Active Vibration Control of Flexible Rotor-Shaft System Subject to Earthquake

This paper presents the results of a numerical simulation to actively control transverse vibration of a flexible rotor shaft subject to seismic base excitation. The active control force is applied over an air gap by an electromagnetic actuator. Equations of motion of the rotor-shaft-system have been drawn up after discretizing the rotor continuum with finite beam elements and taking into account rotor flexibility, internal friction forces due to rotor material damping, inertial forces due to base motion, gyroscopic forces and non-linear electromagnetic control forces from the actuator in addition to harmonic excitation due to unbalance in the steadily spinning rotor-disc. A MATLAB code in the SIMULINK domain has been created for this purpose and the equations developed are solved numerically in the time domain to get the response at each nodal point. Numerical simulation of vibration response of the disc in a single-disc rotor-shaft-system is compared with and without the control action when the rotor base is excited with the El-Centro earthquake data. The comparison shows a remarkable reduction of response amplitude and improvement of rotor-shaft-system stability in comparison with no control action. Hence the usefulness of an electromagnetic actuator is proposed for safe and sound operation of rotor-shaft systems even under the seismic base excitation.