Influence of normal micro-vibrations in contact on sliding motion of solid body

The paper shows results of some simulation studies on: (i) normal contact micro-vibrations in a simple model of a friction system and (ii) the influence of such vibrations upon reduction of friction forces in the system. A model of friction contact with two degrees of freedom is adopted, considering non-linear normal contact flexibility of rough surfaces acting on each other. The mechanisms which cause the reduction of the friction force are investigated and described. It is proved that the main cause of the decrease of the friction force, if normal contact micro-vibrations are present, is due to certain dynamic processes taking place within the contact region. This decrease is not due to lower values of the friction coeffcient, nor lower mean values of the normal reaction and real contact area, as it is often quoted in many publications.