The effect of contact geometry on the rotary bending fretting fatigue of Al 7075-T6 has been investigated. Two types of contact geometries, conforming and non-conforming, have been considered in the investigation. Three different characteristic lengths have been used for each type of contact. In the conforming type, three different contact areas and in the non-conforming type three different fillet radii has been considered in this work. The results show that bending fretting fatigue reduces the life of the material by about 90% in some cases. The reduction varies with the contact type and characteristic length. In the conforming type of contact, fretting fatigue life increases with the increase of characteristic length for low bending stresses but at higher bending stresses the fatigue life converges to the same cycles, regardless of the characteristic length. In the non-conforming type, fretting fatigue life reaches a minimum at the fillet radius of 1.5 mm. Since, contact pressure, shear stress, and slip amplitude have great effects on fretting fatigue life, the distribution of these parameters have been determined using Abaqus software for each contact type. The numerical simulations are quite consistent with the experimental results. The numerical results could reasonably explain the manner of variations observed in S–N curves for different contact geometries considered in this work.

The onset of fretting fatigue is characterized by material microstructural changes in which the extent of the damage is comparable to grain size, and hence, the microstructure characteristics could have a significant effect on fatigue crack initiation. In this paper, a three‐dimensional finite element crystal plasticity framework is presented for simulation of the fretting fatigue. Controlled Poisson Voronoi tessellation (CPVT) method is employed to generate the polycrystalline region. In the CPVT method, regularity parameter controls the shape of grains. In this study, the impact of grain size and regularity parameter on crack initiation life and initiation site has been investigated. Cumulative plastic slip was used as a parameter of microstructure‐sensitive fatigue indicator. This parameter could effectively predict the location of crack initiation and its life. The results show that regularity parameter has a significant effect on the location of crack initiation. Furthermore, the effect of grain size on the fretting fatigue life of 316L stainless steel was investigated experimentally through testing different specimens with different grain sizes, to validate the simulation results.

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