Numerical and Experimental Investigation of Plastic Interaction Between Rough Surfaces

The paper presents a dry friction model considering plastic interactions described by the Oxley equations. The model differs clearly from those published by Oxley due to the fact that it includes a statistical analysis of rough surface interactions. The contact of a single asperity is analyzed in a 3D—not 2D—space. The results of this analysis are further extended to the contact of two rough-surfaces by accomplishment of an appropriate summing (integration) of individual elementary forces of friction and pressure occurring in discreet contacts. In the case of papers based on the Oxley model, their authors analyze the contact of a single asperity with a plane and thus compute the macroscopic friction coefficient. On the basis of the achieved mathematical model of dry friction, the friction force was determined and consequently, the friction coefficient. In order to verify theoretical speculations, an experimental test was carried out in the system consisting of a steel disk with a galvanized coating and a steel pin. The results of experimental tests comply with the solutions achieved via a computer simulation. The resistance to motion results mainly from plastic deformations, which in turn result in adhesion tacking. Among investigated galvanic coatings, the highest motion resistance was revealed by a nickel coating, whereas the lowest one was revealed by a silver coating.