinds of defects. Understanding the effect of defects on the mechanical properties of CNTs is essential in the design of nanotube-based structures. It has been found in various past studies that these defects can affect considerably the tensile strength and fracture of CNTs. Comprehensive studies on the effect of defects on the buckling and vibration of nanotubes is however lacking in the literature. In this paper, the effect of atomic vacancy defect on the axial buckling of single-walled carbon nanotubes (SWCNTs) is investigated using molecular dynamics simulations. COMPASS force field in Material Studio commercial software is employed for the molecular dynamics simulations. Results obtained in the present study revealed that even a single missing atom can cause a significant reduction in the critical buckling strain and load of SWCNTs. As the number of missing atoms increases, the percentage reduction of buckling strain and load due to each missing atom reduces. Moreover, due to the higher flexibility resulted from more missing atoms, significant strain energy drop cannot be observed at the buckle. However, drop of load can still be observed at the buckle even for the SWCNTs with more missing atoms. Moreover, as the number of missing atoms increases non-linear portion can be seen in the load displacement curve before buckle.