VIBRATION ISOLATION OF ROTATING MACHINERY BY PARAMETERS SWITCHED MAGNETIC BEARING AND HIGH STATIC LOW DYNAMIC STIFFNESS SUPPORTS

Vibrations in rotating machinery cause many problems such as excessive noise and the vibration transmission to the supporting structure. In addition, the vibration isolation of the machinery with a wide range of rotational speed is a vital requirement and different to realize in practical engineering. As one of the key components in rotating machinery, bearing is not only the major vibration excitation source, but also the main vibration transmission path. Therefore, the mechanical property of the bearing has a significant effect on the vibration of the rotating machinery. Compared with traditional mechanical bearing, the equivalent stiffness and damping of magnetic bearing can be changed by adjusting its control parameters. On this basis, a novel design strategy of parameters switched magnetic bearing and high static low dynamic stiffness (HSLDS) supports for the vibration isolation of rotating machinery is proposed in this article. The design changes the equivalent linear stiffness and damping of the magnetic bearing by adjusting the control parameters according to the rotor speed, which will improve the vibration isolation capability of magnetic bearing at different rotor speed. Meanwhile, to further reduce the vibration transmission, the rotating machinery was suspended by nonlinear isolator with high static low dynamic stiffness characteristic. As an example, a rotating machinery system consisting of a rigid rotor supported by parameters switched magnetic bearings and high static low dynamic stiffness supports is studied. In this model, the rotor is excited by the unbalance force with different rotational speed. The amplitude of force acted on the base and the maximum relative displacement between the journal and the bearing are used to judge the isolation performance. Simulation results show that the demonstrated the effectiveness of this design strategy and the force transmission is significantly reduced with a wide rotational speed range.