Half a croissant, on a plate, with a sign in front of it saying '50c'
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The phrase 'crumpled heap' comes to mind.

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Self Healing Bullet-proof Vest

Kevlar vest with 'dilatant' mixture breast and back plates
  (+26, -1)(+26, -1)(+26, -1)
(+26, -1)
  [vote for,

Whilst reading the 'Custard-Filled Speed Bumps' notion I was reminded of an idea I had at the age of ten as I was smashing a plate of cornflour and water with a spoon (at this age I thought this phenomenon was called Thixotropism but I stand corrected).

The modern bullet-proof jacket is made of Kevlar with ceramic breast and back plates, clearly to add additional protection to the vital organs from gun shot by spreading the pressure of the impact across the entire plate. The problem with this design is that once one bullet has penetrated the ceramic plate it breaks leaving you open to further and more likely fatal injury.

My idea is to replace the ceramic plate with a dilitant mixture (a little more advanced than cornflour) which would act much like the ceramic on impact by spreading the pressure and taking the pace out of the bullet but would then re-form almost immediately ready for a subsequent strike.

I still haven't worked out a method of ensuring the liquid doesn't drain out after the initial impact (perhaps the nature of the mixture would prevent this) but I don't see that as a major stumbling block as I guess you would only need protection for a matter of minutes after the initial blow.

davmac, Apr 10 2001

Custard-filled Speed Bumps http://www.halfbake...led_20Speed_20Bumps
as requested [marmite, Apr 10 2001, last modified Oct 04 2004]

Dilatant powder coated fabric http://164.195.100....839&RS=PN/5,776,839
using a powder instead of liquid... [ldischler, Oct 04 2004]

Army scientists are raiding the halfbakery for ideas! http://vfte.cyberpu...ndex.php/t3641.html
[ldischler, Jun 22 2006]

Bulletproof Gel http://www.telegrap...-stops-bullets.html
[imaginality, Mar 02 2009]

Armour made from 'bullet-proof custard' http://www.telegrap...-proof-custard.html
Yet another half-baked invention becomes real [krelnik, Jul 16 2010]

Ouch - oh, never mind No_20Pain_2c_20No_20Drain_20Body_20Armor
[normzone, Jul 19 2010]


       Prehaps the fluid could clot?
Aristotle, Apr 10 2001

       Only if the self-healing occurs very quickly.
PotatoStew, Apr 10 2001

       Perhaps a mixture of dilatant liquid and ceramic plate might be an idea, so that the liquid, if subjected to sufficient dynamic stress, would heal the cracks in the plate. In this way, the plate could probably take several hits and, and long as no 2 shots were co-located, the wearer would have enough time to scarper.
Granpa, Apr 10 2001

       What a great idea. I love you young genius
ncw, Apr 10 2001

       Peter: I believe the self-healing heals the jacket, not the person.
Aristotle, Apr 11 2001

       I didn't have my glasses on and I thought you wanted a jacket made out of debutants, which seems like it could be equally effective, if a little unwieldy
charleston, Apr 11 2001

       More custard references [Applause]   

       Have you considered colouring the custard with red food dye; that way the would-be assassin will think that they got you and leave.
riposte, Apr 11 2001

       I am not entirely sure you are on the same planet as the rest of us, the mixture is not custard. I am unaware of anyone who has shielded themselves from a speeding bullet with a bowl of custard.   

       We could try it, providing you have some custard handy.
Tico, Apr 11 2001

       There are plenty of stories of English soldiers surviving being shot in WWI due to trifles being carried in their breast pockets ...
Aristotle, Apr 11 2001

       The boys would like to know where they can obtain a copy of Custard Filled Speed bumps. :)
kal, Apr 11 2001

       And presumably this freedom of movement would facilitate the development of a full body suit thus protecting the body's extremities.   

       A possible downside of this may be if you were running across a road wearing the suit when a car on the other side backfires or suffers from a blow-out causing the wearer to freeze in the middle of the road in a comedy pose before getting mown down by a lorry.   

       I still dont see how this is better than my idea, although I accept that it's a damn site more scientific and makes you look much cleverer.
davmac, Apr 11 2001

       It would be better if instead of being sound activated, there was some sort of proximity sensor array that could detect the velocity of any approaching object. Anything coming at you above a certain threshold of speed would trigger the mechanism. Of course, then you'd have sort of a Dune situation.
PotatoStew, Apr 11 2001

       Another major downside of your ill thought out contribution being that the wearer of the electrorheological fluid suit would be a laughing stock amongst snipers who generally strike from distance.   

