A Rotor Looseness‒Rub-Impact‒Resonance Fault Mechanism Modeling

Abstract

In view of the limitation of the numerical method for coupling faults of rotating machinery, a modeling method for coupling faults of rotor, Deformation Motion Vector Analysis Method, is purposed in order to explain the fault mechanism more thoroughly and universally. Firstly, the “Deformation-Motion” is defined by fault and the relationship between fault deformation and periodic signal is established by Fourier series. Secondly, the “Vector Analysis” analyzes the deformation-motion in the dynamic coordinate system, and establishes the relationship between the fault deformation-motion and the periodic excitation force by using the dynamic and static coordinate systems. Thirdly, the analytical solution is obtained by harmonic balance method, and the coriolis acceleration term is first found in the analytical solution of rotating machinery failure. By further analysis of the analytical solution, we find that the general
trend of the natural frequency of the rotor system will gradually approach the excitation source frequencies and eventually lead to the resonance: that is the law of Natural Frequency Migration Resonance Theory. Finally, the validity of the modeling method and the correctness of the analytical solution are verified by engineering practice.