Abstract

MARWAH, T.  and  HEYNS, P.S.. New criteria for comparing frequency response functions. R&D j. (Matieland, Online) [online]. 1998, vol.14, pp.49-55. ISSN 2309-8988.

Measured frequency response functions are commonly used for the extraction of modal properties of structures. These properties may then be used for the updating of finite element models. The updating requires suitable criteria to quantify the success of the updating procedure. Such criteria exist in the literature for the comparison of models in terms of modal parameters, but there is a need for a convenient procedure based on frequency response functions. In this work a frequency response function scaling factor, which directly compares frequency response functions, is proposed. As an intermediate step, a frequency response function assurance criterion, which is the ratio of the analytical to the measured frequency response functions is also proposed. These two methods are compared to simplified versions of the well-known modal assurance and co-ordinate modal assurance criteria, by applying a frequency response function updating method and a modal property updating approach to a freely suspended beam, a freely suspended beam with holes, and an unsymmetrical H-shaped structure. Where the frequency response function method was implemented, the frequency response function scaling factor and frequency response function assurance criterion were found to be better comparators than the modal assurance and co-ordinate modal assurance criteria. Where the modal properties method was implemented, it was found that the modal assurance and co-ordinate modal assurance criteria performed better than the frequency response function scaling factor and frequency response function assurance criterion.

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