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Science Technology

Super Strong Metal Foam Discovered 367

Posted by ScuttleMonkey
from the body-armor-in-a-can dept.
MikeChino writes to tell us that a North Carolina State University researcher has discovered what appears to be the strongest metal foam yet, capable of compressing up to 80% of its original size under load and still retain the original shape. The hope is that this amazing material could be used in cars, body armor, or even buildings to absorb the shock from earthquakes. "Metal foam is exactly what you might think – a cellular structure made from metal with tiny pockets of space inside. What makes Rabiei’s metal foam better than others is that she’s been able to make the tiny pockets of space more uniform. And that apparently is what gives it the strength as well as elasticity it needs in order to compress as much as it does without deformation. Many tests are being performed in the laboratory to determine its strength, but so far Rabiei says that the spongy material has 'a much higher strength-to-density ratio than any metal foam that has ever been reported.' Calculations also predict that in car accidents, when two pieces of her composite metal foam are inserted 'behind the bumper of a car traveling at 28 mph, the impact would feel the same to passengers as an impact traveling at only 5 mph.'"
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Super Strong Metal Foam Discovered

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  • Is it simply the uniformity in the cellular structure? What is the difficulty/breakthrough in achieving higher uniformity?
    • Re:Uniform fab (Score:5, Insightful)

      by Anonymous Coward on Monday February 01, 2010 @04:52PM (#30986664)

      Uniformity is one of the hardest things to accomplish when manufacturing anything. If it were easy, then first pass yield would be 100% every time. In reality, you are lucky if FPY reaches 95%, and if you've ever been in quality control, you know that 95% FPY is shit depending on the industry. If you aren't above 99% your nothing.

      This is especially important and difficult in metallurgy. This is why there are highly trained material scientists and metallurgists working in the Aerospace industries. A well designed part is worthless if the heat from the tools changes the metal properties at the joints.

      To go back to TFA, how would you suppose you form a foam out of metal? Now how you you ensure consistency?

      I don't know, and neither do you. That's why it's a breakthrough.

      • A well designed part is worthless if the heat from the tools changes the metal properties at the joints.

        Annealing and heat treating?

        I don't know, and neither do you. That's why it's a breakthrough.

        No, that's why neither you, I, nor oldhack are metallurgists. "I don't know and neither do you" is like two chemists agreeing that a bubble sort is a breakthrough because neither one of them know how to write computer code. Yes, it's a breakthrough because they found a way to do it better, with a corresponding improvement in the properties of the final product. However, I took oldhack's post to mean, "what was the breakthrough that allowed them to achieve grea

      • Random side note. I mentally swapped FPY into PFY, or pimply faced youth. One of the main characters in the Bastard Operator From Hell. Which is the single greatest collection of stories about IT workers abusing users.

  • I think I'd rather have some of this between me and a potential impact than a classic airbag, if it came to the crunch. What do they use for an inflation gas generator - sodium azide is it? Nasty stuff. Like driving around with a firecracker held in front of your face.
    • Have you ever seen someone inflate regular foam? I'm pretty sure it comes full size when it's made and then you can compress it, but it doesn't inflate up like an airbag.
      • by Ironchew (1069966)

        Um...
        Whoosh? ::facepalm::

        • Really? what am I missing here, he seems to genuinely believe this foam could replace airbags which leads me to believe he thinks it can be inflated on the fly rather then being a solid chunk of metal that deforms. I realize that is so insane that I wish it was a joke, but if it was it wasn't made very apparent.
          • by Rakishi (759894)

            Or he thinks it can be used in the crumple zones and remove the need for an airbag. I mean, did you even bother reading the article summary? Whoosh, indeed.

          • by natehoy (1608657) on Monday February 01, 2010 @05:27PM (#30987280) Journal

            I read it as his desire to use this foam as a replacement for the bumper and crumple zones. It would turn the existing crumple zones into something in the car's frame and bumper system that would absorb a great deal more of the impact and, therefore, largely eliminate the need for airbags.

            I'm not sure I'm buying it, though. Airbags are an "also need" feature, and cannot be replaced wholly by a better crumple zone.

            The problem lies in the elasticity and the distance. If you hit a brick wall doing 65MPH and your crumple zone is too squishy, it will continue crumpling up until you are included in the crumple zone. In other words, you're dead.

            Make it too hard, and the car will stop more quickly than your flesh can handle. The airbag is a crude but effective way of allowing a relatively stiff crumple zone that can manage to keep your passenger cabin intact during a VERY major impact, and still accommodate your body's need to decelerate as gradually as possible. If you hit a brick wall doing 65MPH, the crumple zone decelerates the car from 65MPH - 0MPH in the distance represented by the zone (usually a few feet at best), and materials aren't going to improve on that a whole hell of a lot. You are still going from 65MPH-0MPH in just a few feet. That's a SERIOUS amount of deceleration.

