Mahmoud El-kafafy, Bart Peeters, Patrick Guillaume

Research output: Chapter in Book/Report/Conference proceedingConference paperResearch


Traditionally, modal parameters are experimentally extracted from FRFs measured in laboratory conditions. However, most of the real structures (e.g. bridges, in-flight testing of aircrafts) have to be tested in their real operational conditions rather than the laboratory conditions; this is called operational modal analysis (OMA). In OMA, the real loading conditions on the structure are present, but these operational inputs cannot be quantified and only the output responses are available. Therefore, the industrial need arises to study techniques that are capable of extracting the modal parameters from output-only data. In this contribution, the applicability of a recently developed frequency-domain modal parameter estimation method called MLMM in the field of OMA is investigated. The MLMM method fits directly the modal model to the measured data using an advanced non-linear optimization technique. One of the advantages of the MLMM over the existing methods is the capability of delivering a high-quality curve-fit in case of fitting a frequency-domain data matrix (e.g. FRFs or power spectra) with so many columns, the classical modal parameter estimation methods sometimes fail to achieve that. In terms of OMA, the quality of the estimated modal parameters is highly dependent on the number and location of the selected references. Having more references helps to better estimate, for instance, the very close modes and the mode shapes in general. Therefore, the expected benefit of the MLMM in the field of OMA is that the user can build a spectra matrix with so many columns while achieving a high-quality curve-fit of the measured spectra. In this paper, the MLMM method is applied to real case studies and a comparison of the MLMM results with an existing method is made.
Original languageEnglish
Title of host publicationIOMAC'17 : 7th International Operational Modal Analysis Conference , Ingolstadt - Germany
Number of pages11
Publication statusPublished - 11 May 2017
Event International Operational Modal Analysis Conference (IOMAC'17) - Ingolstadt , Germany
Duration: 10 May 201712 May 2017
Conference number: 7th


Conference International Operational Modal Analysis Conference (IOMAC'17)
Abbreviated titleIOMAC'17
Internet address

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