Abstract
Urbanization and industrialization have brought about technological advancements and convenience to our lives, while also causing significant pollution. Among them, noise pollution is becoming increasingly severe. Exposure to excessive noise can lead to hearing loss and other adverse health effects. This research focuses on a series of strategies aimed at enhancing the sound absorption performance of honeycomb acoustic absorbers, as well as examining the impact of relevant parameters on this characteristic. The purpose of this endeavor is to design and produce honeycomb acoustic muffles with lightweight, broadband-absorption, spacing-saving, ecological, and load-bearing advantages.Common acoustic liner structures include micro-perforated panels (MPP), honeycomb, and a rigid layer behind them. Inspired by this kind of acoustic liner structure, this research first conducted a pre-screening study of a honeycomb sandwich structure filled with green materials for noise reduction. The filler’s porosity and density, along with the configuration of the fibre products were calculated and measured. The findings indicate that filling within the honeycomb structure notably enhances the sound absorption coefficient and broadens the frequency range of sound absorption. Additionally, the Micro-Perforated Panel (MPP) parameter dictates the peak frequency of the sound absorption curve. These outcomes demonstrate that a filled honeycomb structure with an MPP face sheet can effectively attenuate noise while preserving mechanical integrity. Integrated structures with noise reduction capabilities have the potential to revolutionize construction, transportation, and infrastructure by offering lightweight and space-efficient solutions.
Furthermore, a representative natural fibres, Juncus effuses, was used as the filler to further research the sound absorption of MPP-type honeycomb. The parameters of fillers and MPPs were all studied to design the acoustic absorbers. Numerical models and machine learning models are employed for predicting sound absorption performance and understanding the mechanisms of acoustic attenuation.
Apart from the filling method, which bolstered the sound absorption function of the MPP-type honeycomb absorber, we discovered that the combination of fabric and cavities behind it also holds great promise as a potential candidate for noise reduction. Inspired by this, we designed a novel composite fabric with triaxial fabric (TWF) with ultralight and ultrathin properties to transplace the traditional MPP for the facesheets of honeycomb sound absorbers. This type of composite fabric is up-and-coming in the field of sound absorption. Whether it is used to fabricate single-degree-of-freedom or multi-degree-of freedom absorbers, its sound absorption performance is superior compared to materials of the same thicknesss.
| Date of Award | Nov 2024 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Xiaosu Yi (Supervisor) |