The effect of contact compliance of sliding pair on friction force reduction at longitudinal tangential vibrations

Abstract

The main purpose of this work was to experimentally test the impact of modification to the tangential contact stiffness of the friction pair, caused by changing the kind of material, roughness of the contact surfaces and surface pressures, on the level of friction force reduction in the sliding motion, under the influence of high-frequency longitudinal tangential vibrations introduced into the contact area. The tests were carried out on an original test stand for three kinds of friction pair materials, such as: steel C45, cast iron GGG40 and polytetrafluoroethylene PTFE – Teflon, working in homogeneous connections: steel – steel, cast iron – cast iron and Teflon – Teflon and in mixed connections: steel – Teflon, steel – cast iron and cast iron – Teflon. For each friction pair, at defined values of normal pressures, the compliance characteristics of the contact in the tangential direction were determined. On their basis, as a function of normal pressures, values of the tangential contact stiffness coefficient were calculated. Then, also as a function of normal pressures, experimental tests were carried out on changes in the friction force in sliding motion occurring in the contact under the influence of longitudinal tangential vibrations. The tests were carried out for different speeds of the drive, with fixed vibration parameters, such as amplitude and frequency. On the basis of obtained results of the dependence of contact compliance on the kind of material of the friction pair, contact surface roughness and surface pressures, as well as on the dependence of friction force changes under the influence of tangential vibrations on the same factors, the relationship between the level of friction force reduction under the influence of these vibrations and contact compliance was examined.