Predictions by load interaction models in AA6082-T6 aluminium alloy

The strip-yield model and the Generalized Willenborg model from the Nasgro 7.0 software have been applied to predict fatigue crack growth in an AlMgSi aluminium alloy under constant amplitude loading and single peak overloads. The model performance has been evaluated based on the comparison between the predicted and the experimentally observed crack growth behaviours. The crack propagation tests have been performed in agreement with ASTM E647 standard, using Middle-Tension, M(T), specimens under load control conditions. The strip-yield model enables the reproduction of the retardation behaviour following a single overload. Generally, the predictions are in agreement with the typical experimentally observed crack growth rate response. A high effect of the constraint factor in the predictions by the strip-yield crack closure model is observed. The Generalized Willenborg model is always significantly more conservative than the strip-yield model. However, it is clear that more investigation is needed in order to clarify some assumptions.