A finite element based approach to simulating the effects of debris on fretting wear

Previous studies by the authors have developed finite element (FE) based approaches to simulate fretting wear by material removal without consideration of the effects of debris. It was assumed that, wear particles, once generated, were immediately removed from the fretting interfaces and disappear. This method calculates the local wear as a function of local contact pressure and local slip, and incrementally updates the contact geometry with material removal. However, in reality, wear particles can become entrapped in the fretted regions and undergo a series of processes before they are eventually removed. The effects of trapped debris are important in fretting wear as debris naturally provides a load-carrying plateau. A revised modeling approach for incorporating the salient different effects of debris on the fretting wear process including the formation, trapping and removal of debris is therefore proposed in this study. In this approach the debris accumulated on the fretting interface is modeled as a layer structure with the mechanical properties being described by an anisotropic elastic-plastic material model. Migration of wear particles within the fretting surfaces after their formation is also considered, which determines the evolution of the thickness of the debris layer and its movement. The simulation tool incorporating the debris effects permits the redistribution of contact pressure and slip over the contact region to be estimated to ultimately predict debris effects on wear damage. The predicted results are calibrated and compared with measured fretting wear results from Hertzian fretting tests.