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Military Develops Liquid Body Armor
Posted by
simoniker
on Fri Apr 23, 2004 05:07 PM
from the wet-n-wild dept.
from the wet-n-wild dept.
kai5263499 writes "Military.com has an article about a new liquid body armor the U.S. Army Research Laboratory has developed. According to Dr. Eric Wetzel, the project coordinator: 'The key component of liquid armor is a shear thickening fluid. STF is composed of hard particles suspended in a liquid. The liquid, polyethylene glycol, is non-toxic, and can withstand a wide range of temperatures. Hard, nano-particles of silica are the other components of STF. This combination of flowable and hard components results in a material with unusual properties'."
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Flexible Body Armor 210 comments
dotmax writes "One item to pop out of the Turin Winter Olympics is the use of flexible body armor. Similar to silly putty, this shear rate material is flexible under normal load and hardens under impact. Sounds expensive, but could offer some great alternatives for traditional hard shelled impact gear in active sports and military applications."
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Screenshots. (Score:5, Funny)
- Man in liquid armor
walking down the lab hallway. [digitalacb.com]
- Man
in liquid armor enduring heat. [goingfaster.com]
- Liquid
armor on half a face [squidge.org]
Your tax dollars at work.This is joey, the lab assistant, going on a coffee run.
This test killed a few of our volunteers, but after many tries we finally worked out all the kinks.
We do half the face in case the armor blinds the test subject, at least he'll have one good eye left. (Lessons learned from the "heat" test, we apply the same principal for the genitals as well.)
Countermeasures (Score:5, Funny)
Call me dense (Score:5, Interesting)
Re:Call me dense (Score:5, Informative)
If you jab it, it feels hard and your finger won't go in very far. You can pour it slowly, but you can grab a clump of it, almost as if it's a solid. This kind of fluid is called dilatant. It becomes more viscous when agitated or compressed.
The cornstarch mixture is sometime called ooblick [clueless.com].
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Re:Call me dense (Score:5, Interesting)
We tried to use experimentation to illustrate rheological properties, including using cornstarch in solution. This demonstrates dilatancy (shear thickening), and we would put a spoon in a jar of the stuff, which was very fluid. When you try to pull the spoon out quickly, viscosity increases, and the solution gets real "thick".
Well, of course, I thought this was pretty boring, so I decided to punch it up a bit. I made a much larger sample of the solution, and put it in a large bowl. I would swirl it around and show everyone how liquid it was. Without warning, I would then move the bowl quickly, like I was going to completely douche someone with it. The solution would thicken, and stay in the bowl (thank you Penn & Teller). Pretty cool, actually, but god help you if you got the mixture wrong!
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Slap me bald and call me, "Myrtle" (Score:5, Funny)
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Could be good for VIP protection (Score:5, Insightful)
Sounds like Snow Crash (Score:5, Interesting)
I imagine this could be combined with a chem warfare suit (maybe with build-in cooling) to make an ABC system for the footsoldier that's actually practical.
Snow Crash (Score:5, Interesting)
Next James Bond Movie! (Score:5, Funny)
Re:Next James Bond Movie! (Score:5, Funny)
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Don't know about liquid armor (Score:5, Funny)
Very cool technology (Score:5, Insightful)
As a former member of the US armed forces I had to wear a kevlar vest from time to time. The vests I wore hindered movement considerably. They were not that heavy, but the inflexibility was the worst part. As I was finishing my term new vest were just making their way into use that incorporated ballistic plates (steel I think, maybe ceramic) to actually stop bullets. The vest I wore were only said to stop fragments not a direct bullet impact. The downside to the newer vests was heavier weight. If they can make the vest more flexible, lighter weight, and have better stopping great.
Our service members need every advantage they can get. Wether or not you agree with the politics that puts our troops in harms way a person must be very anti-American to not want them all to come home again.
That is all for my rant. Time to go home for the day. :)
the_crowbarAs someone who opposes the war... (Score:5, Insightful)
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Inflexibility (Score:5, Informative)
For example, in urban combat, you are constantly looking up, and pointing your weapon up. As you crane your neck backward and move your non-firing hand above your head, with a traditional kevlar vest you reach a flexibility limitation. If you then have to contort your body laterally for some reason (and they always arise) your trunk is limited in flexiblity as well.
