Active stabilisation of a rigid rotor by piezoelectrically controlled mobile journal bearing system

Abstract

The paper is concerned with the problem of active stabilisation of a rigid rotor supported on journal bearings by application of piezoelectric actuators. The actuators are capable of changing their size when subject to voltage. In the considered system the piezoelectric elements move the bearing shell in order to protect the journal from excessive vibration. Motion of the journal is followed by inductive sensors, which transmit an electric signal to the control system. The signal is differentiated with respect to time and then sent to the actuators controlling current position and velocity of the mobile shell (state-based control). Such an approach endows the system with an increased inertia and damping, and both the quantities enhance stable working of the system. The stability is determined by analysing eigenvalues of the equations of motion linearised around a non-trivial equilibrium position. Carried out numerical simulations prove that the method is effective as it increases the critical speed twice or even more. The efficiency is confirmed for various loading conditions.

Keywords:

• journal bearing
• active stabilization
• self-excitation
• piezoelectric actuators
• state-based control

Additional information

Notes on contributors

P M Przybylowicz

Piotr Przybylowicz was born in 1968 in Gdansk, Poland. In 1992 he completed engineering studies at Warsaw University of Technology and entered post-graduated studies at the faculty of Vehicles and Heavy Machine Engineering, Warsaw. In 1995 he obtained his Ph.D. His thesis was concerned with the problem of active stabilization of non-conservative mechanical systems subject to follower load as well as active damping of torsional vibration by making use of piezoelectric materials. The same year, he commenced work as a researcher and teacher at the Institute of Machine Design Fundamentals in Warsaw. His scientific interests then focussed on the application of piezoelectric actuators to rotating structures such as slender transmission shafts and rigid rotors supported on journal bearings. In both cases, active control was to enlarge operational domain within which these systems operate safely, i. far from the critical threshold. At present, he concentrates his scientific effort on fundamental problems related to stability and bifurcation of rotating structures, including journal bearings, whose dynamic properties are enhanced by active laminates or functionally graded materials based on piezoceramics. In 2002 he finished his habilitation thesis on that subject.

Dr Przybylowicz has presented his papers at numerous congresses and symposia, e.g. GAMM, EUROMECH, DINAME, IFToMM, IUTAM. He is an author and co-author of several articles in Meccanica, ZAMM, Int. Journal of Solids and Structures, Journal of Thermal Stresses, Systems Analysis Modelling Simulation and almost fifty conference papers. He can be contacted at: Institute of Machine Design Fundamentals, Narbutta 84, 02-524 Warsaw, Poland E-mail: [email protected]