Energy Dissipation at Plane Surfaces in Contact

Abstract

Experiments are described in which the frictional damping occurring at plane stainless steel contacts under oscillating tangential loads was measured for different periods up to a maximum of 5 times 10⁶ cycles. Expressions for the damping under partial slip and gross slip conditions are derived using the Panovko-type approach and compared with experimental results. Close agreement is obtained for the partial slip region and fair agreement in the gross slip region. Discrepancies are traceable to variations in the experimental coefficient of friction. The variations of energy dissipation and coefficient of friction under constant normal load conditions and the development of surface damage are described and discussed. The nature of the damage has a major influence on the friction and thus on the damping. The fretting damage appeared to consist of flattened areas, inclined at a slight angle to the plane of contact, interspersed with pits. Loose oxidized debris had accumulated in the pits and because of its low resistance to sliding, caused a fall in the overall coefficient of friction. The resistance of the debris was found to vary with the applied load conditions.