Abstract: The stability and bifurcation of a rotor system with non-analytical elliptical bearing supports are analyzed. The effects of inertia can be taken into consideration in the model of rotor system. Nonlinear oil film force is adopted to increase the numerical accuracy. Based on the isoparametric finite element with eight nodal points method, variational inequalities with Reynolds boundary arising in fluid lubrication are solved. Nonlinear oil film forces and their Jacobian matrices that are needed at dynamic integration are calculated simultaneously, and compatiable accuracy is obtained with little increase of computing efforts. In the stability analysis, the periodic unbalance responses of the system are obtained by shooting method and path-following technique. The local stability and bifurcation behaviors of periodic motions with the change of bearing design parameter value are obtained by the Floquet theory. The numerical examples show that the schemes of this study have good precision.

Key words: Bearing-rotor system, Finite element method, Nonlinear, Rotor dynamics, Stability