scholarly journals Design, Manufacturing, and Acoustical Analysis of a Helmholtz Resonator-Based Metamaterial Plate

Acoustics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 630-641
Author(s):  
Sourabh Dogra ◽  
Arpan Gupta
Keyword(s):  
Transmission Loss ◽  
Sound Transmission ◽  
Helmholtz Resonator ◽  
Acoustic Properties ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Acoustic Metamaterials ◽  
Additional Advantage ◽  
Helmholtz Resonators ◽  
High Sound

Acoustic metamaterials are materials artificially engineered to control sound waves, which is not possible with conventional materials. We have proposed a design of an acoustic metamaterial plate with inbuilt Helmholtz resonators. The plate is made of Polylactic acid (PLA) which is fabricated using an additive manufacturing technique. It consists of Helmholtz resonator-shaped cavities of different sizes. In this paper, we have analyzed the acoustic properties of the Helmholtz resonators-based metamaterial plate experimentally as well as numerically. The experimental results are in good agreement with the numerical results. These types of 3D-printed metamaterial plates can find their application where high sound transmission loss is required to create a quieter ambience. There is an additional advantage of being lightweight because of the Helmholtz resonator-shaped cavities built inside the plate. Thus, these types of metamaterial plates can find their application in the design sector requiring lighter materials with high sound transmission loss.

scholarly journals Non-Wovens as Sound Reducers

2018 ◽  
Vol 55 (2) ◽  
pp. 64-76
Author(s):  
D. Belakova ◽  
A. Seile ◽  
S. Kukle ◽  
T. Plamus
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Material Structure ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

Biobased insulating panels from mulberry stems

2021 ◽  
pp. 089270572110108
Author(s):  
Vijaykumar Guna ◽  
Manikandan Ilangovan ◽  
Narendra Reddy ◽  
PG Radhakrishna ◽  
VH Maharaddi ◽  
...  
Keyword(s):  
Transmission Loss ◽  
Sound Transmission ◽  
Green Building ◽  
Barrier Properties ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Soil Burial ◽  
Sound Barrier ◽  
Automotive Parts ◽  
Pp Composites

In this work, Mulberry Stems (MS) obtained as a by-product of sericulture have been used as reinforcement for Polypropylene (PP) composites intended for green building, furniture and automotive applications. Mulberry stems are lignocellulosic and are renewable and sustainable sources but remain unutilized and are usually discarded as waste by burning or burying. An attempt has been made to utilize mulberry stems as substitutes for commonly used non-biodegradable composites using a simple and clean fabrication technique. The effects of reinforcement percentage (80% to 95% w/w) of MS and density (0.5 g cm−3 to 1.25 g cm−3) of composites on the properties have been studied. Results revealed that, 90/10 (MS/PP w/w %) was the optimum ratio that provides highest mechanical strength. Increasing the density enhanced the strength, thermal insulation, sound transmission loss, water stability and flame retardancy. The 1.25 g cm−3, 90/10 ratio composite had a high sound transmission loss of 46.6 dB and thermal conductivity of 0.130 W/mK which is 70% lower than neat gypsum board used in false ceiling applications. The high insulation and sound barrier properties of mulberry stem based composites are due to the unique hollow morphology of MS which aids in efficient absorbtion and dissipation of the thermal energy and sound waves. Weight loss of MS/PP composite after soil burial test for 120 days varied between 8.9% and 31.4%. MS/PP composites could be potentially used as a green replacement for ply, particleboards, false ceiling, automotive parts and other applications.

Sound transmission loss of a Helmholtz Resonator-based acoustic metasurface

2022 ◽  
Vol 188 ◽  
pp. 108569
Author(s):  
Ahmad Yusuf Ismail ◽  
Jisan Kim ◽  
Se-Myong Chang ◽  
Bonyong Koo
Keyword(s):  
Transmission Loss ◽  
Sound Transmission ◽  
Helmholtz Resonator ◽  
Sound Transmission Loss

Incorporation of Nanofiber Layers in Nonwoven Materials for Improving Their Acoustic Properties

2013 ◽  
Vol 8 (4) ◽  
pp. 155892501300800 ◽  
Author(s):  
Amir Rabbi ◽  
Hossein Bahrambeygi ◽  
Ahmad Mousavi Shoushtari ◽  
Komeil Nasouri
Keyword(s):  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Wide Band ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Sound Transmission Loss ◽  
Factors Affecting ◽  
Nonwoven Materials ◽  
Field Noise

Due to numerous developments in most industries and the increase in the usage of massive and powerful machines in every field, noise has become an unavoidable part of mechanized life and has brought about serious health hazards. The main aim of this work was to investigate the usability of polyurethane and polyacrylonitrile nanofibers for improving sound insulation properties over a wide band of frequencies and reducing weight and thickness of conventional polyester and wool nonwovens. The effect of the number of nanofiber layers and associated surface densities on acoustic properties was investigated. Sound transmission loss and sound absorption analysis using the impedance tube method were carried out as the main factors affecting acoustic behavior of samples. The results show that incorporation of nanofiber layers in nonwoven materials can improve both sound absorption and sound transmission loss simultaneously, especially in mid and lower frequencies, which are difficult to detect by conventional materials.

scholarly journals Analyzing and evaluation of effective parameters on sound transmission loss of the triple-layered acoustic panels with sound-absorbing middle layer

2015 ◽  
Vol 4 (2) ◽  
pp. 250
Author(s):  
Nader Mohammadi
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Elastic Layer ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Air Gap ◽  
Acoustic Properties ◽  
Sound Transmission Loss ◽  
Static Young’S Modulus ◽  
Wide Range

In this research, a triple-layered acoustic panel with sound-absorbing intermediate layer materials is modeled analytically in order to calculate the sound transmission loss in the normal incidence field. This information provides an appropriate platform for optimum noise control. In this paper, porous material is used as an absorbent layer between two elastic panels. In modeling these triple-layered panels, theory of wave propagation in porous materials is used and bounded boundary condition of the first elastic layer and unbounded boundary condition of the second elastic layer is applied. To validate the model, the results of this model are compared with the results of the Bolton. Comparison of results revealed very good compatibility. Here, the effect of the length of the air gap between the elastic layers, density and the material of the elastic plate, the thickness and vibro-acoustic properties of the intermediate porous material on the values of transmission loss is investigated.In a wide range of frequencies, increasing air gap, density of elastic panels and porous layer thickness, increase the transmission loss up to 10 dB. At frequencies above 10 kHz, a reduction in porosity, static Young's modulus, the loss coefficient, increasing bulk density of the solid phase, the factor of geometrical structure and viscosity of porous material, increase the sound transmission loss up to 15 dB.

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