Strength of graphenes containing randomly dispersed vacancies

Abstract

In the present work, the tensile strength of graphenes containing randomly dispersed vacancies is predicted using an atomistic-based continuum progressive fracture model. The concept of the model is based on the assumption that graphene, when loaded, behaves like a plane-frame structure. The finite element method is used to model the structure of graphene and the modified Morse interatomic potential to simulate the nonlinear behavior of the C–C bonds. Randomly dispersed vacancies (1 missing atom) are introduced into graphene using a random numbers algorithm. Graphenes are subjected to incremental uniaxial tension. The model is capable of simulating fracture evolution considering defect interaction. The effects of size, chirality, defect density and defect topology on the Young’s modulus, strength and failure strain of graphenes are examined. Computed results reveal that vacancies may counterbalance the extraordinary mechanical properties of graphene, since 4.4% of missing atoms, corresponding to 13.2% of missing bonds, result in a 50% reduction in Young’s modulus and tensile strength of the material. Also found is a secondary effect of defect topology.