A new model for fatigue crack growth retardation following an overload

Abstract

This paper details the theoretical development of a new model for fatigue crack growth retardation resulting from an applied overload. The model is based upon the concept that residual stresses due to plastic deformation reduce the value of the stress intensity range that drives fatigue crack propagation. A calculation is presented showing the variation of plastic zone size as the crack tip advances through the overload plastic zone. This information is used to define an effective stress intensity range that applies during the retardation period. A strip-yield representation of crack tip plasticity is employed in the analysis, and the effect of crack closure is included by means of a previously developed analytic function method. The fracture mechanics based model predicts the delayed retardation effect and other experimentally observed features of overload-influenced fatigue crack growth.