For all machine elements:
$G_{al} = 40 N/mm^2$, $G_{a} = 60 N/mm^2$, $Pol = 100 N/mm^2$
A shaft and hub connection is welded to a square flange, and the flange is fixed to the wall by four rivets. The hub is connected to the shaft by a rectangular key. The force is acting on the lever arm F at a distance L from the shaft centre.
1) Calculate the necessary diameter of the rivets.
2) Calculate the shear stress in the weld seam under torsion.
3) Calculate the $l_0$ length of the key.
4) Calculate the rotation (in degrees) of the free end of the shaft regarding the shaft as a torsion spring.