Fullerene vests vs Kevlar and steel

PeZook · Post by **PeZook** » 2003-01-02 05:11am

Ok, a topic for the engineers in here.
I've been hearing a lot about fullerene nanotubes and their supposed properties. There are people claiming that such tubes are 100 times more durable than steel, and as such would be great for replacing kevlar as a material that bulletproof vests are made from.
The question is this - how do fullerenes relate to steel rifle plates? From what I know, they are pretty resilient to shear stress, but are not very hard. Can a vest made out of fullerene tubes stop a modern rifle round? Or would it still need hard rifle plates?

Sienthal · Post by **Sienthal** » 2003-01-02 05:19am

Nanotubes are indeed quite strong, but I believe the real reason behind their superiority to kevlar is their flexibility and impact absorbtion/dispersal. Kevlar, after all, is simply a collection of strong fabrics woven together in a sort to slow bullets. The neat thing I'd think about the nanotubes is that they'd be much more resistant to armor piercing bullets, being closer together and much more difficult to separate than, say, kevlar.

Anyway, don't take my response as the main response, since I expect that Wong will give you the full information on it, and perhaps slap aside my pitiful collection of thoughts,

.

PeZook · Post by **PeZook** » 2003-01-02 05:27am

As I understand it, armor piercing bullets defeat kevlar armor by applying force to the smallest area possible. This is why you need a material that can resist schock well (eg. steel), so that it won't break under the stress. Fullerenes would be closer together, yes, but would this property in itself be enough to disperse the impact of a penetrator?
Can anyone confirm/deny this? It bugs the hell out of me

aerius · Post by **aerius** » 2003-01-02 11:04am

The problem with fullerene nanotubes right now is you still need an epoxy of some sort to hold everything together. They still can't weave together a sheet of nanotubes like they can with kevlar. What they have right now is a a bunch of nanotubes soaked in epoxy, which is then pressed/molded and allowed to harden. They're just basically sheets of carbon fiber, but with nanotubes instead of the much larger carbon fibers. There's nothing special about them and they're more of a curiosity now than anything else, and as far as I know they're hideously expensive without being any better than carbon fiber sheets, they might actually be inferior but I'm not sure.

As far as bullets are concerned, carbon fiber gets holes blown through it with ease, I'd expect a current nanotube composite to perform in a similar manner. If in the future they can make nanotube strands that they can weave together instead of using epoxy, I'd expect it to perform a lot better. But it hasn't been done yet so I can only speculate.

Post by **Darth Wong** » 2003-01-02 12:44pm

Nanotubes have good tensile strength, but I don't think they have particularly good characteristics for anything else, and I seem to recall their tensile elongation before failure is quite low. I can't see them making good armour, particularly since a woven fabric will never be like a solid block.

0.1 · Post by **0.1** » 2003-01-02 03:38pm

Haven't heard of nanotubes before, any decent site with info on it?

Cthulhu-chan · Post by **Cthulhu-chan** » 2003-01-03 12:45am

Word from american scientist is, strength is high for just about any deformation. While it's only in simulation at the moment, the results on elongation tests predict a strength of 130 gigapascals. To those of you whom that would mean nothing (like me), it would make a rope of nanotubes 100 times stronger than steel at a sixth of the weight.

Keevan_Colton · Post by **Keevan_Colton** » 2003-01-03 12:59am

In relation to this...more than armour...simply not being there is a much better defense.
I've got to see bodkin arrows in action....its nice to see some tech does age well. The arrow passed straight through the kevlar vest it was used on, through the straw and wood target the vest was set on....through the other side of the vest and into the ground behind.

I dont think the vest was fitted with rifle plates though.....

Keevan.

PeZook · Post by **PeZook** » 2003-01-03 03:44am

Keevan_Colton wrote:In relation to this...more than armour...simply not being there is a much better defense.

That's all fine and dandy, but I was asking about armor

Word from american scientist is, strength is high for just about any deformation. While it's only in simulation at the moment, the results on elongation tests predict a strength of 130 gigapascals.

Do you have a URL for that? I didn't seem to come across this article.

Cthulhu-chan · Post by **Cthulhu-chan** » 2003-01-03 04:50am

Here ya go: http://www.sigmaxi.org/amsci/articles/9 ... obson.html

Used "fullerene nanotube applications" as the search querry on google.

aerius · Post by **aerius** » 2003-01-03 10:42am

Keevan_Colton wrote:I've got to see bodkin arrows in action....its nice to see some tech does age well. The arrow passed straight through the kevlar vest it was used on, through the straw and wood target the vest was set on....through the other side of the vest and into the ground behind.

I dont think the vest was fitted with rifle plates though.....

Kevlar vests are horrible at stopping edged weapons. As strong as the fibers may be they're still easily cut by a sharp edge. It's not that impressive really, a good sharp knife will easily stab through a bulletproof kevlar vest, and a large knife or sword will slash it to ribbons. This is why vests used by prison guards are usually fitted with trauma plates, as shanks and other stabbing weapons are quite common among the inmate population.

0.1 · Post by **0.1** » 2003-01-03 06:23pm

Thanks... didn't want to just go blindly through Google and be stuck going through tons of useless links.

SyntaxVorlon · Post by **SyntaxVorlon** » 2003-01-03 11:51pm

At the moment however, you better hope that you can pay for the vest at all. Fullereens themselves are extremely hard to make, nanotubes would be much harder. The only really effective way I can see, not yet possible but it has been speculated, that special proteins could be used to build materials like nanotubes, or even highly organized metal crystals, and the proteins could be produced by the first of all nanorobots, the bacteria.

Post by **Darth Wong** » 2003-01-04 12:06am

Cthulhu-chan wrote:Word from american scientist is, strength is high for just about any deformation.

Wrong. They bend easily.

While it's only in simulation at the moment, the results on elongation tests predict a strength of 130 gigapascals.

Tests on actual manufactured nanotubes are more like 30 GPa, with a LOT of variation.

To those of you whom that would mean nothing (like me), it would make a rope of nanotubes 100 times stronger than steel at a sixth of the weight.

There are lots of material strength properties to consider, besides the tensile stress test.

SyntaxVorlon · Post by **SyntaxVorlon** » 2003-01-04 12:13am

Until fullerenes can be massproduced, and the nanotubes as wll, testing will be limited to the current materials. I've heard that the electrical properties of fullerenes warrent interest, in that the carbon wall does not allow electrons to pass through, but over. This suggests, to me, a possible use in places where electrical work is being done. (Please please please do not take my word for it, I learned most of this when I was in the 5th grade and did not know covalent from ionic bonding)

Gil Hamilton · Post by **Gil Hamilton** » 2003-01-04 12:59am

SyntaxVorlon wrote:Until fullerenes can be massproduced, and the nanotubes as wll, testing will be limited to the current materials. I've heard that the electrical properties of fullerenes warrent interest, in that the carbon wall does not allow electrons to pass through, but over. This suggests, to me, a possible use in places where electrical work is being done. (Please please please do not take my word for it, I learned most of this when I was in the 5th grade and did not know covalent from ionic bonding)

This is what I heard as well. In the Scientific American article about them, they said that one interesting property of them is that they have almost no resistance whatsoever. One of the applications that they will likely be apart of are next-generation electronics, even if we don't necessarily use them for construction.