Torsion and buckling

[bkal]

I would appreciate some advice and warnings from experienced ABAQUS users. I might need to model and assess a coring machine driveshaft for combined torsion and axial compression. The driveshaft consists of a number of flanged steel tubes with a longitudinal slit (open section), bolted together to get a required length of the shaft. While the geometry of the model is reasonably simple, I assume that I will need to use something like 20 noded hex elements. My main concerns are: how many elements through the thickness, what steps of analysis should I use, is eigenvalue buckling appropriate?

Any advice will be greatly appreciated.