Analysis of vibration signals for a ball bearing-rotor system with raceway local defects and rotor eccentricity

The transient impulses are one of the most important features for the defective bearing diagnosis. Many methods like the envelope analysis are created to analyze the fault-induced impulse. The situation is however different for high-speed bearing-rotor systems whose rotor runs in flexible bearing supports such as aero-engines and gas-turbines, as the impulsive responses are affected by resonance characteristics and rotor eccentric excitation. Few scholars pay attention to the phenomena, since one speed is usually chosen for dynamics or diagnosis in the state-of-the-art research. In this work, a symmetrical rigid bearing-rotor system running in flexible bearing supports was modeled. The influence of the resonance characteristics and rotor eccentric excitation on the fault characteristic frequencies was analyzed via envelope analysis performing on the dynamic response from the numerical simulation at different speeds. Besides, the contrast of the fault characteristic frequencies demonstrated the favorable and unfavorable influence of the resonance characteristics and the rotor eccentric excitation on the quality of the bearing fault vibration signal in different speed ranges, respectively. Accordingly, the mechanisms were explained by analysis of the resonance characteristics and bearing contact force of the system. Finally, the influence of the resonance characteristics was qualitatively verified by the experimental results. • High-speed has unfavorable effects on the impulsive transients and diagnostic results. • The influence of dynamic characteristics on the impulsive transients is discussed in detail. • A strategy for bearing signal enhancement based on dynamic characteristics is proposed.