Liquid Armor the New Bulletproof Vest

kjh1 writes "Armor Holdings Inc. plans to start selling their 'liquid armor' next year. The new armor, originally envisioned to be spread on like peanut butter, is instead sprayed onto Kevlar in ultrathin coats. From the article: 'it's a mix of polyethylene glycol, a polymer found in laxatives and other consumer products, and nanobits of silica, or purified sand. Together they produce a "sheer-thickening liquid" that stiffens instantly into a shield when hit hard by an object. It reverts to its liquid state just as fast when the energy from the projectile dissipates.'"

Video link

[skurk]

There's a video on break.com where you can see the liquid armor in action - it's pretty amazing:
clicky [break.com]

...the slow blade penetrates the shield

[ElHorrendo]

...but look down. We'd have joined each other in death.
    --Dune

What about Ringworld?

[spun]

Larry Niven's Known Space series has armor exactly like this, that stiffens on impact. The only thing the armor has in common with Dune is that a slow impact gets through, IIRC in Dune they used some kind of force field. Larry describes what it's like to try to run in a suit like this while being peppered with automatic gunfire. Kinda funny. I don't think the Dune force fields stiffened up and made you fall over while being shot...

Re:Video link

[BarryNorton]

So how would this have protected his Sergeant's groin?

"What are you doing, soldier?"

"Painting my groin, sir..."

Re:Video link

[corychristison]

Great....

So I have the choice of one DRM infested video, or another DRM infested video wrapped in a Flash Movie. Thank you. :-P

I was forced to see it in a slightly different version of the DRM infested video wrapped in a Flash Movie [google.ca]. ;-)

Re:Video link

[Agent00Wang]

That video is pretty neat. Maybe there could be an application on rigid surfaces like reinforced windows and such.

Re:Video link

[CaseyB]

Yeah, because when they say "bounce off", they obviously mean that it reflects the bullets away perfectly at their original speeds. Hence, they are *doubling* the energy of the impact in the perfectly ideal billiard-ball reaction that happens every time a bullet hits the armour in real life.

Of course, they also have the benefit that whenever someone shoots at the armour, the bullet is bounced directly back down the barrel of their gun, possibly killing them.

Re:Video link

[rco3]

Right you are. "Stuck or bounce off" is correct. GP's point is that a bullet that hits and sticks imparts energy to the target equal to the kinetic energy with which it arrives. A bullet which hits and bounces off imparts energy equal to the kinetic energy with which it arrives PLUS that with which it leaves (more or less, assuming that it leaves in exactly the opposite direction, etc. Yes, I'm simplifying). In other words, a ball that bounces off your nuts hurts more than one which sticks.

Re:Video link

[kkwst2]

Your logic is indeed false. First, it is arriving with a velocity and an associated momentum, not a force. Force is imparted on the bullet to change it's momentum and direction. Thus if it's really bouncing in the opposite direction, then twice the energy is required to stop it is imparted to the armor. See the sarcastic reply under yours for why this is unlikely the case. Most fo the time it would likely be deflecting off, requiring less energy than that required to stop the bullet. However, this still tells you nothing of the force. The peak force imparted to the bullet will be determined by the interaction of the bullet with the armor and contact time of the bullet with the armor. However, it's not even the force that you care about, it's the pressure imparted to the tissue. This will be determined by how the force is distributed over the armor. The force will be much greater if it's distributed over a 1 cm^2 area as opposed to a 1 m^2 area. To sum up, it's complicated and you can't draw conclusions of the performance of this armor by whether it "bounces off" or not.

Re:Video link

[X0563511]

True, but if the flesh under the armor gets hit too hard (penetrated or not) hemorrhaging will result, a situation possibly more dangerous than an open wound. Also consider that if that hit your kneecap, it would likely shatter it... and the bone fragments moving in response to that impact would likely cause bleeding on their own.

Re:Video link

[Hadlock]

I don't know about you, but I'd rather chance a massive bruise than a hole going through me, , potentially puncturing a vital organ. It's incredibly difficult to get blunt trauma of such impact that it creates internal bleeding that could kill you in less than 30 min. It's a small bullet, not a Mack truck. You can run away with a bruised calf muscle; you can't even walk when a bullet just shredded your calf into hamburger. This is a stupid argument.

Re:Video link

[SatanicPuppy]

You're right. The only "extra" energy is elastic recoil from the material, and that is not amplified. Getting "extra" force off an impact would violate conservation of energy.

The real reason it's better to have it bounce off is that the energy of impact is distributed over a wider area. Sure, getting shot in the nuts with no protection but this armor is going to put your childbearing days to an end, but it's probably not going to kill you, as opposed to the massive tissue damage that would result in getting shot with no protection. the bullet might go all the way through (thus imparting less energy) but everything between the point where it entered and the point where it exited would be hamburger, and an area in diameter proportional to the caliber of the bullet would suffer serious shock damage.

