Theoretical modelling of coiled-channel type metamaterials design

Recent advancement in acoustic metamaterials hold great promise for creating highly effective sound absorbers. Due to the compact nature of these metamaterials, precise manufacturing is crucial to achieving optimal absorption peaks. Therefore, it is essential to develop more reliable and accurate models to predict the acoustic properties of metamaterials, ensuring their precise configuration. This study presents a comprehensive theoretical model incorporating acoustic modal superposition and couplings for the design of coiled-channel type metamaterials (CCTMs). By utilizing this two-dimensional approach, our model accurately predicts the acoustic performance and peak frequencies, including higher-order peak frequencies of CCTMs. This model surpasses traditional methods relying on calculating the acoustic impedance based on empirical estimation of effective propagation length and plane wave assumptions. Additionally, we introduce a novel coiled-type metamaterial with strategically placed perforations, achieving wide and adjustable absorption band, particularly in the low-frequency regime. Comparative analysis with traditional CCTMs demonstrates that our design outperforms them in terms of acoustic properties and compact configurations. Furthermore, we explore configurations with dual coiled-type metamaterials of varying lengths arranged to enhance broadband sound absorption. Finally, experimental investigations validate the sound absorption performance of these configurations, highlighting the potential of our theoretical model in advancing acoustic metamaterial design.