Vibroacoustic metamaterial for enhanced Sound Transmission Loss with variable frequency range designed for serial production

Abstract

Recently, vibroacoustic metamaterials have been broadly investigated, especially for noise and vibration mitigation. By creating a band gap effect in flexural wave propagation in a base element, metamaterials improve its vibroacoustic parameters in low and mid frequency range while preserving low mass and structure dimensions. While the foundational assumptions and lab validations highlight the advantages of these metamaterials, the practical application of these structures in real-world scenarios remains a challenge. The main aspect that is widely investigated is achieving maximum effectiveness while maintaining the simplicity of geometry to optimize mass production costs. This work presents a vibroacoustic metamaterial design with geometry adapted to serial production using injection molding. The proposed geometry allows for adjusting the effective frequency range of the structure after the production process. Due to the distinctive configuration of the elements and the grouping of unit cells, the design facilitates the generation of broadband and multi-band structures as well. Numerical simulations were employed to assess the impact of the proposed metamaterial on Sound Transmission Loss and other vibroacoustic parameters. Experimental validation of prototype effectiveness was conducted through Sound Reduction Index measurements in a diffuse field.