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Re: [PSUBS-MAILIST] Re: Viewport Toughness
The penetration resistant quality of "bulletproof" glass has more to do with the material construction than the material itself. Polycarbonate is a type of plastic that has excellent properties for use in this application, but it is the composite layering of sheets of polycarbonate (alternating mean axes of the polymer chains) that stops the projectile. The individual sheets deform, and the composite delaminates, which absorbs the energy in the projectile. In the same way that bulletproof vests use multiple layers of high strength fibers to absorb the energy of impact, plastic composites can be constructed with glass, kevlar or carbon fiber reinforcements which act to distribute the stress of a bullet impact over a larger area within the window. The closer you can get to using the cumulative strength of the entire window, as opposed to the region immediately surrounding the bullet, the better chance you have of stopping it.
-Sean
Quoting Michael B Holt <tlohm@juno.com>:
> On Mon, 06 Oct 2003 13:32:39 -0600 Coalbunny writes:
> >I don't know about it making the glass or arcrylic "bullet proof".
>
> I've seen windows that were hit but not penetrated. It's possible
> to make a window bulletproof, but I don't that relates in any way
> to submarine viewports. Glass made bulletproof is glass made
> resistant to one impact on a tiny point. A window that's taken a
> bullet is probably not going to survive a second impact.
>
> Viewports have to be proof against pressure over their entire face,
> and for a long time.
>
> On the other hand, what can we learn from the idea?
>
>
>
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> unto the bottom, and so to come up againe at your pleasure ...
> -
> William Bourne, 1576
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