Bandgap Properties Of The Convex At The Edge Of The Scatterer In Phononic Crystals

The periodic composite materials or structures with the band gap properties are called phononic crystal.The concept of phononic crystal is presented when the frequency of elastic wave located in the band gap of phononic crystal interval,and the elastic wave propagation will be restrained,which called the band gap characteristics.Moreover,the phononic crystals,in transmission,also has the properties of negative refraction,focus,asymmetric transmission,acoustic waveguide,and others.It has a great application prospect.As a core issue in phononic crystal research,the band-gap characteristics have always been the focus in the whole research work.In this paper,the convex elements are setting at the edge of the scatterer.The finite element method(FEM)is used to study the influence from the band gap characteristics and propagation behavior of phonon crystals,which is mainly divided into the following parts:(1)First of all,triangular convex elements are attached to the edge of the square scatterer,based on treating the arranged number and height of the convex elements as the control parameters per unit,the band structure of 2-D Al-EPOXY phonon crystal was calculated by using the finite element method,and the changes of the width and center frequency of the first complete band gap of phonon crystal were analyzed in detail.(2)Then rectangular and ellipse convex elements are setting at the edge of the scatterer,the variation of band gap width with the arranged number and height of structural elements is analyzed,the influence law of three shapes is compared,and the approximate rule of their influence on band gap and applicable under different scatterer material parameters are obtained.Then the model is extended to solid/gas phononic crystal,and the variation of the band structure with the convex elements is studied briefly.The influence is obviously greater than that of solid/gas phononic crystal brings.(3)Finally,considering the industrial design and application of phononic crystal,in order to verify the effectiveness of the algorithm,it studied the solid/solid phononic crystal board and solid/gas transmission characteristics of phononic crystal,among which,the type of solid/gas is aluminium column-epoxy resin type phononic crystal and split ring type phononic crystal.The convex elements have a certain influence on its sound insulation effect,which can make the frequency of the acoustic peak position to move to the low frequency direction,and the intracavity or outer convex elements structure of the split ring type phononic crystal makes the opposite effects.