       The bullet would have passed through our hero and embedded itself into an innocent child by the time the rifle sound causes the suit to harden around the already dead and convulsing body.
davmac, Apr 11 2001

       UB's sound-activated electrorheological suit would work in Film Noir - the assailant would say something like 'hey, mister' to get the victim to turn round so they could shoot them face on. And it wouldn't matter if it was just a conversation the assailant wanted, because you would get an appropriate stiffening-up of the potential victim (no, not the way you're thinking, davmac) in a hairs-on-back-of-neck-bristling styley.   

       Alternatively the 'Matrix' version would activate at the sound of 'beep beep Neo'. etc etc.   

       people are beginning to call your bluff UnaBubba - perhaps someone has realised you're not a world authority on all things, after all...
lewisgirl, Apr 11 2001

       This couldn't be worn in a war/assault type situation where many guns are being fired at a rate of loads per minute (very technical).   

       A battlefield full hardened soldiers all striking catatonic poses might make for humorous viewing mind you.
ChewTheBeef, Sep 28 2001

       What if the vest has sensors that sensed when the wearer stood a little straighter or had a little more sweat then usual? That way, when a gun was pointed at the wearer their endorphines or whatever owuld kick it up a notch and the vest would go hard. Not so hard as to restrict movement, but hard enough to stop a bullet.
barnzenen, Sep 28 2001

       During WWII my father was hit by a bullet - probably from a German aircraft. The bullet was stopped by a pair of scissors he had in his chest pocket. At home we still have the two parts of them - both bent into crescent-like shapes (croissants?). So (as a child) I always had the idea of bulletproofing being achieved by a jacket with lots and lots of scissors sewn into it. But a good layer of custard on the inside would probably have reduced the bruising.
snagger, Sep 28 2001

       UnaBubba: Larry Niven uses something similar in his books occasionally...a suit of tough memory plastic that when it's deformed <by a bullet or arrow, or spear or what have you>, goes rigid to block it.
StarChaser, Sep 29 2001

       Anybody can teach me how to contribute? Why aren't pple here commercialising their ideas? I am into defence equipment, eg bullet proof and solar panels... how do i contact those who are interested?
vistalyst, Dec 01 2002

       Well the real problem with this is, body armor is usually made out of Kevlar (a tightly woven material) then covered by a “ballistic plate” (steal or ceramic) even if the bullet passes through the plate it still causes it to “Mushroom” enough for the Kevlar layer to stop it. Even if the plate cracks it still usually has enough pieces to stop other rounds.
imburton, Apr 03 2003

       Electrorheological fluid.   

       Silenced is not the question. Supersonic vs. Subsonic is the question.   

       The problem with the reactive armor is that a .223 caliber bullet traveling at 2,700 fps would take .1112 seconds to hit a target at 100 yards. Isaac Newton said the speed of sound was 968 ft/sec but was off by about 13% when it is actually 1116 ft/sec. So at 100 yards the sound would be heard .2688 seconds after the round was fired. Leaving a .1576 difference in impact time. So the bullet would have already killed the Armored person and be gone before the armor even hardened.
imburton, Apr 03 2003

       This, sadly, is already baked in a form.   

       Unfortunately, since I have the memory of a goldfish, I don't know where the link is, but!   

       The baked product was a type of plastic polymer that, in sensing a breach, would respond very much like actual skin in that it would liquify, fill the cracks, clot and 'heal' completely, having roughly 80%-90% of the origional integrity.   

       Of course, this would be an overlay for a kevlar vest, but it solves alot of problems.
JackandJohn, Apr 03 2003

       Instead of a liquid, try using a powder. The powder will act very much like a dilatant liquid at ballistic velocities. If you coat the Kevlar fabric with the appropriate powder, the powder will temporarily solidify at the high pressures at the point of impact, helping to spread the impact energy to adjacent fibers.
ldischler, Apr 03 2003

       The problem with powder or liquid armor is that the water (or what ever) would flow with gravity. So you would have a inner tube of liquid around your waist and no chest coverage.   

       So the natural solution would be to have pouches to hold it in. But then you run in to the seam problem. So the natural solution is layers of pouches. But I would bet, you would need 3-4 layers of pouches to protect from angled shots .   

