The Algorithm of Mode Isolation (AMI) extracts modal properties from complex frequency response data. Previous work used classic undamped modes as the analytical framework for the algorithm. The present work extends the algorithm to implement damped modal analysis, in which the eigenvalues and eigenvectors are complex. In order to assess how well this reformulation performs when natural frequencies are close and drive point mobilities are low, a prototypical system consisting of a cantilever beam with attached subsystems is introduced. One of these subsystems is selected to be a tuned vibration absorber for the isolated beam, so the system features a combination of modes whose natural frequencies are close and modes whose drive point mobility is low. The time domain response of this system is evaluated, contaminated with substantial white noise, and then FFT processed in order to obtain synthetic complex frequency response data. The performance of AMI is evaluated by comparing extracted values for natural frequency, modal damping ratio, and complex normal mode vectors to the analytical values. The results reveal that the pair of modes having proximite natural frequencies are accurately identified. Natural frequencies and damping ratios for those modes whose drive mobility is low are identified by processing the ensemble of frequency response functions, but identification of normal mode coefficients for such modes remains problematic.
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April 2003
Technical Papers
State Space Implementation of the Algorithm of Mode Isolation
Michael V. Drexel,
Michael V. Drexel
G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
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Jerry H. Ginsberg,
e-mail: Jerry.ginsberg@me.gatech.edu
Jerry H. Ginsberg
G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
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Bassem R. Zaki
Bassem R. Zaki
G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
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Michael V. Drexel
G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
Jerry H. Ginsberg
G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
e-mail: Jerry.ginsberg@me.gatech.edu
Bassem R. Zaki
G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332
Contributed by the Technical Committee on Vibration and Sound for publication in the JOURNAL OF VIBRATION AND ACOUSTICS. Manuscript received October 2001; revised September 2002. Associate Editor: C. Farrar.
J. Vib. Acoust. Apr 2003, 125(2): 205-213 (9 pages)
Published Online: April 1, 2003
Article history
Received:
October 1, 2001
Revised:
September 1, 2002
Online:
April 1, 2003
Citation
Drexel, M. V., Ginsberg, J. H., and Zaki, B. R. (April 1, 2003). "State Space Implementation of the Algorithm of Mode Isolation ." ASME. J. Vib. Acoust. April 2003; 125(2): 205–213. https://doi.org/10.1115/1.1547463
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