Torsional buckling of double-walled carbon nanotubes

The mechanical instability of doubled-walled carbon nanotubes subject to torsion motion is investigated through molecular dynamics. A newly revealed buckling mode with one or three thin, local rims on the outer tube was discovered while the inner tube shows a helically aligned buckling mode in three dimensions. The distinct buckling modes of the two tubes imply the inapplicability of continuum mechanics modeling in which it is postulated that the buckling modes of the constituent tubes have the same shape. In view of this problem, a new concept of the equivalent thickness of double-walled carbon nanotubes is introduced, which enables the Kromm shell model to be applied to the derivation of the torsional buckling angle without the restraint of the two tubes having identical shapes. (C) 2008 Elsevier Ltd. All rights reserved.