pic: Broken Output Shaft

[JamesCH95]

Originally Posted by AdamHeard

I'm certain the large slot for the dog shifter was more of a stress riser than the snap ring grooves.

And Chris, not that most teams use snap rings on the extremes of the shaft, where there is no load being applied; it's less common to see them between loads like this.




It wouldn't be a universally accurate demonstration.

The location of all such features and loads would have a large effect on the result.

This. They're fine if they're no appreciable torque is being transmitted through it, which is the proper way to utilize snap rings. Heck, two of the FSAE cars I worked on had drive shaft components retained with snap rings in no-load areas.

About an FEA model of the stress concentrations... in my experience many FEA programs don't pick up on stress risers much of the time. I just tried to do it with Solidworks Simulation and the program didn't pick up on the groove as a stress riser. This is a problem when a designer doesn't use common sense and simply trusts FEA results without question.

Here is an interesting FSAE thread on a similar topic with a very good explanation about why the drive shaft failed at the groove.

Again, non-torsionally-stressed grooves are okay. Torsionally stressed grooves will very likely fail.