Military Develops Liquid Body Armor

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'."

Screenshots.

[monstroyer]

No screen shots on the linked page, but i work as personel in the michigan militia and have set up some servers to show you what the armor in action looks like.

• Man in liquid armor walking down the lab hallway. [digitalacb.com]
  This is joey, the lab assistant, going on a coffee run.
  
• Man in liquid armor enduring heat. [goingfaster.com]
  This test killed a few of our volunteers, but after many tries we finally worked out all the kinks.
• Liquid armor on half a face [squidge.org]
  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.)

Your tax dollars at work.

Countermeasures

[Anonymous Coward]

Lots of salt or huge silica gel packets.

Picture

[Anonymous Coward]

Here is a picture of a soldier wearing some [ibiblio.org]

Re:Picture

[AstrumPreliator]

I think he ate some too.

Re:Picture

[pixel-fodder]

amazing how less manacing the soldier looks as a result. Maybe an unanticipated side effect of this kind of body armour is that the opposing forces would be temporarily confused / rolling around in puddles of piss from too much laughter.

Call me dense

[Millbuddah]

I seem to remember a gradeschool experiment where we mixed cornstarch and water in a pan and tried to slap it. Thanks to the starch, the stuff would just kinda slap you back. Is this body armor kinda doing the same thing then?

Re:Call me dense

[lacheur]

Yes, this is the same type of process. Fluid when handled gently, but it becomes rigid when subjected to a sharp impact.

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].

Re:Call me dense

[pipingguy]

Fluid when handled gently, but it becomes rigid when subjected to a sharp impact.

I can see a huge market for this in sports gear (protective equipment). How would it react to an Al MacInnis slapshot [findarticles.com]?

Re:Call me dense

[kalel666]

I worked a few years ago for Brookfield Engineering (a viscometer and rheometer manufacturer) as Rheology Lab Manager. Part of my duties included conducting training classes monthly for customers.

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!

Re:Call me dense

[deglr6328]

" 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

Wow, these demonstrations sound very up close and intimate.

N on-Newtonian Fluids

[Anonymous Coward]

These are called non-Newtonian fluids. Here is the Wikipedia entry.

http://en.wikipedia.org/wiki/Non-Newtonian_fluid

Slap me bald and call me, "Myrtle"

[Roadkills-R-Us]

Don't tell the military! They'll really be annoyed they wasted all that money when they could have just used cornstarch.

Could be good for VIP protection

[Dav3K]

Armor that is lighter and more flexible would be more comfortable to wear. This makes it more likely to be worn. I would expect to eventually see designer suits utilizing this stuff to be bought up by politicians, rap stars, etc. Bascially anyone who would be interested in an armor plated limo.

Sounds like Snow Crash

[Trespass]

The skate couriers in the novel wore armor based on this principle. Flexible, but with an increasing resistance curve like a catcher's mitt. It's good that it's lightweight, because if it's too bulky to do your job in, it's not really useful.

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.

ThinkGeek Inspired!

[JNighthawk]

Very similar to Smart Mass Thinking Puddy [thinkgeek.com]. Is the military beginning to read /. and buy products from ThinkGeek for inspiration for R&D?

Snow Crash

[theparanoidcynic]

"sintered armorgel: feels like gritty jello, protects like a stack of telephone books."

See the effect for yourself

[Animus Howard]

Mix corn starch and water to form a paste. Stir slowly, or pour the mixture, and it acts like a liquid. Stir fast, or hit the surface, and it "breaks" like a solid, dissipating energy.

Next James Bond Movie!

[radiumhahn]

In the next james bond movie they will use this stuff in breast implants to make SUPER boobs.

Re:Next James Bond Movie!

[drinkypoo]

Shear-hardening breast implants are no joke - soft and pliable when you're nice to them, but try to bite down hard, and you're going to lose some teeth.

Don't know about liquid armor

[pegr]

Don't know about liquid armor, but I imagine if I was in an active war zone, I might fill my own armor with liquid!

Re:Don't know about liquid armor

[Soko]

Heh.

That would be STFU, bud.

