Designcoeng:
The devil’s going to be in the details of the schematic idea you are trying to show. Goodness knows what you are really trying to do, or how. You are keeping that a secret, and trying to cover it up with a bunch of fancy FEA calcs. The type of calcs. BA has done are really all you need until you start to hone in on the details. He apparently didn’t notice your right support (pin support, your first sketch), so he is using 34" as a cantilever length. I agree with the 5.7ksi normal bending stress. And, I suspect that the large (33.69ksi) torsional stress is some small area of stress concentration immediately around the load application point, an anomaly having to do with the exact way the software assumes you have applied the eccentric load, or the way you have imported the model to the FEA. And, I would bet it is on the side of the load application too, where the pin shearing stress will be greatest.
You would do well to do these types of hand calcs. and hand sketching, rather than CAD and FEA when you start a problem. Although, your second CAD sketch is fine, but missing a bunch of important detail. Think about how it works, how it is manufactured, and goes together while you are doing your hand calcs. and sketches. You can just draw and analyze the hell out of things which can’t be practically built when you rely totally on CAD and FEA to start your analysis. The fact that you have fixed so many of your boundary conditions at the two supports is likely making the FEA software think that warping and parallelograming can’t take place, and this could lead to some very high localized stresses.
I don’t really think you have fixity in any direction at either of your reaction points, and you don’t explain what those reactions are or how they work to cause any fixity. You do limit the y & z displacements to some amount. But, even that is a funny number because you have a telescoping cantilever within an outer supporting tube member which will bend and deflect. And, now all of a sudden, you show a new support from above and about 18" left of your right support. It’s really difficult to find two perfectly square and straight tubes which will slide, one inside the other. So, you’ll end up with 4" wide (5" less the corners) x 2 or 3" long bearing pads; one set of 4 pads at the back end of the sliding tube; and the other set of 4 pads at the front end of the support tube. Thus, it is only about 24" btwn. the reaction points. Now, the question is, should there be a wear pad on top of the inner tube in the region of that new top support point? If you want the sliding/telescoping action to be smooth and easy, you might consider cam rollers as your support points. How are you getting the 7.5k eccentric load into the tube wall nearest the load, what’s the pin through the tube for? What is that whole elliptical device at the load point? You might want to put end plates on each end of the inner tube as stiffeners. What is the actual support structure and what is this thing actually supposed to do?