A vest that could incorporate greater flexiblity and some sort of heat-dissipation mechanism would be a real boon to soldiers who need body armor protection.
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That "Poly" makes a huge difference (Score:5, Informative)
Scientific Paper & News Article (Score:5, Informative)
For a scientific paper on the subject, see Advanced Body Armor Utilizing Shear Thickening Fluids [asc2002.com], by Y. S. Lee, R. G. Egres Jr. and N. J. Wagner, all of the Center for Composite Materials and Dept. of Chemical Engineering, U. of Delaware, and E. D. Wetzel of the Army Research Laboratory, Weapons and Materials Research Directorate Aberdeen Proving Ground.
For a University of Delaware Press Release (with photos), see here [udel.edu].
Motorcycles? (Score:5, Interesting)
Also, perhaps this stuff could give stuntmen a whole new level of safety while still giving them a lot of mobility.
Degradation (Score:5, Insightful)
Bulletproof Inners (Score:5, Funny)
Military.com ripped the story (Score:5, Informative)
And they even have a picture!
Sounds like it might be handy as bike armour. (Score:5, Interesting)
If this stuff goes rigid when there's an impact it might just distribute the impulse over a large enough area to reduce the internal injuries.
Follows the existing pattern... (Score:5, Funny)
The question of the future (Score:5, Funny)
So the hookers of the future will ask soldiers, "Is that shear-thickening liquid armor in your pants, or are you just glad to see me?"
Re:Polyethylene Glycol? (Score:5, Informative)
http://www.google.com/search?q=Polyethylene%20Gly
That's from the first link.
Parent
There is a commercial preparation (Score:5, Informative)
It's commonly used by gastroenterologists to clean out the colon prior to endoscopy. You have to drink an entire gallon...it's usually referred to as a "bowel prep."
To those of us familiar with it, it's also affectionately known as "GoHeavily," "GoFrequently," or "GoEndlessly." I've also seen it used to treat bad constipation... ingestion of the required amount virtually guarantees an impressive "code brown."
Yes, I realize that's waaaaay more than you wanted to know. Sorry.
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Re:Polyethylene Glycol? (Score:5, Informative)
Polyethylene glycol is actually really bio-friendly. Proteins don't stick to it well so it can be used in the body. You can even eat the stuff. I can't think of specific products, but I know it's on the ingredient label of lots of things we eat.
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Re:Polyethylene Glycol? (Score:5, Insightful)
Sodium explosively combusts in water! Chlorine gas is highly toxic! Can the combination really change their properties all that much?
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Re:Polyethylene Glycol? (Score:5, Funny)
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Re:Polyethylene Glycol? (Score:5, Informative)
EG is toxic because it's metabolized by alcohol dehydrogenase to form glycolic acid, causing acidosis (too much acid in the bloodstream), or various other nasty downstream products. PEG isn't metabolized, so it's safe.
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Re:Polyethylene Glycol? (Score:5, Informative)
Polyethylene Glycol: C2H4O
So they are pretty different from a chemical standpoint. Good old Ethylene Glycol melts at -13C, while the "poly" melts at 60C. However, when looking up an MSDS on this stuff, I get "May act as an irritant. Toxicology not fully investigated" so I wonder about it being completely non-toxic.
See link here. [ox.ac.uk]
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Re:Polyethylene Glycol? (Score:5, Informative)
HO-CH2-CH2-OH
The repeat unit of polyethylene glycol looks like this:
-CH2-CH2-O-
So with polyethylene glycol, just attach that unit end-to-end over and over again. How many repeat units you have in the polymer will determine the melting point and many other properties. The MSDS you link to is for PEG-8000, which probably means it has a molecular weight of 8000.
Incidentally, you'll notice that the ethylene glycol unit (the monomer) is different from the PEG repeat unit by an H2O -- water is a byproduct of the polymerization.
Polymerization does make a huge difference in properties. Polyethylene is basically ethane (or, if you look at it another way, methane) attached end-to-end, but polyethylene, of course, is very different chemically from methane.
Finally, I get to post to Slashdot about a technical subject I know something about. Quick, someone, mod me up! It may never happen again! :)
Parent
Re:Polyethylene Glycol? (Score:5, Informative)
Absolutely.
Ethylene glycol is OH-CH2-CH2-OH and is fairly toxic. I would suspect it behaves similarly to ethanol (CH3-CH2-OH) in the bloodstream, but I don't really know. Contrast this with propylene glycol, CH2-CH2-(CHOH)-OH which is pretty much completely non-toxic.
