Time–frequency features of two types of coupled rub-impact faults in rotor systems

Ma, Hui; Yu, Tao; Han, Qingkai; Zhang, Yimin; Wen, Bangchun; Chen, Xuelian

doi:10.1016/j.jsv.2008.09.054

Cited by 62 publications

(33 citation statements)

References 18 publications

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“…Zhou and Chen [7] introduced a dual rotor-ball and bearing-stator coupling dynamic system. However, those physical models are relatively simple to describe complex, nonlinear, rotor-bearing systems such as, e.g., large centrifugal compressors and steam turbines, etc., where strong nonlinearities have to be taken into account [8]. Moreover, in practice, it is also difficult to establish the physical model of a system due to its complexity and the lack of physical knowledge [9].…”

Section: Introductionmentioning

confidence: 99%

The NARX Model-Based System Identification on Nonlinear, Rotor-Bearing Systems

Liu

Zhu

et al. 2017

Applied Sciences

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Abstract:In practice, it is usually difficult to obtain the physical model of nonlinear, rotor-bearing systems due to uncertain nonlinearities. In order to solve this issue to conduct the analysis and design of nonlinear, rotor-bearing systems, in this study, a data driven NARX (Nonlinear Auto-Regressive with exogenous inputs) model is identified. Due to the lack of the random input signal which is required in the identification of a system s NARX model, for nonlinear, rotor-bearing systems, a new multi-harmonic input based model identification approach is introduced. Moreover, the identification results of NARX models on the nonlinear, rotor-bearing systems are validated under different conditions (such as: low speed, critical speed, and over critical speed), illustrating the applicability of the proposed approach. Finally, an experimental test is conducted to identify the NARX model of the nonlinear rotor test rig, showing that the NARX model can be used to reproduce the characteristics of the underlying system accurately, which provides a reliable model for dynamic analysis, control, and fault diagnosis of the nonlinear, rotor-bearing system.

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Section: Introductionmentioning

confidence: 99%

The NARX Model-Based System Identification on Nonlinear, Rotor-Bearing Systems

Liu

Zhu

et al. 2017

Applied Sciences

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“…Many nonlinear dynamic phenomena, such as bifurcation, synchronous vibration, sub-synchronous vibration, super-synchronous vibration and chaos motion can be observed in rub-impact rotor bearing systems [1]. Ma et al [2][3][4] focused their studies on the nonlinear dynamic response and fault feature extraction of rub-impact rotor bearing systems, the dynamic responses under different rubbing forms were discussed, and some signal analysis methods were developed to recognize the rub-impact fault. Weaver et al…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, the oil whirl is weaker or even disappears at a certain rotating speed. 4 It is unsuitable to take the rod fastening rotor as an integral rotor in analyzing the coupled nonlinear dynamic responses of the system under rub-impact and initial permanent deflection.…”

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confidence: 99%

Nonlinear Coupled Dynamics of a Rod Fastening Rotor under Rub-Impact and Initial Permanent Deflection

Liu

Teng

et al. 2016

Energies

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Abstract:A nonlinear coupled dynamic model of a rod fastening rotor under rub-impact and initial permanent deflection was developed in this paper. The governing motion equation was derived by the D'Alembert principle considering the contact characteristic between disks, nonlinear oil-film force, rub-impact force, unbalance mass, etc. The contact effects between disks was modeled as a flexural spring with cubical nonlinear stiffness. The coupled nonlinear dynamic phenomena of the rub-impact rod fastening rotor bearing system with initial permanent deflection were investigated by the fourth-order Runge-Kutta method. Bifurcation diagram, vibration waveform, frequency spectrum, shaft orbit and Poincaré map are used to illustrate the rich diversity of the system response with complicated dynamics. The studies indicate that the coupled dynamic responses of the rod fastening rotor bearing system under rub-impact and initial permanent deflection exhibit a rich nonlinear dynamic diversity, synchronous periodic-1 motion, multiple periodic motion, quasi-periodic motion and chaotic motion can be observed under certain conditions. Larger radial stiffness of the stator will simplify the system motion and make the oil whirl weaker or even disappear at a certain rotating speed. With the increase of initial permanent deflection length, the instability speed of the system gradually rises, and the chaotic motion region gets smaller and smaller. The corresponding results can provide guidance for the fault diagnosis of a rub-impact rod fastening rotor with initial permanent deflection and contribute to the further understanding of the nonlinear dynamic characteristics of the rod fastening rotor bearing system.

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“…Al-Badour et al [11] investigated statorto-blade rubbing phenomena of a running machine and it was found that the combination of continuous wavelet and wavelet packet transforms provides a better means to monitor vibration signal induced by rubbing. Ma et al [12] studied two different phenomena of rotor rubbing, which are rotor rub coupled with crack and bearing rub coupled with oil-film instability. It was found that by combining spectrum cascade, reassigned wavelet scalogram, rotor trajectory, and frequency spectrum, some novel fault features useful for rubbing detection can be discovered from the vibration signals measured in rotor runup and rundown.…”

Section: Introductionmentioning

confidence: 99%

Detection of Early Faults in Rotating Machinery Based on Wavelet Analysis

Lim

Leong

2013

Advances in Mechanical Engineering

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This paper explores the application of wavelet analysis for the detection of early changes in rotor dynamics caused by common machinery faults, namely, rotor unbalance and minor blade rubbing conditions. In this paper, the time synchronised wavelet analysis method was formulated and its effectiveness to detect machinery faults at the early stage was evaluated based on signal simulation and experimental study. The proposed method provides a more standardised approach to visualise the current state of rotor dynamics of a rotating machinery by taking into account the effects of time shift, wavelet edge distortion, and system noise suppression. The experimental results showed that this method is able to reveal subtle changes of the vibration signal characteristics in both the frequency content distribution and the amplitude distortion caused by minor rotor unbalance and blade rubbing conditions. Besides, this method also appeared to be an effective tool to diagnose and to discriminate the different types of machinery faults based on the unique pattern of the wavelet contours. This study shows that the proposed wavelet analysis method is promising to reveal machinery faults at early stage as compared to vibration spectrum analysis.

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Time–frequency features of two types of coupled rub-impact faults in rotor systems

Cited by 62 publications

References 18 publications

The NARX Model-Based System Identification on Nonlinear, Rotor-Bearing Systems

The NARX Model-Based System Identification on Nonlinear, Rotor-Bearing Systems

Nonlinear Coupled Dynamics of a Rod Fastening Rotor under Rub-Impact and Initial Permanent Deflection

Detection of Early Faults in Rotating Machinery Based on Wavelet Analysis

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