The procedures used to estimate structural modal parameters as natural frequency, damping ratios, and mode shapes are generally\nbased on frequency methods. However, methods of time-frequency analysis are highly sensible to the parameters used to calculate\nthe discrete Fourier transform: windowing, resolution, and preprocessing. Thus, the uncertainty of the modal parameters is\nincreased if a proper parameter selection is not considered. In this work, the influence of three different time domain windows\nfunctions (Hanning, flat-top, and rectangular) used to estimate modal parameters are discussed in the framework of ISO 18431\nstandard. Experimental results are conducted over an AISI 1020 steel plate, which is excited by means of a hammer element.\nVibration response is acquired by using acceleration records according to the ISO 7626-5 reference guides.Theresults are compared\nwith a theoretical method and it is obtained that the flat-top window is the best function for experimental modal analysis.
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