pps proceeding - Abstract Preview
pps proceeding
Symposium: S01 - Additive manufacturing (3D printing)
Poster Presentation
 
 

Quarter-wave resonator-based acoustic metasurface fabricated by 3D printing

Sun Jia-Hong (1)*, Liao Yi-Han (2), Chen An-Hsiang (1)

(1) Department of Mechanical Engineering, Chang Gung University - Taoyuan - Taiwan, (2) Institute of Applied Mechanics, National Taiwan University - Taipei - Taiwan

  An acoustic metasurface is a metamaterial for sounds, in which artificial structures were designed on the object surfaces. In this paper, we presented the design and fabrication of acoustic metasurfaces made of quarter-wave resonators to absorb low-frequency audio waves. Firstly, finite element method and impedance matching method were employed to calculate the absorption coefficient of quarter-wave resonators. A modified equivalent cavity length was proposed to adjust models in the impedance matching method. For space saving, the quarter-wave resonator was coiled up into coplanar spiral resonator. The absorption coefficient of a spiral quarter-wave resonator was compared to the properties of a straight tube to assure the feasibility of the impedance matching method. Then a metamaterial surface was designed to absorbing sounds in the range of noise measured from the airport MRT, and we used polylactic acid (PLA) to fabricate the acoustic metasurfaces by 3D printing technology. The specimen was tested in an acoustic impedance tube and the absorption coefficients higher than 0.9 were measured at the resonant frequency. The fill density of PLA was varied in different specimens and the result showed a specimen with low fill density had a lighter weight and still had proper functions. The length of tube determined the resonant frequency but roughness on the surface did not alter the performance obviously. In conclusion, the experimental result showed agreement with the simulation, and polymer is a very suitable material for acoustic metasurface which has the potential to be used on site.