Vibration absorption in a rotor-bearing system using a cantilever beam absorber

This work treats the problem of vibration control in a rotor-bearing system using a passive absorber with controllable stiffness. 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 displaced 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. The rotor-bearing system with the passive absorber is modeled using Finite Element Methods (FEM). To control the slider bearing position a PD control scheme is used, which is parameterized in terms of the spin speed of rotor. The vibration control scheme proposed is validated by numerical results, obtaining reductions up to 84% in the unbalance response of the primary system in relation with the open loop operation.