On 2/1/2018 9:09 PM, Emanuel Berg wrote:
AMuzi wrote:

Kevlar/Aramid excels in tensile strength.
Maybe you should review this:
http://www.instron.us/en-us/our-comp...s/tensile-test

OK, seems like a lot to digest but no one said
it was supposed to be easy, right?

but it's unremarkable in shear.

One better double-check the direction of the
fibers before pulling on the bulletproof
vest

BTW I wonder if this is why it is used in
hockey sticks, skis, etc. "Hard and flex at the
same time", remember?

The hockey stick for sure cannot be pulled any
longer than its original 60 inches (~152cm) but
one can budge it on the middle leaning on it
and giving it just a small extra push.
This property in the hockey world is called,
with this instance as an example, "flex 85"
(which is pretty hard, for a strong but
medium-sized player). I'm unsure if this is
just a digit the manufacturers use or if it has
some scientific ground as well WRT
the material.


I'm sure Frank could discuss tension and compression in a
beam better but here you go:

http://people.virginia.edu/~pjm8f/en...and_strain.htm

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971