Dislocation Shielding of a Nanocrack in Graphene: Atomistic Simulations and Continuum Modeling

Combining atomistic simulations and continuum modeling, we studied dislocation shielding of a nanocrack in monolayer graphene under mode-I loading. Different crack-dislocation configurations were constructed and the shielding effects on the threshold stress intensity for crack propagation were examined. Excellent agreement between simulation results and linear-elastic fracture mechanics (LEFM) predictions was achieved. As the separation between the crack-tip and dislocation, that is, r(R), varies (with respect to the crack size a), the shielding effect exhibits two different dependences on r(R), scaling as 1/r(R)(1/2) for r(R)/a << 1 (near-tip), whereas 1/r(R) for r(R)/a >> 1 (far-field), respectively. Particularly, the far-field 1/r(R) scaling was shown to be a direct manifestation of the stress field of dislocation in graphene. Our work presents a systematic study of nanoscale crack-dislocation interactions in graphene, providing valuable information on defect engineering of graphene.