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

Hu, Liang; Liu, Yibing; Teng, Wei; Zhou, Chao

doi:10.3390/en9110883

Cited by 30 publications

(9 citation statements)

References 26 publications

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“…Throughout the years, several works have been published on the subject of nonlinear rotor dynamics considering the bolted joint. Hu et al [23][24] developed the dynamic model of rod fastening rotor system, where the interaction between two disks was equivalent to a contact layer with nonlinear flexural stiffness. And then analyzed the bifurcation and chaos phenomena of the system under rub-impact and initial deformation of the shaft.…”

Section: Numerical and Experimental Analysis Of The Effect Of Eccentricmentioning

confidence: 99%

Numerical and experimental analysis of the effect of eccentric phase difference in a rotor-bearing system with bolted-disk joint

Zhang

Wang

et al. 2021

Nonlinear Dyn

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Bolted joints are widely used in industrial rotating machines to fasten the adjacent disks together and affect system dynamic properties. Therefore, there is a strong need to study their influence on the response of such systems. This paper investigated the effect of the eccentric phase difference of the disk and bolted-disk joint on rotor dynamics, which takes into account the time-varying bending stiffness of the bolted joint. The bolted-disk joint is modeled as a two-node element based upon the energy theorem and Lagrange's principle, where the relative lateral displacement stiffness, relative bending stiffness, and coupling stiffness between the adjacent disks are considered. And then the dynamic model of the rotor-bearing system is derived based on the proposed bolted joint element and lumped mass modeling method. Combining with the Newmark-β integration scheme, the established model allows the dynamic response characteristics of the rotor-bearing system with the bolted joint to be predicted, and the impact of eccentric phase difference in the rotor system on the response to be investigated. The validity of the simulation results was confirmed by experiment. Through the modeling method proposed in this paper and obtained results, the bifurcation characteristics of the bolted joint rotor system can be predicted.

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Section: Numerical and Experimental Analysis Of The Effect Of Eccentricmentioning

confidence: 99%

Numerical and experimental analysis of the effect of eccentric phase difference in a rotor-bearing system with bolted-disk joint

Zhang

Wang

et al. 2021

Nonlinear Dyn

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“…It is according to the finite element analysis results of the force and deformation of the micro body element on the elastic-plastic rough surface, which improved the calculation accuracy. Hu et al [24][25][26] studied the nonlinear dynamic response of a two-disk rod fastening rotor with transverse crack, initial bending, rub impact and other faults, and analyzed the influence of system parameters such as speed, crack size, crack angle, contact surface damping coefficient, initial bending and rub impact stiffness on the dynamic characteristics. Li et al [27] studied the nonlinear dynamic characteristics of a three-disk bending torsional coupling rod fastening rotor under rub impact fault, concluded that the influence of torsional vibration on bending vibration gradually increases with the increase in rotating speed.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Dynamic Characteristics of Rod Fastening Rotor with Preload Relaxation

Li¹,

Zhang²,

Shen³

et al. 2022

Energies

Self Cite

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Compared to ordinary rotor, rod fastening rotor has the advantages of lighter weight, higher strength and easier installation, so it is widely used in gas turbine. However, in the process of a long-term operation, the rod may be deformed due to the influence of alternating load, high temperature and other uncertain factors. In serious cases, it can even lead to a major accident. The discontinuous characteristic of rod fastening rotor leads to great differences in dynamic characteristics compared to ordinary rotor. Based on the Herz contact theory and GW contact model, the contact effect between two discs was studied, and the relationship among the contact load, the distance between two disks and the equivalent bending stiffness was obtained. Findings show the bending stiffness to decrease nonlinearly with the decrease in contact load. The lumped mass method was used to establish the rotor model. The contact effect was considered and the Runge–Kutta method was used to solve the model. Combined with the bifurcation diagram, time domain diagram and spectrum diagram, the influence of contact stiffness on rotor dynamic characteristics was analyzed. The results show that the dynamic characteristics of the rod fastening rotor are rich due to the influence of nonlinear factors. In the case of uniform relaxation, the contact stiffness has different effects on the response state and frequency doubling amplitude of the system at different speeds, which is mainly related to the motion state of the system. In the case of non-uniform relaxation, the degree of relaxation does not affect the motion state of the system, but only changes the amplitude of vibration. The results provide theoretical support for condition monitoring and fault diagnosis of rod fastening rotor.

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“…The bearing-rotor system is widely used in many rotating machineries, such as industrial compressors, steam turbines and aero engines. These shafts are usually composed of several sections which may not reach the proper design state due to structural characteristics or insufficient machining during the installation process [1,2]. As a result, the initial bending is inevitably generated and dynamic vibration of the rotor system is increased together with mass eccentricity.…”

Section: Introductionmentioning

confidence: 99%

Vibration and Stability Analysis of a Bearing–Rotor System with Transverse Breathing Crack and Initial Bending

Wang

Xiong

2021

Machines

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This paper focuses on the stability and nonlinear response of a bearing-rotor system affected by a transverse crack and initial bending which was thought to be part of an unbalance or had been neglected before. The differences of breathing functions for the transverse breathing crack caused by initial bending is presented here, and the calculation of time-varying finite elements stiffness matrix of the cracked shaft is improved by replacing traditional the approximate crack segment with an exact area. After establishing the dynamic model of the cracked rotor with initial bending, vibrational characteristics such as amplitude-speed diagram, frequency spectrogram and bifurcations are investigated in detail. The eigenvalues of the transition matrix are calculated and analyzed as an indicator of dynamic stability with the growths of crack depth and initial bending. Many differences are found between the two cases of dynamic response of rotor system by numerical simulation. The frequency change with the growth of initial bending is opposite to the change with the growth of crack depth, and the shapes of amplitude-speed also having great different features. Stable regions are reduced and extended laterally by initial bending. All these results obtained in this paper will contribute to identify the bending fault and assess the stability of the bearing-rotor systems.

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

Cited by 30 publications

References 26 publications

Numerical and experimental analysis of the effect of eccentric phase difference in a rotor-bearing system with bolted-disk joint

Numerical and experimental analysis of the effect of eccentric phase difference in a rotor-bearing system with bolted-disk joint

Nonlinear Dynamic Characteristics of Rod Fastening Rotor with Preload Relaxation

Vibration and Stability Analysis of a Bearing–Rotor System with Transverse Breathing Crack and Initial Bending

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