Finite Element Model of Asymmetrical Rotor Bearing Systems

Abstract

Recently, the finite element method has been successfully used in rotor dynamic analysis. However, the previous works have been restricted to axi-symmetrical rotor-bearing systems. This paper extends the previous finite element modeling to include asymmetrical rotor-bearing systems, consisting of rigid disks, finite shaft elements with distributed mass and elasticity, and discrete bearings. The finite element model developed includes the effects of rotary inertia, gyroscopic moment, transverse shear deformation, internal damping and gravity. The dynamic analysis of multiple shaft rotor-bearing systems modeled by finite element method requires the solution of large order sets of linearized differential equations of motion. To reduce the size of the resulting matrices, the modal transform technique is applied. Finally the accuracy of the finite element model and the modal transform technique is demonstrated.