Fatigue Crack Growth Modelling of Aluminium Alloy under Constant and Variable Amplitude Loadings

This paper presents a study on fatigue crack growth modelling of thin walled tube aluminium alloy with circumferential crack under constant and variable amplitude loadings. Three fatigue crack growth models were investigated for this purpose, i.e. Walker, Forman and NASGRO. The results showed the differences in the fatigue crack growth simulation under both loading types, although, they have the same stress ratio for the maximum value. Subsequently, it was found that, different models gave different fatigue crack growth behaviour. In another case, many factors were identified towards the fatigue crack growth affection in structures. Hence, an initial crack length and the stress ratio are then studied and they showed a great influence in the life of the thin walled tube. From the detail analysis of this paper, the NASGRO model was found to be the most appropriate model for the variable amplitude loading. Therefore, this model can be suggested for the use in critical applications with respect to the fatigue crack growth studies for different structures under variable amplitude loadings.