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Metal foam obliterates bullets

phys.org

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Re: Metal foam obliterates bullets

#61

Post by rmelly »

chillydawg wrote: post #56
dkbrk wrote: post #29

This doesn't have much in the way of interesting details, you need to go to the paper for that. The armour is a composite sandwich, with boron carbide on the front face (a hard ceramic), followed by the metal foam, and either aluminium or kevlar on the rear face. The boron carbide layer blunts the bullet and distributes the compressive stress over a large area of the metal foam. The metal foam is made of 2mm-diameter…

Presumably very expensive and one-time usable. I guess that's true of most types of armour anyway.

Dragon Skin (https://en.wikipedia.org/wiki/Dragon_Skin) claimed to withstand multiple hits without loss of performance, although there was some controversy around it.

https://www.youtube.com/watch?v=aYaSRIbPWkM&nohtml5=False

Re: Metal foam obliterates bullets

#63

Post by hga »

coldtea wrote: post #60
chillydawg wrote: post #56

Earlier quoted context omitted.

Presumably very expensive and one-time usable. I guess that's true of most types of armour anyway.

> and one-time usable It's not like you want it to save your life more than once...

"Once" though is one event, which might include your body armor getting hit more than once. If you're up against automatic weapons, especially the more stable heavy ones (e.g. belt fed General Purpose Machine Guns), a plate getting hit more than once in one moment is fairly likely. The military SAPI and ESAPI standards require stopping 3 hits: https://en.wikipedia.org/wiki/Small_Arms_Protective_Insert

Re: Metal foam obliterates bullets

#64

Post by SEJeff »

refurb wrote: post #20
SEJeff wrote: post #19

Earlier quoted context omitted.

This is exactly how a Soviet style RPG works. Ironically, it is also why the "bird cage armor" works so well against the RPG. Here is a picture of a Stryker combat vehicle from when I was in Mosul Iraq circa 2004ish: http://www.digitalprognosis.com/album/images/iraqpics/the-st... The slats are smaller than the height of the outer explosive and prematurely detonate it. As a result, the penetrator simply bounces off th…

I thought the slats were to provide stand off distance for explosively formed projectiles. If the explosively formed jet forms more than a few inches from the armor, it's way less effective.

Nope, we had them in Iraq before EFPs were really a thing (Thanks Iranain Quds Force for that). They were specifically for RPGs, which was one of the few things that could take out a Stryker without it. They even tried those Soviet parachute anti-tank grenades, but the Stryker is much faster than a tank and just moved away in time. That being said, the I'm sure this slat (birdcage as we called it) armor would help with that as well.

Re: Metal foam obliterates bullets

#65

Post by SEJeff »

spatulan wrote: post #50
SEJeff wrote: post #19

Earlier quoted context omitted.

This is exactly how a Soviet style RPG works. Ironically, it is also why the "bird cage armor" works so well against the RPG. Here is a picture of a Stryker combat vehicle from when I was in Mosul Iraq circa 2004ish: http://www.digitalprognosis.com/album/images/iraqpics/the-st... The slats are smaller than the height of the outer explosive and prematurely detonate it. As a result, the penetrator simply bounces off th…

I though slat armour worked because RPGs only had a detonator in the nose, so unless you were very unlucky and the tip of the RPG hit a slat, the RPG would just jam itself between two of the slats.

I saw that a few times actually, but only when the idiot firing the thing didn't pull the safety pin out of the warhead. The RPG is surprisingly safe when you neglect to remove the safety and will happily fire, but not explode in that circumstance. It was around the height of the Fallujah offensive we saw that happen.

Re: Metal foam obliterates bullets

#66

Post by the8472 »

dkbrk wrote: post #29

This doesn't have much in the way of interesting details, you need to go to the paper for that. The armour is a composite sandwich, with boron carbide on the front face (a hard ceramic), followed by the metal foam, and either aluminium or kevlar on the rear face. The boron carbide layer blunts the bullet and distributes the compressive stress over a large area of the metal foam. The metal foam is made of 2mm-diameter…

There's a 4th layer: The whole thing is vacuum-wrapped in epoxy-fiberglass composite to catch spall.

Re: Metal foam obliterates bullets

#67

Post by JoeAltmaier »

dexterdog wrote: post #59
awalton wrote: post #58

Earlier quoted context omitted.

...which is already defeated by reactive armor, which you'd presumably layer underneath this ablative mesh armor layer to prevent this kind of attack. So, three projectiles in the same spot?

Better start with four so you're ready for the next shielding upgrade.

How about 180?

https://www.youtube.com/watch?v=xe-QP8s1ZJc

Re: Metal foam obliterates bullets

#69

Post by guard-of-terra »

I read about it as a child. On earth, molten metals readily lose gas by the force of gravity, but in space, you can easily make metal foams that will be very strong and light. Sounds like a good material for spacecrafts.

Also, how about glass foam? I imagine you can blow large and cheap hulls from foamed molten glass.

Re: Metal foam obliterates bullets

#70

Post by tim333 »

Looking at the ammo channel for I think the same ammo the results don't seem that remarkable. The foam article quotes "less than an inch", the ammo test article has about 1 inch for mild steel and 0.319 inches for AR500 plate

http://www.ammochannel.com/30-06-30-cal-m2-ap-armor-piercing...

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