Twisting effects of carbon nanotube bundles subjected to axial compression and tension

Molecular dynamics simulations were performed on twisted carbon nanotube (CNT) bundles, which comprise seven (5,5) single-walled carbon nanotubes (SWCNTs) that are spaced 0.34 nm apart, under axial compression and tension. A twisting load was applied to six of the (5,5) SWCNTs that surround a core SWCNT to form a twisted CNT bundle. The interaction force between the atoms was modeled using Brenner's "second generation" potential together with the van der Waals force as characterized by the Lennard-Jones (12,6) potential. The critical buckling and failure loads and the compressive and tensile strains were obtained for both the axial compression and tension scenarios, and it was found that severely twisted CNT bundles suffered badly in both cases. During tensile loading, the intertube distance decreases to 0.2 nm lower, which gave rise to intertube repulsive energy. At the same time, the attractive van der Waals force on the opposite faces of each individual SWCNT contributes to the collapse of the twisted CNT bundle. (c) 2006 American Institute of Physics.