Lattice shearing in nano-grained graphene sheets: a molecular dynamics simulation

A set of nano-grained graphene models are established and molecular dynamics simulations are conducted to investigate mechanical deformation in the vicinity of grain boundaries under tensile loading. Similar to single-crystalline graphene, lattice shearing is initiated at the boundaries between grain domains with the armchair orientation close to the loading direction and extends to the grain domains. This results in a structural transition from a hexagonal structure to an orthorhombic one and enhanced plastic deformation in local regions. However, because of the limited number of grains orientated along a given direction and homogenization of randomly orientated grains in nano-grained graphene sheets, the enhancement is not substantial and an isotropic behavior is usually observed. The results provide physical insights into the role played by grain boundaries in mechanical deformation of nano-grained graphene.