MICRO CONTACT MODEL FOR RELATIONSHIP BETWEEN THE SIEBEL`S AND COULOMB FRICTION COEFFICIENTS

Abstract

The purpose of the work is to establish the relationship between the Coulomb and Siebel friction coefficients based on micromechanical modeling of the parameters of the elastic-plastic contact interaction of surface roughness protrusions using the adhesion theory of friction. The research methodology included a theoretical substantiation of the relationship between the friction coefficients of Siebel and Coulomb using the adhesion theory of friction, as well as the development of a micro contact model of elastic-plastic deformation of rough surfaces. Roughnesses were modeled by spherical micro protrusions. In the main part of the work, based on the adopted model of microcontact interaction, the force parameters of the transition from constrained elastoplastic deformation to free plastic flow are determined, taking into account the action of the Siebel friction law on model contact spots. A transition has been made from contact pressures and specific friction forces on individual contact spots to averaged nominal pressures and specific friction forces. An analytical relationship has been obtained that relates the Siebel and Coulomb friction coefficients, as well as the Poisson's ratio of the softest material of the friction pair. Using the example of carbon and alloy steels, as well as non-ferrous metals and alloys, a calculation estimate of the relationship between the Siebel and Coulomb friction coefficients has been made for a wide range of changes in the Poisson's ratio. The calculated values agree with the available experimental data. The research results can be used in the educational process in the study of tribological disciplines, as well as in engineering and research practice.