The impact of surface roughness on an additively manufactured acoustic material: An experimental and numerical investigation

Ciochon, Agnieszka; Kennedy, John; Leiba, Raphaël; Flanagan, Lara; Culleton, Mark

doi:10.1016/j.jsv.2022.117434

Cited by 15 publications

(5 citation statements)

References 27 publications

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“…However, there are other factors which may also influence the attenuation of the panel, as is the case of the surface roughness. In this regard, some authors have investigated these effects using computational models [27] or analyzed the case of a coiled-up resonator system using different additive manufacturing techniques [28]. All the same, the previous results show the good absorption performance of the proposed solutions and highlight their tuning capabilities, which are their main advantages when compared to traditional variable air cavity systems, as they avoid the misuse or loss of room space.…”

Section: Variable Solutionmentioning

confidence: 78%

Tunable Perforated Panel Sound Absorbers for Variable Acoustics Room Design

Carbajo,

Poveda-Martínez,

Godinho

et al. 2024

Applied Sciences

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Variable acoustics systems are promising engineering developments for multi-purpose rooms and workspaces in many buildings. However, due to space requirements associated with most of the tuning devices used for that purpose, these solutions are hardly adopted in practice. In this work, two innovative tunable sound absorbers that cope with this drawback are proposed, one consisting of rotating perforated panels and the other being a panel with an iris-type aperture. Compared with conventional perforated panel sound absorbers, the designed solutions yield a variable open area ratio system, whose configuration allows tuning the absorption bandwidth without misusing space. To assess their sound absorption coefficient, impedance tube experiments were carried out following the standardized method described in ISO 10534-2 over specimens fabricated for this purpose using laser cutting and additive manufacturing technology. The results not only show their good sound absorption performance but also highlight their tuning capabilities. Complementarily, a model based on the ray tracing method was developed to evaluate the performance of these solutions in a case study room, for different occupancy levels, with the results supporting the previous assertions and revealing the improved intelligibility features when used in such scenarios. The proposed solutions, together with the prediction model, provide a feasible approach for the design and development of tunable sound absorbers in variable room acoustics.

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Section: Variable Solutionmentioning

confidence: 78%

Tunable Perforated Panel Sound Absorbers for Variable Acoustics Room Design

Carbajo,

Poveda-Martínez,

Godinho

et al. 2024

Applied Sciences

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“…The resin sample (Figure 1a) is of very high quality in terms of mapping the designed geometry as well as surface smoothness, while the gypsumbased sample (Figure 1c) has rough surfaces and many albeit rather minor geometrical imperfections. It is known, however, that such imperfections, and especially surface roughness, should rather enhance the sound absorbing properties [6,7]. More importantly, it was found that the skeleton 3D printed from gypsum powder is microporous and permeable, with the experimentally determined mi-croporosity ϕ m = 44% and static permeability K 0m = 1.64 • 10 −12 m 2 .…”

Section: D Printed Samplesmentioning

confidence: 96%

Low frequency absorption by 3D printed materials having highly tortuous labyrinthine slits in impermeable or microporous skeletons

Zielinski,

Opiela,

Dauchez

et al. 2024

Proceedings of the 10th Convention of the European Acoustics Association Forum Acusticum 2023

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The low frequency peaks in the absorption spectra of layers of conventional porous materials correspond to quarter wavelength resonances and the peak frequencies are determined essentially by layer thickness. If the layer cannot be made thicker, the frequency of the peak can be lowered by increasing the tortuosity of the material. Modern additive manufacturing technologies enable exploration of pore network designs that have high tortuosity. This paper reports analytical models for pore structures consisting of geometrically complex labyrinthine networks of narrow slits resembling Greek meander patterns. These networks offer extremely high tortuosity in a non-porous solid skeleton. However, additional enhancement of the low frequency performance results from exploiting the dual porosity pressure diffusion effect by making the skeleton microporous with a significantly lower permeability than the tortuous network of slits.

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“…Numerous references with the formulation of innovative structures designs and simulation methods have been published [2][3] [4], while only a few of them cover the fundamentals for the actual sample preparation and measurements. Usually, the prototype samples are manufactured in the 3D printing process and some works on the resulting surface roughness and its influence on the simulated sound absorption coefficient values have been published [5]- [7]. In the current project, we have experienced a great dispersion in the measured and simulated sound absorption values in a prototyped singlecell metamaterial structures, and one of the explanations for this phenomenon was the additional sound absorption of the bare material walls manufactured with 3D printing.…”

Section: Introductionmentioning

confidence: 91%

The effect of sound-absorbing walls in the design of cavity- based metamaterials

Chojak,

Binek,

Chojnacki

et al. 2024

Proceedings of the 10th Convention of the European Acoustics Association Forum Acusticum 2023

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Cavity-based metamaterials are a type of acoustic metamaterials, usually designed for sound absorbing or sound scattering performance. They consist of an arrangement of ducts and slits, forming acoustic resonators: Helmholtz resonators and quarter-wavelength resonators. Designing perfectly absorbing structures is usually a problem of matching the impedance of the structure with the impedance of the surrounding medium, which is realized through the manipulation of the open area of the unit cell and the viscothermal losses inside the ducts. When the structure is perfectly matched, complete sound absorption is observed for a given frequency range. However, the structures are designed under the assumption that the walls are perfectly rigid, i.e., they do now show sound-absorbing properties. The paper discusses the influence of the sound absorption of the walls on the sound absorption of the whole metamaterial unit in the case when the designed structure is and is not perfectly matched. Large differences are observed between the results, which is reflected by the measurement results.

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The impact of surface roughness on an additively manufactured acoustic material: An experimental and numerical investigation

Cited by 15 publications

References 27 publications

Tunable Perforated Panel Sound Absorbers for Variable Acoustics Room Design

Tunable Perforated Panel Sound Absorbers for Variable Acoustics Room Design

Low frequency absorption by 3D printed materials having highly tortuous labyrinthine slits in impermeable or microporous skeletons

The effect of sound-absorbing walls in the design of cavity- based metamaterials

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