Fast crack kinking manipulated by atomic hoop stress in monolayer hexagonal boron nitride strip

A model of monolayer hexagonal boron nitride strip with initial zigzag crack under displacement loading is built in molecular dynamic simulation. The interaction between boron and nitride atoms is modeled by a modified Tersoff potential. The propagation speeds of edge cracks, the crack paths and the stresses around crack tip are analyzed, which show that the crack propagates smoothly and symmetrically at low speed, while rapid crack oscillate and its surface becomes rough when its speed rises up. Moreover, the hoop stress around crack tip calculated by virial stress components varies with the crack speed. Hoop stress reaches its maximum at 60 degrees to the crack tip once the crack moves fast beyond a critical velocity of 8.37 similar to 8.61 km/s ( similar to 78% Rayleigh wave speed), and cracks deviate from its original trail, kink along the direction perpendicular to the peak hoop stress.