Thermal relaxation and deformation of indented graphene

The nanomechanical properties of graphene under nanoindentation are studied using molecular dynamics simulations based on the Tersoff–Brenner many-body potential and Lennard-Jones potential. The effects of the indentation temperature, indentation velocity, and indenter size are evaluated in terms of atomic trajectories, deformation velocity, indentation force, and strain field. The simulation results show that graphene deformation increases with increasing indentation depth, indentation velocity, temperature, and indenter size. During the holding process, a slight deformation between the center and the edges of the graphene remains due to relaxation, which increases with increasing temperature and indentation velocity. Cracks easily form with high-velocity indentation due to large strain energy accumulation in the material. The area of the deformation region increases with decreasing indentation velocity.