Investigation on the stability of periodic motions of a flexible rotor-bearing system with two unbalanced disks

The stability of periodic motion of a rotor-bearing system with two unbalanced disks is analyzed based on a multi-degree of freedom(M-DOF) finite element model. Nonlinear effects of supporting oil-film and inertia distributions as well as shearing effect are taken intoaccount. Focusing on the more realistic FE method to study the stability of nonlinear rotor-bearing system with the influence of the eccentricityphase, the stability calculation of the M-DOF FE model is done by using the combination of Shooting method and Newmarkmethod. Experiments with a rotor-bearing test rig (two disks on a shaft with two bearings) are then performed and results are presented. Itis found that typical instability characteristic is successfully produced. Through comparisons between calculated results and measurements,it is shown that the combination of Shooting method and Newmark method in studying the M-DOF rotor-bearing system is useful,especially for the complex rotor-bearing system. In addition, altering eccentricity phase of the two disks can significantly influence instabilitytype and speed. When the two disks are out of phase, the occurring of oil whip is restrained effectively. It is suggested that a carefulexamination should be made in modeling more complex non-linear rotor-bearing system. KCI Citation Count: 2