Jim;
There are two "strengths" to consider-- the yield strength and the ultimate
strength. Yield strength has to do with how much you can deform the material
until it won't go back to its original shape. If you slightly bend a bar of
mild steel, it will straighten itself back out when you let it go, bend it
further and at some point it takes a permanent set. You have exceeded its
yield strength when that happens. If you bend it even further it will break
when you exceed its ultimate strength. The region between "bent" and
"broken" is where energy is absorbed by the structure. Mild steel absorbs a
lot of energy while 4130N is ultimately stronger but absorbs somewhat less
energy. An extreme example is glass; it has surprisingly high ultimate
strength but its yield strength is exactly the same as its ultimate
strength. At room temperature you can't make a permanent bend in glass.
Regards, Neil Tucson, AZ
-----Original Message-----
From: land-speed-bounces+neil=dbelltech.com@autox.team.net
[mailto:land-speed-bounces+neil=dbelltech.com@autox.team.net] On Behalf Of
Jim Dincau
Sent: Friday, October 05, 2007 8:34 PM
To: DougOdom
Cc: Landspeed List
Subject: Re: [Land-speed] John Force car
Hi all,
For what it's worth a friend of mine at Lockheed, Leroy Pane, was one
of A. J. Watson's part time engineers. He said the only reason they used
chrome molly tubing on Indy roadsters was that it could be straightened more
times than a mild steel chassis, it wasn't any stronger.
Jim Dincau
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