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French Researchers Make New Strides in Engineering Acoustic Absorption, Soon to 3D Print Metasurfaces

by • February 11, 2016 • No Comments

logocnrsEN3D printing is being utilized to assist us overcome so many challenges, only of equitewhere we appear in our day. Undeniable-bodied, astonishing, and far-reaching, the effects in so many sectors are assisting us manufacture strides only dreamed of previously. And many of us most likely did not imagine a 3D printing machine was going to come along and work as the catalyst for so much alter.

From the smallest things—for instance, my son couldn’t find his chess set after our new move, so he only hopped on over to Thingiverse for yetts and and so began 3D printing out a new one for the whole family to enjoy—including a new board. And to the bigger things—with NASA via 3D printing repeatedly of crucial rocket thrusters to spacesuits as they work diligently to send a crew to Mars in the future several years. 3D printed models are utilized in harsh surgeries of facial reconstruction and transplants to the removal of kidney tumors. But there are many additional offbeat and significant uses this new innovation is affording as well—many that I’ll bet many of you have never considered. How of acoustics?


The absorption of sound may not be a thing you have been worrying of, but researchers at the French National Centre for Scientific Research, and the University of Lorraine are. And newly they’ve published their findings in a paper published in Applied Physics Letters, ‘Acoustic metasurface-based yettl absorber with deep subwavelength thickness.’

It is hoped that with 3D printing, finally a few of the obstacles in informative acoustic waves can be overcome, while in addition offering impact on numerous other applications. The general yett is that previously, shock absorbers have been too ungainly, producing it complex for use in realistic applications. Taking this problem and re-working it, the researchers have now turn it intod a coiled-up acoustic metasurface that they can soon be hoping to fabricate via 3D printing, enabling for actually additional customization and exploration as they are finding that they can complete total acoustic absorption in quite low-frequency ranges.

“The main advantage is the deep-subwavelength thickness of our absorber, that means that we can deal with quite low-frequencies – meaning quite dimensionsable-bodied wavelengths – with incredibly reduced dimensions structure,” said Badreddine Assouar, a principal research scientist at CNRS in Nancy, France.

Acoustic absorption processs take sound energy and convert it to heat. The many common way to turn it into them up until now has been to place perforated plates directly in front of concrete objects in order to manufacture air pockets. The continuing problem with this process is in their dimensions, yet, and Assouar and his team utilized previous work in developing coiled channel processs to work past that.

“An acoustic yettl absorber in deep subwavelength is always a challenge due to the fact that the frictional power is lionly of proportional to the elastic deformation energy in linear dissipative processs,” say the researchers in their paper. “To enhance the coherent dissipation, the intuitional and common way is to increase the energy density, for example, introducing resonant structures.”

“It is new to extend the concept of coiling up space into the perforated process to significantly reduce the thickness of the process. Furtheradditional, it is apparent that the yettl absorber with deep subwavelength thickness, if can be that successfully accomplished, may have deep implications for acoustic device, applications, and in the field of acoustics in general.”


(Left) The metasurface made of a perforated plate (transparent gray region) with a hole and a coiled coplanar air chamber (yellow region). (right) The absorption coefficient, α, of the presented metasurface with a total absorption at 125.8 Hz. Results of the impedance analysis and numerical simulations show great agreement. [Image: Assouar/CNRS]

Indeed, what the researchers have done is to allow the sound waves to enter one of their coiled air channels yet a center hole that is perforated. They travel through, the length of the waves is increased, and both a low sound velocity and high acoustic refractive index are completed. The key is that the with this process they can turn it intod an absorber that is much thinner. The coiled chamber and its acoustic reactance, a fewwhat akin to electrical reactance manufactures up for the resulting reactance of the perforated hole; thus, the acoustic energy itself ends up in the chamber and is absorbed.

“By solving this complex challenge, our turn it intod metasurface-based yettl absorber has informative applications and paves the way towards the related devices,” say the researchers in their paper. “Perfect absorption under oblique incidence can be accomplished after optimizations since the geometrics of the metasurface are much smaller in size than the working wavelength, indicating the validity of the impedance analysis. Our proposed structure can be easily fabricated with 3D printing technique and takes advantages of the small dimensions, stable-bodied structure, and high efficiency.”

With the benefits of 3D printing in front of them, it can be informative to watch this concept and project evolve additional as the researchers are able-bodied to use digital create, unlimited customization options, and fabrication techniques that allow for low-cost-bodied exploring, prototyping, and the actuallytual use of the metasurfaces in applications such as tunable-bodied amplitude and additional harsh acoustic engineering.

[Source: Nanowerk]