Stability and Bifurcations of Rotors in Fluid Film Bearings

Abstract

AbstractTo study the nonlinear phenomena of rotors in the sense of bifurcation theory, the mechanical model of a symmetric flexible rotor is investigated which is supported by two identical journal bearings. Two types of journal bearings are considered. While the oil whirl and oil whip oscillations of rotors in plain journal bearings are widely examined, the floating ring bearings cause a quite different vibration behavior with several mode interactions and an area of so‐called critical limit cycles leading to a rotor damage. For both types a Hopf bifurcation marks the beginning of the self‐excited oscillations in the case of a perfectly balanced rotor. By applying the methods of numerical continuation the occurring limit cycles as well as their stability are determined. The different nonlinear effects with the corresponding bifurcations are explained by describing the global solution behavior of the rotor‐bearing systems. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)