Vibration Analysis of a Rotating Flywheel/Flexible Coupling System with Angular Misalignment and Rubbing Using Smoothed
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ORIGINAL PAPER
Vibration Analysis of a Rotating Flywheel/Flexible Coupling System with Angular Misalignment and Rubbing Using Smoothed Pseudo Wigner–Ville Distributions Zhiwei Liu1,2 · Kun Wu1,2 · Zhisai Ma1,2 · Qian Ding1,2 Received: 24 August 2019 / Revised: 21 October 2019 / Accepted: 27 October 2019 © Krishtel eMaging Solutions Private Limited 2019
Abstract Purpose Detection of early faults such as misalignment, rotor rubbing, shaft crack and bearing fault is necessary to avoid harmful and even catastrophic influences on rotating machinery. Methods In this paper, the accelerating horizontal and pitching vibration responses of flywheel/flexible coupling model of an actual diesel generator, with angular misalignment and rubbing faults, are investigated using the smoothed pseudoWigner–Ville distributions (SPWVDs). Results and Conclusions Numerical simulations are performed through the dynamical equations of the flywheel/flexible coupling system; the results suggest that when an angular misalignment fault occurs, the super-harmonic resonance of order 3 can be found in the horizontal and pitching vibration signals. Meanwhile, both the 3fr and 5fr components (i.e., 3 and 5 times of the rotating frequencies) can also be found in SPWV distribution spectra. When rubbing fault occurs, more abundant sub- and super-harmonic frequency components can be observed in SPWV distribution spectra. Overall, the investigation shows that the smoothed pseudo-Wigner–Ville distribution spectra reveal obvious differences between the acceleration responses of the rotating system with different faults. Keywords Flywheel/flexible coupling system · Angular misalignment detection · Rubbing detection · Smoothed pseudoWigner–Ville distribution
Introduction Vibration faults of diesel generator sets can bring negative influences on the reliability, stability and dynamic performance of vehicles [1]. The ever-increasing demands for higher speed and longer working time cause the rotary machinery to operate under excessive vibration and severe shaft distortion cases. To prevent serious vibration faults of mechanical equipment, condition monitoring and early fault diagnoses are very important [2, 3]. Common faults such as shaft crack, bearing fault, rotor/ stator rub, coupling misalignment can be identified based on * Qian Ding [email protected] 1
Department of Mechanics, Tianjin University, Tianjin 300350, China
Tianjin Key Laboratory of Nonlinear Dynamics and Control, Tianjin 300350, China
2
vibration responses. Among a diesel generator set, mechanical coupling is used for transmitting the power from the diesel engines to electric generator. Coupling misalignment is the most common fault for diesel generator sets. To identify the fault characteristic, many researches have been carried out focusing mainly on the steady-state vibration of the rotating machinery. There are three modeling methods for coupling misalignment, the force analysis method, the Lagrange energy method and the finite element method. Gibbons presented the misalign
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