| Large-scale rotary machines are key equipments in national basic industry. The safety in productions is of very significance to social life and economic development. Rotor-bearings system is the kernel mechanism rotary machinery, which stability is key to safe operation. It is not only a great basic scientific research subject to study the stability of rotor bearing system, but also helpful to solve the dynamic problems when large-scale rotating machinery is in the process of operation. So the stability of rotor bearing system motion has been paid attention increasingly. In this paper, a feasibility experimental research was studied in actually rotor system with the definitions and regularity of the three kinds of typical motion stability margins, which come from the paper'Quantitative Methodology for the Stability Analysis of Nonlinear Rotor Systems'.Firstly, the research status and development tendency of rotor-bearing system dynamics are summarized. And then especially put the stress on the quantitative methodology for the stability analysis of rotor systems, which is presented based on trajectory. Dynamic center point (DCP) of a subsystem is defined on the extended phase plane, namely force-position plane. Characteristics of curves on the extended phase plane and the kinetic energy difference sequence of the DCP for general motion in rotor system are studied. The corresponding stability margins of trajectory are evaluated quantitatively.A numerical simulation analysis for the Jeffcott rotor system stability is carried out by means of the Capone nonlinear oil force model. Then a bifurcation point prediction to the system response is done through two examples at two different mass eccentricities by sensitivity analysis, which is based on the three kinds of typical motion stability margin definition of the rotors system.Finally, the change rule was studied by means of experiment in a single and double span rotor system respectively which based on the definition of the three kinds of typical motion stability margin of rotor bearing system with lubricated bearings and its operability was verified. The result shows that the definition of frequency periodic motion stability margin has a certain difficulty in the practical applications and has poor maneuverability. It is proposed to re-give the definition of frequency periodic motion stability margin and mine it from steady-state data. The definition of double periodic motion and quisa periodic motion stability margin are better in the practical application operability, but the latter has a certain difficulty in selecting and calculating data. |
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