Abstract
The increasing concern about noise pollution has accelerated the development of acoustic absorption and damping devices. However, conventional subtractive manufacturing can only fabricate absorption devices with simple geometric shapes that are unable to achieve high absorption coefficients in wide frequency ranges. In this paper, novel multi-layer micro-perforated panels (MPPs) with tunable wideband absorption are designed and fabricated by 3D printing or additive manufacturing. Selective laser sintering (SLS), which is an advanced powder-based 3D printing technique, is newly introduced for MPP manufacturing with polyamide 12 as the feedstock. The acoustic performances of the MPPs are investigated by theoretical, numerical, and experimental methods. The results reveal that the absorption frequency bandwidths of the structures are wider than those of conventional single-layer MPPs, while the absorption coefficients remain comparable or even higher. The frequency ranges can be tuned by varying the air gap distances and the inter-layer distances. Furthermore, an optimization method is introduced for structural designs of MPPs with the most effective sound absorption performances in the target frequency ranges. This study reveals the potential of 3D printing to fabricate acoustic devices with effective tunable sound absorption behaviors and provides an optimization method for future structural design of the wideband sound absorption devices.
Highlights
Micro-perforated panels (MPPs) are the next-generation solutions for noise reduction with the potential of achieving high absorption coefficients for wideband sound absorption
Results and Discussion triple-layer structures tune the peaks of the absorption curves to different frequencies so that the frequency bandwidth is broadened with the values of the absorption coefficient kept at 0.8 or above
The experimental results agree well with the theoretical and numerical results. Both of the double-layer and triple-layer structures tune the peaks of the absorption curves to different frequencies so that the frequency bandwidth is broadened with the values of the absorption coefficient kept at 0.8 or above
Summary
Micro-perforated panels (MPPs) are the next-generation solutions for noise reduction with the potential of achieving high absorption coefficients for wideband sound absorption. The MPP was first studied by Maa for sound absorption research [1,2,3]. The applications of MPPs have been broadened to room acoustic conditions, duct silencing, acoustic window systems, and noise barriers [4,5,6]. An MPP system consists of a thin panel with perforations, a back wall, and an air gap. The acoustic resistance is provided by the lattice of perforations with the diameter in a sub-millimeter range on the thin panel. The air gap between the wall and the panel generates an acoustic stiffness dependent on the depth of the air gap
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