Rotordynamic coefficients of a controllable magnetorheological fluid lubricated floating ring bearing

Rotordynamic coefficients of a controllable floating ring bearing (FRB) are measured in the presented study. Controllability of the bearing is achieved by using magnetorheological fluid (MRF) as lubricant along with external magnetic field. Magnetic field induced field-dependent viscosity of the MRF changes dynamic coefficients (stiffness, damping, etc.) of the bearing, and vibration amplitudes of the rotor will be suppressed by enhanced stiffness and/or damping. The rotating floating ring in the FRB separates the MRF into two lubricant films. Since the ring rotates slower than the shaft, shear rate in the outer film is lower compared to the inner film, pertaining controllability by limiting the so-called shear-thinning effect of the MRF. A test rig is built to measure and identify the rotordynamic coefficients of the MRF lubricated FRB. Coefficients of the bearing with various magnetic field strength are compared. Results show enhancements of dynamic properties of the bearing with external magnetic field, demonstrating the viability of this type of smart bearings in rotor control or behavior alteration applications.