Stability Analysis of Rotor-Bearing Systems Using Component Mode Synthesis

A method of component mode synthesis is presented for the analysis of multishaft rotor-bearings systems. The motion of each component of the system is described as the superposition of constraint modes associated with boundary coordinates and constrained precessional modes associated with internal coordinates. The constrained precessional modes for each component are truncated and the reduced component equations are assembled to yield a set of system equations. The nonsymmetric nature of the general problem requires the utilization of biorthogonality relations between right and left vector sets in order to decouple the component precessional modes. The method is developed for damped whirl speed/stability analysis and comparative results are presented for various levels of mode truncation for two example systems.