Discrete dislocation modelling of near threshold fatigue crack propagation

At low crack propagation rate in metals and alloys the discrete nature of plasticity is essential to understand the fatigue phenomena. A short overview of the different types of performed discrete dislocation simulations of cyclically loaded cracks and their essential results are presented. The discrete dislocation mechanics deliver the changes of the stresses and displacement during cyclic loading. However, it does not give directly the crack propagation rate. In the simulations one has to assume a propagation mechanism. A comparison implies two things: the different simulations, the experimentally observed crack growth behaviour and crystallographic features will be used to show, which crack propagation mechanism is more appropriate in which case.