Parametric instability of flexible rotor-bearing system under time-periodic base angular motions

Han, Qinkai; Chu, Fulei

doi:10.1016/j.apm.2014.10.064

Cited by 64 publications

(24 citation statements)

References 21 publications

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“…3. The equation of motion of the rotor shaft element under constant spin speed Ω rad/sec including the translation, rotary inertia, gyroscopic effects and internal material damping of the shaft is given by [31][32][33]:…”

Section: Shaft Elementmentioning

confidence: 99%

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Vibration attenuation of rotor-bearing systems using smart electro-rheological elastomer supports

Rkabi

Moeenfard

Rezaeepazhand

2019

J Braz. Soc. Mech. Sci. Eng.

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Nowadays, capability of safe operation sufficiently away from the critical speeds is one of the most important design requirements of rotating machineries. The focus of this paper is the application of smart electro-rheological (ER) elastomers to rotor dynamics field to reduce the vibration level of a rotor system. A Jeffcott rotor, supported via two bearings at both ends augmented with ER elastomers, is considered. A finite element approach, based on the Rayleigh beam theory, is used to model the dynamics of the system, and the proposed model accounts for the rotary inertia, gyroscopic effects and shaft's internal damping. The ER elastomer supports are simulated with four-parameter viscoelastic model. The simulation results reveal that the use of ER elastomer in the conventional bearing supports leads to downshifting of the critical speeds and a considerable reduction in its corresponding vibration amplitude. Also, the stability limit speed of the system is improved by employing the ER elastomer technology. To extend the stability region of the rotor system to higher operating rotational speeds, a simple on-off control strategy is employed. The proposed control scheme determines the required real-time voltage to be applied at ER elastomers and guarantees low vibration amplitude over a wide frequency range. The novel idea of using ER elastomers for vibration suppression of rotor systems can be fairly extended to other applications which suffer from unwanted high amplitude vibrations.

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Section: Shaft Elementmentioning

confidence: 99%

“…5. The corresponding equations for the bearing force placed at the i th node can be obtained as [32,35] where…”

Section: Bearing Elementmentioning

confidence: 99%

Vibration attenuation of rotor-bearing systems using smart electro-rheological elastomer supports

Rkabi

Moeenfard

Rezaeepazhand

2019

J Braz. Soc. Mech. Sci. Eng.

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“…Fawzi developed a formulation for the dynamic analysis of the rigid rotor subject to base excitations plus mass imbalance. Han and Chu acquired the parametric instability regions induced by the periodic base angular motions based on the discrete state transition matrix method [10,11]. Dakel et al investigated the dynamics of two different rotor configurations under various support motion through the numerical method [12].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear Dynamics of Marine Rotor System Coupled with Air Bag-Floating Raft Subjected to the Basement Excitations in Lateral Directions

Liu

2020

Shock and Vibration

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This paper presents an investigation into the nonlinear dynamic behaviors of the mechanical isolation system coupled with air-bag and floating-raft subject to basement excitation in lateral directions. First, the coupling effects between the excitation source and isolation system are considered. Also, the mechanical isolation model under basic excitation and its motion equation are deduced, and then the dynamic responses are mainly investigated by using the techniques of displacement response, frequency spectrum, rotor orbit, Poincaré maps, and the bifurcation diagram. Last, the bifurcations of the mechanical isolation system with different parameters are analyzed through numerical methods, especially the effect of excitation frequency and amplitude. The result predicts that period-5 is mainly performed, with the increase of rotor speed, and the system moves into quasi-bifurcation. However, the system stays in chaos state at high rotor speed, and the vibration amplitude rises rapidly until against bearing bush. Furthermore, the effects of basement excitation on the mechanical isolation system are mainly concentrated on the stage of lower rotor speed, but with the increasing speed, the effects become weak and at the same time the vibration amplitude reduces significantly. The points projected on the Poincaré section are five, three, or two solitary attractors, in which the system stays in periodic motion. Above all, the dynamic characteristics can provide the theoretic supporting for the dynamic, vibration control and its parametric optimization of the marine mechanical isolation system coupled with air-bag and floating-raft.

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“…Another topic of interest is the nonlinear dynamical response due to sudden unbalance, suppression effects of the damping structure on the transient vibration and numerical calculation methods for the transient response. [15][16][17][18][19][20][21][22][23][24] Ma et al 25 analyzed the dynamic characteristics of rotor system under different rubbing forms caused by sudden unbalance excitation. Zhou et al 26 compared the performance of different floating ring squeeze film dampers in controlling the transient response of sudden unbalance.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the transient response of a speed-varying rotor with sudden unbalance and its application in the unbalance identification

Xia

Ren

Qin

et al. 2019

Journal of Low Frequency Noise, Vibration and Active Control

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It is well known that the sudden unbalance is harmful for rotor systems, since it is in huge amount and has a strong impact. Thus, it is difficult to identify the unbalance from the sudden unbalance response of rotor and very few studies have been done on this topic. This paper focuses on the transient response characteristics of the speed-varying rotor when the sudden unbalance occurs, and the inherent correlation between the unbalance and the transient characteristic quantity. First, different time-dependent functions modelling the loading process of sudden unbalance are derived and compared with the experiment results of the test rotor. The selection principles of function type and duration value are presented. Analyses of transient response characteristics are conducted over the run-up process of the rotor with different parameters of sudden unbalance. Variations of transient response characteristics are summarized into three forms. The varying laws and interrelations of characteristic quantities, and the corresponding parameter region of sudden unbalance are illustrated for each form. Based on the transient analysis results, the momentary positions and angular variations of the rotor disc at some key time instants are illustrated via introducing the key-phase signal. A novel transient-vibration-based method for unbalance identification is proposed. Only a single run-up measurement is required. Numerical experiments verify the effectiveness of the method. In summary, the proposed method can provide a new way for the unbalance identification using the transient response.

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Parametric instability of flexible rotor-bearing system under time-periodic base angular motions

Cited by 64 publications

References 21 publications

Vibration attenuation of rotor-bearing systems using smart electro-rheological elastomer supports

Vibration attenuation of rotor-bearing systems using smart electro-rheological elastomer supports

Nonlinear Dynamics of Marine Rotor System Coupled with Air Bag-Floating Raft Subjected to the Basement Excitations in Lateral Directions

Investigation on the transient response of a speed-varying rotor with sudden unbalance and its application in the unbalance identification

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