Forced Oscillations of a Continuous Asymmetrical Rotor With Geometric Nonlinearity (Major Critical Speed and Secondary Critical Speed)

Nagasaka, Imao; Ishida, Yukio; Li, Jun

doi:10.1115/1.2890734

Cited by 15 publications

(10 citation statements)

References 5 publications

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“…Nonlinear resonances of continuous asymmetrical slender shafts were also investigated. Nagasaka et al (61) also investigated the nonlinear phenomena at the major critical speed and the secondary critical speed of a continuous asymmetrical rotor. Fig.11 Major critical speed (56) Fig.12 Combination resonance (…”

Section: Nonlinear Resonances In Continuous Rotor Systemsmentioning

confidence: 99%

Review of Research on Nonlinear Rotordynamics in Japan

Ishida

2013

JSDD

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This article introduces research on nonlinear rotordynamics in Japan. In most cases, the nonlinearity treated there was weak and it was approximated by a power series of low order. Firstly, the research on various nonlinear resonances due to the weak nonlinearity is introduced. Next, those on more complicated nonlinear phenomena, such as entrainment, internal resonances, chaotic vibrations, nonstationary vibrations, and more complicated systems, such as cracked rotors and continuous rotors, are explained. Then, research on phenomena due to strong nonlinearity is introduced. Various vibration suppression methods where the nonlinearity plays an important role are also explained. Finally, studies on the models representing helicopters and wind turbines are explained.

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Section: Nonlinear Resonances In Continuous Rotor Systemsmentioning

confidence: 99%

Review of Research on Nonlinear Rotordynamics in Japan

Ishida

2013

JSDD

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“…Sinou et al [4] developed an experimental analysis to study the modal characteristics including modal frequencies and shapes of a flexible rotor system for different speed cases. Nagasaka et al [5] analyzed the effects of the damping ratio, lateral force, and unbalance on the major and secondary critical speeds of a uniform rotor system. Dikmen et al [6] presented the FE and experimental methods to the effect of the support stiffness of the bearings on the modal characteristics of a flexible rotor system.…”

Section: Introductionmentioning

confidence: 99%

An analytical investigation for optimizing the support stiffness and positions of the bearings of a flexible rotor system

Liu

Tang

2020

Preprint

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The support stiffness and positions of the bearings can greatly affect the vibrations of flexible rotor systems. However, most previous works only focused on the effect of the support stiffness of the bearings on the critical speeds of the rigid rotor systems or modal characteristics including natural frequencies and mode shapes, which missed the combine effects of the support stiffness and positions of the bearings. To overcome this issue, an analytical dynamic model of a flexible rotor system based on the finite element (FE) method is proposed. The model considers the support stiffness of the bearings and rotational inertia of the rotor system. The frequency equation of the rotor system is established for solving the critical speeds. The critical speeds and modal deformations of the system from the presented model and the numerical model based on a commercial software are compared to verify the effectiveness of the proposed FE model. The effects of the support stiffness and positions of the bearings on the critical speeds of the flexible rotor system are analyzed. The results show that the critical speeds are positively correlated with the support stiffness. The critical speeds of the flexible rotor system are also greatly affected by the support positions of the bearing. This study can provide some guidance for the optimization design method of the support stiffness and positions of the bearings in the flexible rotor systems.

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“…In several studies, rotating shafts with fixed and moving base have been investigated. I. Nagasaka et al . investigated the nonlinear forced oscillations of an asymmetrical rotor.…”

Section: Introductionmentioning

confidence: 99%

“…are subjected to base excitations.In several studies, rotating shafts with fixed and moving base have been investigated. I. Nagasaka et al [1] investigated the nonlinear forced oscillations of an asymmetrical rotor. Owing to the internal resonances various phenomena such as Hopf bifurcation, periodic motion, unstable region, etc.…”

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confidence: 99%

Forced vibrations of nonlinear symmetrical and asymmetrical rotating shafts mounted on a moving base

Shahgholi

Payganeh

2018

Z Angew Math Mech

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This paper deals with the combinational resonances of symmetrical and asymmetrical rotating shafts with base motions. The nonlinearities are owing to the large amplitude of the hinged‐ hinged the shaft. Generally, the asymmetrical shaft has unequal principal mass moments of inertia and flexural stiffnesses. The system is exposed to three sources of excitation as a result of the asymmetry of the shaft, dynamic imbalances, and base excitations. Using the variational approach the nonlinear governing equations of motion and related boundary conditions are derived in the complex form. These equations of motion are analyzed by the use of the perturbation method. It is shown that three combinational resonances occur in the system. In the two cases of combinational resonances the asymmetry of shaft has no effect on the steady‐state responses. However, in one case of the combinational resonances, the asymmetry of the shaft has a significant effect. Also, in each case, the steady‐state solutions and their stability are investigated. The effect of various parameters such as damping coefficient, eccentricities, and asymmetry of the shaft on the periodic solutions, the stability of the solutions and bifurcations are probed. Additionally, the analytical results are verified by the numerical simulations that are obtained a good agreement between these results.

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Forced Oscillations of a Continuous Asymmetrical Rotor With Geometric Nonlinearity (Major Critical Speed and Secondary Critical Speed)

Cited by 15 publications

References 5 publications

Review of Research on Nonlinear Rotordynamics in Japan

Review of Research on Nonlinear Rotordynamics in Japan

An analytical investigation for optimizing the support stiffness and positions of the bearings of a flexible rotor system

Forced vibrations of nonlinear symmetrical and asymmetrical rotating shafts mounted on a moving base

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