The way this stuff will end up being used, is over certain strategic pieces of hard armor, so the problem with transferring more energy to a delicate area will be minimized, and the type of protection can change from heavy plates (which have to be able to stop a bullet themselves) to kinetic padding to distribute impact. The advantage of being able to wear full body armor that is light and breathable cannot be overstated. Currently you can only wear very little armor because of the weight, which increases casualties from things like shrapnel which would be little more than a nuisance to someone wearing a suit of this stuff.

Re:Video link

[SatanicPuppy]

No no, didn't you read the grandparent? When the bullet hits your nuts, your nuts punch back with twice the force of impact doubling the energy of the equation, which means the bullet flies off at between 4600 and 6000fps with no deflection (of course), so it's almost certain to blow a hole the size of (conservatively) a bowling ball in the unlucky terrorist who decided unwisely to try and take on your nuts.

Unfortunately the doubled energy of the equation causes your nuts to collapse into a singularity which is at least as bad as getting shot in the nuts with no armor, and maybe even worse. //Not sure what it is about people and Newtonian physics...Your post made me laugh out loud.

Re:Video link

[Fnkmaster]

Can we ... PLEASE... stop talking about groin shots?!??

Thanks.

Re:Video link

[SatanicPuppy]

It's because they go through it. That's why you wear ceramic armor under your kevlar. Kevlar doesn't resist penetration, its just very strong, so it tends to slow a bullet down considerably.

Re:Video link

[SatanicPuppy]

No, it's not the same thing. Kevlar is just fabric. Bullets go through it because it's individual filaments are not strong enough to resist a kinetic impact from a bullet. It is used because, as a material, it has a very high tensile strength, but even so, kevlar body armor consists of many layers, and is designed to stop the bullet eventually hopefully before penetrating to the person, but not always.

This is why it's useful in tires, not because it "resists punctures". Tell me how well your tire resists pu

Re:Video link

[AJWM]

Kevlar alone just has very high tensile and shear strength. It will resist cutting (which is why kevlar gloves are often used by butchers or fishermen cleaning their catch). It's the particular weave of the kevlar in vests that makes them bullet resistant. (Earlier vests were made of nylon, but that's much bulkier for equivalent stopping power.)

As an ancestor post pointed out, the kevlar just slows down the incoming bullet. For a rifle bullet at 2000-3000 fps, it slows it down enough for the ceramic pla

Energy, yes. Momentum, not so much...

[khayman80]

You're right about energy transfer. A bullet bouncing off really DOES carry away its kinetic energy, rather than depositing it in the armor as heat or deformation or pressure waves. Momentum, on the other hand, is a different story...

Point #1: Momentum is a vector quantity. This means that a bullet approaching a person from the left and a bullet leaving said person, heading right, have totally different momentum vectors.

Point #2: In situations where outside forces can be ignored (such as a bullet impact), momentum is said to be "conserved". This means that any momentum change the bullet experiences has to be equal and opposite to the momentum change the person experiences. A bullet of mass "m" which is travelling to the right at speed "v" has momentum "mv" (taking the direction "right" to be positive). Similarly, the same bullet travelling to the left at speed "v" has momentum "-mv". Therefore, a bullet which ricochets off at its initial speed has TWICE the momentum change compared to a bullet which simply stops. As a result, the person has to experience double the momentum change as well.

This means that a ricochet imparts MORE momentum to the target than an embedded bullet would, which is (as another poster remarked) why solar sails are reflective.

Re:Video link

[AndersOSU]

Not really, polyetylene glycol (PEG) != ethylene glycol.

But anyway, both PEG, and sand are really cheap, so depending on what is published you should be able to make this at home if you are so inclined.

I'd also expect the DuPont company to try to bring this to market - maybe in their auto paints? I'd be willing to bet they provided significant funding based on the fact that the demo utilized kevlar, and that the research was done at the university of delaware.

I wonder how simple this really is, while PEGs vary greatly in molecular weight, and there is an infinite span of concentrations, really, knowing only what the video told us, anyone with an interest should be able to figure it out.

Re:Video link

[IAmTheDave]

I'd also expect the DuPont company to try to bring this to market - maybe in their auto paints?

Just don't paint too quickly, or your brush might suddenly become a hammer.

Re:Video link

[AndersOSU]

There is an interesting point in there, spray applications are characterized as extremely high sheer. It seems that the armor was basically saturated with this stuff, spray coating would probably be impossible, this stuff would turn into a rock in your sprayer. If this were to make it to an auto market it might have to be applied with a squeegee, or a dip process.

