Abstract:

In this paper,the mechanical properties of monolayer and multilayer graphene sheets under tension in two directions were investigated via molecular dynamics simulation,and the corresponding stress-strain relationships and tensile failure modes were discussed. Then,the size effect and the layer effect on the tensile properties of graphene sheets were analyzed by respectively changing the size of the monolayer graphene sheet and the layer number of the multilayer graphene sheet. The results show that ( 1) the monolayer graphene sheet,of which the elastic moduli are respectively 1078.02GPa ( armchair) and 1041.53GPa ( zigzag) ,is isotropic in the linear stretched elastic deformation stage,and its tensile properties are insensitive to size; ( 2) the multilayer graphene sheet is of a stress-strain relationship similar to that of the monolayer graphene sheet and it shows a more obvious isotropic nature in the linear stretched elastic deformation stage; and ( 3) the tensile failure of armchair graphene sheets starts from one side and extends inwards along the 45°direction,while that of zigzag graphene sheets starts from both sides and extends inwards in a symmetrical manner.

Key words: graphene, tensile property, molecular dynamics, size effect, layer effect, isotropy