Chaos and bifurcation of a flexible rub-impact rotor supported by oil film bearings with nonlinear suspension

Abstract

Abstract The dynamic analysis of the rotor-bearing system is studied in this paper and is supported by oil film journal bearings. An observation of a nonlinearly supported model and the rub-impact between rotor and stator is needed for more precise analysis of rotor-bearing systems. Inclusive of the analysis methods of the dynamic trajectory, the power spectra, the Poincare maps, the bifurcation diagrams and the Lyapunov exponent are used to analyze the behavior of the rotor centre and bearing centre in the horizontal and vertical directions under different operating conditions. The periodic, quasi-periodic, sub-harmonic and chaotic motion are demonstrated in this study. A special phenomenon is occurring at s = 2.27, the motions of the bearing centre and the rotor centre in the horizontal direction are still at chaotic motions but the motions of the bearing centre and the rotor centre in the vertical direction are at 3T-periodic motions. It is concluded that the trajectory of rotor centre and bearing centre have undesirable vibrations. With the analysis of the dynamic behavior of these operating conditions, the theoretical and practical idea for controlling rotor-bearing systems with rub-impact condition can be more precise.