JK
J.O. Kuusinen
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1
Environmental noise, particularly within the disruptive frequency range of 500 Hz to 6.4 kHz, poses a significant impact on global health, as well as economic challenges. While Triply Periodic Minimal Surfaces (TPMS) have been researched for their mechanical and energy-absorption properties, the continuous, periodic internal architectures also present an effective candidate for acoustic metamaterials. This thesis investigates the acoustic attenuation capabilities of sheet-based Primitive (P) and Neovius (N) TPMS structures, evaluating their ability to reduce sound transmission by generating acoustic band gaps via Bragg scattering.
The research combines implicit geometrical modelling and numerical Finite Element Analysis (FEA) to simulate Sound Transmission Loss (STL), followed by experimental validation of the structures using FDM 3D-printed PLA prototypes in an impedance tube setup. To determine how these band gaps can be tuned to specific frequency ranges, the study evaluates uniform arrays alongside several geometrical design strategies, including longitudinal unit cell elongation, continuous multi-topology hybridisation, and functional relative density grading.
The findings show that topology fundamentally dictates acoustic attenuation. The Neovius structure exhibited superior STL compared to the Primitive topology, driven by extreme periodic cross-sectional variations that induce strong acoustic impedance mismatches. Experimental measurements strongly validated the numerical models regarding band gaps and primary attenuation peaks, despite some high-frequency discrepancies, likely arising from the finite stiffness of the prototypes. The study also proved that elongating unit cells effectively shifts attenuation peaks to lower frequencies, multi-topology hybridisation successfully blends distinct acoustic characteristics, and relative density grading results in tailored attenuation profiles that bridge the amplitude and bandwidth of its uniform base densities.
Ultimately, this research establishes TPMS structures as highly tunable, effective acoustic metamaterials, providing a methodology for engineering multifunctional, load-bearing noise barriers tailored to specific frequencies.
...
The research combines implicit geometrical modelling and numerical Finite Element Analysis (FEA) to simulate Sound Transmission Loss (STL), followed by experimental validation of the structures using FDM 3D-printed PLA prototypes in an impedance tube setup. To determine how these band gaps can be tuned to specific frequency ranges, the study evaluates uniform arrays alongside several geometrical design strategies, including longitudinal unit cell elongation, continuous multi-topology hybridisation, and functional relative density grading.
The findings show that topology fundamentally dictates acoustic attenuation. The Neovius structure exhibited superior STL compared to the Primitive topology, driven by extreme periodic cross-sectional variations that induce strong acoustic impedance mismatches. Experimental measurements strongly validated the numerical models regarding band gaps and primary attenuation peaks, despite some high-frequency discrepancies, likely arising from the finite stiffness of the prototypes. The study also proved that elongating unit cells effectively shifts attenuation peaks to lower frequencies, multi-topology hybridisation successfully blends distinct acoustic characteristics, and relative density grading results in tailored attenuation profiles that bridge the amplitude and bandwidth of its uniform base densities.
Ultimately, this research establishes TPMS structures as highly tunable, effective acoustic metamaterials, providing a methodology for engineering multifunctional, load-bearing noise barriers tailored to specific frequencies.
...
Environmental noise, particularly within the disruptive frequency range of 500 Hz to 6.4 kHz, poses a significant impact on global health, as well as economic challenges. While Triply Periodic Minimal Surfaces (TPMS) have been researched for their mechanical and energy-absorption properties, the continuous, periodic internal architectures also present an effective candidate for acoustic metamaterials. This thesis investigates the acoustic attenuation capabilities of sheet-based Primitive (P) and Neovius (N) TPMS structures, evaluating their ability to reduce sound transmission by generating acoustic band gaps via Bragg scattering.
The research combines implicit geometrical modelling and numerical Finite Element Analysis (FEA) to simulate Sound Transmission Loss (STL), followed by experimental validation of the structures using FDM 3D-printed PLA prototypes in an impedance tube setup. To determine how these band gaps can be tuned to specific frequency ranges, the study evaluates uniform arrays alongside several geometrical design strategies, including longitudinal unit cell elongation, continuous multi-topology hybridisation, and functional relative density grading.
The findings show that topology fundamentally dictates acoustic attenuation. The Neovius structure exhibited superior STL compared to the Primitive topology, driven by extreme periodic cross-sectional variations that induce strong acoustic impedance mismatches. Experimental measurements strongly validated the numerical models regarding band gaps and primary attenuation peaks, despite some high-frequency discrepancies, likely arising from the finite stiffness of the prototypes. The study also proved that elongating unit cells effectively shifts attenuation peaks to lower frequencies, multi-topology hybridisation successfully blends distinct acoustic characteristics, and relative density grading results in tailored attenuation profiles that bridge the amplitude and bandwidth of its uniform base densities.
Ultimately, this research establishes TPMS structures as highly tunable, effective acoustic metamaterials, providing a methodology for engineering multifunctional, load-bearing noise barriers tailored to specific frequencies.
The research combines implicit geometrical modelling and numerical Finite Element Analysis (FEA) to simulate Sound Transmission Loss (STL), followed by experimental validation of the structures using FDM 3D-printed PLA prototypes in an impedance tube setup. To determine how these band gaps can be tuned to specific frequency ranges, the study evaluates uniform arrays alongside several geometrical design strategies, including longitudinal unit cell elongation, continuous multi-topology hybridisation, and functional relative density grading.
The findings show that topology fundamentally dictates acoustic attenuation. The Neovius structure exhibited superior STL compared to the Primitive topology, driven by extreme periodic cross-sectional variations that induce strong acoustic impedance mismatches. Experimental measurements strongly validated the numerical models regarding band gaps and primary attenuation peaks, despite some high-frequency discrepancies, likely arising from the finite stiffness of the prototypes. The study also proved that elongating unit cells effectively shifts attenuation peaks to lower frequencies, multi-topology hybridisation successfully blends distinct acoustic characteristics, and relative density grading results in tailored attenuation profiles that bridge the amplitude and bandwidth of its uniform base densities.
Ultimately, this research establishes TPMS structures as highly tunable, effective acoustic metamaterials, providing a methodology for engineering multifunctional, load-bearing noise barriers tailored to specific frequencies.