Auxiliary state variables for rotor crack detection

Kulesza, Zbigniew; Sawicki, Jerzy T.

doi:10.1177/1077546309360050

Cited by 27 publications

(8 citation statements)

References 28 publications

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“…Other methods include changes in rotor modal parameters such as its natural frequencies and mode shapes [3,4], state observers [5,6], Kalman filters [7], genetic algorithms [8], wavelet [9,10] or Huang-Hilbert transforms [11], and many others.…”

Section: Controlled Deflection Approach For Rotor Crack Detectionmentioning

confidence: 99%

Controlled Deflection Approach for Rotor Crack Detection

Kulesza

Sawicki

2012

Volume 7: Structures and Dynamics, Parts a and B

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A transverse shaft crack is a serious malfunction that can occur due to cyclic loading, creep, stress corrosion, and other mechanisms to which rotating machines are subjected. Though studied for many years, the problems of early crack detection and warning are still in the limelight of many researchers. This is due to the fact that the crack has subtle influence on the dynamic response of the machine and still there are no widely accepted, reliable methods of its early detection. This paper presents a new approach to these problems. The method utilizes the coupling mechanism between the bending and torsional vibrations of the cracked, non-rotating shaft. By applying an external lateral force of constant amplitude, a small shaft deflection is induced. Simultaneously, a harmonic torque is applied to the shaft inducing its torsional vibrations. By changing the angular position of the lateral force application, the position of the deflection also changes opening or closing of the crack. This changes the way the bending and torsional vibrations are being coupled. By studying the coupled lateral vibration response for each angular position of the lateral force one can assess the possible presence of the crack. The approach is demonstrated with a numerical model of a rotor. The model is based on the rigid finite element method (RFE), which has previously been successfully applied for the dynamic analysis of many complicated, mechanical structures. The RFE method is extended and adopted for the modeling of the cracked shafts. An original concept of crack modeling utilizing the RFE method is presented. The crack is modeled as a set of spring-damping elements (SDEs) of variable stiffness connecting two sections of the shaft. By calculating the axial deformations of the SDEs, the opening/closing mechanism of the crack is introduced. The results of numerical analysis demonstrate the potential of the suggested approach for effective shaft crack detection.

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Section: Controlled Deflection Approach For Rotor Crack Detectionmentioning

confidence: 99%

Controlled Deflection Approach for Rotor Crack Detection

Kulesza

Sawicki

2012

Volume 7: Structures and Dynamics, Parts a and B

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“…Morais et al (2008) used orthogonal functions to identify cracks in a horizontal rotating machine. Kulesza and Sawicki (2010) presented a crack detection methodology based on Luenberger state observers. The estimated lateral displacements and velocities of the shaft were used as crack indicators.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the favorable conditions to apply the combination resonances approach for crack detection purposes

Cavalini

Morais

Silva

et al. 2020

Journal of Vibration and Control

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Various structural health monitoring methods were recently applied to fault diagnosis of rotating machinery, in which vibration response–based techniques demonstrated to be well adapted for different scenarios. However, only severe cracks are detected when most of such techniques are applied. Thus, innovative methods are proposed to identify the existence of incipient cracks in rotating shafts. In a previous contribution, the combination resonance approach for crack identification purposes was presented. This method is based on the application of additional forces at combination frequencies along with a heuristic optimization method to identify crack signatures in the vibration responses of the rotor. In the present work, the best conditions to apply the combination resonance approach are investigated in terms of the amplitude and frequency of the so-called diagnostic force. The vibration responses and phase angles of a cracked rotor were determined by using the harmonic balance technique. The FLEX approach is used to model the crack. Numerical simulations were performed using the finite element model of a horizontal rotor.

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“…Also a novel signal-based approach, based on support vector machine (SVM) and wavelets as an example for a modern machine learning technique, was introduced. When compared to complicated modelbased [20][21][22][23][24][25], modal testing [26,27] or non-traditional [13,14,[28][29][30][31][32] techniques, the methods based on vibration signal analysis are quick, low cost and simple. They utilize popular, commonly used measurement equipment and well-established computational procedures and software.…”

Section: Introductionmentioning

confidence: 99%

Method of shaft crack detection based on squared gain of vibration amplitude

2019

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Rotating machines are exposed to different faults such as shaft cracks, bearing failures, rotor misalignment, stator to rotor rub, etc. Therefore, turbogenerators, aircraft engines, compressors, pumps, and many other rotating machines should be constantly diagnosed to warn about the probable appearance of a possible rotor failure. Unfortunately, despite the ongoing work on various rotor fault detection methods, there are still very few techniques that can be considered as reliable and applicable in practical problems. The difficulty lies in the fact that usually the fault introduces very subtle local changes in the overall structure of the rotor. The symptoms of these changes must be isolated and extracted from a wide spectrum of vibration data obtained from sensors measuring the vibrations of the machine. The measured data are usually disturbed with some noise or other disturbances, and that is why the detection of a possible rotor fault is even more difficult. The paper presents a new rotor fault detection method. The method is based on a new diagnostic model of rotor signals and external disturbances. The model utilizes auto-correlation functions of measured rotor's vibrations. By proper processing of the measured vibration data, the influence of environmental disturbances is completely compensated and reliable indications of the possible rotor fault are obtained. The method has been tested numerically using the finite element model of

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Auxiliary state variables for rotor crack detection

Cited by 27 publications

References 28 publications

Controlled Deflection Approach for Rotor Crack Detection

Controlled Deflection Approach for Rotor Crack Detection

Investigation of the favorable conditions to apply the combination resonances approach for crack detection purposes

Method of shaft crack detection based on squared gain of vibration amplitude

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