Study on Acoustic Metamaterial Thin Plate Absorbing Low-Frequency Sound

In the fields of mechanical engineering and architecture, the isolation of vibration noise is an important topic. Currently, low-frequency sound absorption remains challenging. The sound absorbing materials have weak interaction with low-frequency acoustic waves resulting in inefficient dissipation of sound energy, and the resonant structures need large space which is proportional to the wavelength of sound. Thus more research is needed for the development of the low-frequency sound absorption technology. Metamaterials attracted much academic attention in recent years. Metamaterials are artificial materials consisting of some special micro-structures. Wave propagation in the metamaterial has some special properties which can not be observed in the natural media. These micro-structures are usually resonators of waves, and then metamaterials can modulate the propagation of waves with a wavelength of 10 to 100 times of the size of the micro-structures. One of the applications is the efficient sound absorption by using the acoustic metamaterials. In this project, metamaterial based on Helmholtz resonators will be study to design a thin plate which can absorb sound of the wide low-frequency range. The work included numerical simulation, design and fabrication of specimens, and experimental measurements. Firstly, the geometric size of a Helmholtz resonator will be changed to study the effect on absorption. The modified Helmholtz resonant cavities for operation in a wide-frequency range will then be analyzed and used to design the thin plates. Finally, the specimens of metamaterial plates will be fabricated. The frequency response of sound absorption will be measured to be compared with the numerical analyses. The study is expected to be valuable for isolating and controlling the noise from industry and living.

Project ID:PB10507-2935
External Project ID:MOST105-2221-E182-021