Acoustic metamaterial insulator embedded with Helmholtz resonators for extraordinary sound transmission loss.

This paper proposes a new radial membrane acoustic metamaterial (RMAM) structure, wherein a layer membrane substrate is covered with a rigid ring (polymethyl methacrylate frame and aluminum lump). The dispersion relationships, transmission spectra and displacement fields of the eigenmodes of this radial membrane acoustic metamaterial are studied with FEM. In contrast to the traditional radial phononic crystals (RPCs), the proposed structures can open bandgaps (BGs) in lower frequency range (0–300 Hz). Simulation results show that the physical mechanism behind the bandgaps is the coupling effects between the rotational vibration of aluminum lump and the transverse vibration of membrane. Geometrical parameters which can adjust the bandgaps’ widths or positions are analyzed. Finally, we investigate the axial sound transmission loss of this acoustic metamaterial structure, and discuss the effects of factor loss, membrane thickness and the number of layers of unit cell on the axial sound transmission loss. Dynamic effective density proves the accuracy of the FEM results. This kind of structure has potential application in pipe or circular ring structure for damping/noise reduction.

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Broadband and Intense Sound Transmission Loss by a Coupled-Resonance Acoustic Metamaterial

Physical Review Applied ◽

10.1103/physrevapplied.16.054018 ◽

2021 ◽

Vol 16 (5) ◽

Author(s):

David Roca ◽

Mahmoud I. Hussein

Keyword(s):

Transmission Loss ◽

Sound Transmission ◽

Sound Transmission Loss ◽

Acoustic Metamaterial

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Experimental and numerical investigations of ventilated acoustic metamaterial based in-parallel arrangement of Helmholtz resonator for façade screen

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-3078 ◽

2021 ◽

Vol 263 (1) ◽

pp. 5382-5390

Author(s):

Denilson Ramos ◽

Luís Godinho ◽

Paulo Amado-Mendes ◽

Paulo Mareze

Keyword(s):

Potential Application ◽

Noise Control ◽

Transmission Loss ◽

Sound Transmission ◽

Recent Effort ◽

Sound Transmission Loss ◽

Noise Mitigation ◽

Acoustic Metamaterial ◽

Numerical Investigations ◽

Parallel Arrangement

Understanding urban noise as a serious environmental problem in urban centers, the development and application of noise control strategies have demanded a recent effort by several researches. In this case, the development of acoustic metamaterial artificially designed to manipulate the wave phenomena has become a recent topic, aiming at optimized responses, and enables the development of subwavelength devices with potential application in passive ventilation and noise mitigation, providing better environmental conditions in buildings. The present paper intends to contribute to the knowledge in this field by investigating the concept of an acoustic metamaterial with negative bulk modulus based in a parallel arrangement of Helmholtz Resonators. Experimental and numerical investigations are carried out to determine the acoustic potential of the proposed meta structure in terms of sound absorption and sound transmission loss. The developed concept exhibits significant benefits in the properties of sound transmission loss, and seems a potential application for noise control at specific frequency bands (mainly at low to middle frequency) in building façades.

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

Acoustics ◽

10.3390/acoustics3040040 ◽

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.

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