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Talks and Poster Presentations (with Proceedings-Entry):

H. Ecker, H. Springer:
"Stability Limits of a Self-excited Torsional Vibration System";
Talk: 4th International Symposium on Stability Control of Rotating Machinery (ISCORMA-4), Calgary, Canada; 2007-08-27 - 2007-08-31; in: "Proceedings of the 4th International Symposium on Stability Control of Rotating Machinery", Bently Pressurized Bearing Comp., (2007), 10 pages.



English abstract:
Self-excited vibrations may be encountered in drive trains when friction loads decrease with increasing
sliding velocity present in the system. For this reason, some types of high speed centrifuges may suffer
from torsional instabilities which might cause violent torsional vibrations, excessive wear and degraded
performance. A solution to such problems can be achieved by a properly designed vibration absorber.
This contribution deals with a centrifuge system that can be reduced to a minimal torsional vibration
model of three degrees of freedom. The non-linear self-excitation mechanism is acting between two
main masses of the model and can be linearized by a viscous element with negative damping coefficient.
Depending on the location of a vibration absorber and the level of positive damping provided, the system
may behave stable or unstable.
To investigate the system a suitable linearized model is established, and a damped eigenvalue analysis
is carried out to decide on the linear stability limit of the torsional vibration behavior. This numerical
approach is extended and stability maps are calculated for ranges of various system parameters. Different
configurations are investigated to study the effectiveness of measures to prevent the system from becoming
unstable. Numerical simulation is employed to analyze the system in the time domain and confirm the
results obtained from the stability analysis. Aside from conventional tuning of the absorber parameters a
small and isolated region of stability was found that allows to design an optimized small-sized absorber.

Keywords:
Stability analysis, self-excited vibrations, torsional vibration system

Created from the Publication Database of the Vienna University of Technology.