Shell-like instability of large diameter single-walled carbon nanotubes conveying fluid

The instability of large diameter single-walled carbon nanotubes (SWCNTs) conveying fluid is investigated based on the molecular mechanics. Using the modal expansion for structural displacements, the governing equations of coupled fluid-structural dynamics of SWCNTs are derived. The natural frequencies and mode shape of the SWCNTs are obtained based on the molecular structural mechanics to account for the effect of chirality and discrete nature of SWCNTs. The results show that the vibrational behavior of large diameter SWCNTs conveying fluid is size dependent, but the effect of chirality is negligible. The obtained results are compared with the equivalent continuum-based model in the literature and in some cases remarkable deviations between the results are observed. Accordingly, proper values for the equivalent wall thickness and Young’s modulus of SWCNTs are proposed to adopt the results of continuum-based model with the molecular mechanics predictions.