Control of torsional rotor vibrations using an electrorheological fluid dynamic absorber

Torsional rotor vibrations are undesirable phenomena which are very difficult to control in rotating systems. A common method for reducing vibrations involves the use of dynamic absorbers. However, if their physical parameters are constant, the frequency range of efficiency of dynamic absorbers is tight, making them unsuitable for systems with variable speeds. The use of smart materials, due to their variable and controllable mechanical properties, may be a powerful tool for increasing the frequency range. Electrorheological (ER) fluids are attractive materials that undergo very fast reversible changes in their rheological properties upon the application of an electric field. In this study, an electrorheological dynamic torsional absorber, called the Smart ER Dynamic Absorber, has been designed in order to reduce torsional rotor vibrations. Under shear mode, the ER absorber can exhibit various torsional damping and stiffness characteristics when an electric field is applied. A nonlinear empirical model of the dynamic behavior of ER materials has been developed. An On-Off control strategy has been applied and absorber efficiency measured. The results show that the ER dynamic absorber exhibits very good performances.