Design of lightweight multifunctional honeycomb membrane-type acoustic metastructures for sound insulation

Abstract

Honeycomb sandwich structures exhibit outstanding mechanical performance. However, their sound-insulation performance is typically unsatisfactory due to the sound-insulation mass law. In this study, a multilayer honeycomb membrane-type acoustic metastructure (MHMAM) is proposed by combining conventional honeycomb sandwich structures with membrane-type acoustic metamaterial. A theoretical model for calculating the sound transmission loss (STL) of the MHMAM is established using the space harmonic expansion method and the principle of virtual work. Subsequently, the validity and accuracy of the theoretical model are verified using a finite element model. The sound-insulation mechanism of the MHMAM is comprehensively examined from the perspectives of average normal displacement and energy transmission. The results show that, within the sound-insulation frequency band near the STL peak, the average normal displacement reaches a minimum and the power of energy transmission through the honeycomb wall and the air-facesheet pathways is reduced by more than tenfold. Moreover, the effects of membrane tension, membrane thickness, and honeycomb wall spacing on the sound-insulation performance are investigated analytically. Finally, sound-insulation experiments are conducted using an impedance tube system. The results indicate that the MHMAM can generate a higher STL than conventional honeycomb sandwich structures in the frequency range of 500–6300 Hz. Therefore, the MHMAM can simultaneously provide broadband sound-insulation and load-bearing capabilities, making it an effective lightweight multifunctional sound-insulation structure.