AN ELASTIC-PLASTIC CONTACT MODEL FOR A ROUGH-SURFACE WITH AN ION-PLATED SOFT METALLIC COATING

An elastic-plastic asperity contact model for surfaces with an ion-pla ted soft metallic coating is presented. The model reflects the experim ental observations that the wear mechanism for the coating is microcut ting and that for the substrate is adhesive. The Greenwood-Williamson asperity model is used as a basis for a rough surface analysis. A modi fied elastic-plastic contact model is used for the asperities having c ontact with the substrate, and a plastic contact model is used for the asperities having contact with the soft coating. The results indicate that a fully plastic contact model might be sufficient for prediction of the contact area for a surface with a high plasticity index. The c ontact area and the normal contact load of a surface with a higher pla sticity index are less sensitive to the coating thickness than those o f a surface with a lower plasticity index. When the surfaces are light ly loaded, a thin coating could potentially increase the contact stiff ness of the surfaces owing to the increase in the contact area because of plastic deformation of the coating. (C) 1997 Elsevier Science S.A.