From the pictures and my limited engineering education: I would
say the "stress" and "safety" pictures are very significant also. They
show the "points" that the steel comes closest to reaching its limits
and these points could be beefed up with thicker layers. Where as the
"deflection" picture shows where the shape (cross section) of the beam
could be beefed up.

   I think about the "rule of thumb" 50 diameter : 1 wall thickness
for tubing. Think of the beam as a tube. For bending the best possible
use of more metal is to increase the diameter of the tube. While for
those localized stressed areas thicken the wall.
I looks like adding a tie to the top of the beam on the ends and
reinforcing the mounting holes would reduce the stress around the
holes and stiffen the beam the most.
   Of course after differential equations and thermodynamics I
drooped out of mechanical engineering and went into computer science.
So my opinion doesn't mean much.
Blake



The stress and deflections around the large holes on the ends
are probably inaccurate as the beam is supported by rubber bushings
that tend to spread the load. Very difficult to model that situation
and probably not worth the effort. Minor permanent distortion there would
be of little consequence.

My main concern is the stress concentrations around the enlarged
slot. That is easily fixed with the addition of a bit more material.
Not as much as I first thought. I think we are going with the
1/4 square steel key stock as it is very low cost. About $2 per
beam in material.

Paul Lamar

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