Dislocation-based modelling of the growth of a microstructurally short crack by single shear due to fatigue loading

The growth of a short edge crack, located within one grain in a bcc crystal and subjected to cyclic loading, is modelled using a dislocation formulation. The external boundary including the crack itself is built from dislocation dipole elements and the plasticity is represented by discrete dislocations moving along preferred slip planes. The crack propagates by single shear due to emission and annihilation of dislocations, leading to a zigzag shaped crack path. The method allows simulation of the crack growth path, crack shape and the development of the plastic zone in detail. It is shown that the grain orientation, orientation of the activated slip systems, the load and the initial crack configuration all together determines the exact path.