Application of the strip-yield model from the NASGRO software to predict fatigue crack growth in aluminium alloys under constant and variable amplitude loading

The strip-yield model from the NASGRO computer software has been applied to predict fatigue crack growth in two different aircraft aluminium alloys under constant amplitude loading and programmed and random variable amplitude load histories. The computation options realized included either of the two different strip-yield model implementations available in NASGRO and two types of the input material data description. The model performance has been evaluated based on comparisons between the predicted and observed results. It is concluded that altogether unsatisfactory prediction quality stems from an inadequate conception of the constraint factors incorporated in the NASGRO models.