Sound absorption behaviors of composite functionally graded acoustic structure under hydrostatic pressure

Abstract

In order to overcome the drawback that the sound absorption band of traditional cavity resonance acoustic structure is narrow, the functionally graded acoustic structure (FGAS) is designed in this paper according to the characteristics of functionally graded materials (FGMs), and considering the nonlinear term of the structural strain, the graded finite element method (G-FEM) is employed to establish the acoustic calculation model for FGAS under hydrostatic pressure. The correctness of the established acoustic calculation model is verified. Three types of composites functionally graded acoustic structures (CFGAS) are designed based on geometric gradient and material property gradient. The underwater sound performance of CFGAS is investigated, and the effects of hydrostatic pressure on the sound absorption performance of CFGAS are also studied. Numerical results indicate that, the convergence and accuracy of the underwater acoustic calculation model based on the G-FEM are superior than that based on the traditional FEM. In addition, the CFGAS can improve the sound absorption performance of traditional cavity acoustic structure in the middle and high frequency bands, and its acoustic performance is insensitive to pressure, which makes FGMs have potential applications in deep water environment.