Re: ATM Source for Fiberglass, Carbon tubes

[Kurt Hillig <khillig@Chem.LSA.UMich.Edu>]

On Mon, 9 Jun 1997, Spencer Roedder wrote:

> >4" diameter x 1/16" wall aluminum tubing has the same weight per foot of
> >length as 1/2" aluminum rod, but it's many orders of magnitude stiffer. 
> >Since stiffness varies with the cube of the moment, and the moment goes as
> >the square of the dimension, a factor of 10 increase in modulus allows
> >only a 30% reduction in size.
> 
> A little miscalculation there: the 4" tube is equivalent in cross sectional
> area to 1" rod - which is a _heck_ of a lot stiffer than 1/2" rod, though I
> agree, not as stiff as the 4" tube.

Damn, I always screw up the radius/diameter distinction when working on my
lathe, too.  I guess that gets half ;-), half :-( 

I guess it's time to make a big sign:


                        IT'S THE DIAMETER, STUPID!


                            Dr. Kurt Hillig
  UMNet Administration     I always tell the    fax (313)763-2180
 University of Michigan     absolute truth     phone (313)647-8778
Ann Arbor, MI  48109-3297    as I see it.    X.500 khillig@umich.edu

 >> Computers were invented to help people waste more time faster <<