Ed Huntress wrote:

want to take a look at "Design of Weldments", Blodgett, Sec. 2.5. I'd
be surprised if you didn't have *that* book.

I don't, but I still have a couple of Mechanics and Statics-and-Dynamics

You might want to get it. It's put out by Lincolm (the welder people)
and, like most of their books, is both good and cheap. As well as
unusually readable theoretical stuff, there's a lot of charts, tables,
worked problems and comparisons of designs.


About those tubes, Euler's formula and much of the rest are long lost in my
memory, but my non-mathematical recollection of the situation is this.
Increasing resistance to buckling for a given *weight* of of a given tubular
material, by increasing tube diameter and thinning the walls, is
self-limiting.

Correct. As with most things, if you go to extremes, you get into
trouble. Just where that point occurs requires working through a
particular case. My point is that it is not clear that going to
aluminum will improve stiffness - you need to do the calculations for a
particular case.

BTW, similar considerations apply to torsion.

Ted