Sound insulation performance of double membrane-type acoustic metamaterials combined with a Helmholtz resonator

Abstract

As one of the representatives of acoustic metamaterials, the membrane-type acoustic metamaterial has excellent sound insulation performance due to its locally resonant features, which makes an extremely broad development prospect in many fields such as aerospace, ship and civil engineering. At the same time, sandwich structures are widely used because of their great mechanical properties. In this paper, we designed a sandwich structure of double membrane-type acoustic metamaterials combined with a Helmholtz resonator, a new structure is presented with both pleasant mechanical nature and admirable acoustic insulation at low frequency. Based on theoretical derivation we calculated the resonant frequencies and out-of-plane displacements of membrane-type acoustic metamaterials. The sound transmission loss, dynamic response and negative characteristics of the new structure are amply analyzed through numerical simulation, and the accuracy of the simulation is verified through experiments. It can be concluded that the average sound insulation performance of this new sandwich structure at 50 Hz–1600 Hz is 30% higher than the single-membrane type sandwich structure. At the same time, the sound insulation performance is improved by 24.8% compared with the double-membrane type sandwich structure which does not increase the cavity height. To sum up, this sound insulation performance of the structure is significantly higher than that of a single membrane-type acoustic metamaterial, with the possibility of flexible changes in cavity height, additional block arrangement form and membrane defect location from multiple angles, and a variety of configurations can be designed according to the actual engineering requirements of both lightweight, load-bearing and sound insulation requirements.