Re:Video link

[misleb]

But anyway, both PEG, and sand are really cheap, so depending on what is published you should be able to make this at home if you are so inclined.

How do you make nano particles of silica?

-matthew

Re:Video link

[Dun Malg]

I'd also expect the DuPont company to try to bring this to market - maybe in their auto paints?

Sorry? What use is a paint that stays liquid until struck by a sharp blow?

Motorcyclists!

[DonGar]

How well would this work as armor for motorcyclists? I spend a lot of time trying to find gear that's comfortable enough to wear as normal clothing. Both so that I'm comfortable on the bike, and so I don't have to spend so much time gearing up and down for each trip, even it it's only to the convenience store.

Re:One Question...

[budgenator]

Well because it's shear-thickening liquid, the more violent the impact, the more it locks up and spreads out the impact. One market that they are initially targeting is prison guards because the threat to them is from stabbing rather than gunshot or shrapnel, which the liquid armor stops yet remains flexable unlike plate armor that is rigid. The thing that will always annoy you when wearing armor is weight, heat build up and lack of flexability; this stuff should put a dent in all three.

This stuff sounds like..

[cayenne8]

This stuff sounds like liquid "Stretch Armstrong". The thing was pretty mushy and pliable, but, man if you got hit over the head with one of those...you were 'out' for awhile...

Other Applications

[Umbral Blot]

Ok, forget the bulletproof vests, because I'll never need one. But how much would it cost to coat your car in this stuff? And would it give extra protection?

Re:Other Applications

[JanneM]

But how much would it cost to coat your car in this stuff? And would it give extra protection?

Nope, not if it's your safety you're worried about, rather than the cars. You want the car to deform, so your decelleration slows down. Just like a helmet, you want it to break so you don't.

Re:Other Applications

[jimicus]

True story: I had a neighbour who just could not grasp this concept. They'd heard about a modern car which had crumpled really badly in a relatively minor accident, writing it off. They'd therefore decided that older cars built like brick outhouses were far "better", because you might still have a car after the accident.

Try as I might, complete with diagrams and models, I could not get across the idea that this was a good thing, and that had the car not done the crumpling, the passengers would have - and who cares if the car's repairable when everyone in it's dead?

Re:Other Applications

[Anonymous Coward]

Try as I might, complete with diagrams and models, I could not get across the idea that this was a good thing, and that had the car not done the crumpling, the passengers would have - and who cares if the car's repairable when everyone in it's dead?

This is a common fallacy when people have just a rudimentary understanding of physics and no other applicable knowledge. A car that crumples well is only definitely better when it's car vs much more massive stationary solid object (e.g., a rock face). When it's two cars, however, it's more like the game theory example of the prisoner's dilemma. If both cars crumple well, then it's fairly good for both. If, however, one vehicle is both more rigid and more massive—something common to older cars—then the situation is greatly weighted in that vehicle's favor. An extreme example of this would be an M1 Abrams vs a small Toyota.

Thus, if you don't give a shit about the other guys as long as your kids are safe, and you're not a drunk/wreckless driver that is likely to slam into a building/rock face/telephone pole/whatever, the safest option may well be the biggest, heaviest vehicle with a strong frame that you can possibly find.

Re:Other Applications

[Haeleth]

if ... you're not a drunk/wreckless driver that is likely to slam into a building/rock face/telephone pole/whatever

I would think it very unlikely that a driver reckless enough to be likely to slam into buildings or rock faces would remain wreckless for long.

Re:Other Applications

[klaun]

This is a common fallacy when people have just a rudimentary understanding of physics and no other applicable

example of this would be an M1 Abrams vs a small Toyota.

heaviest vehicle with a strong frame that you can possibly find.

Your example relies on a signficant difference in mass as well as overall rigidity of the two vehicles in question. Deformable frames being about absorbing energy (and momentum, being an inelastic collision) in an impact. An M1 brings way more Kinetic Energy to the impact than can be absorbed by a deforming frame of a Toyota.

The safety of the passengers is dependent on how quickly the vehicle passenger compartment decelerates, as that will determine with what force they impact the interior of the vehicle (the so-called "second impact"). The M1 will not decelerate very much, but it is because of the mass disparity, not that it is rigid.

Obviously a crumple zone cannot absorb an unlimited amount of energy, but up to the amount it can absorb it is definitely good for you, whether you are hitting something rigid or not.

Re:Other Applications

[Steve525]

Good point. I'd add that in the example of old rigid car hitting a new car with crumble zones, the crumple zone of the second car will slow down the deceleration of both cars. In effect, the crumple zone of the second car serves both cars equally well (although half as well as if both cars have crumple zones).

