Re: tubes and cosmos analysis

TOP is correct, you'd need to use beam elements --
which Xpress does not have.

For a quick/dirty analysis with the tools you do have, you
might model your frame with solid rounds -- and not tubes.

The stress results from this would of course be totally
meaningless but you may gain some insight from the
displacements -- ie where your structure might benefit
from gusseting, etc.

Be careful of sharp inside corners -- which stinks because
1) a weldment will have lots of these and 2) thats where
your gussets would be. Use some "engineering sense"
and try to guess where the critical points are likely to
be. Fillet these joints with a radius at least equal to
your intended wall thickness.

Try to run as fine a mesh as your machine will handle
(don't know how much control Xpress gives you here
either).

Finally, you'll have no buckling information -- so keep
an eye out where tubes meet at a "T" or where the
displacement analysis bends them significantly from
compressive forces.

Far from ideal -- but again, may give you some insight.

-Tony
.