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Discussion Starter #1
One of the most important developments in armor was that of transparent armor (TA). To the public, transparent armor is known as "bullet proof glass". Even among those who work with it the most common name is "bullet resistant glass". Manufacturers don't want to misrepresent their product as proofed against all bullets so they use the word resistant instead of the word proof.

The irony is that it is rarely glass-only and sometimes there is no glass in it. In fact TA most often takes the form of a laminate consisting of a sheet of polycarbonate with a layer of glass on each side. Think of this symetrical laminated armor like a hamburger where the meat is a plastic and the bun halves are glass. The laminates are bonded with types of glues.

Polycarbonate alone is usably bullet resistant. A half inch thick sheet of polycarbonate can easily stop .22LR bullets. The reason for adding the glass laminates is two-fold. First, the glass serves as a hard, scratch resistant surface. Second, the glass adds to the bullet resistance. Glass is harder than plastic, but is brittle and shatters easily. The plastic offers structural support, holding the bonded glass even after it shatters. Holding the glass in the path of the bullet forces the bullet to expend kinetic energy (energy of motion) breaking the bonds of the glass molecules. Adding more layers of alternating glass and plastic increases the resistance to penetration.

Analyses of injuries by armor penetration has revealed the distinct danger posed by spalling. Spalling is a type of armor impact damage whereby fragments of armor are hurled off of the backside towards the intended victim. These fragments can cause serious bodily harm. To avoid this, TA may be laminated on the backside with a final layer of plastic, possibly as a thin film.
 

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great post!

spalling , in particular, is bad @ss chit in anybodys book, be it a brinks truck or a #5 chat rock/#11 chat rock, laminate mix in a 69 dodge van ,down by the river!



thanks.
 

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Discussion Starter #4
Magnum88C said:
So what are the grades of TA, and what can they stop?
The grading is similar to that of soft body armor. I think it's usually based on United States Institute of Justice (NIJ) standard 0108-01. There is considerable leeway in armor manufacture, so if you're buying it you had better pick a reputable company. Again, it's very much like the soft body armor market.

I've never dealt with the commercial end of it. My knowledge of TA relates to solid mechanics (how stuff breaks).
 

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Are the glass/polycarbonate/glass "windows" more effective than the multi glass layered "glass"?One of my customers has a bunch of armored trucks built in the '80's.The windshields & side door glass are made of 7 layers of safety glass.ie.the windshield is actually 7 windshields stacked on top of each other.
BTW,he tells me that a .30-06 solid will penetrate w/o a problem.

He has a set of back doors that I can have to play with.I just lack a forklift & a permanent place to set them up.:)
 

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Discussion Starter #6
41mag said:
Are the glass/polycarbonate/glass "windows" more effective than the multi glass layered "glass"?
Probably. If it is seven "windshield" layers, there is almost certainly a layer of plastic film between each glass layer. Windshield glass is suprisingly tough.
 

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Sorry,my post should have asked if the glass/poly/glass combo is more effective than multiple layers of regular windshield safety glass?Which,of course,has a this vinyl layer between each glass layer already.

Or is it just lighter?
 

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Discussion Starter #8
Usually the glass/poly/glass was prefered. However, most folks are switching to a plastic/glass laminate with the plastic on the inside of the car or building.
 
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