@scifi and @olympia463 :
the attachment ring you see is actually the front of the low pressure compressor which hangs onto the fan as far as i understand it.
the part in the middle that is sheared off is the connection of the shaft connecting to the fan.
so the shaft connection there needs to carry the torque and pull from the low pressure compressor as well as the fan.
see various depictions / diagrams in the thread.