Morning All - over coffeee I had a further play with the tube model. I made the mesh finer and used an adaptive mesh setting. Plus I set the connections at bonded. This took more time to solve (due to adaptive setting) but each member stretches the same and its 7.56um which is close to the manually calculated stretch of 7.57um. Looking at the adapted mesh it has placed 3 or 4 elements across the thickness, this is what I would have aimed at if manually specing the mesh. Having one element across a thickness is poor practice and the stresses will be inaccurate. In this case stress is not important but it clearly influenced the stretch somehow. All good. Next would be to check a bonded connection in bending to establish that's its OK as well, then we could move onto the real model knowing outcomes are correct... Peter

so next step to speed up the solution is to spec a finer mesh but not use adaptive.

I have not played enough with Fusion that's why I have done this. I mainly use a system called simsolid as most of my current work involves large structures with lots of bolts and SS does bolted connections and extracts bolt loads very well. Fusion has bolted connections but does not extract the bolt load (maybe it does haven't dug that deep yet) I am confident that a good model in Fusion is accurate as this study has shown.... Since Fusion has a ansys and a simsolid port I think its running ansys by default...