Vibroacoustic analysis of multi-layered micro-perforated plates coupled to an acoustic enclosure

Abstract

A vibroacoustic study of multi-layered micro-perforated plates (MPP) coupled to an enclosure cavity excited by internal and external acoustic excitations is presented. Most previous research centered on the multi-layered MPPs structure itself, the absorption and transmission performances were often calculated or tested in a simple acoustic environment. In a more realistic setting, the surrounding systems may affect the efficiency of MPPs. The proper modeling of the MPPs within acoustic enclosures requires careful study. The break-out sound from an enclosure via multi-layered MPP and the energy transmission of the structure into an acoustic enclosure undergoing exterior excitation are studied with an emphasis on the use of MPP in acoustic enclosures to suppress specific resonances of the enclosure. Therefore, an analytical formulation is proposed to model the behavior of the coupled system to address this issue. Using a modified Fourier series for the acoustic pressure, the continuity of the normal velocities at the interfaces of the plate or the MPP and the acoustic medium is assured accurately. A modified variational form for the acoustic and structure medium yields a completely coupled vibroacoustic system. Comparison with the finite element method (FEM) and available literature findings prove the efficacy and precision of the current approach. The effect of important parameters on the vibroacoustic behavior of multi-layered MPPs structure connected to an acoustic enclosure is examined. These parameters include micro-perforation of the plate, hole diameter, air gap thickness, acoustic enclosure dimensions, and the insertion of absorbent material in the gap.