The dynamic behaviour of rotor-bearing systems represents an ongoing field of research.

By increasing the rotational speed of the rotor an instability can be detected which is often referred to as "oil-whirl" or "half-frequency-whirling" in literature. As the frequency of this "whirling" instability meets an eigenfrequency of the associated elastic rotor, its oscillation amplitudes increase tremendously which is also known as "oil-whip". These "oil-whirl" and "oil-whip" effects can be rated as rather critical and should be avoided during the operation of the rotor-bearing system.
Various modifications (compared to the "classical" cylindrical bearing) have been proposed in literature in order to suppress or at least to decrease these unwanted effects. By modifying the shape of the bearing sleeves improvements of the rotor's dynamic behaviour are expected. Starting from an initially circular shape, the bearing sleeve is elastically deformed by piezoelectric actuators which leads to a complex fluid-solid-interaction.

The effects of the piezo actuated shaping on the rotor-bearing system are studied by means of systematic stability and bifurcation analysis, focusing on time-efficient modelling methods.

Contact: Prof. W. Seemann, A. Bitner