Influence of geometric factors on the acoustic absorption performance of three-dimensional dual-graded anechoic coatings

Given the inherently three-dimensional (3D) nature of practical underwater applications, this study investigates the influence of geometric factors on the acoustic absorption performance of three-dimensional dual-graded anechoic coatings (3D DGAC). The 3D DGAC is confirmed to exhibit markedly different acoustic absorption performance compared to its two-dimensional counterpart, despite having identical characteristic lengths. A full parametric study of 729 spherical configurations highlights the importance of geometric gradation, particularly the effect of the first cavity’s size, in determining absorption performance. The 3D DGAC can retain high sound absorption efficiency even with slight deviations from the ideal graded arrangement. An orthogonal array-based analysis of block-shaped inclusions arranged in a cuboid lattice further reinforces the significance of geometric gradation for achieving effective sound absorption. This study provides valuable guidance for the design of 3D underwater anechoic coatings.