21-10-2010 14:20

JesseK

Re: pic: Stress plots related to broken output shaft

Interesting plot and good to know the ramifications of a mis-fitted snap ring. I'm curious to know if the stress loading is the same when a properly-sized snap ring is in place?

21-10-2010 16:08

AdamHeard

Re: pic: Stress plots related to broken output shaft

By properly sized, I assume you mean cut all the way down into the hex? On hex shaft, you can get away with doing the next size larger snap ring, it just won't handle as much load. Somewhat off topic.

Say the groove did go all the way around, it would have similar effects. Stress will concentrate at the sharp cornered junction; the decrease in diameter is much less "damaging" than the sharp corner of the change. Varying diameters and radii (of that diameter change) will all create different reactions. It's really a simple guy to calculate if you know all the physical properties.

I found this book on google that has one of the tables you would use (this for torsion, for other types of loading a different chart is used).

21-10-2010 16:09

JamesCH95

Re: pic: Stress plots related to broken output shaft

Quote:

Originally Posted by JesseK Interesting plot and good to know the ramifications of a mis-fitted snap ring. I'm curious to know if the stress loading is the same when a properly-sized snap ring is in place?

22-10-2010 00:25

M. Mellott

Re: pic: Stress plots related to broken output shaft

One option that comes to mind might be to use a tool that has radii in the bottom corners (or completely rounded on the bottom and cut your groove a few thousandths deeper) rather that sharp points. Sharp edges are stress concentrators, so the blends might remove some of the stress points.

Now, one might say a completely rounded groove bottom might also take away too much of the vertical side walls of the groove and defeat the primary purpose--holding a snap ring and supporting an axial load...but some snap rings have rounded cross-sections, so...

22-10-2010 02:01

AdamHeard

Re: pic: Stress plots related to broken output shaft

Quote:

Originally Posted by M. Mellott One option that comes to mind might be to use a tool that has radii in the bottom corners (or completely rounded on the bottom and cut your groove a few thousandths deeper) rather that sharp points. Sharp edges are stress concentrators, so the blends might remove some of the stress points. Now, one might say a completely rounded groove bottom might also take away too much of the vertical side walls of the groove and defeat the primary purpose--holding a snap ring and supporting an axial load...but some snap rings have rounded cross-sections, so...

22-10-2010 03:36

artdutra04

Re: pic: Stress plots related to broken output shaft

Quote:

Originally Posted by M. Mellott One option that comes to mind might be to use a tool that has radii in the bottom corners (or completely rounded on the bottom and cut your groove a few thousandths deeper) rather that sharp points. Sharp edges are stress concentrators, so the blends might remove some of the stress points. Now, one might say a completely rounded groove bottom might also take away too much of the vertical side walls of the groove and defeat the primary purpose--holding a snap ring and supporting an axial load...but some snap rings have rounded cross-sections, so...