Multi-fault identification in simple rotor-bearing-coupling systems based on forced response measurements

In the present paper, an identification algorithm has been developed to estimate parameters of multiple faults in a turbine-generator system model based on the forced response information. A simple discrete model of the system has been developed with the assumption of the rigid-rotor, flexible-bearings and the flexible-coupling. This is capable of describing the vibration resulting from coupling misalignments and rotor unbalances. A simple flexible-joint has been used to model the coupling between the turbine and generator shafts to take the misalignment effect into account, which accounts for coupling forces and moments due to the restoring and dissipative effects. Equations of motion of the system are derived by using the Lagrangeʹs equation. An identification algorithm based on the least-squares fit technique in frequency domain has been developed for the simultaneous estimation of bearing dynamic parameters, residual unbalances, and the misalignment forces and moments from forced responses of the system. Numerical experiments have been performed to illustrate the effectiveness of the developed algorithm. The algorithm is tested against the measurement noise and found to be robust.