A Sandwich Coating Containing Micro-perforated Panel for Underwater Sound Absorption

Abstract

This paper focuses on the underwater application of Micro-perforated panel (MPP) for broadband sound absorption. In this paper, MPP-rubber coating (MPPRC), a novel sandwich anechoic coating embedded with MPP in high-viscosity condition, is proposed. The acoustic impedance for MPP is derived from Maa's equation and vibration modal modification, while the acoustic propagation property of the viscoelastic rubber layer is obtained by the wave propagation equation. The theoretical calculation for the absorbency of the composite structure is conduced based on electro-acoustic analogy method and transfer matrix approach. The sound absorption validation is carried on in a hydroacoustic impedance tube filled with water, and the experimental results match with the theoretical model. Compared with the equal-thickness rubber, the MPPRC performances better at a lower frequency of 1.6 kHz ∼15 kHz due to MPP, which shows the potential to be utilized as an underwater anechoic coating.