Misorientation angle depended deformation of bilayer graphene sheets under in-plane loading

Abstract

ABSTRACTMolecular dynamics (MD) simulations are conducted to study the deformation behaviors of bilayer graphene sheets under in-plane uniaxial loading. It is found that the bending direction of the bilayer graphene sheet is related to the compression direction rather than depended on the bending stiffness differentiation induced by monolayer rotating. The bending curvature can be positive or negative, unexpectedly, are seriously affected by the mixture edges, but usually opposite when compressed from the two orthogonal directions. The separation between layers increases with compressive strain, but the fluctuation amplitude decreases gradually. It is inferred that the interlayer bonding becomes weaker and weaker and interlayer slipping might take place. As a comparison, the tensile behavior, however, is remarkably related to the misorientation angle. When tensile loaded along ZZ direction, the fracture stress and strain reduces before misorientation angle reaches 30°, and recovers later with the increasing misorientation, which is reverse to that along AC direction. However, it is interesting to note that a high strength differentiation between graphene layers causes a step-by-step fracture mechanism, especially when loaded along AC direction. These results highlight the influence of interlayer coupling on the deformation of bi-layer and even multi-layer 2D materials.