Nonlinear vibration and stability analysis of a flexible rotor-SFDs system with cubic nonlinearity

In this paper, the nonlinear vibration phenomena occurring in a flexible rotor supported on squeeze-film dampers (SFDs) are investigated. The complex nonlinearities caused by cubic nonlinearity in the rotor-bearing system and the fluid-film forces of SFDs are considered as sources of nonlinear phenomena in the system. Also, the dynamic response characteristics of the system, which occur due to asymmetric characteristics of parameters used to model SFDs, are analyzed. The unbalance response of these systems is analyzed by the modified incremental harmonic balance method, and stability analysis is performed on the solutions calculated using the Floquet theory. By comparing the results calculated using the proposed method with the results calculated using the Runge–Kutta method, the validity of the method proposed in this paper is verified. The frequency–response characteristics according to the change of all parameters used to model the system are considered, and whirl orbits, time history, and Poincaré sections are constructed at specific locations. This work can be effectively applied to the study of the nonlinear vibration phenomena of rotor-bearing systems supported on fluid-film bearings such as SFDs.