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Acoustic Materials and Metamaterials: Advanced Modelling and Characterization Techniques

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Acoustics and Vibrations".

Deadline for manuscript submissions: closed (20 November 2024) | Viewed by 9501

Special Issue Editors


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Guest Editor
Department of Applied Physics, Polytechnic University of Valencia, 46022 Valencia, Spain
Interests: noise barriers; numerical methods; sonic crystals
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Civil Engineering, University of Coimbra, 3030-788 Coimbra, Portugal
Interests: numerical modelling; noise barriers; acoustic materials; metamaterials

Special Issue Information

Dear Colleagues,

The modeling and characterization of materials for application in acoustics has been a very active field of research in the last decades. Recently, the emergence of metamaterials and complex advanced materials in different acoustic and vibration applications has posed a challenge to the usual modeling and characterization approaches, as they can present a peculiar behavior when compared to conventional solutions.

Concerning modeling, research continues to offer viable ways to optimize the acoustic efficiency of the materials used. On the other hand, in characterization, work continues to find alternative ways to measure the intrinsic characteristics of the materials to overcome the limitations of traditional methods.

The present Special Issue intends to compile recent advances in this field, as well as new proposals for the modeling and characterization of acoustic materials and metamaterials. The guest editors invite all researchers working in the field to contribute with their recent research to this Special Issue.

Prof. Dr. Javier Redondo
Prof. Dr. Luís Godinho
Guest Editors

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Published Papers (6 papers)

