The videos below show the results of the MbDFEM simulation. The spring force and the cylindrical joint force and torque vectors are also included, for visualization completeness.
Note how, as could be expected, the maximum stress takes place when the spring is at its maximum length (time zero). This is because the stress derived from joint torque is dominant, higher than the stress from joint force and from spring force. This may be better appreciated in the following videos, where the camera is attached to the cylindrical joint and the top-view is shown.
The next videos show a top-view close-up perspective or the videos above, offering a better visualization of the stress distribution.