Acoustic wave propagation in a 1-D lattice: analysis of nonlinear effects by the fractional Fourier transform method

This article deals with a method based on the fractional Fourier transform (FRFT) to estimate the parameters of linear chirps. Appropriate filtering in fractional domains based on this method allows to extract linear chirps out of a multicomponent and noisy signal. This method is used to analyse the propagation of acoustic wave in a dispersive medium (lattice made up of Helmholtz resonators). The nonlinear effects due to the Helmholtz resonators are highlighted. The frequency dependance of the nonlinear processes is shown thanks to the extraction method proposed.