Elastic buckling of multiwall carbon nanotubes under high pressure

This paper studies elastic buckling of individual multiwall carbon nanotubes under radial pressure. The analysis is based on a multiple-elastic-shell model in which each of the concentric tubes of a multiwall carbon nanotube is described as an individual elastic shell. According to their radius-to-thickness ratios, the multiwall carbon nanotubes discussed here are classified into three types: thin, thick, and (almost) solid. The critical pressure for elastic buckling is calculated for examples of all three types. It is found that a thin N-wall nanotube (defined by a radius-to-thickness ratio larger than 4) is approximately equivalent to a single-layer elastic shell whose effective bending stiffness and thickness are N times the effective bending stiffness and thickness of single-wall carbon nanotubes. Based on this result, an approximate method is suggested for replacing the problematic multiwall nanotube of many layers with a multilayer elastic shell of fewer layers. In particular, the critical pressure predicted by the present model is in good agreement with known experimental results.