Absorption Coefficient of a Double-Layer Inhomogeneous Micro-perforated Panel Backed with Multiple Cavity Depths

Mosa, Ali I.; Putra, Azma; Ramlan, Roszaidi; Esraa, Al-Ameri

doi:10.1007/s40857-020-00176-4

Cited by 12 publications

(6 citation statements)

References 23 publications

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“…Under normal incident sound waves, the main mode of air pressure transfer through lattices will be from the pore connections from the top cell to the bottom cell. [ 21 ] Lateral pore connections can essentially be neglected for airflow. As such, the FCC‐plate unit cell can be simplified into an octahedral cavity with perforations interconnecting the adjacent cells (Figure 4A).…”

Section: Resultsmentioning

confidence: 99%

Microlattice Metamaterials with Simultaneous Superior Acoustic and Mechanical Energy Absorption

Chua

et al. 2021

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The advent of 3D printing brought about the possibilities of microlattice metamaterials as advanced materials with the potentials to surpass the functionalities of traditional materials. Sound absorbing materials which are also tough and lightweight are of particular importance as practical engineering materials. There are however a lack of attempts on the study of metamaterials multifunctional for both purposes. Herein, we present four types of face‐centered cubic based plate and truss microlattices as novel metamaterials with simultaneous excellent sound and mechanical energy absorption performance. High sound absorption coefficients nearing 1 and high specific energy absorption of 50.3 J g−1 have been measured. Sound absorption mechanisms of microlattices are proposed to be based on a “cascading resonant cells theory”, an extension of the Helmholtz resonance principle that we have conceptualized herein. Characteristics of absorption coefficients are found to be essentially geometry limited by the pore and cavity morphologies. The excellent mechanical properties in turn derive from both the approximate membrane stress state of the plate architecture and the excellent ductility and strength of the base material. Overall, this work presents a new concept on the specific structural design and materials selection for architectured metamaterials with dual sound and mechanical energy absorption capabilities.

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Section: Resultsmentioning

confidence: 99%

Microlattice Metamaterials with Simultaneous Superior Acoustic and Mechanical Energy Absorption

Chua

et al. 2021

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“…Prototype 1, consisting of one layer composed of four different MPPs facing different cavities, showed a wider absorption bandwidth in the low-mid frequency spectrum (α ≥ 0.5 from 300 to 1250 Hz). Despite some discrepancies, which literature has shown to be quite common in those complex structures [49,50,59], the results indicate a broadening of the absorption coefficient curve because of the multiple resonance peaks each panel introduces. Prototype 2 was composed of two layers having different parallel-arranged MPPs cascaded one after the other, with a distance (D1) in between and various partitioned cavities (D2) after the second layer.…”

Section: Discussionmentioning

confidence: 55%

“…These structures can be an alternative to conventional absorbing materials in architectural applications to attenuate a broader range of frequencies. Many studies [47,49,50,59] have investigated different combinations to address the narrow bandwidth of MPPs, but to the authors' knowledge, none have continued to assess the performance of those materials in architectural applications.…”

Section: Discussionmentioning

confidence: 99%

“…Those innovations have set the ground for the realization of complex structures that exhibit acoustic properties not found in nature [26]. Moreover, the hybrid serial-parallel MPP structures designed on polymers [45][46][47][48][49][50] have shown that the correct combination of multiple parameters may achieve a more efficient and wideband sound absorption.…”

Section: Introductionmentioning

confidence: 99%

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Investigating the Potential of Transparent Parallel-Arranged Micro-Perforated Panels (MPPs) as Sound Absorbers in Classrooms

Fasllija

Yılmazer

2023

IJERPH

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Acoustic deficiencies due to lack of absorption in indoor spaces may sometime render significant buildings unfit for their purpose, especially the ones used as speech auditoria. This study investigates the potential of designing wideband acoustic absorbers composed of parallel-arranged micro-perforated panels (MPPs), known as efficient absorbers that do not need any other fibrous/porous material to have a high absorptive performance. It aims to integrate architectural trends such as transparency and the use of raw materials with acoustical constraints to ensure optimal indoor acoustic conditions. It proposes a structure composed of four parallel-arranged MPPs, which have been theoretically modelled using the electrical Equivalent Circuit Model (ECM) and implemented on an acrylic prototype using recent techniques such as CNC machining tools. The resulting samples are experimentally analysed for their absorption efficiency through the ISO-10534-2 method in an impedance tube. The results show that the prediction model and the experimental data are in good agreement. Afterward, the investigation focuses on applying the most absorptive MPP structure in a classroom without acoustic treatment through numerical simulations in ODEON 16 Acoustics Software. When the proposed material is installed as a wall panel, the results show an improvement toward optimum values in Reverberation Time (RT30) and Speech Transmission Index (STI).

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“…The disadvantage of this type of sound absorber is the narrow frequency range of absorption. Due to an increase in the frequency range of absorption, some suggestions have been proposed such as the use of multilayered MPPs in succession [23][24][25][26][27] and the use of porous material behind the MPP [16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Optimum Design of Multi-layered Micro-perforated Panel Sound Absorbers in Combination with Porous Materials in an Arbitrary Frequency Range

2022

IJE

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Absorption Coefficient of a Double-Layer Inhomogeneous Micro-perforated Panel Backed with Multiple Cavity Depths

Cited by 12 publications

References 23 publications

Microlattice Metamaterials with Simultaneous Superior Acoustic and Mechanical Energy Absorption

Microlattice Metamaterials with Simultaneous Superior Acoustic and Mechanical Energy Absorption

Investigating the Potential of Transparent Parallel-Arranged Micro-Perforated Panels (MPPs) as Sound Absorbers in Classrooms

Optimum Design of Multi-layered Micro-perforated Panel Sound Absorbers in Combination with Porous Materials in an Arbitrary Frequency Range

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