Development of Smart Squeeze Film Dampers for Small Rotors

Squeeze film dampers (SFD) are lubrication elements which provide viscous damping in rotating systems. Squeeze film dampers in rotating machinery provide structural isolation, reduce the amplitudes of rotor response to unbalance and also assist to suppress rotor dynamic instability. They have been long used to subdue instability and vibration issues that are difficult to solve using conventional bearings like journal or ball bearings. Numerous studies have been tried to produce mechanically tunable dampers which allow the damping to be changed during different mode of operation. Magneto-rheological (MR) fluids are one of the strong contenders for tunable dampers. They provide the possibility to control the dynamic characteristics of conventional fluid dampers. Magneto-rheological fluids are viscous fluids suspended with micron sized ferromagnetic particles which on application of magnetic field undergo changes in their physical and mechanical properties like viscosity, stiffness, etc. This characteristic can be used to build squeeze film damper whose damping properties will change based on the input force. In present work a typical SFD is designed and development using MR fluid and tested for different amount of damping. It is observed that the damping provided by MR fluid increases with increase in magnetic field and the amplitude of vibration reduces by 70% at critical speeds.