Characterization of evanescent ultrasonic waves in a band gap of a 1D phononic crystal

This work deals with the propagation of Lamb waves on a plate engraved by a 1D periodic grating. Dispersion curves of the modes exhibit pass bands and stop bands. The aim of this work is to establish a link between the attenuation of the ultrasonic waves observed in the case of a limited grating and the values of the imaginary part of the wave number in a stop band computed for an infinite grating.