In the depths of the ocean, noise pollution is a growing concern, particularly for the energy sector, where underwater structures and equipment generate significant sound waves. Addressing this issue, researchers from Xi’an Jiaotong University have developed an innovative solution that could revolutionize underwater noise control. Led by Jiaming Feng from the State Key Laboratory of Manufacturing System Engineering, the team has created ultrathin hybrid sound absorption metasurfaces that maintain high efficiency even under extreme hydrostatic pressure.
The breakthrough, published in the journal Design of Materials, leverages artificial neural networks (ANNs) to design metasurfaces that can absorb sound waves with remarkable efficiency. The key to their success lies in the unique hybrid structure of the metasurfaces, which combine different proportions of cavities and scatterers. This design not only achieves high sound absorption rates—over 80% and 88% respectively, in the frequency range of 0.8–10 kHz—but also maintains an ultrathin profile of just 32 mm.
Feng explains, “The hybrid coupling effect is crucial. By differentiating the mechanical energy flow among the sub-surfaces, we can significantly enhance sound absorption.” This differentiation is further supported by a honeycomb structure, which plays a vital role in impedance matching, ensuring that the metasurfaces can effectively absorb sound waves without reflecting them back.
One of the most impressive aspects of this research is the metasurfaces’ ability to withstand high hydrostatic pressure. The addition of a matching cover layer creates a synergistic resistance effect, allowing the metasurfaces to maintain their sound absorption capabilities even under pressures up to 3 MPa. This resilience is particularly important for underwater applications in the energy sector, where equipment often operates at great depths.
The potential commercial impacts of this research are substantial. Offshore wind farms, underwater pipelines, and other energy infrastructure could benefit greatly from these advanced metasurfaces. By reducing noise pollution, these structures can minimize their environmental impact and comply with increasingly stringent regulations. Moreover, the ultrathin design of the metasurfaces makes them easy to integrate into existing structures, reducing the need for extensive modifications.
Looking ahead, this research opens up new possibilities for the engineering applications of underwater metasurfaces. As Feng notes, “This work provides more possibilities for the engineering applications of underwater metasurfaces.” The use of ANNs in the design process also paves the way for further innovations, as researchers can continue to optimize these metasurfaces for specific applications and environments.
The study, published in the journal Design of Materials, marks a significant step forward in the field of underwater acoustic absorption. As the energy sector continues to expand into deeper waters, the need for effective noise control solutions will only grow. This research not only addresses that need but also sets the stage for future developments in underwater metasurface technology.