Molecular mechanics-based finite element analysis of graphene sheet and carbon nanotubes using the rebo potential

Abstract

Molecular mechanics-based finite element (FE) models of graphene sheet and single-walled zigzag and armchair carbon nanotubes (CNTs) are developed on the basis of the assumption that the carbon nanostructures, when loaded, behave like frame structures. The behavior of carbon–carbon bonds, which are represented by beam elements, is simulated using the many-body second generation reactive empirical bond order (REBO) potential. By means of the FE models, the tensile behavior of carbon nanostructures is simulated. The FE models are verified against molecular dynamics simulations. The computed results in terms of tensile stress–strain curves and fracture patterns are compared with results obtained using the pairwise modified-Morse potential. Different tensile properties and fracture patterns are predicted using the two potentials. This is mainly attributed to the deviations in the force–bond length curves and to the contribution of bond angle variation which is present in REBO. The present work is the first attempt to implement the REBO potential into a continuum model of carbon nanostructures and paves the way for a more systematic incorporation of atomistic simulation methods into continuum models.