The Project:

Acoustic metamaterials are engineered materials with properties that allow for wave manipulation. Constructing a material shape in a specific geometric pattern, a simple structure can control sound waves to exceed the diffraction limit in acoustic imaging, facilitates acoustic absorbing panel manufacturing that lowers the noise floor, and focus waves to improve capabilities in acoustic imaging. In 2013, Duke University created an acoustic metamaterial structure called the acoustic superlens which placed the material, DSMSomos 9420 Photopolymer, in a specific geometric pattern [see Figure 1]. The structure increases the intensity of sound at a particular point which will govern a clearer acoustic image. Figure 1b demonstrates this effect.

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The Objective:

Acoustic metamaterials rely on two aspects to achieve wave manipulation; geometric pattern and material properties. This project intends to use Duke University’s superlens structure as a starting point. We will machine ABS (Acrylonitrile Butadiene Styrene), or PLA (Polylactic Acid) plastics to understand their properties in an acoustic superlens. We believe that utilizing common plastics will help improve the commercial viability of metamaterials. We will use the basic superlens geometric structure, but adjust dimensions to substitute ABS, or PLA, for DSMSOMOS 9420 Photopolymer.

This project will develop acoustic metamaterials and improve Cal Poly’s acoustic testingcapabilities. Creating an effective acoustic superlens with common materials, Cal Poly can open a new door to an undeveloped field that could create a substantial interest in commercial applications. The project will also outreach to companies like Jabil, and we hope to continue to connect with companies by publishing our results through the nationwide Audio Engineering Society.


 The simulation shows the method of simulating within COMSOL. One can see that the sound wave is focused right outside of the pillars. These pillars do not define the final structure, they simply verify a simulation method. Red areas mean louder sound, i.e. higher dB, while blue is quieter areas. The simulation picture is taken at 1000Hz. The white rectangle at the far left is a speaker.  

The simulation shows the method of simulating within COMSOL. One can see that the sound wave is focused right outside of the pillars. These pillars do not define the final structure, they simply verify a simulation method. Red areas mean louder sound, i.e. higher dB, while blue is quieter areas. The simulation picture is taken at 1000Hz. The white rectangle at the far left is a speaker.  

 

Project Leader:

Matthew Luu