An insight into the breathing mechanism of a crack in a rotating shaft

Georgantzinos, Stelios K.; Anifantis, N.K.

doi:10.1016/j.jsv.2008.04.010

Cited by 50 publications

(26 citation statements)

References 29 publications

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“…In their work, both ends of the shaft were supported rigidly. The breathing of a straight front crack represented by the local flexibilities was studied in a three-dimensional finite element shaft model with a fixed end boundary condition applied to the shafts support ends [19,20].…”

Section: Introductionmentioning

confidence: 99%

Crack breathing behavior of unbalanced rotor system: A Quasi-static numerical analysis

Hossain¹,

Wu²

2018

J. vibroeng.

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Abstract. Crack opening and closing during shaft rotation of a cracked rotor system have long been a focus of many previous studies. Previously published modeling work in the literature uses weight-governed crack breathing model for very large rotor systems. However, for lightweight or vertical or lightly damped rotors the opening and closing statuses of a crack are not always weight dominated as there is significant influence from dynamic loads. Further, the dependence of the breathing mechanism on the crack location has not been investigated yet. In this paper, the crack breathing behavior of an unbalanced shaft at the different crack location of a rotating shaft is investigated. A three-dimensional finite element model, consisting of a two-disk rotor with a transverse crack, is used. Finite element model is simulated using ABAQUS/Standard. Crack breathing behavior is found to strongly depend on its axial position, angular position, depth ratio, unbalanced force ratio and angular position. Two different crack breathing regions along the shaft length are identified, where unbalanced shaft stiffness may be larger or smaller than the balanced shaft, depending on the unbalance force orientation, magnitude and crack location. Further, four specific crack locations along the shaft length have been identified, where the crack remains fully closed or open or just behaves like in the balanced shaft. The results suggest that more accurate prediction of the dynamic response of cracked rotors can be expected when the effects of unbalance force and individual rotor physical properties on the crack breathing have been taken into account.

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Section: Introductionmentioning

confidence: 99%

Crack breathing behavior of unbalanced rotor system: A Quasi-static numerical analysis

Hossain¹,

Wu²

2018

J. vibroeng.

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“…The breathing mechanism is produced by the stress distribution around the crack mainly due to the action of bending moment, while the effect of torsion is negligible. Usually, shaft cracks breathe when crack sizes are small, running speeds are low and radial forces are large [1]. Breathing of the crack comes from the fact that the static deflection of the shaft is much greater than the deflection due to the dynamic response of the cracked rotor.…”

Section: Introductionmentioning

confidence: 99%

A Cohesive Zone Model for the Investigation of the Breathing Mechanism of Transversal Cracks in Rotors

Liong¹,

Proppe²

2014

Proceedings of 10th World Congress on Computational Mechanics

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Abstract. The presence of a crack reduces the mean stiffness of the rotor system and introduces a stiffness variation during the revolution of the shaft. How the variable part of the rotor stiffness varies between a minimum (for a closed crack) and a maximum (for an open crack), depends on the so-called breathing mechanism. The breathing mechanism is known when the open and closed parts of the cracked area are known for all angular positions of the rotor. Here, finite element (FE) and multi-body simulation (MBS) is introduced. It is based on a representation of the fracture process zone by a cohesive zone model (CZM). First, the cracked elastic shaft with various relative crack depths is modelled by FE. As a second step, the FE model of the shaft is transferred into an MBS model in order to

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“…The local flexibility of a rotating shaft is essentially constant for a gaping crack. However it is not constant for a breathing crack, due to the opening and closing mechanism [2]. Clearly, this kind of local flexibility in the structure will influence the dynamic behavior of a rotating system and behaves like external excitation forces acting on the system [3].…”

Section: Introductionmentioning

confidence: 99%

“…[4] and [5]). More advanced cracked rotor models have subsequently been proposed and are used to investigate dynamics of crack behavi or (see f or instance [2], [6] and [7]). Norm ally variati on of stif fness and damping matrices is introduced into the equations of motion of the system to simulate cracks in a rotor shaft.…”

Section: Introductionmentioning

confidence: 99%

The application of order tracking for vibration analysis of a varying speed rotor with a propagating transverse crack

Wang

Guo

Heyns

2012

Engineering Failure Analysis

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Propagating cracked rotor vibrations may contain substantial information on the rotor crack conditions. Capturing the characteristic vibrations due to the non-stationary response of rotors of which the speed change, is useful for condition monitoring of such systems. From the literature it is clear that vibrations at harmonics of the rotational speed, as well as transient responses, may be considered key indicators of cracks in rotors. Since faults other than cracks, such as misalignment and imbalance also generate harmonic vibrations, the non-order related vibrations therefore become important characteristics in detecting cracked rotor problems. But these signals may present with small amplitude and may easily be missed among the non-stationary harmonic vibrations. Therefore, clear identification of harmonic as well as non-order related (transient) vibrations are both important for detecting cracks in rotor systems. In this paper, a finite element model is used to calculate the response of a rotor with a propagating transverse crack under varying rotational speed conditions. various order tracking techniques, i.e. computed order tracking, Vold-Kalman filter order tracking, Gabor order tracking, are implemented to remove the varying speed harmonic vibrations so that the non-order related vibrations in which information about the cracks are contained, are emphasized. And some other signal processing methods that may achieve similar effects, i.e. double re-sampling method and intrinsic mode function from empirical mode decomposition, are also discussed for comparisons to these order tracking techniques. The paper demonstrates the advantages of order tracking methods in rotor crack detection.

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An insight into the breathing mechanism of a crack in a rotating shaft

Cited by 50 publications

References 29 publications

Crack breathing behavior of unbalanced rotor system: A Quasi-static numerical analysis

Crack breathing behavior of unbalanced rotor system: A Quasi-static numerical analysis

A Cohesive Zone Model for the Investigation of the Breathing Mechanism of Transversal Cracks in Rotors

The application of order tracking for vibration analysis of a varying speed rotor with a propagating transverse crack

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