A POSITIVE POSITION FEEDBACK CONTROL SCHEME FOR SEMIACTIVE BALANCING COMPENSATION USING A SQUEEZE FILM DAMPER WITH MR FLUID AND CENTERING RUBBER SEALS

摘要

Squeeze-Film Dampers (SFD) are commonly used in rotating machinery to provide flexibility, damping and extend the so-called stability thresholds. More recently, SFD are combined with Magneto-Rheological (MR) or Electro-Rheological (ER) fluids to introduce a control mechanism to modify the rotordynamic coefficients. There are, however, some theoretical and technological problems that complicate their extensive use, like the relationship between the centering spring flexibility, the rheological behavior of the smart fluid and the SFD forces. In this work it is considered a SFD with MR fluid and rubber seals like centering springs. The validation and the mathematical model analysis include the controllable viscoelastic properties associated to the MR fluid. The so-called Choi-Lee-Park polynomial model is analyzed and adapted to simplify the MR fluid dynamics and synthesize a Positive Position Feedback control scheme. During the analysis is considered a rotor-bearing system modeled using finite element methods. The semiactive control scheme is also combined with a smooth acceleration scheduling of the rotor speed to stabilize and reduce as possible the overall system response in a Jeffcott-like rotor configuration passing through the first critical speeds. The SFD with MR fluid is connected to a platform with a small rotor-bearing system to validate and experimentally evaluate some characteristics.