An Acoustic Metamaterial Bending Waveguide Design Using Transformation Acoustics

2011 ◽  
Author(s):  
Liang-Yu Wu ◽  
Tzeh-Yi Chiang ◽  
Mei-Ling Wu ◽  
Lien-Wen Chen
Keyword(s):  
Layered Structure ◽  
Material Properties ◽  
Mass Density ◽  
Homogeneous Material ◽  
Two Dimensional ◽  
Negative Mass ◽  
Acoustic Metamaterial ◽  
Transformation Medium ◽  
Waveguide Design ◽  
Transformation Acoustics

An acoustic bending waveguide is designed by transformation acoustics. A two-dimensional square area with anisotropic and homogeneous material properties is transformed into a fan-shaped area with anisotropic and inhomogeneous material properties to rotate the direction of beam propagation. The transformation medium can be realized by alternating layered structure consisting of water and fluid with negative mass density. We propose that an acoustic metamaterial composed of three layers in water background can be designed to replace negative mass density fluid and achieve the acoustic bending waveguide.

scholarly journals Design of highly-efficient acoustic waveguide couplers using impedance-tunable transformation acoustics

2020 ◽  
Vol 34 (32) ◽  
pp. 2050250
Author(s):  
Jun Cao ◽  
Fenghua Qi ◽  
Senlin Yan ◽  
Lifa Zhang
Keyword(s):  
Refractive Index ◽  
Impedance Matching ◽  
Coupling Efficiency ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Low Frequencies ◽  
Acoustic Waveguide ◽  
Acoustic Coupling ◽  
Transformation Medium ◽  
Transformation Acoustics

In this paper, the theory of impedance-tunable transformation acoustics in the geometric-acoustics limit is proposed to design efficient two-dimensional acoustic waveguide couplers. By choosing suitable impedance functions in the original space, impedance matching between the transformation medium and the background medium becomes possible, and the reflection at the boundary is reduced. The theory can be used to enable efficient acoustic coupling between waveguides of different sizes and different embedded media. By selecting an appropriate impedance function and a tunable acoustic refractive index, the transformed medium in the coupler can become a simplified parameter medium, for which the bulk modulus is a constant. This makes the experiment substantially easier. The problem of a reduced coupling-efficiency at low frequencies (a deviation from the geometric acoustic approximation) can be mitigated by selecting a large acoustic refractive index. Our two-dimensional numerical simulations indicate that this theoretical design works very well. The method can be extended to other transformation acoustic designs including three-dimensional cases.

Design and measurements of a broadband two-dimensional acoustic metamaterial with anisotropic effective mass density

2011 ◽  
Vol 109 (5) ◽  
pp. 054906 ◽  
Author(s):  
Lucian Zigoneanu ◽  
Bogdan-Ioan Popa ◽  
Anthony F. Starr ◽  
Steven A. Cummer
Keyword(s):  
Effective Mass ◽  
Mass Density ◽  
Two Dimensional ◽  
Acoustic Metamaterial

scholarly journals Inverse Doppler effect of acoustic metamaterial with negative mass density

2017 ◽  
Vol 66 (2) ◽  
pp. 024301
Author(s):  
Liu Song ◽  
Luo Chun-Rong ◽  
Zhai Shi-Long ◽  
Chen Huai-Jun ◽  
Zhao Xiao-Peng
Keyword(s):  
Doppler Effect ◽  
Mass Density ◽  
Negative Mass ◽  
Acoustic Metamaterial

Two-Dimensional Arbitrarily Shaped Acoustic Cloaks With Triangular Patterns of Homogeneous Properties

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Qi Li ◽  
Jeffrey S. Vipperman
Keyword(s):  
Material Properties ◽  
Virtual Space ◽  
Two Dimensional ◽  
Anisotropic Properties ◽  
Triangular Part ◽  
Triangular Domain ◽  
Space Transformation ◽  
Transformation Acoustics ◽  
Method Show

Acoustic cloaking is an intriguing phenomenon that has attracted lots of attention. The required inhomogeneous and anisotropic properties of acoustic cloaks derived with transformation acoustics make them difficult to realize. In this paper, a new mapping relation is presented. An acoustic cloak can be divided into any number of arbitrary triangular patterns, which are mapped from similar patterns in virtual space. Transformation from one triangular domain to another leads to homogeneous properties using transformation acoustics. The resulting cloak is composed of homogeneous triangular parts, each having just two alternating layers of material. The manner of division of the cloak affects the properties of each triangular part dramatically, which can be leveraged to vary the properties of each triangular part for more realistic material properties. Simulations of models based on this method show good cloaking performance at reducing the reflected and scattered waves due to the cloaked obstacle.

Acoustic metamaterial with negative mass density in water

2015 ◽  
Vol 118 (9) ◽  
pp. 094901 ◽  
Author(s):  
Huaijun Chen ◽  
Shilong Zhai ◽  
Changlin Ding ◽  
Chunrong Luo ◽  
Xiaopeng Zhao
Keyword(s):  
Mass Density ◽  
Negative Mass ◽  
Acoustic Metamaterial

Anisotropic Band Gap in a 2D Acoustic Metamaterial

2009 ◽  
Author(s):  
H. H. Huang ◽  
C. T. Sun
Keyword(s):  
Band Gap ◽  
Dynamic Behavior ◽  
Continuum Model ◽  
Wave Motion ◽  
Mass Density ◽  
Internal Mass ◽  
Negative Mass ◽  
Elastic Continuum ◽  
Acoustic Metamaterial ◽  
Band Gap Structure

A two-dimensional (2D) metamaterial possessing an effective anisotropic mass is investigated. This metamaterial is a composite material in the form of an internal mass connected in two directions to the host medium. A 2D mass-in-mass lattice model is used to characterize the dynamic behavior of the metamaterial. If modeled as an effective spring-mass lattice system, the metamaterial may possess a frequency-dependent effective mass. Moreover, if an equivalent homogenous elastic continuum is used to represent the metamaterial, an anisotropic mass density may result and may assume negative values for wave frequencies that are near the local resonance frequency of the internal mass. In fact, it was found that negative mass density occurs in the band-gap of the metamaterial. Unusual wave motion arises from the anisotropic band gap structure. In the present study, wave propagation in the representative continuum model for the metamaterial is studied in order to understand the unusual features of the dynamic behavior of the metamaterial.

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