Residual strain in graphene: Study of temperature and crack effect

Abstract

Graphene is a thin sheet with special properties and complicated mechanical behavior. It is important to study graphene experimentally and theoretically. Stone-Wales defects, cracks, and atom vacancy are popular defects in carbon allotropes, especially in graphene. In this paper, residual strain in graphene was discussed. At first, stress-strain curve of non-defected graphene sheet was obtained using molecular dynamics simulation, and effect of temperature on mechanical properties of graphene was obtained. Then, four different cracks at the center of graphene sheets were considered. Stress-strain curves of defected graphene sheets with different tension strain rates were plotted. The results showed that cracks would lead the graphene to fracture sooner. In addition, increasing temperature leads to a decrease in the Young's modulus of graphene and graphene fracture at lower strain. On the other hand, residual strain of non-defected and cracked graphene increased by increasing temperature from 200 K to 1200 K. It means that graphene is subject to more plasticity behavior in case of temperature increase.