The Behavior of Thrust Washer Bearings Considering Mixed Lubrication and Asperity Contact
The behavior and life of a tilted flat thrust washer bearing is modeled by a comprehensive numerical code. The goal is to investigate the conditions that distress thrust washer bearings through numerical techniques. The thrust washer bearing supports non axisymmetric loads within the planetary gear sets of automatic transmissions and consists of flat faced washers placed between an idle helical gear and its contacting face. Because of non axisymmetric loading, the gears and washers tilt in relation to the carrier, forming a converging gap that may produce hydrodynamic lift. Various coupled numerical schemes model sliding friction, boundary lubrication, asperity contact, thermo viscous effects, and full film lubrication. The model provides predictions of frictional torque, bearing temperature, hydrodynamic lift, and other indicators of bearing performance. The results show that the bearing operates in the regimes of boundary lubrication, mixed lubrication, and full film lubrication, and that the bearing can distress at high loads and speeds. Presented at the STLE Annual Meeting in Toronto, Ontario, Canada May 17 20, 2004 Review led by Jane Wang