Influence of Bond Kinematics on the Rupture of Non-Chiral CNTs under Stretching–Twisting

Abstract

This chapter focuses on the role played by bond kinematics in the collapse behaviour of armchair and zig-zag CNTs under combined stretching-twisting. The analyses are performed through MD simulations, using LAMMPS code with the built-in potential AIREBO for C–C bonds. Incremental combinations of stretching displacements and twisting rotations are imposed to the CNT end atoms. The results are first analyzed in the form of diagrams of energy at rupture versus the twisting-to-stretching rate and diagrams of interaction between the axial stretching displacement at rupture and the angle of twist at rupture. A detailed study on the variation of bond length and angle amplitude with the imposed stretching and twisting deformations is shown. The case of pure stretching is first described, as a reference case. Two combined twisting-stretching cases and the pure twisting case are dealt with separately for zig-zag and armchair CNTs. It is concluded that two kinematic mechanisms influence the rupture of CNTs: one is the bond elongation for low twisting-to-stretching rate and other is the hexagonal cell distortion for moderate to high twisting-to-stretching rate.