Optimization of Acoustic Metasurfaces with Hybrid Structures for attenuation of broadband low frequency sound

An exploratory research on hybrid metamaterials to analyze/uncover possible practical applications/benefits for sound attenuation

Master thesis (2024)

Authors

C. Martinez Fornos Mechanical Engineering

Contributors

A.M. Aragon Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering (supervisor 1)
M.H.F. Sluiter Team Marcel Sluiter - Mechanical, Maritime and Materials Engineering (supervisor 2)
Faculty
Mechanical Engineering
Copyright: © 2024 Carlos Martinez Fornos
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Published Date

26-03-2024

Language

English

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Faculty

Mechanical Engineering

Abstract

We perform a study on acoustic metasurfaces, aiming to achieve simultaneously low resonance frequencies (below 400 Hz), high attenuation bandwidth (greater than 200 Hz), and high attenuation coefficient magnitudes (above 0.8), while maintaining a surface-like structure.
We propose the implementation of geometrical optimization through genetic algorithms, as well as the incorporation of a chamber to induce resonator coupling in a supercell hexagonal Helmholtz resonator metasurface, to achieve the stated objectives simultaneously.
Results show that genetic algorithms can effectively increase the attenuation bandwidth while maintaining a moderate attenuation coefficient magnitude. Incorporating a chamber induces resonator coupling, causing frequency locking and pulling phenomena. A narrow chamber can effectively lower the resonance frequencies and enhance the attenuation coefficients at those frequencies, while maintaining a surface-like structure. However, incorporating a chamber may lead to a reduction in bandwidth. By combining the genetic algorithm optimization with chamber integration, we observe a significant reduction in bandwidth narrowness, while the benefits of frequency locking and pulling are maintained.
In conclusion, genetic algorithms have the potential to achieve wide attenuation bandwidths, while chamber incorporation holds promise for attaining low resonance frequencies with high attenuation coefficients. Using both methods simultaneously may enable the achievement of all objectives.