Mathematical Model of a Rotor-Bearing System and the Passive Control

Abstract

This paper presents a mathematical model of a rotor bearing system and the vibration control using a passive absorber. The system with the passive absorber is modeled using Finite Ele ment Methods (FEM). The primary system consists in a rotor system mounted on two supports at its ends, one of them is a classical journal bearing and the other one is a bearing on a slider which can be dis placed in order to change the distance between supports. The passive absorber is a concentrated mass mounted at the end of a cantilever beam which is an extension of the flexible shaft of the rotor system. The vibration attenuation in the rotor system is achieved modifying the system dynamics by the displacement of the slider bearing which causes changes in the absorber and primary system stiffness and as a consequence in their natural frequencies. To control the slider bea ring position a PD control scheme is used, which is parameterized in terms of the angular speed of rotor. Some numerical simulations are included to illustrate the dynamic performance, obtaining reductions up to 80% in the unbalance response of the primary system.