The interaction of crack and dislocations in cyclic loading in the
body-centered cubic (BCC) crystal
In this paper, the propagation rate of the cracks at different grain
sizes with different grain boundary (GB) angles have been simulated.
During loading, the crack tip (CT) emits dislocations, which are
distributed on the slip plane (SP) in front of the crack, and may
accumulate at the GB, during which the crack expands forward. If the
conditions are met during unloading, the dislocations will rebound.
Dislocation annihilation will occur when distance of dislocation
emitting is less than the distance of dislocation rebound. The
annihilation of the dislocations have an impact on the next loading. The
calculation results show that the crack propagation rate (CPR) is
related to both the grain size and the angle of the GB. The CPR
increases in larger crystals and in larger angle GBs. And the number of
annihilation dislocations and the number and distribution of existing
dislocations will obviously affect the next loading step.