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Message no. 1
From: shadowrn@*********.com (Gurth)
Subject: Body armors (was Re: Monofilament Whips)
Date: Fri Feb 23 05:05:01 2001
According to Stuart Purdie, on Thu, 22 Feb 2001 the word on the street
was...

> That's a bit of an issue. In fact, flexible, bullet proof armour just
> plain doesn't work, unless you invoke very stragne effects
> (superconducting wires in the cloth, forming loops, to resist a change in
> shape), at which point, they lose flexability. Note that the Kevlar vest,
> although woven is not flexable (so as you'd notice). It's woven because
> that's the only way to make it - cast solid it would be stonger.

It is very simple to make "solid" kevlar armor, though -- mold it in resin,
in exactly the same way things like polyester boats are made. If you look
inside a kevlar helmet, it's obvious that it's made from woven kevlar
fibers glued together to form the helmet's shell. (You would also be able
to see this on the outside, were it not for the paint that typically covers
that side :)

The main reason body armor is made from woven materials and not solid
plates is ease of movement. Some plates can be put into the armor (as is
often done with vests intended to stop bullets rather than grenade
fragments), but they will be restricted to those areas that don't flex
much -- that is, the front and back of the torso. If a whole armor were made
from plates, molded kevlar would be far too thick. Metal (or plastic) sheet
can be made into a full-body armor, as was done in the late middle ages,
but it won't be thick enough to stop bullets.

Which probably means that in SR, armor materials are far enouh advanced to
make very thin plates (a few millimeters thick) that still stop SMG bullets.

--
Gurth@******.nl - http://www.xs4all.nl/~gurth/index.html
afblinken
-> NAGEE Editor * ShadowRN GridSec * Triangle Virtuoso <-
-> The Plastic Warriors Page: http://plastic.dumpshock.com <-

GC3.12: GAT/! d-(dpu) s:- !a>? C+@ UL P L++ E W-(++) N o? K w+(--) O V?
PS+ PE(-)(+) Y PGP- t@ 5++ X(+) R+++(-)>$ tv+ b++@ DI- D+ G+ e h! !r y?
Incubated into the First Church of the Sqooshy Ball, 21-05-1998
Message no. 2
From: shadowrn@*********.com (Stuart Purdie)
Subject: Body armors (was Re: Monofilament Whips)
Date: Fri Feb 23 07:05:01 2001
On Fri, 23 Feb 2001, Gurth wrote:

> According to Stuart Purdie, on Thu, 22 Feb 2001 the word on the street
> was...
>
> > Note that the Kevlar vest,
> > although woven is not flexable (so as you'd notice). It's woven because
> > that's the only way to make it - cast solid it would be stonger.
>
> It is very simple to make "solid" kevlar armor, though -- mold it in resin,
> in exactly the same way things like polyester boats are made.

That's not solid Kevlar. That's a Kevlar compsite. Very different. In
the compsite, assuming rules of mixtures applies, and going with a very
dense composite, you only have a tensile strength of 0.85 X (Strength of
Kevlar) + 0.15 X (Strength of resin).
Message no. 3
From: shadowrn@*********.com (Martin Steffens)
Subject: Body armors (was Re: Monofilament Whips)
Date: Fri Feb 23 07:25:01 2001
All this talk about Kevlar made me wonder how heavy a mediaeval style
full plate armour would be in Kevlar form?
I expect heavy, otherwise Kevlar breastplates would be a lot more
common.

Thanks,

Martin Steffens
Message no. 4
From: shadowrn@*********.com (Gurth)
Subject: Body armors (was Re: Monofilament Whips)
Date: Sat Feb 24 06:00:01 2001
According to Martin Steffens, on Fri, 23 Feb 2001 the word on the street was...

> All this talk about Kevlar made me wonder how heavy a mediaeval style
> full plate armour would be in Kevlar form?
> I expect heavy, otherwise Kevlar breastplates would be a lot more
> common.

Depends on whether you want it to be bullet-proof or not...

An armor like that built to the same strength as a modern body armor would
be far too thick to use, IMHO -- a current American kevlar helmet has a
shell that's almost a centimeter thick, and it will not stop most bullets
that hit it directly, certainly not at close range. This helmet weighs 1.7
kg and protects most of the head; a full-body suit of the same material
would, at a quick guess, weigh about the same as a metal full-plate armor,
but it'll be much thicker and more cumbersome.

OTOH, if all you want is the same protection the metal armor provides, you
can have much thinner panels and thereby reduce the weight and especially
bulk to much more manageable levels.

--
Gurth@******.nl - http://www.xs4all.nl/~gurth/index.html
Kogels houden van mensen.
-> NAGEE Editor * ShadowRN GridSec * Triangle Virtuoso <-
-> The Plastic Warriors Page: http://plastic.dumpshock.com <-

GC3.12: GAT/! d-(dpu) s:- !a>? C+@ UL P L++ E W-(++) N o? K w+(--) O V?
PS+ PE(-)(+) Y PGP- t@ 5++ X(+) R+++(-)>$ tv+ b++@ DI- D+ G+ e h! !r y?
Incubated into the First Church of the Sqooshy Ball, 21-05-1998
Message no. 5
From: shadowrn@*********.com (Gurth)
Subject: Body armors (was Re: Monofilament Whips)
Date: Sat Feb 24 06:00:06 2001
According to Stuart Purdie, on Fri, 23 Feb 2001 the word on the street was...

> That's not solid Kevlar. That's a Kevlar compsite. Very different. In
> the compsite, assuming rules of mixtures applies, and going with a very
> dense composite, you only have a tensile strength of 0.85 X (Strength of
> Kevlar) + 0.15 X (Strength of resin).

I'll take your word for it (I don't know much more about engineering than I
need to get by :) but I wasn't replying to your statement that solid kevlar
would be stronger than woven kevlar, I was saying that it is possible to
make solid pieces of armor from kevlar. Those are two different things :)

--
Gurth@******.nl - http://www.xs4all.nl/~gurth/index.html
Kogels houden van mensen.
-> NAGEE Editor * ShadowRN GridSec * Triangle Virtuoso <-
-> The Plastic Warriors Page: http://plastic.dumpshock.com <-

GC3.12: GAT/! d-(dpu) s:- !a>? C+@ UL P L++ E W-(++) N o? K w+(--) O V?
PS+ PE(-)(+) Y PGP- t@ 5++ X(+) R+++(-)>$ tv+ b++@ DI- D+ G+ e h! !r y?
Incubated into the First Church of the Sqooshy Ball, 21-05-1998
Message no. 6
From: shadowrn@*********.com (Paul J. Adam)
Subject: Body armors (was Re: Monofilament Whips)
Date: Sun Feb 25 07:45:01 2001
In article <Pine.SOL.3.96.1010223115946.20915B-100000@****>, Stuart
Purdie <sdjp@**********.ac.uk> writes
>On Fri, 23 Feb 2001, Gurth wrote:
>> It is very simple to make "solid" kevlar armor, though -- mold it in
resin,
>> in exactly the same way things like polyester boats are made.
>
>That's not solid Kevlar. That's a Kevlar compsite. Very different. In
>the compsite, assuming rules of mixtures applies, and going with a very
>dense composite, you only have a tensile strength of 0.85 X (Strength of
>Kevlar) + 0.15 X (Strength of resin).

Of course, if you've had some advances in materials technology that give
you a stronger matrix material... :)

--
Paul J. Adam

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