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MIT breakthrough could lead to paper-thin bullet-proof armor

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November 12, 2012

Edwin Thomas, left, and Jae-Hwang Lee holding a polymer material containing three bullets ...

Edwin Thomas, left, and Jae-Hwang Lee holding a polymer material containing three bullets (Photo: Tommy LaVergne, Rice University)

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Scientists have theorized that paper-thin composite nanomaterials could stop bullets just as effectively as heavy weight body armor, but progress has been hampered by their inability to reliably test such materials against projectile impacts. Researchers at MIT and Rice University have developed a breakthrough stress-test that fires microscopic glass beads at impact-absorbing material. Although the projectiles are much smaller than a bullet, the experimental results could be scaled up to predict how the material would stand up to larger impacts.

The glass beads, described as "millionths of a meter in diameter," are propelled using a laser pulse technique developed by MIT's Keith Nelson over several years. His technique was modified with the help of scientists from Rice University in experiments conducted at MIT's Institute for Soldier Nanotechnologies. Their work, reported in the journal Nature Communications, was supported by the U.S. Army Research Office, which is keen to reduce the burden on soldiers who currently wear armor that contains cumbersome plating an inch thick.

An electron-microscope image shows a cross-section of a layered polymer and the crater lef...
An electron-microscope image shows a cross-section of a layered polymer and the crater left by a glass bead in an edge-on impact (Photo: Thomas Lab, Rice University)

The team's self-assembling polymer is made by alternating flexible and rigid material layers just a nanometer thick, which can be seen clearly in cross-section with an electron microscope. This allows them to see precisely how the material has deformed after an impact. By studying multiple impacts, the team found that their material was 30 percent more resilient to head-on (rather than edge-on) collisions, a discovery which could change how current protective materials are made.

"It’s a novel and useful approach that will provide needed understanding of the mechanisms governing how a projectile penetrates protective vests and helmets," said Donald Shockey, director of the Center for Fracture Physics at SRI International (unaffiliated with the project), as quoted by David Chandler of the MIT News Office.

The researchers still need to develop a way to record these impacts in real time in order to best understand them, but their tests could accelerate the development of paper-thin military body armor or shielding for satellites, space suits, and shuttles, and more.

Source: MIT News Office

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Jason Falconer Jason is a freelance writer based in central Canada with a background in computer graphics. He has written about hundreds of humanoid robots on his website Plastic Pals and is an avid gamer with an unsightly collection of retro consoles, cartridges, and controllers.   All articles by Jason Falconer
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21 Comments

Good stuff!

I wouldn't mind betting that when paper-thin body-armour comes along, it will probably use carbon nanotubes (which are much stronger and lighter than even steel.) I'm sure that they will eventually outdo ceramic armour too.

mooseman
12th November, 2012 @ 09:51 pm PST

The problem with thin is that even if the bullet doesn't go through, the bullet will still do tremendous damage as a blunt impact causing external and internal bruising, therefore this has to be accompanied by other thicker layers which can be of light material, but by itself it is still dangerous.

Dawar Saify
13th November, 2012 @ 02:09 am PST

Anything that reduces the load on dismounts is great but there are a few issues that need to be addressed.

In addition to stopping penetration, body armour and clothing needs also to address the blunt trauma injury caused by absorbing the energy from the strike. There is also performance against blast injury from IED to be considered.

The rigidity of the armour will dictate how it is worn, either like the current plates or more like the steel armour of old, profiled to the body. There is likely to be the need for some energy absorbing material behind and this needs to be reconciled by heat management when the armour is worn in hot climates.

Overall the soldier should end up with something much lighter and with as good or better protection but I hope developments will also make it more comfortable and less restricting and give dismounted troops back some of the mobility (together with the inherant protection that rapid movement provides) that they have lost in recent years.

Tankman
13th November, 2012 @ 03:00 am PST

From the picture it looks like the glass 'bullet' tore a gaping hole, right through the armor.

Am I looking at it, wrong?

Fusiontek
13th November, 2012 @ 04:28 am PST

What everyone else says: The paper-thin armor might stop penetration, but it won't stop broken ribs or the blunt trauma. Some sort of lightweight ceramic plate armor in conjunction with this polymer sheet might help absorb and dissipate the impact.

Warhead
13th November, 2012 @ 09:01 am PST

In regard to stopping blunt object inflicted injuries, all that would be required would be some means of keeping the armour a little distance from the skin- eg selective padding, rubber cones, etc.

Additionally, having the armour held away from the skin could mean that some form of simple ventilation system could be employed to keep the soldier cool- I hate to think how much those guys must sweat in the heat of Afghanistan or Iraq.

bergamot69
13th November, 2012 @ 09:05 am PST

Why not just use good old empirical data?

