Nonlinear Dynamical Analysis Of The Rotor-bearing System With Rub And Pedestal Looseness Faults

The safe operation of large rotating machinery with pedestal looseness and rub faultsis crucial to the social life and economic development. For further realizing the mechanismof rotor system, the nonlinear dynamic behaviors in running are investigated widely on therotor system with pedestal looseness and rub, the results provide the theoretical analysisand numerical calculation.1. Considering pedestal looseness and rub, the dynamic model of rotor system isestablished. The dimensionless processing is made on dynamic model into standard6firstorder differential equations. The influence of the rotate speed and imbalance on the cycleand chaos of the rotor system is analyzed with the FORTRAN programming. The effect ofparameters such time history curve, phase plane portrait, axes track, Poincare map etc, onthe nonlinear dynamic properties was discussed. When the rotate speed is same parameter,bifurcation diagrams of the system are given with the change of imbalance.2. Considering pedestal looseness and oil film force, the nonlinear dynamic model ofrotor-bearing system is established. The dimensionless processing is made on dynamicmodel into standard14first order differential equations. With the Matlab programming, thenumerical integral method is used to obtain nonlinear dynamic responses, the effects ofrotating speed, imbalance, mass of bearing house on dynamic responses are analyzed, andthe bifurcation plot, phase plane plot, and Poincare map are used to carry out the analysisof bifurcation and chaos motion. When the imbalance is same parameter, a series ofbifurcation diagrams of the system are given with the changes of rotate speed and bearingquality.3. At the same time considering the pedestal looseness, rubbing force and nonlinearoil film force, the nonlinear dynamic model of rotor-bearing system is established. Thenonlinear dynamical behaviors of the system were studied using Rounge-Kutta method andits dynamical characters were analyzed with the help of Poincare maps and amplitudeanalysis. When the bearing quality is same parameter, a series of bifurcation diagrams ofthe system are given with the changes of rotate speed and imbalance.To sum up, this paper studies the rotor-bearing system, such as pedestal looseness and rub; pedestal looseness and oil film force; pedestal looseness, rub and oil film force. Thechange rule of nonlinear dynamics under the three conditions, provides a reference basisfor the safe operation and the fault diagnosis of a rotor system.