Research On Acoustic Wave Control Based On Density-near-zero Metamaterial And Collective Surface Oscillations

The research of acoustic metamaterials is one of the frontier issues in recent years,and the breadth and depth of this research are expanding.Several new materials and new structures are proposed in this paper which are based on the acoustic metamaterials.The propagations of sound waves in these materials and structures are systematically discussed by theoretical deduction and finite element numerical simulation.In the first chapter,we review the background of the researches in metamaterials field,the development history of this research field and the research status of this hot field.In the second chapter,we design an anisotropic density-near-zero metamaterial by using of the knowledge of transforming acoustics,and realize the perfect acoustic bending waveguide with this metamaterial.Based on this theory,we design a "T" type multi-channel shunt and convergence,and realize the channel selection by means of the ideal soft defect.In the third chapter,we mainly study the metasurface.To verify the existence of this type of acoustic collective surface oscillations(CSOs),which is similar to the same as the surface plasmas(SPs),we constructed a rigid plate decorated with periodic two-dimensional HRs and rectangular gratings.We have experimentally verified the existence of the acoustic CSOs.Then,we found that the acoustic CSOs can not only transfer in the plane,but also in the bending surface.With the help of acoustic CSOs,we designed two structures to achieve the acoustic beam collimation.In the fourth chapter,we review the whole text and give some prospections in this research field.In short,as a new research field,acoustic metamaterials will develop quickly.More and more exotic phenomena and new findings will appear in this research field.