MICHAL SZOTA THREE-LAYER PERMUTATION OF THE PHONIONIC STRUCTURE AND THE INFLUENCE OF THE ENVIRONMENT The study investigated the influence of permutation of a three-layer structure on the phononic system transmission. Phononic structures are used as mechanical wave filters. These composites are designed and manufactured to have specific properties. The most important property is the presence of phononic bandgaps (PhBG) in these structures. They are designed so that the PhBG occurs in a given frequency range. Knowledge of the impact of deployment of the layets in the structure allows better design of these filters. The analysis was carried out using the transmission matrix method (TMM) algorithm. The transmission structures was examined for all permutations of a system of three layers made of different materials. The structure consisted of mercury, epoxy, rubber and PNM-0.38PT. The materials are chosen so that their characteristics largely differ. The structure was surrounded by water. The tests were carried out for the frequency range up to 1 MHz. Cases with different thickness of layers were analyzed. The tests have shown that regardless of the layer thickness, only three types of transmission structures exist in the six permutations of the system. Systems in which the middle layer remained unchanged, while the outermost layers were changed, were characterized by the same transmission structure. Increasing the thickness of the layers increased the number of transmission bands. Transmission strongly depends on the environment.The absorption of the materials used was not taken into account in the work. Interesting results can be obtained by analyzing the permutation of more complex structures. Changing the order of layers in the filter without changing its characteristics may affect the reduction of production costs and easier design of structures with given properties. The article shows repeating phononic transmission structure for different types of layers alignment.
Keywords: transmission, multilayers, superlattices, phononic, transfer matrix