Sliding Friction Under Extreme Pressures—1

Abstract

Abstract The program of this investigation on sliding friction is concerned with the evaluation of the frictional forces which occur under very high contact pressures and under varying conditions of speed, temperature, and lubrication. The work presented herein covers the experiments which have been made on sliding friction at normal temperatures. Further experiments on boundary lubrication at normal temperatures and sliding friction at elevated temperatures will be reported in a second paper. This report indicates the behavior of sliding friction when large normal loads react between surfaces in contact over a wide range of sliding velocities. At velocities less than one inch per second magnified photographs of the ruptured surfaces indicate clearly this phenomenon of stick-slip. From the experimental records obtained it was possible to show that a functional relation exists between the following variables: (1) The sliding velocity, (2) the normal load, and, (3) the frequency of stick-slip. New experimental evidence is presented indicating that the natural frequency of the apparatus involved influences the phenomenon of stick-slip.