▎ 摘　　要

Wrinkling was observed for a circular monolayer graphene sheet in nanoindentation based on molecular-dynamics simulations. The mechanics fundamentals of this phenomenon were then explored using a two-dimensional plate model. It was found that the graphene wrinkles when the indentation depth reaches a critical value, the wrinkling is induced by the circumferential compression in the graphene, and the bending stiffness of the graphene sheet plays an essential role in stabilizing its one-atom layer nanostructures. It was shown that bending stiffness and in-plane stiffness are key indicators that signify the intrinsic mechanical properties of a graphene.