Sound insulation performance of lamellar composite mass membrane-type acoustic metamaterial

Aiming at the problem of narrow sound insulation bandwidth in traditional membrane-type acoustic metamaterial (MAM), a lamellar composite mass MAM structure is designed. To obtain its sound insulation curve, we analyze its sound insulation characteristics using the finite element method and introduce a piezoelectric resonance circuit, insulation then conduct experiments for verification. The results show that the lamellar composite mass MAM structure has an obvious advantage in sound insulation bandwidth. Compared with lumped mass blocks, the average sound insulation is improved by 5.97 dB in the 0-1000 Hz band. Additionally, as the bending stiffness of the mass sheet increases, the sound insulation bandwidth of the metamaterial increases, the peak value point shifts to higher frequencies. The lamellar composite mass MAM structure containing piezoelectric material generates reverse output voltage at the second sound insulation valley band because of circuit oscillation, causing the piezoelectric sheet to produce a reverse force. It results in bending deformation due to the reaction force, leading to vibration displacement in the opposite direction of the intrinsic modes of the membrane, thereby exhibiting negative equivalent mass characteristics and resulting in a second sound insulation peak, effectively broadening the sound insulation bandwidth.