On the prediction of fatigue crack retardation using Wheeler and Willenborg models

The aim of this work is to evaluate the applicability of the Wheeler and Willenborg models to predicting fatigue crack growth retardation in a flash welded structural steel subjected to a single overload during constant amplitude (CA) fatigue crack propagation test. Compact tension specimens, in different microstructural conditions, were subjected to a single overload at a given crack length during CA fatigue loading and crack growth rate da/dN vs. the stress intensity factor range deltaK was monitored, evidencing the retardation in crack propagation over an interval of crack length. The size of the delay zone as well as the number of the delay cycles were predicted by both the Wheeler and Willenborg models and then compared with the experimental data. Finally, the results are presented and discussed focusing on the comparison between the predictions made by the two models in the light of the experimental data.