STUDY ON NONLINEAR DYNAMIC BEHAVIOURS AND STABILITY OF A FLEXIBLE ROTOR SYSTEM WITH HYDRODYNAMIC SLIDING BEARING SUPPORTS

This paper investigates the nonlinear dynamic behaviours of a flexible rotor sys- temwithellipticalbearingsupports.Basedonthevariationalconstraintapproach, nonlinear oil film forces and their Jacobians are calculated simultaneously. Ac- cording to the local nonlinearity of the flexible rotor system, a modal reduction technique based on a free-interface component mode synthesis technique is uti- lized to reduce linear degrees-of-freedom of the system. Nonlinear unbalance periodic responses of the system are obtained by using PNF (Poincare-Newton- Floquet) method and the bifurcation point of system can be calculated by using the combination of the predictor-corrector mechanism and the PNF method. The local stability and bifurcation behaviours of periodic motions are analysed by the Floquet theory. The numerical examples show that the schemes of this study not only save computing efforts but also have good precision.