2-dof non-linear dynamics of a rotor suspended in the magneto-hydrodynamic field in the case of soft and rigid magnetic materials

Non-linear dynamics of a high-speed rotor symmetrically supported on the magneto-hydrodynamic bearing is analyzed. In the case of soft magnetic materials the method of multiple scales [1] is applied. Non-resonant and primary resonance cases with and without internal resonance are illustrated and discussed. In the case of rigid magnetic materials the hysteretic properties are taken into consideration by means of the Bouc-Wen hysteretic model. In order to characterize the hysteretic close-loop control of the rotor motion, instability regions as well as the amplitude level contours of vertical and horizontal vibrations of the rotor are obtained in the form suitable for engineering applications, i.e. in the ‘frequency-amplitude’ parametric plane.