Simple model for a magnetic bearing system operating on the auxiliary bearing

The present work studies the behavior of a magnetic bearing supported rotor when the flow of electric current to the magnetic actuator is suppressed In this condition the rotor is supported by the auxiliary bearing, which has looseness with the rotor, generating a series of impacts between these components. For the study of this state, a model of a flexible rotor is proposed, and the impacts are simulated using kinematical restitution coefficient theory. The results obtained from the theoretical model are compared with experimental data taken on a test rig using tools for non linear systems analysis such bifurcation diagrams. The comparison shows that, besides the simplification of the contact, the model predicts ranges chaotic, quasi-periodic, and periodic motions in the test rig.