Wyniki wyszukiwania - BazTech

1

Sprawdzenie przydatności metamateriału akustycznego do redukowania hałasu średnio- i wysokoczęstotliwościowego - symulacje numeryczne

Szczepański Grzegorz, Podleśna Marlena, Łada Krzysztof, Włudarczyk Anna

Bezpieczeństwo Pracy : nauka i praktyka

|

2023

|

nr 4

22-27

PL

Hałas na stanowiskach pracy wciąż jest głównym zagrożeniem dla pracowników zakładów przemysłowych. Zastosowanie obudów i barier dźwiękoizolacyjnych w celu ograniczania tego zagrożenia nie zawsze jest możliwe lub wystarczające. Stosunkowo nowym i obiecującym sposobem redukcji hałasu jest wykorzystanie metamateriałów akustycznych, które przekierowują bądź pochłaniają falę dźwiękową, a najwyższą skuteczność wykazują przy częstotliwości bliskiej częstotliwości rezonansowej. Metamateriały akustyczne służą przede wszystkim do redukcji hałasu wąskopasmowego. W artykule przedstawiono ich modele numeryczne, które posłużyły do wyznaczenia częstotliwości rezonansowych. Symulacje przeprowadzono w dwóch różnych programach przeznaczonych do analizy metodą elementów skończonych (MES). Otrzymane wyniki wskazują, że metamateriał o strukturze tunelowej z umieszczonymi wewnątrz rezonatorami Helmholtza może redukować hałas w kilku pasmach częstotliwości (w zakresie średnio- i wysokoczęstotliwościowym) oraz w większym stopniu niż metamateriał o strukturze tunelowej bez rezonatorów.

EN

Noise in workplace environments is still the main risk factor for workers in industrial plants. The use of sound insulation enclosures and soundproof barriers to reduce this risk is not always possible or sufficient. A relatively new solution used to reduce noise are acoustic metamaterials that redirect or absorb the sound wave, and show the highest efficiency at frequencies close to the resonant frequency. They are primarily used for narrowband noise. The article presents the developed numerical models which were used to determine the resonant frequencies. Simulations were performed in two different programs based on finite element method (FEM). The obtained results indicate that the tunnel structure with Helmholtz resonators placed within can suppress the noise in several frequency bands (mid-frequency and high-frequency range) and to a greater extent than tunnel structures without resonators.

2

Investigation of the Acoustic Properties of a Metamaterial with a Multi-Ring Structure

Szczepański Grzegorz, Podleśna Marlena, Morzyński Leszek, Włudarczyk Anna

Archives of Acoustics

|

2023

|

Vol. 48, No. 4

497--507

EN

In this article, the authors present the geometry and measurements of the properties of an acoustic metamaterial with a structure composed of multiple concentric rings. CAD models of the structure were developed and subsequently used in numerical studies, which included the study of resonant frequencies using the Lanczos method and an analysis of sound pressure level distribution under plane wave excitation using the finite element method. Subsequently, experimental tests were carried out on models with the same geometry produced with three different materials (PLA, PET-G, and FLEX) using a fused deposition modeling 3D printing technique. These tests included: determining insertion loss for a single model based on tests using the measurement window of a reverberation chamber and determining transmission loss through tests in a semi-anechoic chamber. Sound wave resonance was obtained for frequencies ranging from 1700 to 6000 Hz. Notably, the experimental studies were carried out for the same structure for which numerical tests were conducted. The physical models of a metamaterial were manufactured using three different readily available 3D printing materials. The results of laboratory tests confirm that the created acoustic metamaterial consisting of multi-ring structures reduces noise in medium and high frequencies.

3

Acoustic Metamaterials

Sztyler Bartłomiej, Strumiłło Paweł

Archives of Acoustics

|

2022

|

Vol. 47, No. 1

3--14

EN

This review article is concerned with metamaterials, i.e. specifically engineered structures with special properties for interaction with sounds. The research on and practical design of these materials have gained momentum in the last decade, when 3D printing techniques provided the possibility to fabricate such geometrically complex structures. We briefly describe the history of research on AMMs and group them into active and passive metamaterials. For each of these groups of AMMs, we discuss the most notable construction achievements and outline the main applications. We conclude this review with a discussion of possible directions for further research and main applications of AMMs such as noise attenuation, acoustic lens, and the cloaking phenomenon.

4

A Honeycomb Based Graded Metamaterial Muffler with Broadband Sound Attenuation and Load Bearing Performances

Li Gen, Chen Yan, He Huan

Archives of Acoustics

|

2022

|

Vol. 47, No. 2

213--221

EN

A challenge for developing acoustic metamaterials (AMMs) is considering the application of broadband muffling and load bearing capacity simultaneously. In this paper, a honeycomb based graded AMM muffler is proposed, which can widen the attenuation band and improve the structural stiffness without any external device by means of integrated design. Firstly, the acoustic and mechanical characteristics of the muffler unit cell are theoretically and numerically studied, and the graded muffler is designed based on these characteristics. The numerical results show that the graded muffler widens the attenuation bandwidth of the unit cell, and the simulation also shows that the graded muffler has greater stiffness than the uniform one. The stiffness driven muffler provides new possibilities for the design of advanced metamaterial with simultaneous sound insulation and load bearing performances.

5

Stopband effect and sound transmission loss of periodic locally resonant structures

Juros Klara, Kras Aleksander, Kamisiński Tadeusz

Vibrations in Physical Systems

|

2021

|

Vol. 32, nr 1

art. no. 2021105

EN

This paper investigates the theoretical aspects of sound attenuation of periodic structures with locally resonant elements. The stopband effect in frequency characteristics of infinite periodic structures created by the resonant elements is investigated. The dispersion curves calculation procedure is described in details with the influence of resonance frequency and mass of added locally resonant structure on width of the obtained stopband is investigated. The theoretical formulation for calculation of the sound transmission loss for periodic structure is derived. The performance of the structure with locally resonant elements is evaluated based on dispersion curves obtained for an infinite periodic structure and transmission loss calculated for finite structure is conducted.

6

Effective properties of periodic media in elastodynamic problems

Yera Rolando, Méndez Carlos G., Sánchez Pablo J., Huespe Alfredo E.

Computer Methods in Materials Science

|

2021

|

Vol. 21, No. 3

139--148

EN

This paper describes a homogenization model for evaluating the effective elastodynamic properties of acoustic metamaterials in problems involving wave propagation. The methodology is based on determining the constitutive equations in terms of averaged quantities observed at the macroscale. In this sense, the approach very closely follows the pioneering ideas introduced by Willis, and afterwards, followed by several authors in the last ten years. The distinctive characteristic of our approach is that we write the microscale equation in the spatial domain. The model is validated with previous results published in the literature, and our results replicate them almost exactly. The resulting homogenization model could be used as an additional tool for the topology design of acoustic metamaterials.