EDIT 21.08.2017 (UR_, I am getting older...
according to the above formula from UR_ for calculating shear-stress under torsional loading, you can
apply a torsion-loading of 0,231 kNm at the 20 mm transmission (when using steel S235 with a maximum
allowable shear stress of 136 MPa). The distance between the holes in the disk and the axis of the transmission is 30 mm,
so you must apply a load of 7100 N at both holes to get the Torsion of 0,231 kNm at both ends of the transmission.
If you run the calculation with your modell, you will get good results (plot: shear-stress). Attached is the modell
with the cleared mesh (doubleclick on mesh, mesh it hyperfine as you did before and have a pizza during ccx-run...