Research On Nonlinear Dynamical Charateristics Of A Bearing-Rotor-Box System With Rub-Impact

In this thesis, a mass of research has been done on the stability of rotor system of scale large rotating machinery, in which most systemic theory research and numerical emulation has been done mainly in the influence of the stability of rotor system caused by nonlinear rub-impact force and unsteady oil-film force. The results provide a reference basis for the safe operation and the fault diagnosis of a rotor system.1. The paper summarizes the engineering background, significance and study actuality of rotor dynamic, narrates the diversified nonlinear forces which impact on the stability of rotor system, and introduces the phylogeny of nonlinear dynamic and chaos.2. Considering the nonlinear rub-impact force, the dynamic model of Jeffcott rotor system with rub-impact is established, and the dimensionless processing is made on dynamic model. The nonlinear dynamic behaviors in running are investigated widely on the rotor system with rub-impact faults, the influence of the rotate speed and imbalance on bifurcation and chaos of the rotor system is analyzed, and nonlinear chaos behaviors of the system are discovered. The effect of parameters such rub-impact force, time history curve, phase plane portrait, axes track, Poincare map, amplitude spectra etc, on the nonlinear dynamic properties was discussed, the bifurcation behaviors and chaos motion of the system were analyzed in detail.3. When rub-impact occurs, there is a rub-impact force on rotor and box. The box vibrates under the effect of rub-impact force, which destroys the stability of the rotor system. The dynamic model of rotor-box system with rub-impact is established on the basis of nonlinear rub-impact force and the influence of vibration of box, and the dimensionless processing is made. The bifurcation and chaos behaviors of rotor-box with rubbing are studied by means of numerical stimulation. In view of the case of multi-parameters, the bifurcation behaviors and chaos motion of rotor-box are analyzed in detail. The system of rotor-box with nonlinear local friction has abundant dynamic behavior.4. Unsteady oil-film force is one of the most important causes to the stability of rotor system. The dynamic model of bearing-rotor-box system with rub-impact is established on the basis of short bearing unsteady oil-film force coupled with nonlinear rub-impact force, with the influence of vibration of box, and the dimensionless processing is made. The numerical simulation on nonlinear dynamic behaviors of bearing-rotor-box system caused by unsteady oil-film force coupled with nonlinear rub-impact force is carried out with the Runge-Kutta method. The characteristic of bifurcation and chaos caused by the rotate speed and imbalance parameter, and abundant nonlinear phenomena such as periodic motion, quasiperiodic motion and chaos are found out.