Dynamic modeling and analysis of nonlinear flexible rotors supported by viscoelastic bearings

Flexible dynamic models of rotors are more efficient to capture the nonlinear dynamic behavior of rotors as compared with conventional rigid body models that ignore the geometric nonlinearities associated with shaft elastic motion. This chapter presents a dynamic modeling approach of a shaft-disk rotor system supported by nonlinear flexible bearings with consideration of the shaft flexibility and corresponding geometric nonlinearities. The system kinematics is formulated and subsequently used to derive the equation of motion considering the linear and nonlinear stiffness and damping properties of the bearings. The analytical approaches used to analyze the free vibration characteristics and nonlinear behavior of the system are then highlighted. Finally, sample results showing the effects of the bearing nonlinear properties on the nonlinear dynamic response of the system to unbalance disk force are presented.