DYNAMIC ANALYSIS OF ANISOTROPIC ASYMMETRIC ROTOR-BEARING SYSTEM BASED ON THREE-DIMENSIONAL FINITE ELEMENT METHOD

3D finite element modeling is a promising method, but it is not well extended to the dynamic analysis of anisotropic asymmetric rotor bearing systems. This paper is aimed at proposing a dynamic analysis method of anisotropic asymmetric rotor bearing systems based on 3D finite element method. In the proposed approach, the advantages of 3D finite element modeling are used to accurately simulate the dynamic characteristics of the asymmetric rotor. The asymmetric characteristics of the stator are considered and simplified as time-varying bearing stiffness parameters in the rotating frame. The time-varying coefficient differential equation of motion of the rotor bearing system is established in a rotating frame by taking consideration of the bearing characteristics. Floquet theory and Hill expansion method are adopted to obtain the set of equivalent linear time-invariant equations of the original time-varying coefficient differential equations. Frequency characteristics and stability of the system were obtained by solving the equivalent linear time-invariant equations. Two numerical examples are analyzed. The results of the two examples show that the proposed 3D finite element method is a good tool for dynamic analysis of anisotropic asymmetric rotor bearing systems.