A model to predict fretting fatigue life including residual stresses

This paper proposes a multiaxial fatigue life model that considers the presence and cyclic relaxation of a residual stress field. Although the model has been developed for fretting fatigue under spherical contact conditions, and considers a residual stress field induced by specific laser and shot-peening treatments, its general structure can be applied to other fatigue configurations in which a residual stress field is present. The model predicts the total fatigue life as a combination of the life spent during the initiation phase and the life associated with the propagation phase. The transition length is not previously fixed but depends on the particular loading conditions, geometry and material properties of the analysed problem. The residual stress field was measured and introduced in the model as cycle dependent stresses, and thus, two types of relaxations were introduced in the model: plastic and cyclic. All fatigue life estimations are compared to the experimental results to understand the effect of stress relaxation on fretting fatigue life.