Starting and stopping behavior of worn journal bearings

Metal-metal contact occurs during the starting and stopping of a shaft in a lubricated journal bearing which causes continuous wear and limits the bearing lifetime. To study the starting and stopping behavior of worn journal bearings, a validated elasto-hydrodynamic simulation approach is applied. A gradually developing wear scar is predicted which is caused by repeated starting of the shaft. Wear depth, geometrical extent of the wear scar, shaft movement, contact pressure distribution and the formation of the lubrication wedge with increasing shaft speed are discussed. Furthermore, friction moment during a start-stop cycle are calculated and compared to measurement results.