Stress gradient effect on crack initiation in fretting using a multiaxial fatigue framework

The paper discusses the stress gradient effect on crack initiation in fretting in medium cycle fatigue. The stress gradient effect is highlighted through fretting experiments in partial slip. Crack initiation is studied with an Inconel 718 cylinder plane contact. Tests are performed using three cylinder radii to sweep a large range of stress gradients. The experimental results confirm the stress gradient effect on crack initiation. A proposal is developed in a multiaxial fatigue framework to predict the experimental results. The proposal is based on a usual multiaxial fatigue criterion weighted by a weight function depending on the stress gradient. The model shows good capabilities to predict the crack initiation conditions for all contact configurations. The proposal is compared to other approaches.