(Sheer Terror Fluid Underwear, for those not versed in TLAs)

Soko

Its not that unusual...

[Cyno01]

Just a non-newtonian fluid. Go mix cornstarch and water, borax and something (forget what, its been a while since 6th grade science, dishsoap maybe) or get some of this [thinkgeek.com]. You get the same basic thing, but the point of this is that it probably doesn't shatter under the impact of a bullet... I've been kicking around the idea of something like this for a while myself actually, but more along the lines of that ferrous oil stuff they use in super high end variable shock absorbers that has a current applied to it and hardens when it senses a projectile. Not sure how to go about sensing that though, so a passive option i probably better.

Re:Its not that unusual...

[NonSequor]

Adding Elmer's glue to a solution of sodium borate (borax) will yield a substance very much like what was once sold as Nickelodeon Gak.

Re:Its not that unusual...

[Jim McCoy]

Not sure how to go about sensing that though, so a passive option i probably better.

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.

So it's a non-newtonian fluid

[swagr]

Like silly-putty or cornstarch and water.

It's actually surprising no-one has figured this out sooner. (or maybe the idea has been around a long time but the perfect materials were the key).

Infiltrate

[nightsweat]

What's the damage if this stuff does get penetrated? Is it worse for the wound than a bullet passing all the way through?

Very cool technology

[the_crowbar]

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_crowbar

As someone who opposes the war...

[Hanna's Goblin Toys]

I think I can speak for nearly all of us when I say the last thing we want is to see American soldiers die. That's kind of the whole point.

Re:As someone who opposes the war...

[Danny Rathjens]

Keeping American soldiers alive is not the whole point of opposing the war.
I do not want non-Americans to die either.

Incidentally, did anyone else note the peculiar capitalization of the word 'soldier' at every occurance in that article? Perhaps this is some kind of tradition in the ancillary defense research/business?

You speak only for Americans

[Gorimek]

By far most of the people who oppose the war are not American, and their primary reason to oppose it is the tens of thousands of Iraqis that were and are killed. Not that most people want the American soldiers dead, but those 700 are a much lesser concern, especially since they did do most of all that killing.

The tendency of Americans to completely forget/not care that there even were any Iraqis hurt is maybe the most disturbing thing about this country to me.

Inflexibility

[Infonaut]

I'm in the same status as Crowbar. The vest I wore had the same inflexibility problem the_crowbar mentions. It may not seem like a big deal, but it really is, particularly when you are in situations where range of motion is critical.

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.

That "Poly" makes a huge difference

[TubeSteak]

waxy substance [asu.edu]

Polyethylene glycol (PEG) is a water-soluble, waxy solid that is used extensively in the cosmetic and toiletry industry. As the molecular weight of PEG increases, viscosity and freezing point increase

Polyethylene glycol-electrolyte solution [nih.gov]

Polyethylene glycol-electrolyte solution (PEG-ES) is used to cleanse the bowel before a gastrointestinal examination or surgery. It works by causing diarrhea... Polyethylene glycol-electrolyte solution (PEG-ES) comes as a powder to take by mouth

Last but not least, the obligatory Google Search [google.com]

Great Armor but Too Late for a Hero

[mfh]

Sadly this invention was too late to save Pat Tillman [msn.com]. Armor like this could save lives, and that's what it's all about. I'm all for it.

not to be an ass...

[Run4yourlives]

But how does a footbal player turn soldier qualify as a hero, exacty?

I was a soldier, am I a hero? Are football players heroes?

What about Iraqi soldiers, are they heroes?

Re:Great Armor but Too Late for a Hero

[droleary]

Sadly this invention was too late to save Pat Tillman.

How very disrespectful to single out this one man out as "a Hero" for the mere media value that he played in the NFL. His pre-war job was to play a silly game for millions of dollars; how is that significant? It is a sad commentary that that is the reason his death gets any more coverage than other soldiers killed in this political bloodbath. The NFL probably paused for all of 5 seconds before casting him aside and filling his position with someone else, and now they're latching on to mountains of press coverage because he's dead.

