The effect of contact edge geometry on fretting fatigue behavior in complete contacts

The effect of contact edge geometry on the fretting fatigue behavior of a complete contact was studied with 34CrNiMo6 quenched and tempered steel. The contact geometries employed were sharp and rounded square-ended pads against a plane surface. A 2D elasto-plastic finite element model of the contact setup was used to calculate fretting cracking risk for these geometries using the Findley multi-axial fatigue criterion and the theory of critical distances. A series of experimental fretting fatigue tests was carried out with two corresponding geometries and loadings using an in-house complete contact fretting test device. It was found that the slightly rounded contact edge has a somewhat higher risk of cracking than the sharp contact edge. This agrees with the experimental results. The effect of the friction coefficient on the cracking risk was also studied. In addition, fretting wear scars from the experimental test specimens were evaluated.