(the following is directed toward the GP...)

So, sure drive a big heavy tank, and if you hit a well engineered Toyota you'll do great. Too bad about that Mom and her kids you just plowed through, tho

Re:Other Applications

[GalacticCmdr]

A couple of friends of mine ran into a M60A2 tank with volkswagen beatle, and I can assure you that any car has plenty of crumple zone when it hits a tank weighing 60-70 tons! Actualy they were quite lucky and both was thrown through the winshield and woke up on top of the tank rather than under it like their car.

Did these "friends" of yours also happen to have a car full of explosives and yelling "God is Great" when they hit the tank.

Re:Other Applications

[Anonymous Coward]

Actually, this is not true. I've got some friends who do car safety analysis all the time and they say that a modern crumple zone + rigid passenger egg is safer than a rigid car or light truck in a collision - the crumple zone absorbs most of its car's energy and the rigid car flips over.

There are many dead SUV drivers to disprove your claim.

Re:Other Applications

[hawg2k]

You could try explaining it in dollars and cents, so to speak. I'm sure your insurance companies claims department could explain how medical costs and bodily injury/death related lawsuits tend to cost much more than repair and property damage related lawsuits do.

Some people don't speak physics, so you just have to find their "language".

Just a thought.

False dichotomy

[snowwrestler]

Even big heavy modern cars have crumple zones engineered in. A 6000 lb car with a crumple zone will always be safer than a 6000 lb car without a crumple zone.

Re:Other Applications

[awol]

I saw a fairly reputable television demonstration (http://fifthgear.five.tv/jsp/5gmain.jsp?lnk=601& f eatureid=301&pageid=-1) of a "rigid" vs "rigid passenger + crumple" offset head on impact. The two cars were a Land Rover Discovery and a Renault Espace MPV. The results were pretty spectacular and the Espace wins clearly. I also recommend the earlier test of "Old Espace" vs "New Espace" if you can track it down on the same site. (Found the video at Renaults web site http://www.renaulttv.co.uk/main.p [renaulttv.co.uk]

Re:Other Applications

[nasor]

How the hell did this get modded to +5? This deserves a "-1, poster probably failed Introduction to Physics" mod option.

It is always safer to be in a deforming vehicle during a crash, assuming the vehicle doesn't deform so much that it crushes you. It doesn't matter whether you're crashing into a tree, an SUV, a tank, or another deforming vehicle.

If you hit a crumpling vehicle with your truck, the crumpling will decrease the elasticity of the collision and reduce the acceleration experienced by both

Re:American SUV?

[Fishead]

Nice stereotyping.

What if the prime reason for my big SUV with the big tires, and the skookum bush bar on the front is so I can say, go offroad? I grew up in a remote town, but now due to work I have to live in the city. I drive my bush beast on the road not to intimidate as you say, but rather for my own reasons. I like to throw my boat on the roof and go where few can go. My friends and I found a sweet de-activated logging road one day with trees growing in the middle of the road that were 2 meters tall. Sorry, but your honda civic can stay in the city. There was nobody around for prolly 15km. When I got back to work the next week, I was much less stressed out and misserable. Something about tossing a new propane cylinder in a fire puts a nice close to a sweet adventure! I believe in low impact offroading, but when the trees are in the middle of the road... fair game I say.

Now, thos SUV's with the low profile tires and chrome bush bars... I agree with you on that.

Re:American SUV?

[Skater]

Yep, and there are plenty of people that need an SUV for work or whatever. Most anti-SUV people I know don't have a problem with people that actually need something like that. The Chevy Suburban has existed since the 30s or something, LONG before the SUV moniker and hatred appeared, and they've sold models every year they made them.

Re:American SUV?

[LurkerXXX]

What if the prime reason for my big SUV with the big tires, and the skookum bush bar on the front is so I can say, go offroad?

If this is really what you bought it for (and actually do), Congratulations. You are one of the 0.5 % of SUV owners who actually should own an SUV. Unfortunately, 99.5 % of them are owened by soccer moms and men who need to overcompensate for something, and are just endangering us all on the roads, and burning very excessive amounts of gasoline.

Re:American SUV?

[Epyn]

My wife's geo prizm handled one of the largest blizzards i'd seen in ND very nicely.

The whole 'big vehicle' = 'better in snow' thing is something people made up. People who rarely drive in snow and don't know that even with snow on the ground you have fine traction.

Then they hit that one special stop sign that has a sheet of ice covered by a layer of snow, and -bam- they slide into an intersection in their biggun truk. Larger mass doesn't fix inattentiveness.

Re:American SUV?

