Effect of topological defects on mechanical properties of graphene sheets: a molecular dynamics study

Abstract

The mechanical properties of graphene may be strongly influenced by topological defects such as vacancies, Stone-Thrower-Wales (STW) defects. In this research article, the effects of Stone Thrower Wales (STW) defect on the mechanical properties such as intrinsic strength and fracture toughness of graphene sheet have been investigated by using molecular dynamics based simulations. The intrinsic properties of graphene sheet are strongly affected by the orientation of STW defects. For STW2 defected graphene sheet, the strength of the armchair direction is much higher than that of zigzag direction. While the scenario for STW1 defected graphene is opposite, the strength of the zigzag direction is much higher than that of armchair direction. Furthermore, we investigated that STW defects can be used for tailoring the fracture toughness of graphene sheet. Significant improvement in the fracture toughness of graphene in armchair direction was predicted, while STW defects were positioned in front of the crack-tip. Interaction of stress fields generated from crack tip as well as from STW defects helps in tailoring the fracture behavior of graphene.