Hello All, Some background information: I'm a co-op engineering student and recently my supervisor asked me to do a bit of research on a solution to a problem we had. Essentially, a cardan shaft connecting a motor and a gear box failed at a joint during operation and caused some extensive damage (luckily no one was hurt). A solution to this was to design a collar placed midway of the shaft to "catch" the shaft if it breaks and prevent damage to the surrounding. This shaft is rotating at high speeds so we are assuming precession plays an important factor as the shaft would hit the side of the collar instead of falling straight down if it breaks at a joint. An important aspect to know before designing the collar is an order-of-magnitude estimation of the impact force from the shaft to the collar. One approach that I have been thinking of is using an energy method where we find the rotational kinetic energy due to precession from the shaft and equating that to the strain energy of the collar when it deforms from impact. Keep in mind that there assumptions that will need to be made (the collar will elastically deform, the shaft is rigid, the collar is circular, there is clearance between the shaft and the collar, etc.). My question is: is this the right approach to find an estimation of the impact force or is there another approach (maybe better) that I can take? If anyone can share any insight on this that would be awesome! I've also included a quick diagram to give a better idea of the shaft and collar.