Title page for ETD etd-04072009-040837

Type of Document Master's Thesis
Author Ishii, Toshiyasu
URN etd-04072009-040837
Title Transient response technique applied to active magnetic bearing machinery during rotor drop
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Kirk, R. Gordon Committee Chair
Mitchiner, Reginald G. Committee Member
Wicks, Alfred L. Committee Member
  • Magnetic bearings
Date of Defense 1990-12-14
Availability restricted

The active magnetic bearing (AMB) is a relatively new technology which has many advantages compared with conventional bearing design. In an AMB system, the rolling-element back-up bearings are indispensable to protect the magnetic bearing rotor and stator, and other stationary seals along the rotor shaft. In this paper, a theoretical formulation is proposed and solved numerically to examine the transient response of the flexible rotor, from the time just previous to the AMB shuts down and including the rotor drop onto the back-up bearing. The backward whirl of the rotor, which may lead to the destructive damage of the machinery, has been analytically predicted at very light support damping and very high support damping. Also, the vibration due to the non-linearity of the contact point geometry has been included in the analysis. The influence of the support damping on the displacement of the disk and also the contact force between the journal and the inner-race of the back-up bearing have been computed for various rotor system parameters. By comparing these results with the optimum support damping for the simple flexible rotor model, it is shown that this support damping optimization can be applicable for specifying the required optimum range of support damping for the back-up bearings of AMB systems.

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