All‐in‐One Underwater Quality Evaluation Metamaterial With Mechanical Robustness, Sound Attenuation, and Diffuse Reflection

To resolve acoustic-mechanical conflicts and integrate research gaps in underwater coatings. Inspired by the biomechanics of jumping spiders and human bones, we design an underwater composite structure subject to hydrostatic pressure. Based on mechanisms involving weak energy entanglement driven by damping and wave-mode conversion driven by impedance mismatch. A synergistic combination of theoretical modeling, numerical simulation, and experimental validation, the structure achieves low-intensity diffuse reflection below 0.8 kHz, and broadband low-frequency sound attenuation at 0.8-2.5 kHz (insulation > 26 dB, absorption > 0.8). Notably, this structure achieves significant sound attenuation with an absorption coefficient exceeding 0.8 below 4 kHz even under 3 MPa of hydrostatic pressure. The sound attenuation performance decreases by an average of only 4.5% per 1 MPa increase in pressure, and the deformation nearly 100% recovers after unloading. By integrating an acoustic-electrical analogy model for component dimensionality reduction and a convolutional neural network for visual quality evaluation, we establish an integrated design-evaluation framework. This strategy provides a scalable approach for next-generation underwater acoustic skins.