[JDevers]

Here is the problem though, you are the type of person who would have bought an SUV 20+ years ago (yea, they've been making several for at least that long). Most people that buy them now are NOT like you. When one can go to a center city Chicago car dealership and the lot is more than half full of SUVs most of their clientele isn't buying them to go offroading.

Another example, I live in a mostly rural state (Arkansas). I happen to live in an area that is fairly urban but not too far from significant outd

Re:Other Applications

[TubeSteak]

My theory is: As long as the other guy's car deforms, things should work out just fine for you and your steel frame retromobile.

Just try not to run into any trees or other non-crumple zoned objects.
 

/Any safety features are irrelevant if you're not wearing a seatbelt.

Re:Other Applications

[Patrik_AKA_RedX]

Other than on the windows it wouldn't protect much, quite the opposite. If you frontaly collide with something, the deforming of the motor compartiment absorbs a lot of the kinetic energy your cars has. If it can't deform, the other parts would have to deal with that energy. And those are the parts you would be sitting in.
That is, assuming such a coating would have any effect when applied in that way.

Re:Other Applications

[mobby_6kl]

> Ok, forget the bulletproof vests, because I'll never need one.

Never say never!

Re:Other Applications

[AndersOSU]

The real selling point of this stuff in car finishes wouldn't be that your car is now bullet proof (although that would make a good bullet point in the brochure.)

Consider this:

We drove this new Ford(TM) Mustang(TM) with DuPont(TM) Protectoguard(TM) coating on the Jersy turnpike, for 200 miles, in construction, behind a Peterbuilt(TM) dumptruck. We recorded 390 discrete stone strikes. But thanks to the Miricles of Science (TM) there isn't a single paint chip in the finish. Blah Blah Blah. Now that's a BOLD move.(TM)

Damn, now I'll have to respec

[Moraelin]

This material (the liquid is only one component, anyway) is protecting against piercing, not crushing.

Darn. Now I'll have to respec my Rogue to use maces instead of daggers.

Re:Other Applications

[AndersOSU]

Not necessarily. The liquid armor in question is a dilatant [wikipedia.org]. It should provide stiffening in any region in which there is a large shear stress (there is definately a large shear component in a "crushing" auto accident.) While I doubt that this technology could protect you from a truck impact, it would likely stiffen the region of impact. This could be a good thing, like if you are being T-boned - the added rigidity increases the amount of impact your vehicle's side could withstand, or it could be a bad

Okay what the fuck

[Anonymous Coward]

First the military is developing something called an "ultrasonic tourniquet", now somebody is making bulletproof peanut butter?? Fuck this shit, the universe is just too weird right now. I am going to bed.

Comment removed

[account_deleted]

Comment removed based on user account deletion

"a polymer found in laxatives"

[Riktov]

"it's a mix of polyethylene glycol, a polymer found in laxatives..."

As if having a gun fired at you isn't enough to make you shit your pants...

Magic Chocolate

[dustpuppy]

... they found that the materials worked best when painted on Kevlar in ultrathin coats. By holding the fibers tight like a flexible glue, the compound spreads out the impact of a blow better than fibers alone.

Imagine the practical jokes you could play with this stuff ... smear a thin coating on eggs and watch as your housemate tries to crack them in the morning. Or smear it on a trampoline ... the more they try and jump up and down, the less bounce they get. Or if you could blow bubbles with this stuff ... would you be able to pop them?

Re:Magic Chocolate

[Ohreally_factor]

I'm wondering if you could effectively immobilize someone wearing this armor by shooting them with a sonic canon.

Re:Magic Chocolate

[FirienFirien]

You'd need to have a high enough amplitude and frequency to cause the goop to shear against itself from the sound; I'm not quite sure, but gut feel says you wouldn't need to immobilize them since you'd be doing horrible things to their skin and organs already.

Re:Magic Chocolate

[hotdiggitydawg]

Yes, but (a) the rigid armor is "flexible" in terms of the joints between the plates, and (b) doesn't cover the whole body - whereas presumably this would be shirt, trousers, the lot. The parent's question was whether they could run in the liquid armor... IE the video states that the liquid solidifies when agitated - are the forces of running enough to trigger the solidification? What about with full battle kit slapping around on your back? Or when you slip in what's left of your buddy's intestines and land flat on your face? Or (as another poster put it) some other applied force may be sufficient to trigger it - sound waves, a blast of air, a sonic boom from a low-flying jet. If the stuff doesn't de-solidify in a hurry then the enemy could have a field day among the now "statuesque" soldiers...

