Mechanism and Optimization of Acoustic Absorption of an Underwater Lattice-Reinforced Meta-Absorber

Conventional rubber-based absorbers containing cavities exhibit a decline in acoustic absorption as hydrostatic pressure rises. To improve sound absorption performance under hydrostatic pressure, a lattice-reinforced meta-absorber (LRMA) is proposed in this paper. The rubber layer is embedded with periodic cavities and aluminum pipes as a lattice reinforcement structure. The energy dissipation density, displacement field, and surface acoustic impedance are employed to reveal the sound absorption mechanism of the LRMA. Then, the collaborative design of material and structure for the LRMA is optimized using a differential evolution algorithm. Finally, the experiment verifies that the average sound absorption coefficient is above 0.9 in the frequency range of 500–5000 Hz under hydrostatic pressure of 1 MPa, 2 MPa, and 3 MPa. The results show that the face sheet and the lattice reinforcement structure have good hydrostatic pressure resistance.