Modeling and experimental validation of transient response of magnetic suspension rotor contacting with auto-reducing clearance auxiliary bearing

The major purpose of this study is to indicate the transient responses of an active magnetic bearing (AMB) rotor contacting with auto-reducing clearance auxiliary bearing (ACAB). Considering the radial vibration of the single support, the real-time clearances between the outer ring (OR) and each support, and the swing of the supports, the dynamic models of the rotor and the ACAB are formulated. The dynamic behavior of the rotor-ACAB system is investigated by the dynamic trajectories of the rotor and the OR, the movement of each support, and the dynamic forces generated in the ball bearing and between the OR and supports. Furthermore, the AMB-rotor dropping tests, in which a strain gauge based measurement system and a high speed camera equipment are adopted to separately survey the interaction force between the support and the OR and record the movements of the OR and the supports, are performed. The results show that, after the rotor drops on ACAB, the swing supports rapidly reduce the protective clearance and then stably maintain the rotor to operate around the center of ACAB. Finally, the ball bearing only suffers the centrifugal force of the rotor without impact forces, while big interaction forces always exist between the OR and each support.