Polyethylene glycol is (-CH2-CH2-O-)n, where n is some large number. It's a polymer. There are different kinds of PEG, but glancing at the web, there appear to be a number of different kinds available, and they appear to be reasonably non-toxic.
Parent
Re:Polyethylene Glycol? (Score:5, Informative)
Does the "poly" really change it all that much?
In a word, yes. Here are the Material Safety Data Sheets for both chemicals:
ethylene glycol [ox.ac.uk]
polyethylene glycol [ox.ac.uk]
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Re:Polyethylene Glycol? (Score:5, Informative)
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Re:It sounds like hitting water at high speed (Score:5, Informative)
According to the article: "Liquid armor is much more stab resistant than conventional body armor. This capability is especially important for prison guards, who are most often attacked with handmade sharp weapons."
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Stabbing... slowly (Score:5, Interesting)
So technically, if you manage to hold that prison guard still while you slowly push the shiv through his armor, it'll work just fine (for you, not the guard). Interesting -- so throwing yourself on the knife might actually be a useful defense!
It reminds me of a fight scene in Dune (was that the movie? -- does anyone remember this?); they had force fields that detected and warded off quick attacks, but allowed a slow entry into the field would be allowed... so the trick to knifing someone was to do it slowly.
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Resistant does not mean impenetrable (Score:5, Interesting)
So just because something resists stabbing doesn't mean it can't be done. Needles more so. The way a knife or needle works is based of of high pressure on a small amount of surface. Well a needle has a much smaller area to penetrate than a knife thus can achieve more PSI with less input force.
It may not be sewable by hand, it may need a machine with an extra hard needle but so what? BP vests are expensive items as is, it is ok if there are some extra manufacturing costs with this new kind.
Parent
Re:It sounds like hitting water at high speed (Score:5, Interesting)
There's an old trick with a paper towel tube, some salt, and wax paper.
If you put a stick through the salt slowly enough it pierces the paper. But if you ram it quickly the particles of salt bind and resist the force.
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Re:It sounds like hitting water at high speed (Score:5, Informative)
(Very) brief lesson in fluid dynamics.. Newtonian fluids obey this "law:"
Shear stress = - viscosity * shear rate.
Imagine you have two panes of glass. You lay one out horizontally and pour a layer of liquid on to it (we'll pretend it stays on and doesn't run off onto the floor). Then you place the second pane of glass on top. You apply a constant, horizontal force to the top pane of glass, and it begins to move at a certain velocity.
shear stress = the force * the area of the glass
shear rate = the velocity / the distance between the two panes (not really, but close enough for our example)
Fluids with viscosities that don't depend on the shear rate are called Newtonian. Water is largely a Newtonian fluid. It's viscosity depends very strongly on temperature, but not much on shear rate. Doubling the shrear stress (the force) would result in a doubling of the shear rate.
Ketchup is a good example of a non-newtonian shear-thinning fluid. If you put ketchup between your glass panes, you'd find that smaller and smaller amounts of additional shear stress are necessary to increase the shear rate by equal amounts. This is easy to understand, b/c our everday experience with ketchup tells us that it can take a big shock to get it moving, but once it goes, it goes quickly. (The viscosity is high at low shear rates, like when it isn't moving, and so a lot of shear stress is required. Once it starts, the shear rate goes up, the viscosity decreases, and less shear stress is needed).
The fluid in these vests is the opposite of ketchup. It is shear-thickening. At the shear rates the armor is subjected to in ordinary movement, its viscosity presumably remains low, allowing the soldier to move. But when someone tries to stab through it (a fast, high shear movement) it thickens (its viscosity increases) and the blade/bullet/whatever is stopped.
I don't know how the stuff is sewn, but it could be sewn slowly without a problem. Remember, it's shear rate that makes it thicken up.
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Re:Picture (Score:5, Funny)
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Re:won't kevlar still be the weak link? (Score:5, Interesting)
Kevlar fabric isn't really a lattice. It's woven from very fine strands of a plastic which is VERY strong under tension. The material also has a tremendous coefficient of friction and even when a strand is broken, it can often be held in place by being squeezed by its neighbouring strands; even under impact. Anyone who has ever handled kevlar can attest to this as the material will give you severe friction burns easily (imagine a bad papercut and carpet burn on one spot just by casually sliding your hand down a thread -- OUCH! I cringe just remembering the stuff).
