Differences between the description of cyclic plasticity using a discrete dislocation model, and its description using classical elasto-plastic continuum theory, were studied. It was shown that both dislocation models and continuum mechanics led to the same results at high stress intensities (Paris regime), but they differed significantly at low stress intensities. It was concluded that the characteristics of near-threshold fatigue-crack growth behavior could be explained only by using a discrete dislocation model.

Dislocation Model of Propagation of Long Fatigue Cracks. R.Pippan, F.O.Riemelmoser: Metallic Materials, 1998, 36[3], 125-30