THE FRICTION FORCE DURING STICK-SLIP WITH VELOCITY REVERSAL

Stick-slip is the well-known phenomenon of intermittent motion caused by a changing friction force in combination with mechanical system ela sticity. Usually, no velocity reversal occurs during the slip-phases o f a stick-slip cycle. However, velocity reversal is observed during st ick-slip motion of a laboratory test rig with oil lubricated centre-pi voted sliding shoes and a very flexible tangential spring connection. The general condition for velocity reversal during the slip-phase of a stick-slip cycle is derived and the friction force during stick-slip with velocity reversal is measured and discussed with reference to the Stribeck-curve, which represents the friction force in steady-state c onditions. In order to better understand the friction force during vel ocity reversal, free vibration tests with friction are also performed and discussed in this paper. (C) 1998 Elsevier Science S.A. All rights reserved.