Abstract
In this paper, the dynamic behavior of a rotor-bearing-SFD system with the inner race defect of bearing is investigated. The contact force between the rolling element and the race is calculated in Hertzian contact and elastohydrodynamic lubrication condition. The supporting force of the SFD is simulated by integrating the pressure distribution derived from Reynolds’s equation. The equations of motion of the rotor-bearing-SFD system are derived and solved using the fourth-order Runge-Kutta method. The dynamic behavior and the fault characteristics are analyzed with two configurations of the SFD: (1) mounted on the unfaulted bearing and (2) mounted on the faulty bearing. According to the analysis of time-frequency diagram, waterfall plot, and spectral diagram, the results show that the characteristics of inner race defects on bearing frequencies are related to the characteristic multiple frequency of the inner race defect and the fundamental frequency. The speed and defect width have different influence on the distribution and amplitude of frequency. The SFD can enhance the system stability under the bearing fault but the enhancement decreases with the increasing speed. Meanwhile, the beneficial effect of the SFD varies according to the mounted position in the rotor system.
Highlights
Bearings are most widely used in rotating machinery as one of the most critical components
In order to study the dynamic characteristics of ball bearing, Kankar et al [6] developed a model of localized defects on a ball bearing and employed the Fast Fourier Transformation (FFT) and the Poincare maps to analyze the defects of bearing components
The rotor-bearing-squeeze film dampers (SFD) system is developed based on the Jeffcott rotor in which the ball bearing B has the inner race defect and the SFD is mounted on one bearing at a time
Summary
Bearings are most widely used in rotating machinery as one of the most critical components. According to the recent research, the vibration signals are nonstationary and time-varying with the effect of speed changing and the nonlinear characteristics of the rotor system caused by faults. Shock and Vibration characteristics with time and is widely used in faults diagnosis [10] Ding and He [9] proposed a novel transient signal reconstruction method for bearing fault features extraction and find this method is effective to verify faults characteristics of bearing fault. On the basis of previous work [16], this paper developed a model of bearing which considered both Hertz contact and elastohydrodynamic lubrication This model was focused on studying the fault characteristics of the rotor system caused by inner race defects. The waterfall map, time-frequency map, and spectral diagram were introduced to analyze the dynamic and signal characteristics of inner race defects, studying the law of the frequency characteristics changing with defect parameters. The effects of SFD to the dynamic characteristics of faults rotor system were discussed
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