A discrete dislocation dynamics study aiming at understanding fatigue crack initiation

We use discrete dislocation dynamics to build a model for fatigue crack initiation in a surface grain. Dislocations are modeled as line singularities in an elastic medium where they can be generated from pre-existing sources, glide or annihilate. The simulation reveals several features that can potentially give rise to fracture initiation. Three different potential areas of fracture—surface, grain interior and grain boundary—are found which correspond to those found in experiments. Comparison with experimental findings on crack nucleation is hampered by the computational expenses that limit the number of cycles that can be simulated.