Singapore: 3D Printing Helps Reduce Noise Pollution with MMP Panels

Researchers from Singapore are working to decrease noise pollution with the help of 3D printing, outlining their findings in the recently published ‘3D Printing of Polymeric Multi-Layer Micro-Perforated Panels for Tunable Wideband Sound Absorption.’ Attempting to overcome the limits of conventional manufacturing, the authors 3D print innovative multi-layer micro-perforated panels (MPPs) with tunable wideband absorption.

Due to so many busy and highly populated areas in the world, finding new ways to deal with noise pollution is a major concern. MPPs—comprised of perforations, a back wall, and an air gap, serve many purposes today, to include improving:

• Room acoustic conditions
• Ducts
• Acoustic window systems
• Noise barriers

The perforations, patterned in a lattice, allow for the desired acoustic resistance. A rigid wall is parallel to the panel, with an air gap in between creating a separate ‘acoustic stiffness.’

“The entire MPP system provides resonant absorption of sound,” stated the researchers. “It should be noted that the absorption effect is independent of the manufacturing materials of the panel.”

Metal and steel have been used in previous research to create MPP panels; however, conventional techniques tend to be expensive, whether industrial users employ laser cutting, etching, or micro punching.

The schematic diagram of an MPP, which consists of a thin panel, an air gap, and a rigid wall.

For this study, the researchers designed and produced MPPS using SLS technology—a first in this type of manufacturing. Samples were designed for damping ‘major traffic noises,’ and optimizing ‘the area under the sound absorption curve at the target frequency range was introduced to design the structural parameters of the effective, acoustic absorption devices.’

The schematic demonstration of the single-layer, double-layer, and triple-layer MPPs.

Experimental results agreed with both theoretical and numerical results, with double- and triple-layer structures tuning the peaks of the absorption curves, allowing for broadened frequency bandwidths.

3D printed samples of MPPs and the setup of the acoustic absorption test.

“The absorption curves of the double-layer MPP and the triple-layer MPP observe two and three peaks, respectively, for the given geometric parameters,” stated the researchers.

The research team noted that results with unpredicted noises and side peaks reflected wider frequency bandwidths and higher peak values of the MPPs. Also noted were more obvious discrepancies at the second peak.

The microscope images of a printed panel: (a) two perforations in imperfect circular shapes and (b) a part of the unsmooth rim with grains.

“The performances of the multi-layer acoustic structures were evaluated by Maa’s theory, FE simulations, and experiments in a wide frequency range. The frequency ranges were tuneable by adjusting the structural parameters such as the number of layers, the air gap distance, and the inter-layer distance,” concluded the researchers.

“The developed FE model was proved to be feasible for the numerical simulation of the multi-layer acoustic structures. An optimization method that maximizes the area under the sound absorption curve was introduced for the acoustic structures with the most effective sound absorption in target frequency ranges.”

3D printing is used more commonly today in sound absorption applications as researchers innovate with new products like metasurface-based absorbers, customized absorbers based on passive destructive interference, and more. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.