Molecular dynamics analysis on buckling of defective carbon nanotubes

Abstract

Owing to their remarkable mechanical properties, carbon nanotubes have been employed inmany diverse areas of applications. However, similar to any of the many man-madematerials used today, carbon nanotubes (CNTs) are also susceptible to various kinds ofdefects. Understanding the effect of defects on the mechanical properties and behavior ofCNTs is essential in the design of nanotube-based devices and composites. It has beenfound in various past studies that these defects can considerably affect the tensile strengthand fracture of CNTs. Comprehensive studies on the effect of defects on the buckling andvibration of nanotubes is however lacking in the literature. In this paper, the effects ofvarious configurations of atomic vacancy defects, on axial buckling of single-walledcarbon nanotubes (SWCNTs), in different thermal environments, is investigatedusing molecular dynamics simulations (MDS), based on a COMPASS force field.Our findings revealed that even a single missing atom can cause a significant reduction inthe critical buckling strain and load of SWCNTs. In general, increasing the number ofmissing atoms, asymmetry of vacancy configurations and asymmetric distribution ofvacancy clusters seemed to lead to higher deterioration in buckling properties.Further, SWCNTs with a single vacancy cluster, compared to SWCNTs with two ormore vacancy clusters having the same number of missing atoms, appeared tocause higher deterioration of buckling properties. However, exceptions from theabove mentioned trends could be expected due to chemical instabilities of defects.Temperature appeared to have less effect on defective CNTs compared to pristine CNTs.