Abstract

In continuum fracture mechanics, it is well established that the presence of crack near an inclusion leads to a significant change in the crack–tip stress field. However, it is unclear how atomistic crack–inclusion interaction manifests itself at the nanoscale where the continuum description of matter breaks down. In this work, we conducted molecular dynamics simulations to investigate the interactions of an atomic-scale boron nitride inclusion with an edge crack in a graphene sheet. Numerical simulations of nanoscale tensile tests were obtained for graphene samples containing an edge crack and a circular inclusion. Stress analysis of the samples show the complex nature of the stress state at the crack–tip due to the crack–inclusion interaction. Results reveal that the inclusion results in an increase (amplification) or a decrease (shielding) of the crack–tip stress field depending on the location of the inclusion relative to the crack–tip. Our numerical experiments unveil that inclusions of specific locations could lead to a reduction in the fracture resistance of graphene. Results of the crack–inclusion interaction study were compared with the corresponding results of crack-hole interaction problem. The study also provides an insight into the applicability of well-established continuum crack–microdefect interaction models for the corresponding atomic scale problems.

Keywords

• Graphene;
• fracture;
• inclusion;
• nanomechanics;
• crack–tip stress field;
• molecular dynamics

The article has been published in Engineering Fracture Mechanics (2018): https://www.sciencedirect.com/science/article/pii/S0013794418301930