WSEAS Transactions on Acoustics and Music

Print ISSN: 1109-9577

Volume 3, 2016

Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of WSEAS Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.

Volume 3, 2016

Title of the Paper: Methodology to Assess the Relationship Between Acoustic Absorption Coefficient, Thickness and Frequency Response

Authors: Deaconu Marius, Toma Adina Cristina, Dragasanu Ioana Luminita

Abstract: Sound absorption coefficient is a commonly used parameter to characterize the acoustic properties of sound absorbing materials that plays an important role in noise attenuation. Commonly, the laboratory experiments stand as basics to determine which thicknesses is more appropriate to be used and on what frequency is obtained the optimum acoustic absorption coefficient. This method is time and money consuming. A more inexpensive method is to use noise simulation, but some adaptations most be performed in order to have a very good accuracy. This paper provides a simple reasonable methodology to assess the relationship between acoustic absorption coefficient, thickness and frequency response. For this study a specific material has been chosen in order to exemplify the methodology and was experimentally evaluated and compared with the simulated results to validate the simulation model. The method used to estimate the sound absorption coefficient is based on transfer function method in accordance with standard SR EN ISO 10354-2. Using simulations, different thicknesses were considered and the acoustic absorption coefficient in relation with the frequency response was assessed, facilitating an easier way to select the proper material thicknesses to design a specific acoustic solution.

Keywords: material noise reduction, sound absorption coefficient, acoustic FEM, Kundt tube, transfer function, methodology, optimization

WSEAS Transactions on Acoustics and Music, ISSN / E-ISSN: 1109-9577 / , Volume 3, 2016, Art. #2, pp. 7-14

Title of the Paper: Design of an Innovative Acoustic Metamaterial

Authors: Pavlos Mavromatidis, Andreas Kanarachos

Abstract: This report presents the design of an innovative acoustic metamaterial, in particular the design of a negative stiffness element that can attenuate the vibration level in a wide range of frequencies. The theoretical basis for the design of the metamaterial is the concept of negative stiffness, in the sense that the slope of the force-displacement diagram for the particular metamaterial becomes approximately zero. This has significant advantages as a zero stiffness element cannot transfer vibrations at any frequency. The downside of many zero stiffness elements is that they cannot carry any dead load. As will be shown in this study, this is not the case for the particular metamaterial. A prototype of this metamaterial has been produced using HDPE and tested under different conditions. The numerical results and experimental measurements demonstrate its intended behavior and provide a basis for further improvements and optimization.

Keywords: acoustic metamaterial, finite element, modal analysis, zero stiffness

WSEAS Transactions on Acoustics and Music, ISSN / E-ISSN: 1109-9577 / -, Volume 3, 2016, Art. #1, pp. 1-6

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