Detecting cracked rotors using auxiliary harmonic excitation

Sawicki, Jerzy T.; Friswell, Michael I.; Kulesza, Zbigniew; Wroblewski, Adam C.; Lekki, John

doi:10.1016/j.jsv.2010.10.006

Cited by 76 publications

(53 citation statements)

References 21 publications

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“…Sawicki et al [12], derived an important formula that can be used to explain the appearance of different harmonics in the vibration spectra of cracked, nonlinear rotors. He employed a harmonic balance analysis of the finite element model of the cracked rotor excited by an external harmonic force perpendicular to the shaft.…”

Section: Results For the 25 Percent Cracked Rotormentioning

confidence: 99%

“…Grabowski's model can be applied, when the weight dominance of the external load is assumed [11][12][13]. In this situation, the constant static deflection of the rotor may be neglected, and only the dynamic, vibration response is calculated, simplifying the analysis.…”

Section: Introductionmentioning

confidence: 99%

“…Sawicki et al [15] combined the Gash, Mayes and Davies models, introducing an additional angle c into the Jeffcott rotor model, in order to determine the amount of crack opening, when the rotor weight-dominance is ignored. Smoother changes from the open to close state of the crack can be obtained by using Fourier expansion for the so called crack steering function, which is especially applicable when approximated methods, such as harmonic balance [12] or multiple scales [16] are applied in order to calculate the response of the cracked rotor. Two new crack steering functions have been recently developed by Al-Shudeifat and Butcher [29] who used them for a more exact evaluation of the cracked shaft stiffness changes.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rigid finite element model of a cracked rotor

Kulesza

Sawicki

2012

Journal of Sound and Vibration

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Section: Results For the 25 Percent Cracked Rotormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rigid finite element model of a cracked rotor

Kulesza

Sawicki

2012

Journal of Sound and Vibration

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“…If the force is harmonic, then the presence of the crack generates responses containing frequen cies at combinations of the angular speed, applied forcing fre quency, and the rotor natural frequencies [14]. It has been shown that the appearance of the combinational frequencies is a very strong signature of the shaft crack [14,15]. However, the research conducted so far has focused on applying the harmonic force, act ing in one fixed direction only [13][14][15].…”

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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“…Faverjon and Sinou [12] demonstrated that it is possible to detect the number of cracks in a beam and estimate both crack positions and sizes despite the presence of noise levels. Cracks can also be detected using observer [30] or using non linear phenomena in the case of cracked beams submitted to forced vibrations [1] or in the case of cracked rotors [29].…”

Section: Introductionmentioning

confidence: 99%

Cracks Detection Using Active Modal Damping and Piezoelectric Components

Chomette

Fernandes

Sinou

2013

Shock and Vibration

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Abstract. The dynamics of a system and its safety can be considerably affected by the presence of cracks. Health monitoring strategies attract so a great deal of interest from industry. Cracks detection methods based on modal parameters variation are particularly efficient in the case of large cracks but are difficult to implement in the case of small cracks due to measurement difficulties in the case of small parameters variation. Therefore the present study proposes a new method to detect small cracks based on active modal damping and piezoelectric components. This method uses the active damping variation identificated with the Rational Fraction Polynomial algorithm as an indicator of cracks detection. The efficiency of the proposed method is demonstrated through numerical simulations corresponding to different crack depth and locations in the case of a finite element model of a clamped-clamped beam including four piezoelectric transducers.

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Detecting cracked rotors using auxiliary harmonic excitation

Cited by 76 publications

References 21 publications

Rigid finite element model of a cracked rotor

Rigid finite element model of a cracked rotor

Controlled Deflection Approach for Rotor Crack Detection

Cracks Detection Using Active Modal Damping and Piezoelectric Components

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