Wavelet-based modal analysis for time-variant systems

• A new method for the analysis and identification of time-variant vibration systems is proposed.
• The method utilises the wavelet-based Frequency Response Function (FRF).
• Random impact excitation is used to obtain the wavelet-based FRF.
• Signal post-processing – based on ridge extraction and the crazy climbers Algorithm – is applied to identify modal parameters, i.e. natural frequencies, damping and mode shapes.
• The method captures the dynamics of the analysed simulated and experimental time-variant vibration systems. All modal parameters - and their evolution in time - are identified correctly.

The paper presents algorithms for modal identification of time-variant systems. These algorithms utilise the wavelet-based Frequency Response Function, and lead to estimation of all three modal parameters, i.e. natural frequencies, damping and mode shapes. The method presented utilises random impact excitation and signal post-processing based on the crazy climbers Algorithm. The method is validated using simulated and experimental data from vibration time-variant systems. The results show that the method captures correctly the dynamics of the analysed systems, leading to correct modal parameter identification.