Phenomenology of the effective stress intensity related to fatigue crack growth thresholds

The fatigue crack growth threshold conditions for effective stress intensity amplitude are examined using simple phenomenological models for crack face interference and internal stresses. We show that behaviors correlating with all pure fatigue classifications can be generated from a single ‘ideal fatigue’ behavior by accounting for internal stress and crack face interference. The possible threshold or near-threshold manifestations of an intrinsic KMAX threshold, independent of effective (delta)K effects, are discussed.