An iterative rational fraction polynomial technique for modal identification |
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Authors: | Antonio Carcaterra Walter D'Ambrogio |
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Institution: | (1) Dipartimento di Meccanica e Aeronautica, Università di Roma La Sapienza, via Eudossiana 18, 00184 Roma, Italy;(2) Dipartimento di Energetica, Università dell'Aquila, 67040 Monteluco di Roio (AQ), Italy |
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Abstract: | The rational fraction polynomial (RFP) modal identification procedure is a well known frequency domain fitting technique. To deal with a linear problem, the RFP procedure does not directly minimize the fitting error, i.e. the difference between the experimental and the analytical frequency response function, but a frequency weighted function of it: this causes bias in the modal parameter estimates. In this paper an iteration procedure is proposed which uses the output of the RFP technique as a starting estimate, and minimizes the true fitting error, expressed as a first order Taylor expansion of the identified parameters. Results are quite satisfactory: the fitting error is notably reduced after few iterations. Moreover, less computational modes with respect to the original RFP method are needed to obtain a good fit in a given frequency band.A first version of this paper was presented at 17th Int. Seminar on Modal Analysis, Leuven (Belgium), 23–25 September 1992, and preprinted in the Proceedings. |
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Keywords: | Identification modal analysis curve-fitting vibrations |
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