ACOUSTIC PROPAGATION IN A PERIODICALLY STRATIFIED MEDIUM

We propose a theoretical analysis of Floquet wave propagation in a periodically laminated composite medium. The wavelengths are assumed to be of the same order as the thicknesses of the layers of the composite material. We obtain two linearly independent solutions which are discussed in terms of their dependence on the angular frequency and the wave incidence angle. In particular, the Brillouin zones corresponding to propagating or evanescent solutions are studied in detail. This study permits consideration of the case of a liquid-composite interface for which a given condition of radiation is necessary. The reflection and transmission coefficients are evaluated for a plane wave and their singularities are determined.