The local buckling behavior of perfect/defective and single/multi-walled carbon nanotubes under axial compressive forces was investigated using the molecular dynamics approach. Effects of different types of defects including vacancy and Stone-Wales defects and their configurations on carbon nanotubes with different chiralities at room temperature were studied. Results showed that defects largely reduced the buckling stress and the ratio of immediate reduction in buckling compressive stress of the defective carbon nanotube to the perfect one, but have little influence on their compressive elastic modulus. Stone-Wales defects usually reduced the mechanical properties more than vacancy defects, and zig-zag carbon nanotubes were more susceptible to defects than armchairs. In addition, increasing the number of defects led to higher deterioration in mechanical properties of carbon nanotubes. The results of simulations showed that in the case of slender single-walled carbon nanotubes, the behavior was primarily governed by the Euler buckling law. On the other hand, in the local shell buckling mode, two distinct behaviors were observed, including the primary local shell buckling mode for intermediate carbon nanotubes, and the secondary local shell buckling mode for short carbon nanotubes. In the local buckling response, carbon nanotubes with smaller diameters sustain higher buckling stresses than carbon nanotubes with larger diameters.

Effect of Defects on the Local Shell Buckling and Post-Buckling Behavior of Single and Multi-Walled Carbon Nanotubes. M.Eftekhari, S.Mohammadi, A.R.Khoei: Computational Materials Science, 2013, 79, 736-44