Review of Underwater Anechoic Coating Technology Under Hydrostatic Pressure

The underwater anechoic coating technology, which considers pressure resistance and low-frequency broadband sound absorption, has become a research hotspot in underwater acoustics and has received wide attention to address the increasingly advanced low-frequency sonar detection technology and adapt to the working environment of underwater vehicles in deep submergence. One the one hand, controlling low-frequency sound waves in water is more challenging than in air. On the other hand, in addition to initiating structural deformation, hydrostatic pressure also changes material parameters, both of which have a major effect on the sound absorption performance of the anechoic coating. Therefore, resolving the pressure resistance and acoustic performance of underwater acoustic coatings is difficult. Particularly, a bottleneck problem that must be addressed in this field is the acoustic structure design with low-frequency broadband sound absorption under high hydrostatic pressure. Based on the influence of hydrostatic pressure on underwater anechoic coatings, the research status of underwater acoustic structures under hydrostatic pressure from the aspects of sound absorption mechanisms, analysis methods, and structural designs is reviewed in this paper. Finally, the challenges and research trends encountered by underwater anechoic coating technology under hydrostatic pressure are summarized, providing a reference for the design and research of low-frequency broadband anechoic coating.