It's hard to say that without seeming to take away from Pat or without seeming to sound like a troll, but it had to be said in light of you being moderated up. So, yes, think about why Pat went to fight, but don't forget about all the others who sacrificed to fight and who died without all the fanfare. You should be far more thankful for their history of anonymous sacrifice [arlingtoncemetery.org].

Re:Great Armor but Too Late for a Hero

[Performer Guy]

Rubbish, it's not disrespectful to anyone. The guy turned down $ millions to volunteer to go fight for a cause he believed in after returning from his honeymoon. That demonstrates unusual and quite incredible selflessness, sacrifice and commitment to his country, he was also well known and liked by many fans whatever you think of that. He made the Army Rangers, an elite force and now he's joined the ranks of America's war dead. Telling his story takes nothing away from the others, I remember when this guy joined up with his brother, he was being interviewed (nobody could quite figure out why he was doing it and he was reticent about going into details) and I remember thinking, "that's one hell of a guy", now we've learned today that he's been killed. If anything it brings the loss of the thousands of family members into sharp focus through our fleeting familiarity with this hero. And no I ain't even an NFL fan.

You belittling his sacrifice and claiming his career was silly is ignorant and disrespectful.

Basic questions

[LittleLebowskiUrbanA]

How heavy is it? How hot does it make the wearer? Can a Private break it?

Re:Basic questions

[raider_red]

Of course a private can break it, but not as fast or effectively as a lieutenant.

Scientific Paper & News Article

[David Hume]

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].

Another scientific paper.

[David Hume]

Another scientific paper on the subject: "The ballistic impact characteristics of Kevlar (R) [udel.edu]
woven fabrics impregnated with a colloidal
shear thickening fluid," JOURNAL OF MATERIALS SCIENCE 38 (2003) 2825 - 2833.

Motorcycles?

[Lord_Dweomer]

You know, just thinking about this stuff made me realize that it might have some great applications worked into motorcycle suits.

Also, perhaps this stuff could give stuntmen a whole new level of safety while still giving them a lot of mobility.

Degradation

[Bowling Moses]

Polyethylene glycol's pretty good on one hand: it's dirt cheap, comes in a variety of weights (we have on the shelf in lab average molecular weight PEGs from 200 to 20,000 daltons) and as has been mentioned above is nontoxic. What's bad about PEG is that it degrades fairly easily--it should be stored in the dark and kept cold, at least if you're going to use it as a reagent. This makes me wonder about the shelf life of the armor, although PEG degredation might not be the limiting factor; physical wear and tear might be.

Bulletproof Inners

[salmonz]

Does this non-toxie liquid stuff mean that if I were to drink it, I would be bulletproof? Wicked!

Re:Bulletproof Inners

[segfault7375]

Probably not, but your toilet would be. :)

Reverse process?

[torok]

So they're thinking of putting it in jump boots - once it stiffens up, does it then just become liquid again immediately afterward? Even when hit with a bullet?

Re:Reverse process?

[Goobermunch]

As I understand the science, the kinetic energy of the bullet causes a state change in the material. It gets hard. It dissipates the energy (most likely as heat) and returns to its liquid state quickly.

--AC

Military.com ripped the story

[NoYes19]

This is straight off of Army News Service. [army.mil]
And they even have a picture!

Sounds like it might be handy as bike armour.

[Moderation abuser]

As a motorcyclist, the kit I wear has a shit load of armour in it, shoulders, hips, elbows, back, shins, ankles but even with that the inevitable is broken bones when you slam into some street furniture.

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...

[Embedded Geek]

After all, liquid courage [guinness.com] has been a part of the military since the beginning of time.

The question of the future

[serutan]

"We would first like to put this material in a soldier's sleeves and pants..."

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?"

What the military needs

[AmericanInKiev]

The modern challenge for our military is not war mongering - we rule at making war - but peace keeping - that is respecting people and serving a population while being vulnerable to rogue dissendents.

This raises the need to identify the location of a stray bullet in real time.

Imagine a self organized network of wearable computers with pretty basic microwave doppler shift detectors.

