Atomic-scale mechanical behaviors of polycrystalline graphene under biaxial loadings and high temperature

摘要

? 2022Graphene is widely utilized due to its excellent properties. Nevertheless, the failure mechanism previously acquired by uniaxial tension needs to be optimized urgently as its service conditions become more and more demanding. Here, the mechanical behaviors of polycrystalline graphene under tensile-shear biaxial strains and high temperature were investigated by molecular dynamics simulations. We proved that the shear strain dominated the failure of polycrystalline graphene when tensile and shear loading were applied simultaneously. As the temperature rises, the structural destruction of polycrystalline graphene changes from stress-dominated to temperature-dominated. Moreover, the ultimate shear stress increases with the increase of grain size, while the ultimate strain is the opposite. The polycrystalline graphene with a large grain size has better high temperature resistance. These results extend our understanding of the mechanical properties of polycrystalline graphene and guide the design of devices composed of 2D materials under extreme conditions.