Fracture toughness of various percentage of doping of boron atoms on the mechanical properties of polycrystalline graphene: A molecular dynamics study

This article investigates the effect of different initial crack sizes on the mechanical response of single-layer boron doped polycrystalline graphene nanosheets by Molecular Dynamics (MD) simulations. We study 1%, 3%, 6% and 10% of boron doped polycrystalline graphene nanosheets with grain sizes of 10 and 15 nm for eight different initial crack lengths of 0.02L, 0.04L, 0.08L, 0.12L, 0.16L, 0.2L, 0.24L, and 0.32L, where L is the initial length of the nanosheet. We found that 1. brittle fracture for boron doped polycrystalline graphene as the failure occurs without any sign of plastic deformation and low energy absorption and 2. the ultimate tensile strength is independent of the initial crack size. For identical grain sizes and doping of boron atoms, the ultimate tensile stress and strain decrease as the crack lengths increases. In contrast, a clear trend was not observed in the ultimate tensile strength for the same crack length and doping of boron atoms as the grain size increases. The highest difference of 13.4% in the ultimate tensile strength was observed between grain sizes of 10 and 15 nm for 3% of boron doped nanosheets with an initial crack size of 20 angstrom.