Design Of Acoustic Focusing Lens Based On H-fractal Acoustic Metamaterials

Until now,the popularity and importance of acoustic technology in military and civilian applications have attracted wide attention.With the development of science and technology,the development and application of new acoustic materials and new acoustic devices become the focus of research in this field.Among them,acoustic artificial materials,especially acoustic metamaterials,can handle and regulate sound waves in a non-traditional way,and often have performance parameters that traditional materials do not have.In recent years,great progress has been made in the development of acoustic metamaterials and in the design of acoustic devices.There are generally two methods for acoustic metamaterial design.One is to design metamaterials with local-resonance characteristics,and the other is based on effective medium theory.However,both methods have their own limit.In this paper,based on the fractal theory,a new type of acoustic metamaterial is proposed and a broadband acoustic focusing lens is designed.The basic theory of acoustic metamaterial design.This dissertation analyzed the derivation formula of the effective parameters of acoustic metamaterials,paving the way for the design of acoustic metamaterials.The working principle of acoustic focusing lens is analyzed,which lays a theoretical foundation for the design of acoustic focusing lens.The proposition and performance of H-fractal acoustic metamaterials.In combination with the fractal theory,the possibility and advantages of using fractal structure in the design of acoustic metamaterials are discussed in this dissertation.We studied the performance parameters of the H-fractal and proposed an open slit design to improve its performance,laying the foundation for the subsequent design of broadband acoustic focusing lenses.Design of the acoustic focusing lens.We simulated the transmitted phase shift of the H-fractal,and obtained the wide transmitted phase shift range based on the variation of the order and structural parameters of the H-fractal acoustic metamaterial.Based on the modulation relationship between the transmitted phase and the structural parameters,an acoustic focusing lens with a circular-arc-shaped transmitted phase was designed,and its focusing effect was simulated in COMSOL.Thus,the application prospect of H-fractal structure and fractal theory in the field of acoustic metamaterials is verified.