| The dissertation is based on the project provided by National Natural Science Fundation, that is:Research on catastrophe failure prognosis of non-linear rotary mechanical system (50975105). Large rolling machine has wide application and high security and reliability requirement in industrialized society. Campare with gradual failures, catastrophe failures without early symptom occur frequently and harmful in actual prodution. So it is necessary to research the catastrophe failures of rotor system. Based on the catastrophe theory, the nonlinear model for steam excitation of rotor-bearing system is used to diagnose and predict faults in this paper. Three parts included in this thesis are as follow:Part1:the analysis of tip clearance steam excitation. According to simplification Alford force, the nonlinear dynamic model with tip clearance steam excitation force is proposed. After frequency-response equation derived by average method, the cusp catastrophe and bifurcation set of tip clearance steam excitation are deduced by catastrophe theory, catastrophe impact factors are identified. The relationships between catastrophe amplitude and impact factors are discussed. Finally, numerical method is employed to verify the results.Part2:steam excitation model cooperated to Capone dynamic oil-film force. Capone dynamic oil-film force has advantages of high precision and good convergence. The dynamic model of rotor-bearing rotor system with steam excitation force and oil-film force is proposed in this paper. Then, fourth-order Runge-Kutta method is used to draw bifurcation diagram among amplitude, speed and bearing clearance, and analyse the affect by other impact factors.Part3:devise shaking table. In order to verify the results and collect working data, it is necessary to design and establish shaking table.Results of this paper provide some technical support for the catastrophe performance’s description and prevention of steam excitation fault. |
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