Even a single bullet fired would create a doppler shifted frequency in a reflected microwave signal, and the network could compare notes and triangulate the trajectory - even calculating a return fire path and indicate if not photograph or return at least rubber bullets on the perpetrator.

That would be awesome defensive gear.

AIK

Try a demonstration...

[Genda]

There is a wonderful demonstration of how this works. Make a wet paste of cornstarch. You'll notice if you take a stick or even your finger and stir it around very slowly... it will act like a viscous liquid. It flows around your stick and the path left in the paste slowly fills back in. Now try moving the stick quickly through the paste and it suddenly becomes solid, the wet gloss of it's surface disappears, and the paste cracks and breaks like a hard material. Literally the force applied to the paste shifts it from liquid to solid state and upon release of stress it becomes liquid again.

This makes for a variety of interesting properties. A protective shield of this material was used as part of an engineering experiment at UCI in 1978, when a box of specific size was thrown off the engineering building and an egg in the box survived.

Genda

Re:Polyethylene Glycol?

[black mariah]

"Polyethylene glycol (PEG) is a water-soluble, waxy solid that is used extensively in the cosmetic and toiletry industry."

http://www.google.com/search?q=Polyethylene%20Glyc ol&sourceid=mozilla-search&start=0&start=0&ie=utf- 8&oe=utf-8
That's from the first link.

Re:Polyethylene Glycol?

[coryboehne]

And is used as a major component of both cough syrup and paintballs...

Re:Polyethylene Glycol?

[cybermace5]

Water-soluble, eh?

So...is this armor pretty much out of the question for amphibious units, or soldiers in the rain?

Does it freeze and shatter in cold weather, or bake out in hot weather? Does it absorb sweat during a march and then your armor runs down your leg?

There is a commercial preparation

[The Tyro]

of PEG... it's called Golytely... here's a bit of info. [pharmacyhealth.net]

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.

Re:Polyethylene Glycol?

[kegger64]

Most anti-freeze is proplyene glycol, not polyethylene glycol.

Re:Polyethylene Glycol?

[ramk13]

"poly" changes it completely. Binyl chloride is pretty nasty (much much worse than ethylene glycol), but polyvinyl chloride is PVC and that's all over the place. Generally when you polymerize a monomer you are using up the reactive sites that would normally cause toxicity to form bonds with other monomer molecules. The same thing goes for a whole lot of other monomers.

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.

Re:Polyethylene Glycol?

[All Names Have Been]

Does the "poly" really change it all that much?

Sodium explosively combusts in water! Chlorine gas is highly toxic! Can the combination really change their properties all that much?

Re:Polyethylene Glycol?

[Sexy Bern]

Any chemist worth his salt would be able to answer that.

Re:Polyethylene Glycol?

[jfengel]

Yeah, it does quite a bit. PEG is used in shampoos and drugs all the time to make them nice and goopy.

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.

Re:Polyethylene Glycol?

[afidel]

The main reason that Ethylene Glycol is toxic is that a metabolic byproduct is glycoaldehyde, a close relative of Formaldehyde, the acidosis is bad but would rarely be fatal on its own. The treatment for Ethylene Glycol poisoning is Ethanol ingestion because "Ethanol will competitively inhibit alcohol dehydrogenase", so if someone ingests EG give them a glass of Vodka and take em to the ER for observation.

You're both right

[The Tyro]

at certain stages of metabolism, both of the products you and the parent poster mentioned are formed.

In years past, the only treatment was competitive enzyme inhibition via an alcohol drip (that's still the treatment in some places)... though fomepizole (Trade name is Antizol, I believe) is the safest treatment now, and a hell of a lot easier to get than persuading the pharmacy to mix up an ethanol drip.

Ethylene Glycol is a nasty poisoning... and thankfully not that common. I'm pretty thankful that I hav

Re:Polyethylene Glycol?

[ItMustBeEsoteric]

Ethylene Glycol: C2H6O2

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]

Re:Polyethylene Glycol?

[Mad Alchemist]

Sort of. Ethylene glycol looks like this:

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! :)

Re:Polyethylene Glycol?

