Time-variant system analysis using wavelet-based transmissibility
Operational modal analysis is widely used in many engineering applications for system identification when excitations measurements are not known or assumed to be broadband and random. The concept of transmissibility, based on the ratio of measured responses, is well known in this approach. This concept is extended for the analysis of time-variant systems. The wavelet-based transmissibility function, that exhibits the combined time-frequency behaviour, is presented. The major focus is on identification and detection of changes to varying physical parameters. Experimental validation is performed using vibration responses captured from a frame-like structure with a tank. This system exhibits varying mass behaviour due to draining sand from the tank. The direct wavelet-based transmissibility function and the relevant coherence function are used for the analysis of this time-variant system. The results demonstrate that the method can be used effectively to capture the time variant behaviour of the system.
KeywordsStructural dynamics Vibration analysis Time-variant systems Transmissibility Wavelets
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The first author would like to acknowledge support from Foundation for Polish Science via START 21.2018 stipend for young researchers.
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