A new crack growth model for life prediction under random loading

The load interaction effect in variable amplitude fatigue test is a very im portant issue for correctly predicting fatigue life. Some prediction method s for retardation are reviewed and the problems discussed. The so-called "u nder-load" effect is also of importance for a prediction model to work prop erly under random load spectrum. A new model that is simple in form but com bines overload plastic zone and residual stress considerations together wit h Elber's closure concept is proposed to fully take account of the load-int eraction effects including both over -load and under-load effects. Applying this new model to complex load sequence is explored here. Simulations of t ests show the improvement of the new model over other models. The best pred iction (mostly closely resembling test curve) is given by the newly propose d Chen-Lee model.