Time-variant systems can be found in many areas of engineering. It is widely accepted that the classical Fourier-based methods are not suitable for the analysis and identification of such systems. The time-variant frequency response function—based on the continuous wavelet transform—is used in this paper for the analysis of time-variant systems. The focus is on the comparative study of various broadband input excitations. The performance of the method is tested using simulated data from a simple MDOF system and experimental data from a frame-like structure.
Time-variant systems can be found in many areas of engineering. It is widely accepted that the classical Fourier-based methods are not suitable for the analysis and identification of such systems. The time-variant frequency response function—based on the continuous wavelet transform—is used in this paper for the analysis of time-variant systems. The focus is on the comparative study of various broadband input excitations. The performance of the method is tested using simulated data from a simple MDOF system and experimental data from a frame-like structure.
“…It is well known that in engineering applications the scaling parameter a can be related directly to frequency. Following the previous work reported in [22][23][24], the complex Morlet wavelet is used, which is composed of the complex exponential carrier and the Gaussian window as an envelope. This wavelet function can be defined as…”
Wavelet analysis is applied to identify the time-variant dynamics of adaptive structures. The wavelet-based power spectrum of the structural response, wavelet-based frequency response function (FRF) and wavelet-based coherence are used to identify continuously and abruptly varying natural frequencies. A cantilever plate with surface-bonded macro fibre composite-which alters the structural stiffness-is used to demonstrate the application of the methods. The results show that the wavelet-based input-output characteristics-i.e. the FRF and coherence-can identify correctly the dynamics of the analysed time-variant system and reveal the varying natural frequency. The wavelet-based coherence can be used not only for the assessment of the quality of the wavelet-based FRF but also for the identification.This article is part of the theme issue 'Redundancy rules: the continuous wavelet transform comes of age'.
“…The calculation procedure is a little bit different. More information about this ratio and its calculation procedure can be found in (Dziedziech et al 2014;Staszewski, Wallace 2014;Dziedziech et al 2015). Equation (5) is relatively simple, yet it is often not easy to use in practice.…”
Section: Analysis Of Time-variant Systemsmentioning
confidence: 99%
“…The wavelet-based FRF proposed in (Staszewski, Giacomin 1997;Staszewski, Robertson 2007) has been recently extended to give a theoretical background along with a physical interpretation and to provide a full framework for modal analysis and system identification (Dziedziech et al 2014;Staszewski, Wallace 2014;Dziedziech et al 2015).…”
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