Re:Magic Chocolate

[FirienFirien]

The eggs one won't work, because the eggshell is rigid, and so provides no shear force on the coating. The trampoline one should work, but the effect you'd feel is negligible - this stuff works well at the speed of bullets, but at that small thickness you'd get little effect at the speed of a person's bounce. If you could get bubbles to work, then they'd still pop - they'd just pop slowly, since as the sides pull away from the initial point of zero thickness they'd cap their own speed.

Yeah, I did projects on this stuff. You can make some yourself with 1 part water and 1.44 parts cornflour; put it in at 1:1.3, then continue to add the rest of the flour while pouring. It'll get difficult to mix (don't do it in a machine, you'll break the machine, it's like stirring rocks at that speed) but a minute of perseverance will give you something you can bounce your thumb off or sink your finger in. Good fun. Kids love it, and it's easy to clean off; if it gets onto clothes then it just rinses out.

Re:Magic Chocolate

[FirienFirien]

While I can't vouch for brainiac, I can agree that cornflour certainly has the strength to do this. If you have a cup full, you can literally bounce stuff off the top of it without any visual change; it feels slightly rubbery. If you move your finger slowly into it it glops onto the finger; if you try to pull the finger out fast it locks it in and only moves slowly.

No more vests?

[Atario]

Just make the whole uniform out of kevlar coated with this stuff. Might not need that many layers before your regular uniform is bullet resistant...

Gloves

[Joebert]

While liquid armor seems tailor-made for combat personnel or police, the company is initially targeting prisons because the fabric resists punctures. That means it can protect guards from stabbings, something even a top-of-the-line bulletproof vest can't do.

Can they produce gloves able to stand up to shark bites ?
How about gloves for butchers ?
Would they be cheaper to produce than the steel-ring gloves used today ?
Are they water proof ?
How do they react to heat; could they be used in motorcycle clothing ?

Re:Gloves

[Ohreally_factor]

Can they produce gloves able to stand up to shark bites ?

Thereby forcing sharks to evolve frickin' lasers on their heads.

Re:Gloves

[im_mac]

I've actually played with some of this stuff (I know the people who developed this, and by the way, there's no hyphen in Delaware, despite what BusinessWeek thinks) and yes, I don't see why they couldn't make butchers' gloves out of it. One of the easy demos they do is give you an ice pick and two pieces of kevlar and ask you to puncture each sheet. You can stab the ice pick through the normal kevlar but not through the shear-thickening fluid treated one. That should provide some protection against sudden knife slips that butchers might experience.

Custard

[Turn-X Alphonse]

So basicly they're making military use custard (being gentle will let you penetrate it, but use force and you bounce off). Buug how will this stand up against a knife or a bayonet? I know in the modern era this is more or less mute, but it's still something I'd personally wonder about.

Re:Custard

[Arimus]

Given it is put on top of an existing kevlar vest I'd imagine the kevlar layer will stand up to the knife/bayonet part...

Re:Custard

[Yaotzin]

But even so, someone using a knife or a bayonet might not be aiming for the area protected by the vest anyway...

Re:Custard

[Shivetya]

If the clothing is loose enough the knife/point object would still penetrate the skin, it just would be taking the fabric along for the ride.

I read awhile back (old wives tale maybe?) that being stabbed while wearing kevlar isn't always going to protect you as the knife does not have to penetrate the kevlar to penetrate the skin, especially cavity areas.

Re:Custard

[MrNaz]

Where on earth did you grow up that old wives talk about knife-fighting while wearing kevlar?

Re:Custard

[FST777]

being gentle will let you penetrate it, but use force and you bounce off

You're sure you're talking about custard?

Sounds like a Non-Newtonian fluid to me.

[forgotten_my_nick]

Although I am not sure what the point of it being in this state protects more? Does it weigh less?

Anyway kids if you want to create your own non-newtonian fluid fluid at home heres how.

1. Get your custard power, or corn starch (think baking soda can be used too).

2. Get a dish or a cup. More fun with a large jar though.

3. Add some water to the container and proceed to mix as much powder as possible into the water until it gets to a weird creamy/solid state.

You now have something which is a liquid and solid at the same time. Enjoy! :D

Emperor with No clothes

[gafferted]

Has someone sold the Emperor a suit made out of Silly Putty [sillyputty.com]

Yin Yang

[el_womble]

The fascinating thing about this is that it will just change the weapons. Better armour means just one thing, better weapons. So you can't stab a guard with a shiv, they'll find another, probably more gruesom way of penetrating the thin blue line.

Never the less, liquid armour sounds cool, can I have it in my motorbike kit? Lighter, more flexible armour that resists penetration can only make landing in a hedge that little bit safer. Of course, better armour means more dangerous riding...

Awesome!

