Thermoelastic Instability of Frictional Contacts

Abstract : This is a study of the stability of frictional contact of elastic solids. To be specific, the problem is to determine when surface pressure or temperature distributions will be damped, or when they will be amplified by the thermal, frictional and elastic interactions of the surfaces. This effort will shed light on the behavior of numerous lubricated and unlubricated sliding systems such as seals, bearings, and piston rings. It should lead to design criteria in terms of materials and operating parameters. The present report is concerned with two phases of the study: (1) a discrete model of surface contact, and (2) a continuous thin-blade model of surface contact. The first sheds light on the processes at work, and analysis of it leads to a 'thermal vibration' equation with a damping coefficient which may be either negative or positive depending upon the specific operating conditions. The second model provides a more complete treatment of the thermoelastic interactions at work in continuous bodies. The work reported carries the analysis up through the derivation of a pair of algebraic equations involving the materials and operating parameters of the system. Because of the complex relationships involved, further work will be required to determine all of their implications. (Author)