ACTIVE VIBRATION CONTROL OF A FLEXIBLE ROTOR

In this work, a finite element model of a multibearing rotor system is presented. The effects of rotary inertia, gyroscopic moments, interna l viscous and hysteretic damping and shear deformations have been incl uded. The characteristics of the fluid-film bearings are represented b y eight stiffness and damping coefficients which are functions of Somm erfeld number. An optimal controller has been derived based on charact eristics peculiar to rotor bearing systems which take into account the requirements for the free vibration and the persistent unbalance exci tations. The controller uses as feedback signals, the states and the u nbalance forces. A methodology of selecting the gains on the feedback signals has been presented based on separation of the signal effects: the plant states are the primary stimulates for stabilizing the rotor motion and augmenting system damping, while the augmented states repre senting the unbalanced forces are the primary stimulus for counteracti ng the periodically excited vibration. The results demonstrate that th e proposed controller can significantly improve the dynamical behaviou r of rotor-bearing systems with regard to resonances and instabilities .