From sonars submarine can hide the "bubble" coating
To shelter a submarine from sonar, an anechoic coating is often used. As a rule, it is a porous rubber plate, about 2,5 thickness, see. However, 10 years ago, scientists hypothesized that this effect can be achieved with a much thinner layer, especially filled with voids, reports Gearmix with reference to the online edition of "Livescience".
As scientists have suggested, “when a sound wave hits a porous layer, the voids in an elastic material change in size and absorb most of the sound energy.”
Theoretical calculations took a lot of time, so the researchers went empirically.
To speed things up, “Professor of Physics from Université Paris Diderot, Valentin Leroy and his colleagues modeled voids inside the material in the form of spherical bubbles, each of which responds subtly to sound waves in accordance with its size and elasticity of the surrounding material,” writes the publication.
This approach allowed scientists to design a “bubble meta-screen”, which was a “soft silicone rubber layer just 230 microns thick”. Internal voids took the form of small cylinders, 24 wide microns.
According to the publication, “field experiments have shown that such a meta-screen dissipates more than 91 percent of the sound energy that falls on it and reflects less than three percent of it (for comparison, an ordinary piece of steel reflects 88% of sound energy)”.
According to the test results, the researchers concluded: “to absorb 99 percent of the energy of modern sonars, you will need a film 4 mm thick.”
According to Professor Leroy, the technical possibility of creating such a coating exists, but making a sample will require considerable effort.
As scientists have suggested, “when a sound wave hits a porous layer, the voids in an elastic material change in size and absorb most of the sound energy.”
Theoretical calculations took a lot of time, so the researchers went empirically.
To speed things up, “Professor of Physics from Université Paris Diderot, Valentin Leroy and his colleagues modeled voids inside the material in the form of spherical bubbles, each of which responds subtly to sound waves in accordance with its size and elasticity of the surrounding material,” writes the publication.
This approach allowed scientists to design a “bubble meta-screen”, which was a “soft silicone rubber layer just 230 microns thick”. Internal voids took the form of small cylinders, 24 wide microns.
According to the publication, “field experiments have shown that such a meta-screen dissipates more than 91 percent of the sound energy that falls on it and reflects less than three percent of it (for comparison, an ordinary piece of steel reflects 88% of sound energy)”.
According to the test results, the researchers concluded: “to absorb 99 percent of the energy of modern sonars, you will need a film 4 mm thick.”
According to Professor Leroy, the technical possibility of creating such a coating exists, but making a sample will require considerable effort.
- gearmix.ru
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