            The airbag is what takes your head and torso and slows them down as gently and slowly as possible, leveraging the deceleration already provided by the crumple zone and making the best use of it to keep your brains from splashing around in your noggin, and/or snapping your neck. Which is not to say the airbag is gentle or slow at all, far from it, just more gentle and slower than making your dainty neck bones absorb all of the force as your torso is stopped by the seatbelt and your several pounds of head really wants to keep going to make Newton happy.

            Could be worse, though. You could be wearing no seatbelt at all and expect your chest and head to absorb all of the speed when they impact the steering wheel and windshield respectively. That always ends colorfully, particularly in shades of red and grey.

            • Re: (Score:3, Informative)

              by drinkypoo (153816)

              When they develop an airbag that can detect your position and avoid punching you in the face, I'll want one. I had one in my Subaru and was always thinking about replacing the steering wheel and getting rid of it in the process. Neither of my vehicles have them and I like them that way.

              If you really care about safety, the thing to do is to wear a helmet and a five- or six-point harness (males prefer six) when driving. The helmet is there not so much to protect your head as to give you a place to mount a hea

    • by Primitive Pete (1703346) on Monday February 01, 2010 @04:53PM (#30986698)
      Maybe, maybe not. Elasticity is not the same thing as softness... steel is pretty elastic, but you don't necessarily want a face full of it in a car wreck. OTOH, landing in a bed of inelastic potato chips wouldn't be particularly painful (though it would be itchy).
      • Re: (Score:3, Informative)

        by SatanicPuppy (611928) *

        Well, and elastic just describes it's tendency to return to it's original shape, it says nothing about how much energy it's going to take to make it change shape in the first place...We're talking about a block of aluminum filled with hollow steel balls here. Anything short of a sledgehammer isn't going to change it in the least.

      • Re: (Score:3, Insightful)

        by autophile (640621)

        OTOH, landing in a bed of inelastic potato chips wouldn't be particularly painful (though it would be itchy).

        As well as delicious.

      • Re: (Score:3, Informative)

        Maybe, maybe not. Elasticity is not the same thing as softness... steel is pretty elastic, but you don't necessarily want a face full of it in a car wreck.

        Correct. For an example, take a large steel ball bearing and a solid rubber ball the same size. Drop them on a concrete floor from the same height.. The steel ball, being more elastic than the rubber(!) will bounce higher.

        The ability of a metal to deform under compressive stress is malleability (the counterpart of this is ductility, which is a measure of tensile stress). Elasticity is an entirely different 'ticity.

    • by SatanicPuppy (611928) * <Satanicpuppy&gmail,com> on Monday February 01, 2010 @04:56PM (#30986740) Journal

      You'd rather have a big hunk of metal than an airbag? Don't let the "foam" fool you: slamming your face into a block of it at 35mph would only be a little better than running face first into a brick wall at the same speed.

      It's squishy and springy...for metal. But it's not what you'd call soft.

      • I think the person meant that they would rather have a traditional seatbelt and a front end crumple zone made of this metal foam versus a seatbelt, a regular crumple zone, and an airbag.

        I'm not sure I agree. I've been in collisions where the vehicles involved were moving at about 20 or 25 mph, and the speed was too low for airbags to deploy. In both cases the vehicles involved were nearly destroyed and none of the occupants were hurt. If you're moving fast enough in a collision that an airbag deploy
      • by flitty (981864)
        Airbags would be bad, but Steering columns might be a better application for this.. perhaps.
        • Re: (Score:3, Informative)

          by SatanicPuppy (611928) *

          This stuff is nice, but it's a mistake to look at it as a drastic improvement in terms of safety.

          The benefit of this is the reduction in weight without loss of strength.

    • by dintlu (1171159) on Monday February 01, 2010 @04:57PM (#30986768)

      Airbags and bumpers serve two entirely different purposes.

      If this material lives up to the hype (unlikely), your next car will feature both items.

      I'm curious to know more about the 28mph -> 5mph assertion. That stat was given to the media because it sounds impressive (grant guff), but how does it compare to the deceleration of a traditional auto bumper.

      • by mcgrew (92797) *

        I'm curious to know more about the 28mph -> 5mph assertion

        I flat out disbelieve it. Extreme claims need extreme proofs.

        • The national standard is for a wimpy 50% reduction (5mph->2.5mph); this isn't the maximum by any stretch, since obviously you can put enough crap on the front to reduce the impact by 99% if you want to. So it's hardly an extreme claim.

          The origin of the 28->5 number should be obvious. The material can compress to 80% of it's original size under load.

      • by PitaBred (632671)

        Perhaps she wasn't comparing the 28mph to a 5pmh with current bumpers, but a 5mph perfectly inelastic collision? Can't tell for sure.

    • Re: (Score:2, Insightful)

      by Anonymous Coward

      I think I'd rather have some of this between me and a potential impact than a classic airbag, if it came to the crunch. What do they use for an inflation gas generator - sodium azide is it? Nasty stuff. Like driving around with a firecracker held in front of your face.

      I'm thinking if your face is traveling at 80+ kph into metal foam there is a going to be a lot of crunch going around. Airbags made of cloth and gas which deflate when you hit them do enough damage. I'd be more concerned with inhaling the fragments of my teeth and skull that resulted from my face colliding with a metal "pillow" than about inhaling the byproducts of the airbag detonation.

