Nonlinear dynamic response and stability of a rod fastening rotor with internal damping effect

The nonlinear dynamic characteristics of a rod fastening rotor-bearing system considering internal damping are investigated in this paper. The governing equations of motion of the rod fastening rotor system, in consideration of nonlinear oil-film force and internal damping, are derived by using finite element method based upon Timoshenko beam theory. On the basis of the mathematical model developed, the rotational speed, contact feature and internal damping are the variables considered in the performed simulations. This work mainly focuses on the internal damping effects on the response amplitude and rotor stability. The obtained results obviously show that the internal damping has a dual effect on the nonlinear dynamic response, i.e., low-speed attenuation and high-speed amplification. In addition, internal damping reduces the threshold of instability by 24.14%. Overall, in order to ensure the operating speed less than the onset speed of whip instability but greater than the critical speed, the internal damping should be strictly considered in dynamic modeling and analysis for such complicated rotors. The research can give a new guidance to the dynamic design and vibration control for such types of rod fastening rotors.