NONLINEAR BEHAVIOR OF A MAGNETIC BEARING SYSTEM

This paper describes the results of a study into the dynamic behavior of a magnetic bearing system. The research focuses attention on the in fluence of nonlinearities on the forced response of a two-degree-of-fr eedom rotating mass suspended by magnetic bearings and subject to rota ting unbalance and feedback control, Geometric coupling between the de grees of freedom lends to a pair of nonlinear ordinary differential eq uations, which are then solved using both numerical simulation and app roximate analytical techniques, The system exhibits a variety of inter esting and somewhat unexpected phenomena including various amplitude d riven bifurcational events, sensitivity to initial conditions, and the complete loss of stability associated with the escape from the potent ial well in which the system can be thought to be oscillating. An appr oximate criterion to avoid this last possibility is developed based on concepts of limiting the response of the system. The present paper ma y be considered as an extension to an earlier study by the same author s, which described the practical context of the work, free vibration, control aspects, and derivation of the mathematical model.