Prediction of stiffness and strength of single-walled carbon nanotubes by molecular-mechanics based finite element approach

Molecular-mechanics based finite element approach was used to predict the tensile stiffness and strength of single-walled carbon nanotubes. Different types of nanotubes, such as Arm-Chair, Zig-Zag, and chiral type, were discussed in detail. Nanotube stiffness was predicted to be independent of both the nanotube diameter and the nanotube helicity, but Poisson ratio was dependent of the nanotube diameter. In addition to the stiffness, nanotube strength was also analyzed by molecular-mechanics based finite element approach. Modified Morse potential function was selected to model the breakage of CC chemical bond with the separation energy of 7.7 eV. Nanotube strength was predicted at 77-101 GPa with the fracture strain around 0.3. The nanotube strength was found to be moderately dependent of the nanotube helicity, but independent of the nanotube diameter.