Investigations of Transient Oscillations of Rotors Supported by Magnetorheological Squeeze Film Dampers Using Bilinear Material to Model the Lubricant

Unbalance of rotors is one of the principal causes of their lateral vibration. A technological solution frequently used to its suppression consists in placing damping devices to the rotor supports. To achieve their optimum performance their damping effect must be controllable. This is offered by squeeze film dampers utilizing the magnetorheological phenomenon to control the damping force. In mathematical models magnetorheological oils are usually represented by Bingham or Herschel-Bulkley theoretical materials. Here the magnetorheological oil is modeled by bilinear material with the yielding shear stress depending on magnetic induction. Its flow curve is continuous which contributes to reducing nonlinear character of the motion equations. The new mathematical model was applied to investigate several operating regimes of rotating machines.