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TECHNICAL PAPERS

A Flexible Rotor on Flexible Bearing Supports: Stability and Unbalance Response

[+] Author and Article Information
José A. Vázquez, Lloyd E. Barrett, Ronald D. Flack

Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Science, University of Virginia, Charlottesville, VA 22903

J. Vib. Acoust 123(2), 137-144 (Dec 01, 2000) (8 pages) doi:10.1115/1.1355244 History: Received October 01, 1999; Revised December 01, 2000
Copyright © 2001 by ASME
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References

Bansal, P. N., and Kirk, R. G., 1975, “Stability and Damped Critical Speeds of Rotor-Bearing Systems,” ASME J. Ind., November, pp. 1325–1332.
Gash,  R., 1976, “Vibration of Larger Turbo-Rotors in Fluid-Film Bearings on an Elastic Foundation,” J. Sound Vib., 47, No. 1, pp. 53–73.
Queitzsch, G. K., 1985, “Forced Response Analysis of Multi-Level Rotor Systems with Substructure,” Ph.D. Dissertation, University of Virginia, Charlottesville, VA.
Earles,  L. L., Palazzolo,  A. B., Lee,  C.-K., and Gerhold,  C. H., 1998, “Hybrid Finite Element-Boundary Element Simulation of Rotating Machinery Supported on Flexible Foundation and Soil,” ASME J. Vibr. Acoust., 110, pp. 300–306.
Fan,  U.-J., and Noah,  S. T., 1989, “Vibration Analysis of Rotor Systems Using Reduced Subsystem Models,” J. Propul. Power, 5, No. 5, pp. 602–609.
Wygant, K., 1993, “Dynamic Reduction of Rotor Supports,” Master thesis, University of Virginia, Charlottesville, VA.
Rieger,  N. F., and Zhou,  S., 1998, “An Instability Analysis Procedure for Three-Level Multi-Bearing Rotor-Foundation Systems,” ASME J. Vibr. Acoust., 120, pp. 753–762.
Barrett, L. E., Nicholas, J. C., and Dhar, D., 1986, “The Dynamic Analysis of Rotor-Bearing Systems Using Experimental Bearing Support Compliance Data,” Proceedings of the Fourth International Modal Analysis Conference, Union College, Schenectady, New York, pp. 1531–1535.
Nicholas,  J. C., and Barrett,  L. E., 1986, “The effect of Bearing Support Flexibility on Critical Speed Prediction,” ASLE Trans., 29, No. 3, pp. 329–338.
Nicholas, J. C., Whalen, J. K., and Franklin, S. D., 1986, “Improving Critical Speed Calculations Using Flexible Bearing Support FRF Compliance Data,” Proceedings of the 15th Turbomachinery Symposium, Texas A&M University, College Station, Texas.
Redmond, I., 1995, “Practical Rotordynamics Modeling Using Combined Measured and Theoretical Data,” Proceedings of the 13th International Modal Analysis Conference, Nashville.
Redmond, I., 1996, “Rotordynamic Modelling Utilizing Dynamic Support Data Obtained From Field Impact Tests,” Paper C500/055/96, Proceedings of Sixth International Conference on Vibrations in Rotating Machinery, Oxford, Sept.
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Feng, M. S., and Hahn, E. J., 1998, “On the Identification of a Flexibly Supported Rigid Foundation with Unknown Location of the Principal Axes of Inertia,” Proceedings of ISROMAC-7, the 7th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, Honolulu, Hawaii, February, pp. 705–714.
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Figures

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Experimental apparatus (dimensions are in mm)
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Bearing stiffness and damping coefficients
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Sketch of the experimental setup
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Detail of the bearing housing and flexible supports
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Flexible support design (dimensions are in mm)
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Estimated static support stiffness
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Spectral map of the rotor displacement in the horizontal direction. Middle stiffness range.
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Schematics of the support testing
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Measured FRF and fitted polynomial transfer function for Gxx. Response in the right support; excitation in the right support. Support’s static stiffness 1.27 106 N/m.
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Measured FRF and fitted polynomial transfer function for Gxx. Response in the right support; excitation in the right support. Support’s static stiffness 1.00 106 N/m.
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Measured FRF and fitted polynomial transfer function for Gxx. Response in the right support; excitation in the right support. Support’s static stiffness 1.38 106 N/m.
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Effect of the support horizontal static stiffness on the controlled support frequency
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Sketch of the analytical procedure
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Comparison between predicted and measured stability threshold
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Unbalance response in the horizontal direction at sensor location 2. Unbalance Distribution 1. Horizontal stiffness =1.00 106 N/m.
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Unbalance response in the horizontal direction at sensor location 2. Unbalance Distribution 1. Horizontal stiffness =1.19 106 N/m.
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Unbalance response in the horizontal direction at sensor location 2. Unbalance Distribution 1. Horizontal stiffness =1.38 106 N/m.
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Comparison between measured unbalance response for support with Horizontal stiffness = 1.00 106 N/m and single mass support model. Sensor Location 2. Horizontal direction. Unbalance Distribution 1.
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Unbalance response in the horizontal direction at sensor location 3. Unbalance Distribution 2. Horizontal stiffness =1.19 106 N/m.
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Unbalance response in the horizontal direction at sensor location 3. Unbalance Distribution 2. Horizontal stiffness =1.38 106 N/m.
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Comparison between measured unbalance response for support with Horizontal stiffness = 1.00 106 N/m and Single mass supports. Sensor Location 3. Horizontal direction. Unbalance Distribution 2.
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Unbalance response in the horizontal direction at sensor location 3. Unbalance Distribution 2. Horizontal stiffness =1.00 106 N/m.
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Percentage difference between predicted and measured critical speeds
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Comparison between predicted and measured critical speeds
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Comparison between predicted and measured amplitudes at the first and second critical speeds

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