Low Frequency Coupling Sound Absorption Mechanism and Regulation Law of Underwater Acoustic Coating

The underwater acoustic coating has a significant influence on the acoustic stealth performance of underwater vehicles. To enhance the low-frequency sound absorption performance of the underwater acoustic coating, a composite model with a local resonance structure embedded into the cavity-type coating is established based on the finite element method, and its sound absorption performance is studied in the 10-2 000 Hz band. The structural vibration mode of the film quality of the composite model is analyzed using local resonance theory. The sound absorption mechanism of the composite model is analyzed in combination with the vibration displacement contour of the cavity-type coating. In addition, by adjusting the geometric parameters of the model, the law affecting the change in sound absorption performance is obtained. The results show that: 1) the coupling between the cavity-type coating and the local resonance structure can improve the low-frequency sound absorption effect and widen the sound absorption band; 2) the sound absorption mechanism of the composite structure is as follows: the cavity in the lower part deforms to realize the transformation of P-wave to S-wave and the upward vibration of the local resonance structure consumes sound energy, which work together to improve the sound absorption coefficient; 3) the sound absorption peak generated by coupling mainly increases with the increase in the loss factor of the coating, and the frequency of the sound absorption peak mainly moves to a high frequency with an increase in the film area.