       Liquid also has much more weight than a thin Kevlar layer. So now you have 4 layers of heavy liquid around your chest. This would very much inhibit movement. And after the first shot it would spill out loosing its reliability.
imburton, Apr 04 2003

       Liquid helium is fairly lightweight.
bristolz, Apr 04 2003

       thanks to the squabbling between unabubba and davmac, we've glossed over potato's idea of a proximity sensor that would stiffen the vest if anything traveling above a certain speed came withing a certain distance. this sounds like the best solution, way better than layers of pouches or sound sensitivity...   

       w/r/t objects carried in soldiers' pockets stopping bullets, there are hundreds of cases, sure, but there are also hundreds of thousands of soldiers who were shot and killed, and i refuse to believe that only a handful of soldiers carried metal items about their person during combat. i submit that the deciding factor is the range of the shot. if one is shot from up close, a pair of scissors in one's pocket will not be of any help. if one is shot from far away, the rigid surface is enough to stop the already slowed bullet. thus a person can be saved by any material, given that the bullet has been fired from far enough away.   

       [unabubba], w/r/t your fantastic memory for arcane crap, i salute you. that is exactly how i operate as well.
urbanmatador, Apr 04 2003

       //The problem with powder//

[imburton] See the powder link above...
ldischler, Apr 04 2003

       Looks like I stand corrected. Thanks [idischler]
imburton, Apr 04 2003

       i saw a tv program where a lady was saved by hher keys reflecting a bullet from a pistol at almost point blank range (in relation to the keys of course) y not use thicker layers of kevlar?
MonsterAar, Nov 02 2003

       And by the way this was a documentary - not a crapppy tv series or anything and y not use biotic materials
MonsterAar, Nov 03 2003

       Hell, I want a bullet-proof vest that dispenses pain-killer on the backside of the area it was hit in. I'm gonna need it, no matter how the rest of the vest works.
normzone, Dec 20 2003

       Feasable, but why not outfit the police in full plate armor?
whatastrangeperson, Dec 21 2003

       I feel there would be a hydraulic effect, transmitting more force than would otherwise be the case with a solid. The ceramic spreads force along lateral lines and broadly forward across the plate, decreasing force per cm3, and the ceramic absorbs energy when it shatters. The arch in achitecture does distribution similarly with downward pressure. I think the spreading material would form a thin spot, which, when compressed, would focus all remaining energy at that spot, and most of the material would absorb only enough energy to move out of the way. If bulkiness wasn't a factor, I think there'd be some room to play with in that you could have enough material to absorb energy and bounce back. But I think that would be a lot of material. If you had a special material, well, people could successfully go over Niagra Falls in a barrel, but I don't think a protected official could walk around very well.
Corona, Jun 24 2006

       Just so I can help; MonsterAar, thicker layers of kevlar would help, but at the point wear the wearer is completely invulnerable, he is also unable to move any limb of his body, kevlar not being extremely flexible. whatastrangeperson, full plate armor that would stop bullets would be ridiculously heavy, and it would actually be cheaper to have several policeman die and collect their death benefits than to outfit a force in the armor. Never mind every cop wearing the armor would have to be impossibly strong to wear the armor for an entire shift, and he would definitely NOT be able to run down any perps. The problem you are going to run into with electroheologicals is time response; first, how ARE you going to sense the incoming bullet? Radar isn't as easy to set up as you think, and modern proximity sensors that small are really only as good as "something is moving" or "nothing is moving". Second, the processing time from detection to reaction, even if in the milliseconds, may cause the armor to harden AFTER THE BULLET HAS ENTERED THE ARMOR. This would result in tragedy. Corona has a good point about hydraulics, but that hydraulic effect would only truly be felt inside the container of electroheological fluid and the net effect on the user should be similar to that of a plate of similar strength and weight. A simple solution to your problem is an "on/off" switch; that is, provided that you can actually make the material harden enough to stop a bullet in the first place. Oh, for all those interested, there is in fact an extremely lightweight material made from synthesized spider webs that will stop bullets; its only about as dense as a heavy winter shirt. Its not rigid at all, so the bullet will still likely drag the material into the body, which is where you get back into armor plating.
killjoy57us, Feb 28 2007

       Maybe a shield version for people in need of mobility? An okay idea, I suppose.
Shadow Phoenix, Oct 21 2007

       Per the two Telegraph (UK) news links, I think this definitely belongs on the "real inventions that the halfbakery thought of first" list.
krelnik, Jul 16 2010


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