CHAOS CAUSED BY HYSTERESIS AND SATURATION PHENOMENON IN 2-DOF VIBRATIONS OF THE ROTOR SUPPORTED BY THE MAGNETO-HYDRODYNAMIC BEARING

2-DOF nonlinear dynamics of the rotor supported by the magneto-hydrodynamic bearing is investigated using the perturbation analysis. The two modes corresponding to the vertical and horizontal vibrations of the rotor are coupled. The nonresonant case and the various resonant cases (with and without an internal resonance) are considered. The frequency-response curves are obtained. When the amplitude of the external harmonic excitation is near to one of the natural frequency of the vibrations and the system experiences conditions of an internal resonance, a saturation phenomenon occurs. When the amplitude of the external excitation increases, after some critical value the energy pumping between various submotions of the rotor occurs for each mode. Further, it was shown, that in the case of rigid magnetic materials, hysteresis may be a cause of chaotic vibrations of the rotor. Chaotic regions and the amplitude level contours of the rotor vibrations have been obtained in various control parameter planes.