Modeling the buckling behavior of carbon nanotubes under simultaneous combination of compressive and torsional loads

A number of studies have been performed on the mechanical and deformational properties of carbon nanotubes under different loading conditions, such as compression, tension, torsion, bending, and hydrostatic pressure. However, in practical applications, such as in nanotube-reinforced nanocomposites, these different loading conditions are present simultaneously. We employ molecular dynamics simulation to compute the behavior and deformation properties of carbon nanotubes under combined application of compression and torsion. The buckling properties and the corresponding mode shapes are investigated, for the first time, for different rotational and axial displacement rates. It is found that the critical loads and the buckling deformations strongly depend upon the ratio of these displacement rates. Finally, a relationship between the shear and normal stresses is established, which can be used for determining the stress limits when designing practical carbon nanotube-based systems in which combined loads may be applied.