Analysis of Acoustics Performance of Double-Layer Micro-perforated Panel Absorbers: A Finite Element Analysis

Micro-perforated panel (MPP) combined with desired cavity depth is considered as a next-generation sound absorber and a better alternative due to the improved acoustic performancePerformance in low-to-medium frequency range and sustainable features in hostile environments compared to the traditional porous materials. A single-layer MPP absorber facilitates absorption in one to two octaves, which can be improved using multiple MPPs in the absorber structure. The acoustic impedance of the single-layer MPP absorber is estimated using Maa modelMaa model and equivalent electro-acoustical circuit (EAC) analysis. The predicted absorption coefficients of the single-layer MPP absorber were validated through measurement in two microphone impedance tubes or numerical analysis in which the actual experimental conditions were simulated. In this study, the absorption characteristics of double-layer MPP absorbers are better predicted through the transfer matrix methodTransfer matrix method (TMM), in which individual transfer matrices of constituting elements of the absorbers are considered. The predicted results are validated through a finite element analysisFinite element analysis (FEA) which incorporates the determination of acoustic impedance through a pore and the effect of pore–pore interaction for MPP. The sound absorptionSound absorption characteristics of double-layer MPP absorbers obtained from FEA show good agreement with the predicted results, thus making the proposed FEA reliable. Moreover, the variation in the sound pressureSound pressure level of the double-layer MPP absorber along the propagation direction is illustrated, justifying the sound absorptionSound absorption phenomena.