In a message dated 96-12-24 12:12:18 EST, you write:
>Now for another "dumb question", what about the Philystran type of guying
>material. Any data on contraction or expansion? Also, given the variation
>in tension with the temperature what should I do? Should the guys be
>retensioned based on a change if temperature? If yes, how big a change in
>temp before doing this? I for one don't relish the though of retensioning
>the guys on two 120+ foot towers when it is 10 below.
I've been going through my Phillystran literature and what I've been
able to find is the "effect of temperature on yarn tensile strength" and
"long-term creep" but no elongation vs. temperature data. Next time I talk
to Ken Knight, I'll ask him.
BTW, both of the aforementioned charts show 1) the benefits of
Phillystran/Kevlar over other synthetic materials and 2) the slow and small
elongation of tensioned Phillystran; at 10% tensile load, the elongation
in/in (x 10 -3) over a couple of years changes is practically constant. I
don't know what the immediate elongation when tensioned is.
It's probably too much to ask for Phillystran to be online and
subscribed to TowerTalk. Just FYI, Hy-Gain and Rohn are just 2 companies
that have employees that are subscribers.
73, Steve K7LXC
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