Fabricate a few different materials and fire some bullets into them. That way the material gets out into the marketplace where it can be utilized and the over focused PhD's can figure out the "why it works" details later.

I wonder how far behind we'd be if we just discovered iron and it was up to the guys at MIT to determine why it's able to cut through wood before we made a saw.

PeteKK
13th November, 2012 @ 09:36 am PST

“inability to reliably test such materials against projectile impacts” What? Give me a Barrett 50, an M-16, AK-47, and maybe a few exotics like the Steyr AUG and FN-SCAR…and limitless access to military and civilian ammunition… and a few “sheets” of this stuff and I will test it for you… has to be a lot simpler than setting up a pulse laser to propel microscopic glass beads for crying out loud… I get that they want to look at this material from the most scientific and molecular level but for crying out loud… analysis paralysis anyone… does it stop a bullet or not… how big… with what kinds of “tips”…what backing does it require to not kill the wearer due to the energy transfer on the backside… Throw some lead at it and Get’er done!

GadgetGeek
13th November, 2012 @ 10:15 am PST

The better solution is robotic war where soldiers are no where near any harm. I know that robotic air craft are now common enough and the Navy will soon have very potent unmanned ships. The foot soldier remains the largest challenge for robotics. Supposed critics make noise about innocents lost in conflict. The normal slaughter of innocents is about 20-25% of all killed in war. So far robotic- drones have a far better gentleness to uninvolved parties.

Jim Sadler
13th November, 2012 @ 10:21 am PST

RE: Blunt trauma: Wrong. Merely adding a puncture-proof layer of "paper thin" material over, say, a standard BDU, provides plenty of room for even the minute resistance of air trapped between the material and the body to slow the projectile (and the material itself) down to acceptable levels. The average bullet, whether pistol or rifle, has less kinetic energy than a decent fastball. The difference is it's really light, really small, and going wickedly fast, so you the timescales of interaction change from "oh, i need to catch that" to "oh, i was shot... and now i'm bleeding to death..."

So, extending the duration of the impact event from microseconds to milliseconds, turns a Gigawatt interaction into a longer, but lower power megawatt or tens-of-kilowatts interaction. Nobody's getting liquefied.

Things do change with a .50 BMG... that's more or less the kinetic energy of a full size pickup being dropped on your chest from about ten-twelve feet up. *Splat*

Rion
13th November, 2012 @ 12:23 pm PST

All good comments to be sure. Even with the blunt trauma, lack of penetration is STILL a huge improvement. A bullet enters the body with a relatively small hole, but the exit hole (if there is one) is MUCH bigger with tremendous tissue damage. So, yeah, not zero impact, but less likely to ruin your day. As far as a 0.50 BMG goes, I doubt any wearable armor is going to help much, Ma Duce speaks with authority to be sure!

Burnerjack
13th November, 2012 @ 02:23 pm PST

You would have to place some sort of impact absorbing material behind the armor, otherwise the kinetic energy would do a lot of physical damage even without penetration. Maybe some of that Aero-gel could be used as a shock absorbing material. It is light and supposed to be able to hold its shape. Then you could run some heat-tubes through the Aero-gel to remove the excess body heat. Its something to think about anyway.

JMOdom
13th November, 2012 @ 08:19 pm PST

@rion

your comment "The average bullet, whether pistol or rifle, has less kinetic energy than a decent fastball" stuck me as being a bit over the top

A bit of research seems to indicate that a 9mm round fired from a pistol has about 400-500 Joules of Kinetic energy.

A fastball weighing 5.25 ounces = .149 KG

if it is traveling at 100 mph (44.7 m/S) then its Kinetic Energy is

.5*m*v^2 (.5*.149*44.7^2) or about 149 joules

Less than half

A 5.56 round (9.7 grams) traveling about 2600 ft/s (800 m/s) is going to have about 3000 joules of KE or about 20 times a fast ball thrown at 100 mph.

Where did you get your information from ?

Captain Danger
13th November, 2012 @ 08:38 pm PST

@ Rion:

"The average bullet, whether pistol or rifle, has less kinetic energy than a decent fastball."

This is wrong and highly misleading... however it's easy to prove it.

Fastball: let's say, to make calculations easier, 146 grams ball at 100 mph ---> you get almost 116 ft-lbs (not bad at all, around 22LR values)

9mm Luger (average handgun cal, most common on the field): http://www.hornady.com/store/9mm-Luger-124-gr-XTP/ 339 ft-lbs at the muzzle, still 259 at 100 meters (or yards?)... still more than double than the peak of energy of the fastball...

5.56 NATO (223 Remington, NATO standard assault rifle round): http://www.hornady.com/store/5.56-NATO-55-GR-GMX-Superformance/ around ten times your fastball...

