The role of atomistic simulations in probing the small-scale aspects of fracture—a case study on a single-walled carbon nanotube

Abstract

This paper reviews atomistic simulation (AS) of fracture of solids along with recent advances reported in the literature. While classical fracture mechanics is based on continuum assumptions, AS can provide a first-principles based description of fracture that accounts for the discrete nature of matter. The idea of atomistic simulation was first applied to fracture during the early 1970s; brittle fracture was studied first using simple potential models and equilibrium conditions. Advances in materials science and computational power have led to significant progress in AS of fracture. Since the early 1990s, complex phenomena such as ductile fracture, fracture of non-homogeneous materials, fracture interaction with other physical and chemical effects have increasingly been investigated by atomistic simulation. This paper discusses achievements and shortcomings in regard to fracture criteria, potential models, initial and boundary conditions, temperature control and multi-scale simulation. An atomistic simulation of the displacement-controlled fracture process of a single-walled carbon nanotube (SWNT) with a pre-existing Stone–Wales defect is given as an example highlighting the essential steps of the methodology. Elastic modulus, ultimate strength and ultimate strain of the tube are determined from the simulation results (both with the defect and in the defect-free case) and the dependence of these parameters on the loading rate is investigated. Time histories of potential energy, temperature, axial force and bond angle are described, and a series of snapshots detailing the progress of the fracture process is provided.