THEORETICAL MODELING FOR FRETTING WEAR

In this paper a model for fretting wear is developed. The model is based on the assumption that a rough surface consisting of an array of conical asperities, all of the same height and cone angle, undergoes oscillatory tangential motion relative to a perfectly smooth surface. Thus, under the applied normal load, the regular array of conical asperities will wipe off the oxide film that covers the flat surface and also, the hard asperities will plough through the softer surface causing additional metal removal. For the proposed model to represent a real rough surface a probability statement of the asperity heights distribution was introduced in the analysis of the fretting wear model. This yields an expression for estimating the total material loss due to fretting wear as a function of the mechanical and surface parameters, namely displacement amplitude, normal load, number of fretting cycles, frequency of oscillation and degree of surface roughness. Using the obtained expression, relationships between the material loss due to fretting wear and the mechanical parameters were obtained. The trends of these relationships and values of volume loss predicted by this model were in satisfactory agreement with experimental results available in the literature.