In order to develop a computationally efficient model for the simulation of the fatigue-crack growth of microstructurally short cracks, two dislocation-based models were compared. In both models, the geometry of the boundary and the crack was described using dislocation dipole elements, whereas the plasticity was described by either discrete dislocations or by distributed dipole elements. The two models were found to agree qualitatively as well as quantitatively. It was concluded that modelling the plasticity by dipole elements became comparatively increasingly more time-efficient with increasing grain size plastic zone size. However, plasticity modelling by dipole elements was shown to predict somewhat higher crack growth rates.

Computationally Efficient Modelling of Short Fatigue Crack Growth using Dislocation Formulations. P.Hansson, S.Melin, C.Persson: Engineering Fracture Mechanics, 2008, 75[10], 3189-205