A lot of the strength of kevlar comes from its weave; bulletproof applications and such have very fine weaves to prevent particles from getting between the threads. I assure you, it is VERY difficult to damage the kevlar weave badly enough that it is rendered useless. I did a university research project that involved kevlar, and I would definitely trust a battered and beaten kevlar helmet over a steel one any day.
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Re:won't kevlar still be the weak link? (Score:5, Informative)
The current limiting factor with soft armor is that it won't stop a rifle round (Due to its extreme speed). So to provide protection to NIJ III+ or IV levels (i.e stopping rifle rounds) hard armor plates (usually a ceramic and titanium composite) are inserted in over vital areas.
The advantage of the liquid armor is that much less fabric will be needed to provide the same level of protection, and the hard armor plates won't be necessary.
Hit www.galls.com 's body armor section for more info on levels of protection and whatnot.
-E2
(BTW: Shadowrun had the liquid armor idea waaayyy before Snow Crash came out.)
Parent
Re:Liquid Armor (Score:5, Insightful)
For example you may want something the country has *cough* oil *cough*. In that case you don't want to make the country uninhabitable. Not only do you want to make sure the occupying army is unharmed but you will need the labor of the civillians to make the gears of industry turn.
If we dropped nukes on iraq who would pump the oil and transport it to our ships? How could our soldiers stay in the country for a decade to make sure people do what we say?
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Put 'em away, kids... (Score:5, Insightful)
1) While logistics would be a pain, if the US camped a couple of carrier battle groups off the coast of a given country, they would own the sky and sea in short order. It becomes much easier to keep supplied when you can do that.
2) Iraq had something like the 3rd largest army in the world back in 1991, which the US effectively neutralized in a month or so. Again, airpower is king. The country isn't large or exceptionally modern, but it was quite a military foe.
3) If Iraq is small, then there aren't many countries that are a big military threat. Germany, the UK, israel... the list is small and we're on good terms of most of the strongest countries (coincidence? I think not)
4) The fact that the US hasn't fought a "big" country in years doesn't mean jack with regards to the ability to. I've never mugged someone, that doesn't mean I'm too weak to.
Sure, there's some arrogance from the US on the military front, it makes sense. Like it or not, the US posesses the strongest military force in the world.
Hate us for our culture, politics, whatever, that's an subjective opinion and you are welcome to them. But military strength is an objective thing, and hatred of the States doesn't diminish that.
And yeah, if we fought a united (!) Europe, we could probably be beaten. There are a zillion better reasons not to attack, least of all being that France is a strong ally...
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Re:Put 'em away, kids... (Score:5, Interesting)
1) Absolutely, air forces aren't a panacea. In responding to the fellow asking how a supply line would be supported, I invoked airpower. Since aircraft are very good at sinking ships and destroying ground forces, the supply lines would be pretty well protected. Of course you need ground forces to _keep_ territory, but you can kill most everything in it from a distance (artillery, air, missles, whatever).
2) Sure, some of the iragi leaders were bad, but there were some very tough forces. Not to mention more of them than american soldiers. I think it's a very bad idea to assume the enemy is stupid.
3) Regarding vietnam and to a lesser extent serbia (and somalia, etc.), the old saying is true: We didn't lose, we left. The US won the vast majority of battles in vietnam, and left for political/public concensus reasons.
4) If none of these float your boat, then just rack me up as a naive fool who refuses to have black and white opinions. You wouldn't be the first.
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Freshly Napalmed Forest (Score:5, Funny)
But wait -- there's more! -- the really best part of the Snow Crash quote is:
"
Stephenson may have his faults, but he's got the gift for cool similes.
-kgj
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not to be an ass... (Score:5, Insightful)
I was a soldier, am I a hero? Are football players heroes?
What about Iraqi soldiers, are they heroes?
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Re:Great Armor but Too Late for a Hero (Score:5, Insightful)
You belittling his sacrifice and claiming his career was silly is ignorant and disrespectful.
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Re:Its not that unusual... (Score:5, Insightful)
How about using a piezoelectric effect? Deforming the outer surface (e.g. a bullet strike) creates a charge that propogates through the fluid beneath the outer sheath and causes it to stiffen.
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