On 8/6/17 8:20 AM, Jim Thomson wrote:
Date: Fri, 4 Aug 2017 10:27:54 -0400
From: Charles Morrison <junkcmp@gmail.com>
To: towertalk@contesting.com
Subject: [TowerTalk] Square tubing
<What changes or corrections are needed to Jim Lesson's formulas to
<calculate survival of square tubing booms ?
It kind of depends on what he was calculating..
Stiffness goes as the section moment, which is proportional to the 4th
power of the radius.
for square tube Ix = (OD^4-ID^4)/12
for round tube Ix = pi * (do^4-di^4)/64
Strength is more about radius and wall thickness. It's a bit tricky with
square tubing because if the bend is exactly in line with the walls,
then you have a very large cross-sectional area to spread the forces
over. But if you're a little bit skew, then it's not hugely different
than a round tube.
<-Charlie N1RR
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