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, <i>r</i>_R, varies (with respect to the crack size <i>a</i>), the shielding effect exhibits two different dependences on <i>r</i>_R, scaling as 1/<i>r</i>_R^1/2 for <i>r</i>_R/<i>a</i> ≪ 1 (near-tip), whereas 1/<i>r</i>_R for <i>r</i>_R/<i>a</i> ≫ 1 (far-field), respectively. Particularly, the far-field 1/<i>r</i>_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