Frictional Properties of a Surface Covered With a Soft Metal Film—Part 2: Analysis of Friction Between a Single Protuberance and a Surface

Analytical investigation of the evaluation of the coefficient of friction is made to clarify the mechanism of the load dependency of friction, which was obtained in Part 1 of this research, and also to ascertain the effects of the surface film on the friction characteristic. The plastic flow of the soft metal film between a protuberance and the subsurface is presumed, and the pressure distribution originating from the side flow is calculated on the basis of the plasticity theory. The effects of the coefficient of friction of the load, the thickness and hardness of the film, and the radius of the protuberance, are examined. As a result, it is clarified that the load dependency of friction arises from the extremely high pressure distribution generated in the film.