A Brief Review on Dynamics of a Cracked Rotor

Kumar, Chandan; Rastogi, Vipul

doi:10.1155/2009/758108

Cited by 55 publications

(28 citation statements)

References 61 publications

(53 reference statements)

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“…Thus the influence of static toque should be considered in crack detection. (2) Owing to the coupling of bending and torsional vibration of slant cracked rotor, the torsional excitation frequency and the combined frequency components of rotating frequency will appear in transverse vibration response of the rotor under the action of periodic torsional excitation, and the higher the exciting amplitude is, the larger the combined frequency components are. (3) As the transmitted static torque will make the crack in normally open state and change the nonlinearity of the system, the crack detection can be carried out by loading and unloading the power transmission, and comparing the vibration characteristics before and after load change; furthermore, the load should be used as an important monitoring parameter in condition monitoring on rotor systems.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, it is significant for crack detection to investigate the influence of torsional excitation on the dynamic characteristic of the power transmission rotor with slant breathing crack. Though much research has been carried out on the cracked rotor dynamics [1][2][3][4] , most of which aim at rotors with transverse cracks and assume the gravity dominant, yet the slant crack is seldom studied at present. However, the cracks in rotors are often slant cracks due to transmitted torque.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Torsional Excitation on Dynamic Responses of Rotors with a Breathing Slant Crack

Hua

Dong

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. Focusing on a rotor-bearing system with a breathing slant crack in the power transmission machine, influence of torsional excitations on the coupled nonlinear responses of the system is studied in this work. The slant crack element stiffness matrix is derived based on energy principal and the crack breathing phenomenon is simulated by the Crack Closure Line Position (CCLP) model; and the timevarying coupled dynamic equation of a rotor with a slant breathing crack considering the eccentricity of static unbalance is established using the finite element method and is solved by the NEWMARK method; then the influences of static torque and periodic torsional excitations on rotor dynamic responses in transverse and torsional directions are discussed. Results show that with the increment of static torque, cracks will become open gradually and the nonlinearity degree of rotors will increase firstly and then decrease. For periodic torsional excitation, the torsional excitation frequency and its rotating frequency combination can be found in transverse vibration response, and the larger is the amplitude of excitation, the larger are the combinational frequency components. Then a crack monitoring method for power transmission machines can be suggested by monitoring the coupled response characteristics and their variation from transverse responses of rotors before and after the loads change.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Torsional Excitation on Dynamic Responses of Rotors with a Breathing Slant Crack

Hua

Dong

et al. 2017

J. Phys.: Conf. Ser.

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“…It has been shown in the literature that the presence of a crack introduces additional flexibility to the shaft, which reduces its overall stiffness and generates complex orbits and super-harmonic frequency components [15,16]. The dynamic analysis of cracked rotor systems has been intensively studied by many researchers [17][18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Experimental Dynamic Analysis of a Breathing Cracked Rotor

Guo

Yan

Bergman

2017

Chin. J. Mech. Eng.

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Crack fault diagnostics plays a critical role for rotating machinery in the traditional and Industry 4.0 factory. In this paper, an experiment is set up to study the dynamic response of a rotor with a breathing crack as it passes through its 1/2, 1/3, 1/4 and 1/5 subcritical speeds. A cracked shaft is made by applying fatigue loads through a three-point bending apparatus and then placed in a rotor testbed. The vibration signals of the testbed during the coasting-up process are collected. Whirl orbit evolution at these subcritical speed zones is analyzed. The Fourier spectra obtained by FFT are used to investigate the internal frequencies corresponding to the typical orbit characteristics. The results show that the appearance of the inner loops and orientation change of whirl orbits in the experiment are agreed well with the theoretical results obtained previously. The presence of higher frequencies 2X, 3X, 4X and 5X in Fourier spectra reveals the causes of subharmonic resonances at these subcritical speed zones. The experimental investigation is more systematic and thorough than previously reported in the literature. The unique dynamic behavior of the orbits and frequency spectra are feasible features for practical crack diagnosis. This paper provides a critical technology support for the self-aware health management of rotating machinery in the Industry 4.0 factory.

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“…Inspired by the work of Tada et al (1973), many researchers have performed the vibration analysis of the cracked structures such as thin walled tubes during the last five decades. Recently, some reviews on vibration of cracked structures were reported by Dimarogonas (1996) and Kumar et al (2010). In some researches the crack has been simulated by a local reduced section or stiffness of the structure around the crack (Sinha, Friswell et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Effect of Open Crack on Vibration Behavior of a Fluid-Conveying Pipe Embedded in a Visco-Elastic Medium

Eslami

Maleki

Rezaee

2016

Lat. Am. j. solids struct.

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In this paper vibration behavior of a fluid-conveying cracked pipe surrounded by a visco-elastic medium has been considered. During this work, the effect of an open crack parameters and flow velocity profile shape inside the pipe on natural frequency and critical flow velocity of the system has been analytically investigated. An explicit function for the local flexibility of the cracked pipe has been offered using principle of the fracture mechanics. Comparison between the results of the present study and the experimental data reported in the literature reveals success and high accuracy of the implemented method. It is demonstrated that the existence of the crack in the pipe, decreases the natural frequency and the critical flow velocity so that the system instability onsets at a lower flow velocity in comparison with the intact pipe. Results indicate that the flow velocity profile shape inside the pipe caused by the viscosity of real fluids, significantly affects the critical flow velocity of both intact and fluid-conveying cracked pipe. For instance, as the flow-profilemodification factor decreases from 1.33 to 1.015, the dimensionless critical flow velocity of intact clamped-clamped pipe increases from 5.45 to 6.24.

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A Brief Review on Dynamics of a Cracked Rotor

Cited by 55 publications

References 61 publications

Influence of Torsional Excitation on Dynamic Responses of Rotors with a Breathing Slant Crack

Influence of Torsional Excitation on Dynamic Responses of Rotors with a Breathing Slant Crack

Experimental Dynamic Analysis of a Breathing Cracked Rotor

Effect of Open Crack on Vibration Behavior of a Fluid-Conveying Pipe Embedded in a Visco-Elastic Medium

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