Experimental investigation of composite metamaterial for underwater sound absorption

We propose an underwater metamaterial combining aluminum foam and polyurea. Three samples with different aluminum foam scatterers were prepared and tested for sound absorption coefficient in the water-filled impedance and anechoic tank. The results show that the large and small conical scatterers significantly improve the sound absorption of the polyurea. This improvement in sound absorption comes from the change in the sound propagation path and waveform transformation. The design of the proposed underwater metamaterial and relevant experimental results presented in this paper have potential guiding values in developing underwater sound-absorbing functional materials.