Research On Annular Acoustic Cloak Based On Pentamode Material

According to the invariance of the acoustic control equation,there exists a corresponding relationship between the material parameter distribution and the coordinate space transformation,and the wave propagation path is changed by controlling the material parameter distribution.The object in the fluid can be perfectly cloaked from detective wave,as long as it is surrounded by a layer of anisotropic material(cloak)with a certain thickness and material parameters varying according to certain laws.This material with continuously changing parameters does not exist in nature and can only be implemented by artificial metamaterials.The mapping function of the coordinate space transformation affects the parameter distribution of the material and the ultimate acoustic stealth effect of the cloak.In this paper,the acoustic control theory of two-dimensional acoustic cloak based on pentamode material is theoretically studied,and the law of parameter distribution is deduced.At the same time,theoretical analysis and numerical simulation of acoustic cloak are carried out,with different transformation functions such as(1)constant density,(2)constant stiffness,(3)linear transformation,(4)power-law density,(5)power-law stiffness.Then,in order to solve the problem of pentamode material construction,starting from the periodicity of pentamode material,the specific configuration and parameter equivalent method of pentamode material cell are studied.The effectiveness of the parameter equivalent method and the five-modal material was verified by numerical simulation.The pentamode cloak studied in this paper takes the coordinate transformation function with constant density.For the continuous parameter distribution of pentamode cloak with isotropic density and anisotropy of modulus,the layered cloak is taken into consideration,and the ideal material parameter distribution is mimiced by the combination of microstructure unit cells.Finally,the numerical simulation of the microstructure pentamode cloak is carried out to verify the effectiveness of the microstructure design of the pentamode cloak.