ICSV16, Kraków, Poland, 5-9 July 2009 1 PIEZOACTUATORS IN ACTIVE CONTROL OF JOURNAL BEARINGS Lubomír Smutný, Jaromír Škuta, Radim Klečka, Jiří Tůma VSB-Technical University of Ostrava, ul. 17. listopadu 15, 708 33 Ostrava, Czech Republic e-mail:lubomir.smutny@vsb.cz, jaromir.skuta@vsb.cz, radim.klecka@vsb.cz, jiri.tuma@vsb.cz Jiří Šimek Techlab s.r.o., Sokolovská 207, 190 00 Praha 9, Czech Republic email: j.simek@techlab.cz The paper deals with the instrumentation of a lab test stand for journal bearing active control. The test stand consists of an inductive motor driving via flexible coupling a rigid or flexible rotor supported by two journal bearing equipped by movable bushing, position of which is adjusted by two piezoactuators. The journal vibration inside bearing sleeve is identified by two couples of proximity probes, which are arranged in the perpendicular direction. The rotor RPM profile (ramps such run-up and coast-down and steady-state rotation at the controlled rotational speed) controls a system based on a PCL. A real-time simulator as a controller is acting as a closed-loop controller with error signals from proximity probes at the input and voltage driving the piezoactuators at the output. The mentioned voltage is connected to the input of the low voltage amplifier, which is controlling force and position of two pairs of pie- zoactuators. 1. Introduction It is known that the journal bearing with an oil film be- comes instable if the rotor rotation speed crosses a certain value, which is called the Bently-Muszynska threshold 1,2 . To prevent the rotor instability, the active control can be em- ployed. The arrangement of proximity probes and piezoac- tuators in a rotor system is shown in Fig. 1. It is assumed that the bushings (carrier ring), inserted into pedestals with clear- ance, is a movable part in two perpendicular directions while rotor is rotating. Therefore the journal bearing active control is based on the carrier ring position manipulation by the pie- zoactuators according to the proximity probe signals, which are a part of the closed loop including a controller. A laboratory test facilities for research in the branch of the journal bearing active control was designed by the TECHLAB company 3 , Prague. Now this equipment is putting into operation at the VSB – Technical University of Ostrava. Proximity probes Journal Carrier ring Im(r) Piezoactuato Re(r) Re(u) Im(u)  Figure 1. Journal coordinates and arrangement.