An investigation on single overload fatigue crack growth retardation, Part-1 (Plasticity zone interactions)

Modeling of life prediction in fatigue is complicated by a host of variables which includes loading history. This research focuses on life prediction of components subjected to variable magnitude single overloads, in a cyclic loading situation. This paper introduces the plasticity range interaction, and crack closure effect for variable magnitude single overload problems. A simple model is presented which captures characteristic features following overloads which include overload plasticity zone, spike-dip in fatigue crack growth rate and retardation in fatigue growth. The study presents numerical procedure for calculation of number of delay cycles and life of components subject to single overloads. Thorough calibrations have been performed to establish the fidelity of the program with experimental data obtained from various sources. Comparisons of numerical predictions with experimental data show good agreement for fatigue crack growth calculations.