[Schraegstrichpunkt]

What we can expect in the 21st century:

• People are going to start fighting with swords again, because bullets won't work.
• Somebody will be able to fill a pool full of this stuff (or, if it floats, it'll be even more feasible), causing the swimmers to be fine, but the divers to suffer spinal cord injuries.

Oobleck

[david.given]

This stuff sounds like a dilatant [wikipedia.org].

Kitchen experiment: take some cornflour and some water. Mix one part of water to about two parts of cornflour until you get a thick paste. Play with it.

If you apply gentle pressure, it behaves like a fluid. If you apply strong pressure, it abruptly solidifies. Scoop up a handful and throw it at something, and it'll bounce. Drop something heavy into a bucket of it and it'll sink.

Beach sand also manifests this behaviour, under certain situations; occasionally you can find a patch of heavily waterlogged sand that's rock hard when you walk across it, but if you stand still you slowly find yourself sinking in.

Disclaimer: cornflour almost certainly does not make good body armour.

Re:Oobleck

[tumbleweedsi]

I saw a thing on Brainiac where they filled a swimming pool full of cornflour and water and got a guy to walk on it... it was ok so long as he kept moving but as soon as he stopped he sank pretty quickly.

Getting out was pretty hard as the more he pulled the more it turned like concrete... pretty scary if you start sinking in this stuff and have nothing to hang on to!

Re:Oobleck

[dpilot]

One of the positive side-effects of having kids - getting to play with stuff like this with mine. (as well as Legos, etc.)

I was going to post about Oobleck, but first did a quick scan to see if anyone else had. We called it corn starch instead of cornflour.

I presume the name comes from "Bartholomew and the Oobleck" by Dr. Suess.

a slow kinjal penetrates the sheild....

[rucs_hack]

Hmm

I wonder if a slow projectile would get through? Ok, obligatory Dune reference in the heading, but still I wonder...

A Similar idea

[07734]

The problem is not only the bullet's ability to pierce the armour, but the energy it transfers through the armour. This company : http://www.d3o.com/ [d3o.com] use a similar technique but instead of leaving it as liquid, they treat it in a way which turns it into a foam structure. I beat the crap out of a friend's elbows and knees with a shovel while he was wearing d30 stuff, and he didn't feel a thing. It's quite amazing.

I'm reminded of two things...

[NevarMore]

1) The 'injured stormtrooper' fan film.

2) What if he shot you in the face?

Re:I'm reminded of two things...

[TubeSteak]

2) http://www.telegraph.co.uk/news/graphics/2006/05/0 9/wus09.jpg [telegraph.co.uk]

That's the new suit they've been handing out to HMMWV turret gunners.
The suit is bullet & shrapnel proof, including the visor.

Cornstarch

[PhotoGuy]

Sounds a bit like corn starch. From my PMK days (sigh, Alisha), I remember seeing demos of cornstarch mixed with water. It appears liquidy, but if you smack your hand down in it, it turns to a solid instantly and temporarily, so no splashing occurs. Kinda freaky.

The WikiPedia [wikipedia.org] entry actually has a video of this.

Snow Crash

[Dr_Barnowl]

Sounds like the stuff that Hiro Protagonist wears to deliver pizza..

"Sintered Armorgel ; feels like gritty jello, protects like a stack of telephone books"

Maybe they should ask Neal Stephenson about using that as an ad slogan.

Also good for sports

[Gulik]

Another company, d3o Labs [d3o.com], has developed a similar substance, but they've been adapting it to sports [theengineer.co.uk] applications -- ski racing suits, hockey pads, and sneakers.

Gloves...

[waferhead]

Everyone has forgotten their classic SciFi.

Nice pair of Deerskin gloves with a layer of this inside would make brass knuckles so obsolete...

Non-Newtonain Fluids

[florescent_beige]

I became suspicious when I read the phrase "nano bits of silica". Nano technology my big toe: that's a marketing flourish.

The article mentions that this is a sheer thickening fluid, what they probably mean is shear thickening. That would be a fluid where the coefficient of viscosity increases with increasing strain rates, instead of remaining the classically Newtonian constant. In this case it's probably because the glycol tangles around the silica particles and can't untangle quickly.

While it's quite possible the material can become a semi-solid for the brief duration of a dynamic impact there is no reason to believe, and lots of reasons to not to believe, it becomes a particularly strong solid. In a particulate reinforced composite, which this is in its pseudo-solid state, the matrix (the ethylene glycol) is important to the strength and being a simple organic molecule it's strength must be on the same order of, say, polyethylene.

TFA itself infers this, noting the original idea of using the material itself (in peanut-butter mode) didn't work out. Instead it is employed as the matix in a conventional fiber composite using Kevar or Spectra or something like that as the workhorse.

