A Flexible Rotor on Flexible Supports: Modeling and Experiments

Dikmen, E.; Hoogt, Peter van der; Boer, A. de; Aarts, RM Ronald; Jonker, Ben

doi:10.1115/imece2009-10851

Cited by 3 publications

(3 citation statements)

References 9 publications

(10 reference statements)

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“…Theodossiades et al [10] proposed a gear transmission model to estimate the vibrations of gear pairs under different working conditions. Dikmen et al [11] proposed a finite-element (FE) model for analyzing the influence of the bearing stiffness on the natural frequencies of flexible shaft system. Xi et al [12,13] established a shaft-bearing system dynamic model based on the FE analysis and studied the relationship between the system manufacturing error and vibrations.…”

Section: Introductionmentioning

confidence: 99%

Dynamic modeling and vibration analysis of a flexible gear transmission system

Liu

Xia

2023

Mechanical Systems and Signal Processing

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Section: Introductionmentioning

confidence: 99%

Dynamic modeling and vibration analysis of a flexible gear transmission system

Liu

Xia

2023

Mechanical Systems and Signal Processing

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“…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. Jalali et al [7] proposed a FE model based on a commercial software to study the critical speeds, unbalance response, and…”

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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“…They show that the support is highly influential on stiff second rotor modes, similar to the trends from this investigation (J. Nicholas and experimental data (Vázquez, L. E. Barrett, and Flack 2001a, b). Dikmen et al generated simple support models using modal analysis data and finite element models, the equivalent models were then used in the finite element model of the rotor to predict rotor response (Dikmen et al 2009). Birchfield et al analyzed the effects of coupling substructure dynamics with turbomachinery and the effect of the two on the system resonances.…”

Section: Introductionmentioning

confidence: 99%

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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A Flexible Rotor on Flexible Supports: Modeling and Experiments

Cited by 3 publications

References 9 publications

Dynamic modeling and vibration analysis of a flexible gear transmission system

Dynamic modeling and vibration analysis of a flexible gear transmission system

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

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

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