Holes Effects in Plane Periodic Multilayered Viscoelastic Media

Copyright © 2013 Emmanuel Siryabe et al. This is an open access article distributed under the Creative Commons Attribution Li-cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This work deals with the study of the reflection and transmission properties of plane periodic structures composed of N periods (1 ≤ N ≤ 3) in the MHz frequency range. The period consists of two bounded plates presenting a high acoustic impedance contrast one of which is in aluminum, the other is in polyethylene. The longitudinal and transversal attenua-tions are considered in polyethylene and neglected in aluminum. We take into account the case of emerging holes in the polyethylene layer. Simulations are based on the stiffness matrix method (SMM) developed by Rokhlin. When attenua-tion is considered in polyethylene, the reflection coefficients are different depending on the insonification side. The comparison of results without or with holes configurations are performed and showed that throughout holes allow the rapid observation of forbidden bands. The attenuation of the whole multilayer is also determined