As in all conventional fiber composites, the fiber bears the load, the matrix supports the fiber. In this case the support, I conjecture, amounts to preventing the fibers from displacing away from the impact point, probably allowing fewer layers of fiber to absorb a given impact energy.

Whle this is innovative and a good idea, it's hardly liquid armour. What I would hope for and maybe expect is better performance against pointy, hard, teflon-coated projectiles of the cop-killer variety which work by nosing the fibers out of the way.

Re:Non-Newtonain Fluids

[technococcus]

Teflon-coated bullets [wikipedia.org] are teflon coated to reduce barrel wear, not to provide any performance increase with respect to penetrative capabilities. Other lubricants are often used, but teflon works very well even with high velocity projectiles. Handloaders who shoot USPSA/IPSC handgun competitions often lube their bullets to decrease wear on their 1000USD high-polish barrels. "Cop-killer" is a sensationalist name first applied to Teflon-coated bullets and later to Jacketed Hollow Points when that term was all the rage in the liberal media. Remember, only YOU can prevent the spread of FUD!

Bill Hicks

[giminy]

Bill Hicks predicted the future:

*pshwhshswsh*

"What's that?"

"Musket repellant."

Re:Shear-thickening

[Qzukk]

Surely shear-thickening?

maybe they plan on making bulletproof pantyhose?

Re:Shear-thickening

[Alaria Phrozen]

Product Announcement! New, glistening panty-hose. Shimmering as if they're wet. Catches eyes. Attracts only the daring. Promotes celibacy and abstinence!

In the heat of the moment, you push her against the wall and kiss. Heat. Fire. Desire. You reach down below her skirt, and trying to be spontanious, rip at her pantyhose... but wait! No satisfying tear or gasp escape from her lips... ... humiliation as you try again and again, unable to even stretch the panty-chasty-hose. The situation goes... limp.

"Liqui-hose, helping you dodge a bullet every night."

Re:Wolverine

[Flounder]

But could it stop a lightsaber? Cause you know there's scientists in North Korea working on lightsaber technology. Mr. President, we cannot allow a lightsaber gap!

Re:First real users will be...

[Patrik_AKA_RedX]

One solution: mandatory full-body coating!

Just imagine a war in a few decades:
Soldiers of opposite side standing a few metre appart, shooting at each other with hundreds of bullets without any effect what so ever. Now that would be, ..., intresting.

Re:First real users will be...

[cnettel]

You'll still get an impact from the energy alone. You're not thrown back, but certainly hit. I imagine that hundreds of bullets would be enough to cause some quite significant effects anyway. (The total heating alone could be "interesting".)

Re:First real users will be...

[Broken scope]

Except 3 rounds from a 45. planted square on his chest will either A: Knock him on his ass. B: Bruise his chest and wind him C: If your lucky pop his sternum D: All of the above Body armor just makes it so the round doesn't kill you. It still hurts like hell. Your body is still absorbing the energy of the round.

Re:

[account_deleted]

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[account_deleted]

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Re:Dune had it

[87C751]

it's a pity that Herbert didn't stop at the first book because the rest were so poor by comparison.

A friend of mine once met Frank Herbert and asked why Dune was so good, yet the other two (at the time) were so weak. Herbert reportedly answered that Dune was a labor of love, and the followups were contractural obligations.

Re:Dune - a common misunderstanding

[Paul Carver]

You make the common mistake of considering the sequels to be the same sort of book as the original Dune. The first book is mostly an adventure novel. The later books are much more weighted towards religion, politics, and philosophy. Book 2 and 3 are tough to get through (at least the first time, I found they were easier and more enjoyable upon re-reading). You definitely can't approach them expecting the same hero-villian adventure-battle-conquest scenario.

Frankly, Lord of the Rings is a grade school fairy

Re:Better armor = better weapons

[Detritus]

Armor-piercing bullets tend to create less damaging wounds than soft bullets that are designed to expand upon impact and dump all of their energy quickly.

Re:Gotchas

[Frightening]

I stand corrected. View the very nice clicky post at the beginning of the comments to understand how it really works.

The question is, can it be used (in sufficiently thick amount?) without hard-to-get materials like kevlar? I am really asking if you can make this at home. From the brief vid, it looked like point 5) above is very possible.

Re:You ever notice that in Starship Trooper, the g

[codegen]

You ever notice that in Starship Trooper, the guns were basically 20th century? They have these huge space-faring ships and bunch of sooped-up M16s ?

That was my objection to the movie. If you read the book, they all had mobile armour (and not soft, liquid armour either) with jetpacks and were spread about 100 yards apart when in combat. The only thing in that movie had in common with Heinlien's work was the title