Investigation of the mechanism of noise radiation reduction from an ABH-cavity under interior acoustic excitation considering multistage coupling

Abstract

The acoustic black hole (ABH) structure exhibits superior vibration and sound radiation control capability compared to its flat counterpart. However, for a coupled plate-cavity system under interior acoustic excitation, the underlying suppression mechanism of noise radiation has not been explored, especially below the critical frequency of the structure. In this paper, the noise suppression mechanism of an ABH-cavity system under interior acoustic excitation is investigated both theoretically and numerically. Based on the theoretical analysis, the noise radiation depends on both the structural modes and the cavity modes, which can be suppressed in two ways. One is to lower the magnitude of structural transfer functions. The other is to change the mapping matrix which maps the structural modal amplitude to the amplitude of radiation modes. For the former, numerical analysis based on FEM demonstrates that a lower structural transfer function is obtained in the ABH-cavity system compared to its flat counterpart because of the damping enhancement characteristic of the ABH structure. Therefore, attenuated flexural vibrations and reduced sound radiation are achieved at corresponding modal frequencies. For the latter, ABH-cavity systems with varying numbers of ABHs are constructed to demonstrate a simple solution of manipulating the mapping matrix to achieve the reduced radiation efficiency of structural panels and the enhanced suppressing effect of noise radiation. The study in this paper indicates a feasible direction for the further optimization analysis of noise radiation suppression of the ABH-cavity system.