The change in the local field during a fatigue cycle was studied for a mode-I and mode-III cracks. It was shown that the change in the global crack-tip field governed cyclic plastic deformation of the crack tip, rather than the local field. The dislocation shielding of fatigue cracks was therefore an intrinsic mechanism and not an extrinsic one.

Dislocation Shielding of Fatigue Cracks. R.Pippan, F.Riemelmoser: Zeitschrift für Metallkunde, 1995, 86[12], 823-6