Curved Fatigue Cracks Under Complex Loading

Abstract

A reliable and cost effective two-phase methodology is proposed to predict crack propagation life in generic twodimensional structural components under complex fatigue loading. First, the usually curved fatigue crack path and its stress intensity factors are calculated at small crack increments in a specialized finite element software, using automatic remeshing algorithms, special crack tip elements and appropriate crack increment criteria. Then, the calculated stress intensity factors are transferred to a powerful general purpose fatigue design software based in the local approach, which has been designed to predict both initiation and propagation fatigue lives by all classical design methods. In particular, its crack propagation module accepts any K I expression and any da/dN rule, considering sequence effects such as overload-induced crack retardation to deal with one and two-dimensional crack propagation under complex loading. Non-trivial application examples compare the numerical simulation results with those measured in physical experiments.