(383a) Elastic Properties and Fracture Mechanics of Graphene Nanomeshes

Graphene nanomeshes (GNMs) are graphene nanostructures consisting of a periodic arrangement of nano-scale holes or pores in the graphene lattice with neck widths less than 10 nm, mimicking dense arrays of ordered nanoribbons.  Establishing rigorous structure-property-function relationships in such patterned graphene nanostructures is of utmost importance for their optimal design toward enabling a broad range of technological applications.

In this presentation, we report the results of a systematic computational study on the elastic response and fracture dynamics of GNMs based on molecular-statics and molecular-dynamics simulations of uniaxial tensile deformation tests.  Both the elastic properties and the dynamical response to mechanical loading are determined as a function of the nanomesh architecture, namely, the lattice arrangement of the pores, pore morphology, material density (ρ), and pore edge passivation.  Scaling laws for the density dependence of the elastic modulus M, M(ρ), are established.  We find that, for circular unpassivated pores, M scales with the square of ρ.  Deviations from quadratic scaling are most strongly influenced by pore morphology and, to a lesser extent, by pore edge passivation and temperature.  In addition, for the numerous GNM structures examined, stress-strain curves are generated, the corresponding fracture mechanisms are investigated, and the ultimate tensile strength, fracture strain, and toughness are determined as a function of the GNM architectural parameters.  We find that GNM fracture is characterized by a brittle-to-ductile transition as the GNM density decreases and determine the critical density for the transition.