Numerical investigations of membrane-type acoustic metamaterials with eccentric masses for broadband sound isolation

Membrane-type acoustic metamaterials (MAMs) which are novel, lightweight and compact materials can be used to screen sound at a particular frequency band. Thus, it opens many possibilities toward producing a new generation of acoustic materials and sensor devices. In the present paper, an efficient scheme of finite element modelling for the acoustic-structural interaction of MAMs with eccentric masses is developed, and this model is used to optimize the eccentric masses' distributions (such as thicknesses, weights, shapes, separations and locations of the masses) for improving acoustic performance. Results show that the optimized eccentric masses' distribution can significantly broaden the frequency range of sound insulation. Furthermore, the membrane-acoustic interactions are explored for better understanding the physical mechanism.