Extracting Modes of Constrained Structure with Elastic Supports from Free Test Data
Publication: Journal of Aerospace Engineering
Volume 20, Issue 1
Abstract
The dynamic flexibility (DF) and improved dynamic flexibility (IDF) methods can be applied to extract constrained structural modes from free-free modal test data. The residual flexibility method is also good for boundaries of constrained structure with rigid supports. Under elastic support boundary conditions both the DF and residual flexibility methods cannot produce accurate results. This paper expands the previously published IDF method to become a more general approach for structural design engineers. A new method called the general dynamic flexibility (GDF) method has been developed in this paper to extract constrained structural modes from free test data. The GDF method can always be applied as follows: (1) when the boundary support stiffness is very stiff, the GDF method can accurately obtain results from rigid support as by Liu et al. in 2001 and Zhang and Wei in 2003; (2) when the support stiffness is soft, the present method can produce results similar to those free-free modal parameters measured by hanging structures using rubber band; (3) when the support stiffness is zero, the method can reproduce true free-free modal parameters; and (4) when the support stiffness has any finite values, the GDF method can also achieve satisfactory results for engineering use. The algorithm included in the GDF method converges rapidly and is numerically stable in the analysis. This feature is very practical for many engineering applications for using the GDF method.
Get full access to this article
View all available purchase options and get full access to this article.
References
Admire, J. R., et al. (1994). “Residual flexibility test method for verification of constrained structural models.” AIAA J., 32(1), 170–175.
Baruch, M. (1984). “Methods of reference basis for identification of linear dynamic structure.” AIAA J., 22(4).
Bathe, K. J., and Wilson, E. L. (1976). Numerical method in finite element analysis, Prentice-Hall, Englewood Cliffs, N.J.
Berman, A., and Nagy, E. J. (1983). “Improvement of a large analytical model using test data.” AIAA J., 21(8).
Chen, J. C., and Garba, J. A. (1980). “Analytical model improvement using modal test results.” AIAA J., 18(6).
Hu, H. C. (1987). Structural natural vibration theory, Science, Beijing.
Liu, F., Zhang, D. W., and Zhang, L. (2001). “Dynamic flexibility method for extracting constrained structural modes from free test data.” AIAA J., 39(2), 279–284.
Rubin, S. (1975). “Improved component-mode representation for structural dynamic analysis.” AIAA J., 13(8), 995–1006.
Zhang, D. W., and Wei, F. S. (1992). “Model correction via compatible element method.” J. Aerosp. Eng., 5(3), 337–346.
Zhang, D. W., and Wei, F. S. (1997). “Efficient computation of many eigenvector derivatives using dynamic flexibility method.” AIAA J., 35(3), 712–718.
Zhang, D. W., and Wei, F. S. (1999). Model updating and damage detection, Science Press, Beijing.
Zhang, D. W., and Wei, F. S. (2002). “Dynamic flexibility method with hybrid shifting frequency for eigenvector derivatives.” AIAA J., 40(10), 2047–2052.
Zhang, D. W., and Wei, F. S. (2003). “Improved dynamic flexibility method for extracting constrained modes from free test data.” AIAA J., 41(3), 498–503.
Information & Authors
Information
Published In
Copyright
© 2007 ASCE.
History
Received: Mar 25, 2003
Accepted: Jun 28, 2005
Published online: Jan 1, 2007
Published in print: Jan 2007
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.