Proposed modifications to the Wheeler retardation model for multiple overloading fatigue life prediction

A number of modifications to the Wheeler fatigue crack retardation model were proposed. The modifications allow the model to account for the delay retardation due to applied overloads, initial crack growth acceleration immediately following an overload, overload interaction and the net section yielding effect observed in the fatigue crack growth retardation behaviour of many materials. The modified model was used to predict the fatigue life of a series of single and multiple overloading fatigue tests conducted on 350 WT steel. The results showed that the modified model predicted the fatigue lives with a greater accuracy than the original model.