Bullet strikes the nanotube at a relative height of 0.31
(a) with both ends fixed and (b) with one end fixed.
Posted on 11/23/2006 12:05:52 PM PST by LibWhacker
(Nanowerk Spotlight) Carbon nanotubes (CNTs) have great potential applications in making ballistic-resistance materials. The remarkable properties of CNTs makes them an ideal candidate for reinforcing polymers and other materials, and could lead to applications such as bullet-proof vests as light as a T-shirt, shields, and explosion-proof blankets. For these applications, thinner, lighter, and flexible materials with superior dynamic mechanical properties are required. A new study by researchers in Australia explores the energy absorption capacity of a single-walled carbon nanotube under a ballistic impact. The result offers a useful guideline for using CNTs as a reinforcing phase of materials to make devices to prevent from ballistic penetration or high speed impact.
Professor Liangchi Zhang from the School of Aerospace, Mechanical and Mechatronic Engineering at the University of Sydney explained the new research to Nanowerk: " Especially in making bullet-proof vests, shields, and explosion proof blankets, the best protective material will have a high level of elastic storage energy that will cause the projectile to bounce off or be deflected, i.e., the objective is to reduce the effects of 'blunt trauma' on the wearer after being struck by a bullet. We therefore tried to understand the impact behavior of CNTs."
Zhang published his recent findings, titled "Energy absorption capacity of carbon nanotubes under ballistic impact", in the September 18, 2006 issue of Applied Physics Letters.
Zhang's study analyzes the impact of a bullet on nanotubes of different radii in two extreme cases. For a nanotube with one end fixed, the maximum nanotube enduring bullet speed increases and the energy absorption efficiency decreases with the increase in relative heights at which the bullet strikes; these values are independent of the nanotube radii when the bullet hits at a particular relative height. For a nanotube with both ends fixed, the energy absorption efficiency reaches minimum when the bullet strikes around a relative height of 0.5.
Bullet strikes the nanotube at a relative height of 0.31
(a) with both ends fixed and (b) with one end fixed.
"Specifically, we investigated the relationship between the nanotube radius, the relative position at which the bullet strikes, the bullet speed, and the energy absorbed by the nanotube for a particular bullet size and shape" says Zhang.
A piece of diamond having 1903 atoms was used as a bullet with its speed varying from 100 to 1500 m/s. The bullet dimension was selected such that the width is larger than the width of the biggest nanotube after flattening. The bullet was released from a target about 15 Â from the center axis of the nanotube and moved at a constant speed in the horizontal direction i.e., perpendicular to the nanotube axis, as shown in the graphic above. The nanotube performance was examined for bullet released with various speeds at various positions using the classical molecular dynamics method.
In his experiments, Zhang found that, for a nanotube with one end fixed, the CNT could be resilient to projectile traveling at speeds of 200–1400 m/s (for comparison, the initial velocity of modern rifle bullets is somewhere between 180 and 1500 m/s, depending on gun and bullet type. For a typical over-the-counter gun the speed is below 1000 m/s); the nanotube enduring projectile speed increases whereas the absorption efficiency decreases with the increase in relative height ρ. For a nanotube with both ends fixed, the absorption energy reaches maximum whereas the absorption efficiency reaches minimum when the bullet strikes the nanotube in the middle.
Zhang is excited by the great potential offered by CNTs in making ballistic-resistance materials and his research in this area is ongoing: "We'll continue to try to understand the impact behavior of CNTs under more complicated loading conditions."
I was wondering if it would be possible/effective to make a latticework of CNTs in the lenses of some eye protection to increase their overall protective ability. It seems like they're thin enough where they wouldn't interfere with vision, but would they still retain their effectiveness?
from the planet of Krypton!
Where does the line form to get this technology? I think the Chinese would be interested. So would the Iranians, North Koreans, Cubans, Venezuelans, ...
... Hamasians, Hezbollahians, Al Qaida-ians, ...
You're assuming the armor consists of one layer of fabric. Once you have bullet-proof fabric the weight of t-shirt material, all sorts of body armor lighter, and more comfortable, than what is now available become feasible: a layer of the (still hypothetical) CNT fabric, a layer of something to absorb and distribute energy (anything from cotton batting to fine-mesh titanium chainmail to the other hypothetical body-armor component: fabric impregnated with a non-newtonian fluid) and another layer of the CNT fabric would do nicely.
Of course, the less protective, but far less obtrusive, one-layer of fabric version might become normative for folks who have reason to fear assassination.
At some point, what they call a t-shirt just isn't a mere t-shirt anymore.
The "silk" analogy makes much more sense, though I'd suggest that it would more accurately "bullet resistant."
So why not just make bullets out of carbon nanotubes?
Way to go blab...
I see a great marketing oppurtunity here for bullet-proof pajamas. Just the thing for the WOD, no-knock raids that seem to be so popular.
hmmm..Seems so, Massive internal injuries (broken bones/ruptured organs....dead person)
...bright side..no holes / tears in the Tee-shirt.
ping
There would be perforation with this nanotube armor, but a great deal less trauma than a through and through wound channel.
Friction alone would significantly impede dragging of the nanotube undershirt into the wound, i.e., a significant amount of the round's energy would be transferred to the skin surface surrounding the impact.
Other materials such as fluids with extremely high shear forces would probably be added so that the result would be like wearing a thin, flexible suit of armor that would harden in an instant and dissipate the mechanical force of impact into chemical and thermal energy. The concept is contrary to common sense and it took me several readings and some thought before I understood it.
Sounds cool, but I don't want to be the first to test it.
Protection against head shots.
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