Abstract
We develop an analytical model of adhesive wear between two unlubricated rough surfaces, forming micro-contacts under normal load. The model is based on an energy balance and a crack initiation criteria. We apply the model to the problem of self-affine rough surfaces under normal load, which we solve using the boundary element method. We discuss how self-affinity of the surface roughness, and the complex morphology of the micro-contacts that emerge for a given contact pressure, challenge the definition of contact junctions. Indeed, in the context of adhesive wear, we show that elastic interactions between nearby micro-contacts can lead to wear particles whose volumes enclose the convex hull of these micro-contacts. We thereby obtain a wear map describing the instantaneous produced wear volume as a function of material properties, roughness parameters and loading conditions. Three distinct wear regimes can be identified in the wear map. In particular, the model predicts the emergence of a severe wear regime above a critical contact pressure, when interactions between micro-contacts are favored.
Highlights
Wear is an ubiquitous phenomenon, and yet it is still hardly predictable
This paper focuses on the emergence of the severe wear regime in dry contact conditions and assuming adhesive wear processes, for materials of similar hardness
The model takes into account elastic interactions between several nearby micro-contacts and allows for the formation of combined wear particles encompassing multiple micro-contacts
Summary
Wear is an ubiquitous phenomenon, and yet it is still hardly predictable. It is usual that factors contributing to or limiting wear are studied via extensive experimental campaigns. Brink et al [21] followed the same principle but added the notion of sliding distance to compute a wear volume over time and obtain a more physically accurate wear coefficient These models give promising results, but their downside is that they do not take into account elastic interactions and assume that each microcontact is isolated from the others, overlooking the potential transition to a severe wear regime. We will discuss how the approximation that was made in the released energy, while allowing for a high computational efficiency, does not capture the full effect of the elastic interactions As a consequence, they obtain wear particles that can enclose several junctions, but do not observe a transition to a severe wear regime. A salient feature of the model is that the produced wear maps are function of well-defined physics-based model parameters, including material properties, surface roughness, and load
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