[IO ERROR]

Polyethylene glycol is found in a lot of cosmetics and even some foods. It is sometimes used to treat constipation. Remember, Google is your friend.

Re:Polyethylene Glycol?

[evanbd]

Yes, it does. Or at least can, I don't know about this specific case. Ethylene Glycol has an ethylene functional group in it, which is characterised by a reactive carbon-carbon double bond. That reactive bond is almost certainly related to its toxicity. The poly in polyethylene glycol refers to polymerization. In this process, that double bond is converted into a single bond, and attaches on either end to another ethylene glycol molecule, creating a long chain of single bonds, which are far less reactive and quite possibly nontoxic. I don't know about PEG in specific, but a modest knowledge of polymer chem suggests that is what's happening. I'm sure someone can correct me if I've got it wrong, though.

Re:Polyethylene Glycol?

[sTalking_Goat]

chemistry is a starnge and wonderous thing. One electron on a chlorine molecule stands between it possibly giving you cancer.

Re:Polyethylene Glycol?

[eaolson]

How is that non toxic? Ethylene Glycol is the antifreeze you find in coolant and windshield wiper fluid and I assure you it is very toxic. Does the "poly" really change it all that much?

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.

Re:Polyethylene Glycol?

[rrkap]

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]

Re:Polyethylene Glycol?

[emarkp]

Not only is it "non-toxic", but it's an ingredient of one of my favorite carbonated beverages, Dr Pepper [wiw.org].

Re:It sounds like hitting water at high speed

[jimmcq]

its resistance to stabbing has to be called into question

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."

Re:It sounds like hitting water at high speed

[sTalking_Goat]

*sigh*

that is exactly the parent's point. If its stab resistant how can it also be sewable. Since sewing is essentially stabbing a piece of cloth with a needle that has some thread going through it.

Re:It sounds like hitting water at high speed

[Threni]

>*sigh*
>
> that is exactly the parent's point. If its stab resistant how can it also be sewable. Since > sewing is essentially stabbing a piece of cloth with a needle that has some thread going > through it.

It's probably the same reason you can pour it slowly as a liquid. When you sew it you're using a small amount of energy on a small area, whereas a bullet has a lot more energy and mass and causes more of a chain reaction. Probably.

Resistant does not mean impenetrable

[Sycraft-fu]

All body armour is resistant against what is intended to prevent, not invincible. Bullet proof vests are actually nothing of the sort, they are bullet resistant. Shoot a Type II vest with a 9mm pistol round, it won't penetrate, shoot it with a 5.56mm rifle round, it'll go right through.

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.

Re:It sounds like hitting water at high speed

[Cruciform]

Speed is probably a factor as well.

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.

Stabbing... slowly

[jtheory]

I wonder... sewing it at a high speed would probably break the machine, but as long as you keep everything slow, you're fine.

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.

Re:Stabbing... slowly

[Verteiron]

That was Dune, yes. Although this stuff reminds me more of Niven's "impact armor", a sort of jumpsuit that would go completely rigid upon impact. Padding on the inside would shield your body from the transferred kinetic energy. If the impact was localized, the rest of the suit retained mobility. With a full suit of this stuff it was possible to fall off a small building and land on your head. You'd be jostled and have a mild concussion, but you'd be alive and able to walk away in one piece.

Re:Stabbing... slowly

[SatanicPuppy]

I keep thinking of Neal Stevenson:
"Sintered ArmorGel...Feels like gritty jello, protects like a stack of telephone books"

Re:It sounds like hitting water at high speed

[kippy]

Nifty stuff, although it seems that its resistance to stabbing has to be called into question when you consider that it's also sewable.

not getting into situations where it breaks down to a knife fight is probably the best defense against that.

Re:It sounds like hitting water at high speed

[chadjg]

Sure, you're right, but is that realistic?

Take a prison guard, for example. I'm sure they have institutional procedures and general street smarts to help them out, but they still get hurt. That's why they need things like this.

But, 7.5 pounds of sweaty armor just for stab protection is a lot of weight, and asking someone to wear another vest just for ballistic protection may be unrealistic. A vest that does both and is more comfortable than standard armor could be useful.

