An Investigation in Stiffness Effects on Dynamics of Rotor-Bearing-Foundation Systems

Yuan, Kun; Chang, Yeon‐Pun; Tsai, J.-W.; Mu, Li Hua

doi:10.1006/jsvi.1999.2719

Cited by 39 publications

(19 citation statements)

References 19 publications

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“…Kang et al (2000) studied the effect of the flexible support (foundation) on the dynamic characteristics of the rotor-bearing systems using a FE modeling. Edwards et al (2000) verified experimentally a method which identifies both the excitation and the flexible support parameters of a rotor-bearing-foundation system.…”

Section: Introductionmentioning

confidence: 99%

Steady-state dynamic behavior of an on-board rotor under combined base motions

Dakel

Baguet

Dufour

2013

Journal of Vibration and Control

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To cite this version:M. Zaki Dakel, Sébastien Baguet, Régis Dufour. Steady-state dynamic behavior of an on-board rotor under combined base motions.. Journal of Vibration and Control, SAGE Publications, 2014, 20 (15) AbstractIn the transportation domain, on-board rotors in bending are subjected not only to rotating mass unbalance but also to several movements of their base. The main objective of this article is to predict the dynamic behavior of a rotor in the presence of base excitations. The proposed on-board rotor model is based on the Timoshenko beam finite element. It takes into account the effects corresponding to the rotary inertia, the gyroscopic inertia, the shear deformation of shaft as well as the geometric asymmetry of disk and/or shaft and considers six types of deterministic motions (rotations and translations) of the rotor rigid base. The use of Lagrange's equations associated with the finite element method yields the linear second-order differential equations of vibratory motion of the rotating rotor in bending relative to the moving rigid base which forms a non-inertial frame of reference. The linear equations of motion highlight periodic parametric terms due to the geometric asymmetry of the rotor components and time-varying parametric terms due to the rotational motions of the rotor rigid base. These parametric terms are considered as sources of internal excitation and can lead to lateral dynamic instability. In the presented applications, the rotor is excited by a rotating mass unbalance combined with constant rotation and sinusoidal translation of the base. Quasi-analytical and numerical solutions for two different rotor configurations (symmetric and asymmetric) are analyzed by means of stability charts, Campbell diagrams, steady-state responses as well as orbits of the rotor.

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Section: Introductionmentioning

confidence: 99%

Steady-state dynamic behavior of an on-board rotor under combined base motions

Dakel

Baguet

Dufour

2013

Journal of Vibration and Control

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“…Birchfield et al analyzed the effects of coupling substructure dynamics with turbomachinery and the effect of the two on the system resonances. The authors investigated structural modifications based on the transfer functions of the structure alone in order to change the overall system's dynamic response (Birchfield, Singh, and Singhal 2013 (Kang et al 2000). The aforementioned works are fundamental in analyzing the effects of flex-ible supports on rotating machinery, two critical aspects of which are the lowering of system natural frequencies and damping (Caruso, Gans, and Catlow 1982), both confirmed by this investigation.…”

Section: Introductionsupporting

confidence: 55%

Investigation of the American Petroleum Institute's Support Stiffness Ratio Threshold Specification

Griffin

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In the design phase of developing a rotating machine, it is important to consider the effect that the supporting structure has on the rotordynamic behavior of the system. The American Petroleum Institute's (API) Standard Paragraphs state that if the support stiffness is greater than 3.5 times the bearing oil film stiffness, the designer may omit the supports from the rotordynamic analysis. As discussed in this paper, there is concern that machines operating near the second critical speed may not be adequately modeled using the rigid support assumption allowed by API. Due to the suspected influence of support dynamics on problem machines in industry, this paper investigates the effectiveness of the support to bearing stiffness ratio threshold of 3.5.A Jeffcott rotor model is used to capture the effect of the support on the separation margin and amplification factors of the first and second critical speeds. The trends are then validated using numerical models of two case studies. Results show that the API support stiffness ratio of 3.5 has limitations as a rigid support threshold and should be used with caution when the second critical speed is near a separation margin boundary.The paper proposes an addendum to the current API specification intended to reduce the risk of separation margin encroachment due to a rigid support assumption. Unlike other papers discussing the influence of flexible supports on rotating machinery, this investigation studies the effects at API's support stiffness ratio of 3.5 and compares them to a rigid support system.

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“…The Harmonic Solver of ANSYS will be used to determine the steady-state responses for structures including rotor-bearing systems. The details are described in Kang et al (15,16) .…”

Section: Modelling a Rotor-bearing System By Finite Element Methodsmentioning

confidence: 99%

Rotor Balancing with Considering Measurement Errors

Yuan

Lin

Chang

et al. 2007

JAMDSM

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When influence coefficient (IC) method is used in rotor balancing, it is possible that serious errors could be resulted in unbalance determinations due to the contamination of measurements and IC matrix being ill-posed. In this study, the availability of least squares algorithm (LSA) and Tikhonov regularization (TR) is studied by error estimations of unbalance determination with considering measurement errors. Also, the influence of illness of the IC matrix equation on the change of balancing accuracy relative to the measurement error will be simulated. The finite element method is used to analyze unbalance responses of a rotor-bearing system and the analysis results of both TR and LSA are compared in case studies. Furthermore, the validations of both methods are realized by balancing experiments of a rotor kit.

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An Investigation in Stiffness Effects on Dynamics of Rotor-Bearing-Foundation Systems

Cited by 39 publications

References 19 publications

Steady-state dynamic behavior of an on-board rotor under combined base motions

Steady-state dynamic behavior of an on-board rotor under combined base motions

Investigation of the American Petroleum Institute's Support Stiffness Ratio Threshold Specification

Rotor Balancing with Considering Measurement Errors

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