Identifying the Nonlinearity of Structures Dynamics by Wavelet Packet Decomposition

Abstract

In this study, an application of Wavelet Packet Decomposi (WPD) for modal analysis of a circular cylinder supported by two elastic cantilever beams and wires was developed. The Frequency Response Functions (FRFs) analysis was typically calculated by means of Fourier transform method that worked well with linear systems but had limitations when nonlinearities were present mainly due to their inability to examine the non-stationary data. More recently, a WPD-based technique that calculates complex, time-varying FRFs for input/output relationships has been developed. This method represents a unique fundamental advance regarding time-frequency measurement techniques, since, time-varying transfer function is computed while the direct response time-frequency decomposition on wavelets is not, which have been introduced as an alternative method to FRF calculation.