Influence of R ratio and stick zone eccentricity on the prediction of the fretting fatigue limit with spherical contact

One of the principal factors governing fatigue crack growth under fretting conditions is the large stress gradient produced by contact loads in the material. This suggests that crack propagation can be examined in the light of models similar to those designed for notched components. In this work, we assesses the ability of some methods originally applied to fatigue of notched components to predict the fretting fatigue limit of elements with spherical contact. The effect of the local variation of the R ratio along the crack path is taken into account. The predictions thus obtained are compared with experimental data for Al-7075-T6 specimens with spherical contact under fretting fatigue conditions. The influence of the eccentricity of the stick zone on the fatigue failure is also discussed.