Design Of Acoustic Metamateria Units And Device Based On Optimization Algorithm

Acoustic metamaterial is an artificial composite structure made up of sub-wavelength units with periodic or specifically aperiodic spatial arrangement.Acoustic metamaterial has the excellent characteristics that acoustic materials in nature do not have.The acoustic metamaterials break the limitations of traditional acoustic materials and provide new ideas for the design and application of functional devices.Here,the properties of acoustic metamaterials are studied,and the element optimization and design is realized by the combination of algorithms and finite elements analysis.At the same time,the applications of acoustic meta-atoms are studied including acoustic localized surface plasmon devices and the metasurface with orbital angular momentum.The contents of the work are listed as follows:(1)Acoustic meta-atoms are designed effectively based on combination of Covariance Matrix Adaptation Evolutionary Strategy(CMA-ES)and Finite Element Method(FEM).An acoustic meta-atom with large refraction index n=7.56 is realized and validated.A thin acoustic lens is designed based on the optimized element to realize sound bending.(2)The concept of localized surface plasmon in electromagnetic field is extended to the acoustic field,and two-dimensional periodically grooved cylinders are designed to achieve the localization of the acoustic surface wave.(3)The acoustic metasurface with helical phase surface is designed to achieve acoustic orbital angular momentum(OAM).The structure can transform the plane sound wave into a vortex beam with wide application prospects in biology and medical fields.