Tran-Van-Nhieu Michel, Pham Thi Mai, Divay Laurent, Maze Gérard, Décultot Dominique, Léon Fernand, Chati Farid, Lardat Raphael, Hladky Anne-Christine, Croenne Charles, Dubus Bertrand
Thales Research and Technology, Campus Polytechnique, 1 avenue Augustin Fresnel, Palaiseau, 91767, France.
Université du Havre, Normandie Université, Laboratoire Ondes et Milieux Complexes UMR CNRS 6292, 75 rue Bellot, Le Havre, 76058, France.
J Acoust Soc Am. 2018 Aug;144(2):785. doi: 10.1121/1.5049933.
Double layer structures consisting of stainless steel and polymer rods are designed to blur and attenuate Bragg and Bloch-Floquet scattering from a periodically ribbed plate in a given frequency bandwidth. These structures can be considered as ribbed plate-spring-mass systems, the resonance frequencies of which are obtained from random and circular permutations of five basic oscillators. Analytical and finite element methods are used to find their parameters and tank tests have been carried out to ensure the accuracy of the numerical results and validate the relevance of such a model. It has been found that the typical features associated with the periodicity of the ribs are replaced by a "Christmas tree" appearance when the far field pressure backscattered from the model is displayed in the (frequency, aspect angle) plane. An analysis of backscattering patterns is presented and comparisons with Naval Research Laboratory results are made.
由不锈钢和聚合物棒组成的双层结构旨在在给定频率带宽内模糊并减弱来自周期性带肋板的布拉格散射和布洛赫 - 弗洛凯散射。这些结构可被视为带肋板 - 弹簧 - 质量系统，其共振频率通过五个基本振荡器的随机和循环排列获得。采用解析法和有限元法来确定其参数，并进行了水槽试验以确保数值结果的准确性并验证该模型的相关性。研究发现，当在（频率，方位角）平面中显示从模型反向散射的远场压力时，与肋条周期性相关的典型特征被“圣诞树”外观所取代。本文给出了反向散射图案分析，并与海军研究实验室的结果进行了比较。
