A STUDY OF RANDOMNESS IN FRACTURE OF CARBON NANOTUBES USING ATOMISTIC SIMULATION

The intense interest in carbon nanotubes (CNTs) in recent years owes in part to their extraordinary mechanical properties. Yet, enormous scatter is observed in their strength and stiffness properties. This scatter originates at least in part from the presence of nanoscale defects and the insufficient understanding and controlling of these defects by the interested community. This paper investigates the effect of randomness in atomic arrangements on the strength, stiffness and fracture properties of SWNTs (single wall carbon nanotubes) using the technique of atomistic simulation (AS). The focus is on the Stone-Wales (SW or 5-7-7-5) defects that either exist naturally or are introduced to improve performance. The core of any atomistic simulation is a deterministic set of rules governing the interaction among a large number of atoms and randomness needs to be introduced carefully. Nanotubes with (6,6) armchair configuration and aspect ratio 6.05 subjected to displacement controlled axial loading are simulated with the modified Morse potential. The distribution of SW defects is modeled with a Matern hard-core spatial process based on a homogeneous Poisson field. Effects of varying spatial distributions of the SW defects on the fracture process including elastic modulus, ultimate strength and ultimate strain are studied