▎ 摘　　要

We perform molecular dynamics simulations on large-area polycrystalline graphene containing a pre-existing circular notch with focus on the notch effect on tensile strength and failure pattern. Our results show that the failure of polycrystalline graphene becomes notch-sensitive if there is an overlapping of stress concentration zones induced by the notch and grain boundaries (GBs); otherwise, the failure becomes notch-insensitive. More specifically, when the notch diameter is larger than the average grain size, the failure is generally notch-sensitive. However, if the notch size is smaller than the grain size, whether the failure is notch-sensitive or not depends on the notch location. These observations can be well explained by following attributes: (1) Both GBs and circular notch can create stress concentration; (2) The stress concentration created by the notch is generally weaker than that by GBs; and (3) The strength of GBs is weaker than that of the grain interior. Our work provides useful guideline for designing polycrystalline graphene for structure and device applications. (C) 2014 Elsevier Ltd. All rights reserved.