Effect of gravity-induced asymmetry on the nonlinear vibration of an overhung rotor

Chipato, Elijah T; Shaw, Alexander D.; Friswell, Michael I.

doi:10.1016/j.cnsns.2018.02.016

Cited by 18 publications

(16 citation statements)

References 20 publications

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“…Due to the overload operations of rotors in large rotating machineries, cracks in the rotation shafts often occur. In the recent decades, crack has become a central issue of concerns in the faults of rotor systems, attracting the attention of researchers in many areas [1][2][3][4][5]. Many vibrational characteristics-based crack detection methods have been developed [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Dynamics analysis of a hollow-shaft rotor system with an open crack under model uncertainties

Yang

et al. 2020

Communications in Nonlinear Science and Numerical Simulation

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This paper focuses on the vibration behaviors of a hollow-shaft rotor in presence of an open crack under inherent uncertainties. Non-probabilistic interval variables are used to represent the uncertain parameters, which releases the high demands of probabilistic knowledge in traditional methods. In modeling the shaft, local stiffness matrix of the cracked element is derived by using the neutral axis method. The periodic response of the rotor system is solved by combination of the finite element method (FEM) and the harmonic balance method (HBM). A simple mathematical function, termed as the uncertain response surrogate function (URSF), is constructed to estimate the vibration response in various cases where different parametric uncertainties are taken into consideration. To verify the robustness and accuracy of the URSF, the bounds of estimated response are compared with those obtained from the classical methods. Results show that the surrogate function has good accuracy and robustness, providing an effective method and guidance for diagnosing crack in uncertain context.

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Section: Introductionmentioning

confidence: 99%

Dynamics analysis of a hollow-shaft rotor system with an open crack under model uncertainties

Yang

et al. 2020

Communications in Nonlinear Science and Numerical Simulation

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“…Ehrich [10] described the following phenomena occurring in the nonlinear response of rotating systems: asynchronous response, changing amplitude for constant rotor speed, discontinuous amplitude response as rotor speed changes. Synchronous partial contact response have been observed [5,8].…”

Section: Introductionmentioning

confidence: 92%

“…This complication is accentuated in rotating machinery because of gyroscopic coupling which makes the response modes complex and whirl frequencies dependent on the rotor speed. These systems exhibit rich phenomena including period doubling, aperiodicity, and even chaos in the system's response [1,5,37].…”

Section: Introductionmentioning

confidence: 99%

Continuation analysis of a nonlinear rotor system

2021

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Nonlinearities in rotating systems have been seen to cause a wide variety of rich phenomena; however, the understanding of these phenomena has been limited because numerical approaches typically rely on “brute force” time simulation, which is slow due to issues of step size and settling time, cannot locate unstable solution families, and may miss key responses if the correct initial conditions are not used. This work uses numerical continuation to explore the responses of such systems in a more systematic way. A simple isotropic rotor system with a smooth nonlinearity is studied, and the rotating frame is used to obtain periodic solutions. Asynchronous responses with oscillating amplitude are seen to initiate at certain drive speeds due to internal resonance, in a manner similar to that observed for nonsmooth rotor–stator contact systems in the previous literature. These responses are isolated, in the sense that they will only meet the more trivial synchronous responses in the limit of zero damping and out of balance forcing. In addition to increasing our understanding of the responses of these systems, the work establishes the potential of numerical continuation as a tool to systematically explore the responses of nonlinear rotor systems.

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“…Chipato et al. 55 analyzed the nonlinear vibration of overhung rotors by employing lump parameter model by considering the effect of gravity. Annular rubbing was studied by Zilli et al.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the effects of gravity and initial static deflection on the modal properties of nonlinear overhung rotors were not considered previously. In a recent paper, 55 in the absence of geometric nonlinearity, the effect of gravity was considered in a rotor with rub-impact. It is shown here that the inclusion of this type of nonlinearity (geometric) on the problem (rotor under the influence of gravity) leads to peculiar behaviors.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear free vibrations analysis of overhung rotors under the influence of gravity

Tiaki

Hosseini

Nezhad

2019

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this paper, nonlinear free vibration of a cantilever flexible shaft carrying a rigid disk at its free end (overhung rotor) is investigated. The Rayleigh beam model is used and the rotor has large amplitude vibrations. With the assumption of inextensibility, the effect of nonlinear curvature and inertia is considered. The effect of disk mass on the dynamical behavior of the system is studied in the presence and absence of gravity (horizontal and vertical rotors). By using perturbation technique (method of multiple scales), the main focus is on the influence of gravity on equations of motion and on quantities such as amplitude and damped natural frequency. Here, a different behavior is observed due to the rotor weight. Indeed, the combination effects of gyroscopic term, nonlinearity and gravity are studied on the modal behavior of the system. It is shown that the static deflection creates second order nonlinear terms and changes the nonlinear damped natural frequency. With considering of gravity, both beat and high frequency in beat phenomenon increase. With increasing of the rotor weight, the minimum value of amplitude is extremely amplified in the direction of gravity but in the other transverse direction, amplitude of vibrations decreases. In addition, it is found that the weight has directly influence on beat frequency, while the mass ratio between disk and beam affects the high frequency.

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Effect of gravity-induced asymmetry on the nonlinear vibration of an overhung rotor

Cited by 18 publications

References 20 publications

Dynamics analysis of a hollow-shaft rotor system with an open crack under model uncertainties

Dynamics analysis of a hollow-shaft rotor system with an open crack under model uncertainties

Continuation analysis of a nonlinear rotor system

Nonlinear free vibrations analysis of overhung rotors under the influence of gravity

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