And notice that the above item is designed for protection against ice picks. Knives aren't the only things that can puncture a person's hide. I defy anyone to see and avoid an ice pick in the middle of a crowd.

Re:It sounds like hitting water at high speed

[Rostin]

Actually, no, it doesn't.

(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.

Where does Kevlar Putty [tm] come from?

[Roadkills-R-Us]

...Silly Putty , but presumably it's hard to impregnate Kevlar with it.

I really don't want to know how this works.

Re:It sounds like hitting water at high speed

[gbjbaanb]

yes I have - at school (years back) we had a term where we were taught 'home economics' (as it was called back then). I learned how to use a sewing machine, and how to cook rice. Can't remember anything else though, but it's good to know that the taxpayers money wasn't entirely wasted.

You have a foot pedal where you can change the speed. you can make the needle rattle along pulling the fabric out of your fingers (well... oops, ow, ow, scissors needed here), or really, really, really slowly - generally used

Re:Liquid Armor

[killjoe]

What's funny is that we already have a massive kill to killed ratio.

Even in iraq we have only lost 700 soldiers compared to tens of thousands of iraqis killed. One day in the not too distant future we will be able to kill hundreds of thousands of people without losing a single US soldier or even having one injury.

I don't know if that's good or bad to tell you the truth. When wars become even more painless I suppose we might wage them more often. OTOH we tend to wage war every few years now as it is.

Re:Liquid Armor

[Anonymous Coward]

One day in the not too distant future we will be able to kill hundreds of thousands of people without losing a single US soldier or even having one injury.

Been there. Done that. It's called Hiroshima and Nagasaki. Look it up.

Re:Liquid Armor

[John Courtland]

All but one of the guys who dropped the nukes committed suicide. 3:250000. Respectable I suppose.

Re:Liquid Armor

[orthogonal]

All but one of the guys who dropped the nukes committed suicide.

And so did many victims of the Holocaust. [healthscout.com]

And yet, many of the Nazis who committed what were -- unlike Hiroshima and Nagasaki -- unarguably war crimes, did not commit suicide, and some continue to collect pensions from the German government to this day.

I'm not trying to say that no American ever committed war crimes; My Lai [wikipedia.org] was also unarguably a war crime (and may Calley burn in Hell!), and some of the U.S. military's actions in Iraq -- as in throwing prisoners in a river to drown [libertypost.org] -- surely are atrocities.

I'm just pointing out that suicide isn't necessarily what the guilty do. Indeed, I'd be inclined to suggest that the really guilty, people like Josef Mengele [wikipedia.org] ("Angel of Death" responsible for human experimentation at Auschwitz, died vacationing at a Brazilian beach), Rudolf Höß [wikipedia.org] (first commandant of Auschwitz, executed), and Erich_Priebke [wikipedia.org] (perpetrator of the Ardeatine caves massacre, still alive), tend to be so -- for lack of a better word -- evil that they feel they're not guilty and therefore feel no need for suicide or other punishment. (Indeed, Priebke so strongly felt that the killing 350 Italian civilians was not his responsibility but the responsibility of those who ordered him to do it, that he openly admitted his actions from fifty years later to a television news crew's cameras -- and it was only this admission that led to his trial).

For the record, I believe that the bombings of Hiroshima and Nagasaki were no more illegal than any bombing of cities in the war -- and all major combatants bombed cities in World War II. Dead by conventional bomb, dead by V1 rocket, dead by fire-bombing, dead by atomic bomb -- they're all dead. I'm unaware of any difference in ways of being dead, with the possible exception that atomic bombs mean a quicker death.

Also, for the record, I believe any crime involved in dropping the atomic bombs pales beside the atrocities committed by the Japanese in Korea, China (in "the Rape of Nanking" [tribo.org] (warning: link includes a disturbing picture of mass decapitation) the word "rape" is used pretty literally -- but includes ripping babies from their mothers' arms and bashing the babies' heads against walls, prior to raping the mother), the Philippines, and the Bataan Death March, not to mention the Japanese forced labor camps in which tens of thousands died.

