Slashdot Mirror
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'."
- Man in liquid armor
walking down the lab hallway.
- Man
in liquid armor enduring heat.
- Liquid
armor on half a face
Your tax dollars at work.This is joey, the lab assistant, going on a coffee run.
This test killed a few of our volunteers, but after many tries we finally worked out all the kinks.
We do half the face in case the armor blinds the test subject, at least he'll have one good eye left. (Lessons learned from the "heat" test, we apply the same principal for the genitals as well.)
Lots of salt or huge silica gel packets.
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?
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.
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.
"Polyethylene glycol (PEG) is a water-soluble, waxy solid that is used extensively in the cosmetic and toiletry industry."
c ol&sourceid=mozilla-search&start=0&start=0&ie=utf- 8&oe=utf-8
http://www.google.com/search?q=Polyethylene%20Gly
That's from the first link.
'Standards' in computing only impress those who are impressed by things like 'standards'.
"sintered armorgel: feels like gritty jello, protects like a stack of telephone books."
Only in a Slashdot fantasy can a Slackware install turn into several hours of sex . . . . .
In the next james bond movie they will use this stuff in breast implants to make SUPER boobs.
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."
"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.
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_crowbarHave you read the Moderator Guidelines
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.
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.
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
polyethylene glycol
I like my beverages with warning labels!
For a scientific paper on the subject, see Advanced Body Armor Utilizing Shear Thickening Fluids, 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.
Only Women Bleed (Sex, Sharia remix)
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.
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?
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.
Does this non-toxie liquid stuff mean that if I were to drink it, I would be bulletproof? Wicked!
Any chemist worth his salt would be able to answer that.
This is straight off of Army News Service.
And they even have a picture!
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...
"Faith: Belief without evidence in what is told by one who speaks without knowledge, of things without parallel." - A.B.
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?
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.
"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?"
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! :)
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.
All but one of the guys who dropped the nukes committed suicide.
And so did many victims of the Holocaust.
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 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 -- 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 ("Angel of Death" responsible for human experimentation at Auschwitz, died vacationing at a Brazilian beach), Rudolf Höß (first commandant of Auschwitz, executed), and Erich_Priebke (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" (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"
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 ?
Opinions on the Twiddler2 hand-held keyboard?