Log in

View Full Version : one way bullet proof glass, self healing too!


Mick
October 1st, 2003, 08:39 AM
http://www.nola.com/news/t-p/metro/index.ssf?/base/news-0/105764923388880.xml - article
http://www.labock.com/english/bpg.htm - product info/labock website
http://www.labock.com/videos/labock_one_way_test.ram - demo movie (2.7mb, i haven't seen it yet)


what do ya think guys?..sounds very interesting indeed..

(btw, mods, move this topic, i took a page from the noobs book with this one. i couldn't figure out where to put it, so, all else fails - water cooler )

arsoniztonfyre
October 19th, 2003, 01:38 PM
That's very interesting indeed. I just don't see how it is possible to heal itself.

chemwarrior
October 19th, 2003, 03:27 PM
Read the article... it doesnt actualy 'heal', but it does not shatter the glass like a normal bullet would. From the inside, it hits a soft layer first, then the ballistic glass. The inner layer is soft enough that after the bullet passes through it, it can 'close up' a small ammount. However, when shooting from the outside in, the bullet hits the ballistic glass first, stoping the bullet before it gets to the softer inner layer.

Jacks Complete
January 7th, 2004, 07:07 PM
From the thread I started before Rhadon pointed out this one.
----
one-way bulletproof glass

Haven't found this on the search.

I remember seeing a demo of this on Tomorrows World, back when I had TV. The way it was made was a couple of sheets of plastic, bonded together.

Basically, the trick was, to glue the two types of sheet so that the hard one was on the outside, and the soft was on the inside.

The bullet from the outside hit, and was distorted by, the hard outer sheet, which flexed the inner sheet, absorbing the energy. The shattered bits stayed in place, on the softer sheet, held by the glue.

Bullets from the inside hit the softer layer, and pushed through it, then shattered the hard outer layer, which was then pushed away from the glue and the softer layer, letting the bullet pass through. The hole would then shrink as the inner layer pulled back in, with the hard bits still glued to it.

Hence, one-way bulletproof glass. Obviously, it wouldn't be as strong as normal multi-layer polycarbonate and glass would, but it could be designed for the required threat level. Of course, you would need the occupants to be armed with something potent enough to pass cleanly through the outer layer, or you have one hell of a ricochet danger! It does, however, allow the option of shooting back, unlike the "fish in a barrel" approach otherwise employed.

Suggestions for the materials, anyone? I would think glass would do for the outer surface, and perhaps polystyrene for the inside, and some kind of superglue. Anyone know for sure? Any better suggestions?

I can't wait to make some! It is something I never got round to.
---

Can we delete that thread, and move this to improvised weapons or something?

Marvin
January 9th, 2004, 06:53 AM
From memory the way it worked depended on a property of polycarbonate. Aparently its a very strong material under compression, but not so on expansion, where is just seems to shatter. So you make a 2 layer window with polycarbonate on the outside and a bullet hitting the outside compresses the polycarbonate against the inner lining and thisis strong enough to stop it. In practice it seems to end up wedged between the layers, splitting them. A bullet from the inside peirces the inner lining with no difficulty and the pressure on the polycarbonate is expansion which probably just shatters it locally and it passes though.

Jacks Complete
January 9th, 2004, 08:05 PM
Marvin,

that's the one. Now we need to know which other materials are needed.

Someone said acrylic for the softer side, but we would need to find the right glue.

streety
January 11th, 2004, 02:57 PM
I think you have it the wrong way round.

http://www.labock.com/english/bpg_oneway.htm

On the protective side, as a bullet strikes the acrylic (brittle, but very strong when compressed) outer layer, the acrylic is compressed, strengthens, and absorbs/distributes the bullet's energy. Simultaneously, the polycarbonate layer, which has flexible characteristics, stretches as it dissipates all the remaining bullet energy, and there is no full penetration. There is some "spider webbing" on the impact side, but the inside of the glass remains smooth and undamaged.

On the One Way side, the reverse occurs - The polycarbonate is compressed, and the acrylic is stretched. The bullet easily passes through the soft polycarbonate layer, and into the acrylic layer, which becomes weak as it is stretched. The bullet shatters the acrylic and continues onward, with negligible loss of velocity, and practically no deflection.

Begste
March 8th, 2004, 12:34 PM
Marvin,

that's the one. Now we need to know which other materials are needed.

Someone said acrylic for the softer side, but we would need to find the right glue.

I used to have the exact specs. Something like 11mm acrylic and 8mm of polycarbonate. Or the other way around. There is a epoxy called Lexseal.

Jacks Complete
March 9th, 2004, 08:56 PM
The exact thicknesses would depend on the threat level, as well as the power of whatever you were shooting through it with. Otherwise your .22 pistol hits you with the ricochet, or you get killed by some bugger with a 30-06.

I will have to look up Lexseal. Ok, looked, and google said "No pages were found containing <b>"lexseal"</b>."

I have just emailed ICI Bondmaster, I will post the answer if I get one.