A COMPARATIVE OF CURVE-FITTING ALGORITHMS FOR THE EXTRACTION OF MODAL PARAMETERS FROM RESPONSE MEASUREMENTS

Authors

  • R. B. Randall The University of New South Wales
  • Grover Zurita Universidad Privada Boliviana
  • T. Wardrop The University of New South Wales

Keywords:

Rational Fraction Polynomial, Complex Exponential, Complex Cepstrum, Hilbert Envelope, Ibrahim Time Domain Method

Abstract

The main objective of this paper is to perform a comparison of several curve-fitting methods for extraction of the modal parameters from response vibration measurements, and in particular the best damping estimates. Measurements were carried out on a steel beam to which a constrained layer had been added to make the damping more similar to that of vehicle structural components. Two shakers with different excitation signals, a periodic impulsive and a random signal, respectively, excited the structure, but after separation, only the random part was analysed for the results of this paper. This study compares a number of common curve fitting methods, viz: The Rational Fraction Polynomial Method, the Complex Exponential Method, the Complex Cepstrum Method, the Hilbert Envelope Method and the Ibrahim Time Domain method. The most accurate results for detection of the damping and natural frequencies were obtained by using the Ibrahim Time Domain Method, with the Rational Fraction Polynomial method very similar. The Hilbert Envelope method gave comparable damping estimates. The Cepstrum and Complex Exponential methods gave reasonable results for the frequencies, but not for the damping.

Downloads

Download data is not yet available.

Author Biographies

R. B. Randall, The University of New South Wales

School of Mechanical and Manufacturing Engineering

T. Wardrop, The University of New South Wales

School of Mechanical and Manufacturing Engineering

References

R. Ford et al. “Updating modal properties from response-only measurements on a rail vehicle”. Proc. ISMA 2002, KUL, Leuven, Belgium.

B.P. Bogert et al. “The Quefrency Alanysis of Time Series For Echoes;Cepstrum, Pseudo-autcovariance, Cross-cepstrum and Saphe Cracking”. Proc. Symp. On Time Series Analysis, Wiley, 1963.

R.B. Randall. Frequency Analysis, Bruel & Kjaer, Denmark, 1987.

A.V. Oppenheim & R.W. Schafer. Discrete Time Signal Processing, Prentice-Hall, 1989.

Y. Gao and R.B. Randall. “Determination of frequency response functions from response measurements - part I. Extraction of poles and zeros from response cepstra, - part II Regeneration of frequency response functions from poles and zeros” Mech. Systems and Signal Processing, vol. 10, no, 3, pp. 293-317 & 319-340, 1996.

S. Braun (ed.). Mechanical Signature Analysis, Academic Press, 1986.

Bruel and Kjaer Application Note. Hilbert Transform Envelope.

S.R. Ibrahim & E.C. Mikulcik. “A method for the direct identification of vibration parameter from time responses”. Shock and Vibration Bulletin, no 47, 183-198, 1977.

Y. Gao and R.B. Randall. “The ITD mode shape coherence and confidence factor and its application to separating eigenvalue positions in the z-plane”. Mech. Systems and Signal Processing, vol. 14, no. 2, pp. 167-180, 2000.

M. Richardson and D. Formenti. “Global curve-fitting of frequency response measurements using the rational fraction polynomial method”. 3rd IMAC conference, Orlando, pp. 390-397, 1985.

Published

2005-01-31

How to Cite

Randall, R. B., Zurita, G., & Wardrop, T. (2005). A COMPARATIVE OF CURVE-FITTING ALGORITHMS FOR THE EXTRACTION OF MODAL PARAMETERS FROM RESPONSE MEASUREMENTS. Revista Investigación &Amp; Desarrollo, 1(4). Retrieved from https://www1.upb.edu/revista-investigacion-desarrollo/index.php/id/article/view/120

Issue

Vol. 1 No. 4 (2004)

Section

Ingenierías

License

Creative Commons Attribution-Noncommercial-Share Alike
CC BY-NC-SA

This license lets others remix, tweak, and build upon your work for non-commercial purposes, as long as they credit the author(s) and license their new creations under the identical terms.

The authors can enter additional separate contract agreements for non-exclusive distribution of the version of the article published in the magazine (for instance, they may publish it in an institutional repository or a book), subject to an acknowledgement of its initial publication in this magazine.