Tensile and bending properties of double-walled carbon nanotubes

Atomistic simulations are performed to investigate the mechanical properties of uniaxial tensile and bending behaviours of double-walled carbon nanotubes. The second-generation reactive empirical bond-order potential and four different van der Waals (vdW) potentials are used to describe bonding and non-bonding atomic interactions, respectively. It is found that the tensile and bending behaviours are insensitive to the choice of vdW potential. It is shown that the effect of the helicity of nanotubes on the elastic modulus and the tensile strength is significant, while the effect of the nanotube diameter is moderate. Our simulations show that the outer tube always reaches its tensile strength first, suggesting the 'sword-in-sheath' failure mechanism. For the bending deformation, a strong non-linearity between the deformation and load is observed at small deformations, while a nearly linear relation is observed at large deformations.