On the application of a micromechanical small fatigue crack growth model to predict fretting fatigue life in AA7075-T6 under spherical contact

• A two-threshold micromechanical model is extended to fretting fatigue crack growth.
• The model gives fairly good estimations of the fretting fatigue live.
• The model also gives fairly good estimations of non-propagating cracks formations.
• The model predicts with a good accuracy the fretting fatigue limit.

This work presents a method for assessing the fretting fatigue life by estimating the fatigue crack growth rate from the regime of microcracks to the final failure, which is achieved using a two-threshold small fatigue crack growth model. The propagation thresholds are associated with the interaction of the "monotonic plastic zone" and the "cyclic plastic zone" with the microstructure of the material. The predicted fatigue life and the estimated non-propagating cracks agree very well with the experimental fretting fatigue tests with spherical contact in 7075-T6 aluminium alloy.