Abstract: Using magnetorheological(MR) fluid in place of lubricating oil in a normal squeeze film damper(SFD) can build a damping-variable SFD controlled by magnetic field, used to control the vibration of rotor systems. The Reynolds equation of MR fluid squeeze film and its resolution are derived based on the Bingham model, and the calculating formulas for flowing velocity, pressure distribution, reaction force of the squeeze film and the magnetic pull force inside the damper are presented. Using a rigid rotor supported on the MR fluid SFDs as an example, the mechanical properties of the squeeze film and the unbalance response characteristics of the rotor system are analyzed theoretically. A squeeze mode MR fluid damper used for rotor vibration control is designed and manufactured, and the unbalance response properties and control method of a single-disk flexible rotor system supported by the damper are studied experimentally. The study shows that the magnetic pull force can decrease both the first critical speed and the critical amplitude. The oil film reaction force can decrease the amplitude at the undamped critical speeds and increase the damped critical speed. The damper may have the best effect to make the vibration minimize within the range of all working speed by using on-off control method.

Key words: Magnetorheological fluids, Rotor, Squeeze film damper, Vibration control