Physics – Metamaterial Supplies Underwater Stealth
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• Physics 16, s63
A light-weight construction fabricated from rubber and steel layers can present an object with underwater acoustic stealth over a broad frequency vary.
An acoustic “cloak” might disguise an underwater object from detection by sonar units or by echolocating marine animals. Very similar to camouflage clothes permits figures to fade right into a background, acoustic camouflage could make an object indistinguishable from the encompassing water. Underwater acoustic cloaks have beforehand been demonstrated, however they sometimes work over a slim vary of frequencies or are too cumbersome to be sensible. Now Hao-Wen Dong on the Beijing Institute of Expertise and colleagues show a light-weight, broadband cloak fabricated from a skinny shell of layered materials. The cloak achieves acoustic stealth by each blocking the reflection of sonar pings off the floor and stopping the escape of sound generated from throughout the cloaked object [1].
Dong and colleagues designed a 4-cm-thick construction—combining an outer rubber layer and a “metamaterial” fabricated from porous aluminum—which lined a metal plate. Utilizing a genetic algorithm, they optimized the metamaterial’s elastic properties to tailor the interplay with underwater sound waves. Particularly, the metamaterial converts impinging longitudinal sound waves, which may journey lengthy distances underwater, to transverse sound waves, which can’t propagate via water. These transverse waves get trapped within the rubber layer, the place they get absorbed, eliminating mirrored and transmitted waves concurrently. The researchers constructed and examined a prototype cloak, confirming that it behaved as predicted. Particularly, it absorbed 80% of the vitality of incoming sound waves whereas providing 100-fold attenuation of acoustic noise produced on the facet of the metal plate.
Dong says {that a} related design may very well be utilized to motorized marine automobiles—to guard wildlife from noise—or to submarines—to reinforce their stealth.
–Maggie Hudson
Maggie Hudson is an Affiliate Editor for Bodily Assessment Supplies, Bodily Assessment Utilized, and PRX Vitality.
References
- H. W. Dong et al., “Porous-solid metaconverters for broadband underwater sound absorption and insulation,” Phys. Rev. Appl. 19, 044074 (2023).
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