Analyses of the growth of a plane-strain crack subjected to remote mode-I cyclic loading under small-scale yielding were carried out by using discrete dislocation dynamics methods. Cracks along a metal/substrate interface, or in a single crystal, were studied. The formulation was the same as that used to analyze crack growth under monotonic loading conditions; except that the remote stress intensity factor was a cyclic function of time. Plastic deformation was modelled by the motion of edge dislocations in an elastic solid, with the lattice resistance to dislocation motion, dislocation nucleation, dislocation-

obstacle interaction and dislocation annihilation being incorporated according to a set of constitutive rules. The cyclic crack growth rate versus applied stress intensity factor range curve, that resulted naturally from the solution of the boundary value problem, exhibited distinct threshold and Paris-law regimes. Paris-law exponents of 4 to 8 were deduced for the present parameters. Rather uniformly-spaced slip bands, corresponding to surface striations, developed in the wakes of propagating cracks.

Discrete Dislocation Modelling of Fatigue Crack Propagation. V.S.Deshpande, A.Needleman, E.Van der Giessen: Acta Materialia, 2002, 50[4], 831-46