Kang, Xiao (2019-05). Simulation and Test of the Auxiliary Bearings and Their Dampers in Magnetic Bearing Systems. Doctoral Dissertation.
Auxiliary bearings (AB) support the rotor and protect the magnetic bearing (AMB)system when the AMB is disabled due to power loss or excessive loads. Firstly, this study developed a high fidelity nonlinear elastic-thermal coupled ball bearing type auxiliary bearing model and a two-dimensional plane strain elastic-thermal couple sleep type auxiliary bearing model. These two models can effectively predict the dynamic and thermal response when a flexible rotor drops onto a ball bearing type or a sleeve type auxiliary bearing. Additionally, the rain flow counting method is utilized to count the stress cycles and calculate the bearing fatigue lives along with the Miner's rule. Secondly, because large vibration and contact forces will occur during rotor drops, this study demonstrates that installing a damping device along with the AB can yield extended AB fatigue life, protect the AMB, reduce vibration, contact force and AB heating. The introduced high fidelity damper models include the squeeze film damper, wavy spring and elastomer O-ring. Thirdly, a rotor-auxiliary bearing test rig is developed to experimentally investigate the rotor's drop behavior and the dampers effect.