And these aren't at al the most powerful rounds that a bdy armor has to protect from...

So, yes, the teory behind your words is probably true... it's just the example you used that is pretty much wrong! ;-)

Anyway blunt trauma is common with regular body armors even when they successfully stop bullets... it doesn't kill but sure as hell it hurts!

Giolli Joker
13th November, 2012 @ 09:10 pm PST

The article offers no explanation why "progress has been hampered by their inability to reliably test such materials against projectile impacts" which makes it rather meaningless.

nutcase
14th November, 2012 @ 01:33 am PST

Body armor has been around ever since Gilgamesh Jr went to battle in a thick leather vest. Experimenting with different materials is unlikely to lead to any sudden breakthroughs. That's the significance of this stress test. It gives the ability to precisely scale the energy of the projectiles. Is it going to lead to "paper thin" armor? Unlikely. But maybe substantially thinner & lighter than current armor.

theotherwill
14th November, 2012 @ 02:12 am PST

Look at their own numbers: 30% more resilient. This doesn't mean much to start with. Does is have 30% more undamaged material than current what (ceramics, steel, high hard titanium ?) And if they mean it is 30% more effective: is that an a mass basis or thickness or ??? Either way: 30% off an inch-ceramic plate get you nowhere in the neighborhood of paper thin armor ! Think about what mechanisms that can convert the kinetic energy into ? in the thickness of a sheet of paper. A lot of energy absorption in such little space is unfathomable.

Dekarate
14th November, 2012 @ 08:44 am PST

Yes it is less energy, but you're still within an order of magnitude. So perhaps a rock... Thanks for actually doing the math ;-)

The point remains, however, that the impact event occurring a half inch from the body gives a significant increase in the effective pulse duration, thus the small energy (still not enough to boil a few grams of water, mind you) is dissipated gradually. The full size pickup example stands well here. If I park on a hill and standing front of the truck and release the brake, I can hold the truck back easily, or allow it to gradually slide back. If I stand at the bottom of the hill, and someone releases the brake, I'm soup. Its all in the impact duration. Likewise with light - stand in the sun for an hour, and you've recieved ~1000 watts (assuming a square meter if surface area?) that comes out to 3.6 megajoules. If I instead ahot you with a 1 second pulse from a 3.6 megawatt laser, you'd be toast. Or at least have a fairly painful hole in you. Increasing that to 100 seconds is a significant improvement, to 36kilowatts. Over the whole surface of your body, for 100 seconds, this is survivable with a modest thermal protection system. Which, by coincidence, doesn't really avoid the heat, it slows the transfer, just as the padding or even dead air space of the armor providing a delay in the impact energy transfer.

The unfortunate thing for large calibers like .50 BMG and even 338LM, is the kinetic energy, no matter how slowly applied, still accelerates a human-body-equivalent mass to velocities that are dangerous, or simply crushes your chest or skull after turning tour armor into a sort of projectile, even if the armor doesn't fail. Kind of like in the movie U-571- a crewman is told not to lean on the bulkhead due to depth charges... The bulkhead could flex quickly enough to literally split you in half.

Kinetics are fun, no?

Rion
14th November, 2012 @ 10:24 am PST

1) A lot of you seem to be missing the fact that there is a major difference in cost and timing between research scale materials and production scale. No one wants to drop a big time and money into setting up large scale production of a material that hasn't been tested, even if it means that the material could be produced at a few dollars a yard when one-off production would be several hundred thousand a yard... if you don't think production scales that way, try making your own cell phone from dirt. As such, by scale, it's probable that they only have a few micrometers of material to test and that even a 22 bullet would be like throwing a bus at it. Find a material configuration that works, THEN scale it (then re-test it, of course).

Charles Bosse
14th November, 2012 @ 01:37 pm PST

I'm interested in personal protection against IED's.

We're talking serious pressures against the body at speeds that realistic

fibre thicknesses can't take care of SO i'm introducing the idea of a

reactive armour system that the outer layer detects the incoming blast

and reacts with it's own counter blast. A weave of some sort of det. cord

that pushes away the blast. Comes with basic ballistic protection too cause it wouldn't be nice to be in a Hummer when 6 suits go off at once.

Reactive armour may be the future??!

PickledOnion
23rd May, 2014 @ 05:32 pm PDT

What was the point of the photo of the polymer with the three bullets? I've seen high velocity ammo actually leave a melted hole through steel plate. There is a huge amount of heat that goes with the impact of a high velocity bullet. I really don't see a paper thin nano armor handling both the impact and the heat. It takes a certain amount of mass to dissipate both. I'm sure that lighter armor is possible but it will be limited in its effectiveness.

Bob
27th July, 2014 @ 12:57 pm PDT
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