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Research

14 pages, 9732 KiB  
Article
A Novel Acoustic Ventilation Barrier Based on the Block-Shaped Space-Coiling Metamaterial
by Qiaoyun Wu, Zhe Xu, Zhifeng Xu, Lan Ding and Chunfeng Zhao
Appl. Sci. 2025, 15(2), 619; https://doi.org/10.3390/app15020619 - 10 Jan 2025
Viewed by 730
Abstract
Newly emerged acoustic barriers provide effective solutions for noise reductions of varied kinds in which acoustic barriers made of Fano resonance-based space-coiling metamaterial are reported to have promising application prospects for their broadband noise reduction ability and good ventilation performance. However, current Fano [...] Read more.
Newly emerged acoustic barriers provide effective solutions for noise reductions of varied kinds in which acoustic barriers made of Fano resonance-based space-coiling metamaterial are reported to have promising application prospects for their broadband noise reduction ability and good ventilation performance. However, current Fano resonance-based acoustic ventilation barriers are hard to practically apply since most of them are difficult to manufacture or install. To this end, this research proposes a novel acoustic ventilation barrier based on block-shaped space-coiling metamaterial, which is not only as functional as other acoustic ventilation barriers but also easy to manufacture and install. To obtain a more in-depth understanding of the noise reduction effect, the influence of the design parameters on transmission loss is numerically studied. Additionally, we conduct both numerical and experimental studies on the transmission loss and the ventilation performance of a full-scale meta-unit. Furthermore, through the corresponding optimization process, the proposed acoustic ventilation barrier can have transmission loss consistently above 10 dB across the frequency range of 495~1063 Hz. Lastly, a composite ventilation acoustic barrier obtained by stacking two layers of different proposed metamaterials is presented, which achieves multiband noise reduction performance across the ultra-broad frequency range of 479~1758 Hz. Full article
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10 pages, 1389 KiB  
Article
An Alternative Approach to Determine the Dynamic Stiffness of Resilient Materials under Low Prestatic Load
by Jesús Carbajo, Pedro Poveda, Enrique Segovia, Andrés Prieto, Laura Río-Martín, José Daniel Pastor and Jaime Ramis
Appl. Sci. 2024, 14(11), 4925; https://doi.org/10.3390/app14114925 - 6 Jun 2024
Cited by 1 | Viewed by 1327
Abstract
Dynamic stiffness is a parameter of great importance for the assessment of the sound insulation properties of resilient materials commonly used under floating floors in dwellings. This work proposes a simplified approach that relies on an electro-mechanical circuit model for the determination of [...] Read more.
Dynamic stiffness is a parameter of great importance for the assessment of the sound insulation properties of resilient materials commonly used under floating floors in dwellings. This work proposes a simplified approach that relies on an electro-mechanical circuit model for the determination of this parameter using a two-degree-of-freedom system of masses and springs. Unlike the method described in the standard ISO 9052-1, the proposed approach uses a single electrodynamic actuator both as an impulser and vibration sensor, thus reducing the instrumental requirements and yielding a more stable arrangement. By measuring the input electrical impedance of the mass-loaded actuator when coupled to a slab–material system it was possible to retrieve the mechanical mobility function thereof and thus obtain the dynamic stiffness of the material. Several materials were tested following the proposed approach, with results showing good agreement when compared to those obtained following the standardized procedure. In general, the preliminary research encourages the use of the proposed approach for characterization purposes. Full article
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18 pages, 7607 KiB  
Article
Collaborative Design of Static and Vibration Properties of a Novel Re-Entrant Honeycomb Metamaterial
by Jiawang Yong, Yiyao Dong, Zhishuai Wan, Wanting Li and Yanyan Chen
Appl. Sci. 2024, 14(4), 1497; https://doi.org/10.3390/app14041497 - 12 Feb 2024
Cited by 3 | Viewed by 2325
Abstract
A novel re-entrant honeycomb metamaterial based on 3D-printing technology is proposed by introducing chiral structures into diamond honeycomb metamaterial (DHM), named chiral-diamond-combined honeycomb metamaterial (CDCHM), and has been further optimized using the assembly idea. Compared with the traditional DHM, the CDCHM has better [...] Read more.
A novel re-entrant honeycomb metamaterial based on 3D-printing technology is proposed by introducing chiral structures into diamond honeycomb metamaterial (DHM), named chiral-diamond-combined honeycomb metamaterial (CDCHM), and has been further optimized using the assembly idea. Compared with the traditional DHM, the CDCHM has better performance in static and vibration isolation. The static and vibration properties of the DHM and CDCHM are investigated by experiments and simulations. The results show that the CDCHM has a higher load-carrying capacity than that of the DHM. In addition, the vibration isolation optimal design schemes of the DHM and CDCHM are examined by experiments and simulations. It is found that the vibration suppression of the CDCHM is also improved greatly. In particular, the optimization approach with metal pins and particle damping achieves a wider bandgap in the low-frequency region, which can strengthen the suppression of low-frequency vibrations. And the introduction of particle damping can not only design the frequency of the bandgap via the alteration of the dosage, but also enhance the damping of the main structure. This work presents a new design idea for metamaterials, which provides a reference for the collaborative design of the static and vibration properties of composite metamaterials. Full article
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21 pages, 5492 KiB  
Article
Numerical Equivalent Acoustic Material for Air-Filled Porous Absorption Simulations in Finite Different Time Domain Methods: Design and Comparison
by P. C. Iglesias, L. Godinho and J. Redondo
Appl. Sci. 2024, 14(3), 1222; https://doi.org/10.3390/app14031222 - 1 Feb 2024
Viewed by 1298
Abstract
Extracting the microscopic parameters of a porous material is a complex task, and attempts have been made to develop models that can simulate their characteristics, gathering the least amount of information possible. As a case in point, tests to evaluate macroscopic behaviors such [...] Read more.
Extracting the microscopic parameters of a porous material is a complex task, and attempts have been made to develop models that can simulate their characteristics, gathering the least amount of information possible. As a case in point, tests to evaluate macroscopic behaviors such as tortuosity, which depends directly on the microscopic fluid velocities, are highly susceptible to generate errors if the precision of the measurement devices is not correct, and the same goes for the other parameters. For this reason, in this paper, a sound propagation model in porous materials with a rigid frame is presented based on a local theory, which tries to simplify, even more, the way to obtain the basic characteristics of porous materials, such as their absorption coefficient at normal and random incidence, and their normal surface impedance. The proposed linearized equivalent fluid model presents four phenomenological coefficients, which characterize acoustic propagation trough the material. Their values are obtained from the material thickness and a measurement in an impedance tube following the ISO 10534 standard. Thus, what is only required is the measured absorption coefficient, either on one third or one octave bands, to fully represent the acoustic behavior in the finite different in time domain (FDTD) method. The model has been simulated with FDTD in porous and fibrous kernels, and the results show a strong agreement with the laboratory measurements and with the analytical results calculated with well-established semi-phenomenological models. Full article
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20 pages, 6787 KiB  
Article
From Micro-Perforates to Micro-Capillary Absorbers: Analysis of Their Broadband Absorption Performance through Modeling and Experiments
by Cédric Maury and Teresa Bravo
Appl. Sci. 2023, 13(19), 10844; https://doi.org/10.3390/app131910844 - 29 Sep 2023
Viewed by 1135
Abstract
A challenging issue is currently the design of non-fibrous ultra-thin acoustic absorbers that are able to provide broadband performance in demanding environments. The objective of this study is to compare using simulations and measurements the broadband absorption performance of highly porous micro-capillary plates [...] Read more.
A challenging issue is currently the design of non-fibrous ultra-thin acoustic absorbers that are able to provide broadband performance in demanding environments. The objective of this study is to compare using simulations and measurements the broadband absorption performance of highly porous micro-capillary plates (MCPs) to that of micro-perforated panels (MPPs) under normal incidence while considering unbacked or backed configurations. MCPs are unusual materials used for sound absorption with micron-sized channels and a high perforation ratio. Impedance-based modeling and Kundt tube experiments show that MCPs with suitable channel diameters have a pure constant resistance that outperforms the acoustic efficiency of MPP absorbers. Unbacked MCPs exhibit a controllable amount of high absorption that can exceed 0.8 over more than five octaves starting from 80 Hz, thereby achieving a highly sub-wavelength absorber. MCPs still provide broadband high absorption when backed by a rigid cavity. Their bandwidth-to-thickness ratio increases toward its causal limit when the cavity depth decreases. A parallel MCP resonant absorber partly backed by closed and open cavities is proposed. Such MCP-based absorbers could serve as short anechoic terminations for the characterization of acoustic materials at low frequencies. Full article
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13 pages, 1186 KiB  
Article
Band Gap Properties in Metamaterial Beam with Spatially Varying Interval Uncertainties
by Feiyang He, Zhiyu Shi, Zexin Zhang, Denghui Qian and Xuelei Feng
Appl. Sci. 2023, 13(14), 8012; https://doi.org/10.3390/app13148012 - 8 Jul 2023
Cited by 1 | Viewed by 1712
Abstract
First, this study proposed a metamaterial beam model with spatially varying interval density. The interval dynamic equation of this model could be established by incorporating the decomposition results of the interval field based on Karhunen–Loeve expansion into the finite element method. An interval [...] Read more.
First, this study proposed a metamaterial beam model with spatially varying interval density. The interval dynamic equation of this model could be established by incorporating the decomposition results of the interval field based on Karhunen–Loeve expansion into the finite element method. An interval perturbation finite element method was developed to evaluate the bounds of the dynamic response interval vector. Then, an interval vibration transmission analysis could be performed, and the frequency range of the safe band gap could be determined. Meanwhile, Monte Carlo simulations and the vertex method are also presented to provide reference solutions. By comparison, it was found that the calculation accuracy of the interval perturbation finite element method was acceptable. The numerical results also showed that the safe band gap range was significantly smaller than that of the deterministic band gap. Full article
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