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Metamaterial undermines 250-year-old construction principles

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  Metamaterial undermines 250-year-old construction principles Sam Wormley <swormley1@gmail.com> - 2015-07-23 08:15 -0600
    Re: Metamaterial undermines 250-year-old construction principles jimp@specsol.spam.sux.com - 2015-07-23 17:30 +0000

#508882 — Metamaterial undermines 250-year-old construction principles

Metamaterial undermines 250-year-old construction principles
> http://phys.org/news/2015-07-metamaterial-undermines-year-old-principles.html

> Researchers have demonstrated how a rubber beam subjected to less
> pressure bends faster. This behaviour defies expectations and appears
> to undermine centuries-old bending laws. The beam is made from a
> metamaterial, which gives it the name "metabeam." Metamaterials have
> special properties that do not occur in nature. By providing the
> metabeam with a carefully chosen pattern of small holes, the
> researchers induced the strange behaviour. They published their work
> on 21 July online in Physical Review Letters.

> The metabeam is a rubber beam about twenty centimeters long patterned
> with elliptically shaped holes. These holes give the metabeam an
> unusual property. The researchers noticed that at a critical
> pressure, there is a tipping point at which a self-reinforcement
> effect occurs: the beam continues to bend further even though the
> pressure decreases. Group leader Martin van Hecke: "It is just like
> pushing a car. You expect that you have to push harder to make the
> car go faster, but here we have a situation in which the car goes
> faster and faster even though you are pushing less."

> Tailored bending

> The researchers investigated the cause of this self-reinforcement
> effect. They discovered that the metabeam under a slight pressure
> compresses easily but stretches with difficulty. In normal materials
> without holes, the difference between compression and stretching only
> plays a role at high pressures. This sensitivity to the difference
> between compression and stretching causes the strange effect during
> the bending of the metabeam. The shape and position of the holes
> accurately determine the pressure at which this effect occurs. The
> researchers can therefore specifically tailor the properties of the
> material by changing the pattern of holes.


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#508919

Sam Wormley <swormley1@gmail.com> wrote:
> Metamaterial undermines 250-year-old construction principles
>> http://phys.org/news/2015-07-metamaterial-undermines-year-old-principles.html
> 
>> Researchers have demonstrated how a rubber beam subjected to less
>> pressure bends faster. This behaviour defies expectations and appears
>> to undermine centuries-old bending laws. The beam is made from a
>> metamaterial, which gives it the name "metabeam." Metamaterials have
>> special properties that do not occur in nature. By providing the
>> metabeam with a carefully chosen pattern of small holes, the
>> researchers induced the strange behaviour. They published their work
>> on 21 July online in Physical Review Letters.

So it is a lab curiosity and has nothing what so ever to do with
"250-year-old construction principless".


-- 
Jim Pennino

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