  • ...for the downstairs neighbor's protection.

  • by jayemcee (605967) on Monday February 01, 2010 @04:52PM (#30986666)
  • Body Armor (Score:5, Insightful)

    by SignalFreq (580297) on Monday February 01, 2010 @04:53PM (#30986692)
    Place this behind an existing body armor compound (one that stops the bullet) and use the foam to absorb the remaining shock. Then you could survive being shot and also continue to return fire without being thrown back or suffering bad bruising.
    • Unless the guy firing it gets knocked on his ass your own shock will be the only thing knocking you on yours...

      • People don't generally lean into a bullet, but they do take a proper firing stance, so that's not completely true.
      • Maybe if you are wearing full Level IV body armor. Most of the lighter stuff traditionally worn by law enforcement still imparts a great deal of impact to the body, especially with higher mass or higher velocity rounds.
        • Re: (Score:3, Interesting)

          by Chirs (87576)

          The total impact energy (and momentum) of the bullet is constant regardless of vest type.

          Lighter vests may not be able to spread the force of the impact over as large an area, so may be more likely to cause bruising.

          In any case, the person firing the gun (assuming they're hand-holding the gun rather than having it fastened to something rigid) will need to absorb more energy/momentum when firing the gun than the target will when hit by the bullet. (Because the bullet is slowed slightly by air resistance.)

          Th

    • by vlm (69642)

      Place this behind an existing body armor compound (one that stops the bullet) and use the foam to absorb the remaining shock.

      http://en.wikipedia.org/wiki/Spalling [wikipedia.org]

      Probably would make a nice spall liner for tanks.

      • Re: (Score:3, Interesting)

        by afidel (530433)
        More like as a replacement for the ceramic ballistic inserts needed to obtain class iv ratings for body armor. This might be very useful for the military as the ceramic tiles generally only provide single shot protection as they shatter with the first round. That's where price comes in, the Dragon Skin body armor is already available for ~$5,000 for class iv rating.
    • Place this behind an existing body armor compound (one that stops the bullet) and use the foam to absorb the remaining shock. Then you could survive being shot and also continue to return fire without being thrown back or suffering bad bruising.

      FWIW, I think we're a long way away from metal foams being used as personal body armor. Yes, they'll absorb some of the energy, but they'd still be bulky and heavy.

      Vehicular armor is a much more likely use with the foams we have today.

      • Actually, they use steel and ceramic plates behind the kevlar even now, so you could switch out those and maybe see an improvement in protection to weight.

    • Re: (Score:3, Interesting)

      by BitZtream (692029)

      The problem is the use of the word 'absorb'.

      You aren't going to absorb it in any useful amount, you have to spread it. The energy HAS to go somewhere.

      People aren't really thrown back, they are knocked off balance because they weren't prepared for the energy imparted on them. If getting shot actually 'knocked you back' it would do the same to the person firing.

      Body armor just helps spread the force across a larger area. Your body is pretty damn resilient, but when you rich the breaking point it just falls

  • YouTube videos (Score:5, Informative)

    by Terrasque (796014) on Monday February 01, 2010 @04:57PM (#30986778) Homepage Journal

    Two youtube videos about the material:
    http://www.youtube.com/watch?v=mI5ZzfOlbKA [youtube.com] - earlier video
    http://www.youtube.com/watch?v=wfFcs25KmMc [youtube.com] - one week old video

    Shows among other things compression tests of the material.

  • We just griped about that.

    >capable of compressing up to 80% of it's original size

    "It's" == "It is." No exceptions.
    The genitive of "it" it "its."

    Sincerely,
    Grammar Police greetings from somebody for whom English is the 3rd language.

    • by mcgrew (92797) *

      The reason people do this is because they remember the rule that possessives use apostrophes, but forget that some possessives don't.

      He's, she's, it's (contraction)
      His, hers, its (possessive)

  • when two pieces of her composite metal foam are inserted "behind the bumper of a car traveling at 28 mph, the impact would feel the same to passengers as an impact traveling at only 5 mph."

    Yeah, try that without a seatbelt or airbag then. You'd still be crushing your chest into your steering wheel at 28 MPH, unless this stuff also generates a star trek inertial dampening field.

    • Re: (Score:3, Interesting)

      by mcgrew (92797) *

      In 1976 I was driving a 1974 Gremlin at 50 mph, and had a head on collision with a quarter ton pickup truck that was doing 70. Back then they didn't even have padded dashes, let alone airbags; it was naked steel. I wasn't wearing a seat belt. I bent the steering wheel, and bent the dash where my shoulder hit it. The shoulder was permanently dislocated, but I had no organ damage (well, I may have suffered a concussion) or broken bones.

      After the wreck you couldn't even tell what kind of car it was. I'll tell

  • by thanasakis (225405) on Monday February 01, 2010 @05:40PM (#30987498)

    This material reminds me of the lunar module's landing gear, made out of collapsible aluminum honeycomb. Look here for the word aluminum [teamfrednet.org]. Highly interesting.

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