To those who contend that we "could have" beaten Japan without recourse to atomic bombs, I ask them how many more America boys would have had to have died to achieve an unconditional Japanese surrender using only conventional weapons -- and if those arguing against using atomic bombs had any of their family members on the line.

I wasn't in the Pacific fighting Japan, but Paul Fussell (later professor of English at the University of Pennsylvania) was -- after fighting Hitler's legions in Europe -- and I'll defer to his opinion and that of the other boots on the ground: "Thank God for the Atomic Bomb" [cuny.edu]

But let me ask you: how many American boys would you have sacrificed in further conventional war against Japan, so that you, safe at home, could claim the moral high ground of an atomic-bomb-free but protracted conventional war ?

Re:Liquid Armor

[It'sYerMam]

"with the possible exception that atomic bombs mean a quicker death."

Excuse me? A quicker death my ass! If you were dying of radiation sickness right now, or were a child with one and a half arms, soon to die from cancer I don't think you'd be so keen to drop nuclear bombs.
I do not know whether it was "economical" (although using that word in references to human lives disgusts me) to drop the bombs, but doing something such as that was definitely an atrocity. Perhaps it was the lesser of two evils, but it was still damn evil - and everyone should recognise that.

When it comes to a falloutesque situation, I hope it was, at least, "economical."

Re:Liquid Armor

[Anonymous Coward]

Nukes are not always desirable.

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?

Put 'em away, kids...

[el-spectre]

Couple of issues here (avoiding the whole flame aspect):

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...

Re:Put 'em away, kids...

[el-spectre]

Just to clarify a couple of things:

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.

Re:Don't think so..

[killjoe]

Israel is more likely to explode bombs in the US by smuggling them in then to try and launch them from missiles. They have a very large spy network in the US and it would be very easy to smuggle in nuclear bombs and plant them at the hundred largest cities in the US. Let them all go at once and we are pretty much sunk.

The worry about israel is not so much that they see us a threat (after all they suckle on our teats) it's that they are a rougue nation which believes that international law does not apply to them.

Re:won't kevlar still be the weak link?

[Thai-Pan]

I think your instructor is a little bit misinformed.

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.

Re:won't kevlar still be the weak link?

[theLOUDroom]

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.

I think you're forgetting a KEY factor here. A kevlar helmet would be useless. The bullet

Re:won't kevlar still be the weak link?

[paganizer]

You may take the steel helmet, but i'll go for the Mithril every time.
Stylish, light and very, very expensive(Have you priced it lately? it's out of this world).

Re:won't kevlar still be the weak link?

[eericson]

Your instructor was talking about the hard Kevlar for the PAGST helmets. Kevlar vests (which ironically usually aren't Kevlar anymore, rather some kind of Aramid fiber) are still a lattice or weave of fibers. They work on two priciples 1) Extending the moment of impact by stretching out, and 2) by spreading the force of the impact across a wider area. When a bullet hits a "Kevlar" vest, the vest doesn't stop it cold instantly, rather the vest fibers stretch and entangle the round and slow it's progress. (The vest and bullet do actually move back into the body cavity slightly, but not enough to do permanent damage).

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.)

Re:Emergency Laxative!

[gbjbaanb]

"Sarge! I gotta crap bad, but I can't!"

"dont panic son, we're into combat soon, oh, and you're on point"

"phhhrrrrrrrrp" :)

Re:Sounds like a Good Idea

[Shinobi]

Read this, it could be useful for you: Data about vest classes [bulletproofme.com]

Freshly Napalmed Forest

[handy_vandal]

All the Snowcrash quotes left out the best part about the armor: "A bullet will bounce off its arachno-fiber weave like a wren hitting a patio door." Probably not applicable, but damn I love that line... I'm still laughing about it years later.

But wait -- there's more! -- the really best part of the Snow Crash quote is:

" ... but excess perspiration will waft through it like a breeze through a freshly napalmed forest."

Stephenson may have his faults, but he's got the gift for cool similes.

-kgj