Fatigue analysis on ring springs

[prabeshlohani]

I'm trying to analyze fatigue behavior in compression rings, and was wondering if anyone could help me find appropriate loading, size, surface etc. factors I could use for my calculations. Most of the data published are for beams in bending. Any help would be greatly appreciated.

 

[israelkk]

What do you mean by "compression rings" springs? This is not a common name for the known spring types.

http://israelkk.googlepages.com/home

 

[prabeshlohani]

Sorry for the confusion. I am trying to calculate fatigue life of rings under axial compression. The rings will be forced to expand radially outward due to the loading.

 

[israelkk]

If you compress a ring axially it will expand on the outside diameter and toward the inside diameter. Usually there is no fatigue under compression stresses.

 

[GregLocock]

Springs do fatigue in compression because they work in shear. Bosch blue book has page after page of fatigue life predictions for compression springs.

Also I think you'll find the ID increases in compression.



Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[israelkk]

GregLocock

I do not think prabeshlohani refers to compression coiled spring made of wire (at least he didn't say it even though I asked for clearer info). To my understanding from the post he is referring to one piece metal ring. At least my post was for such a spring. But, you may be right because many times people do not bother to inquire for correct names of springs thereby create confusion.

 

[GregLocock]

Yes, I'm still puzzled by his terminology

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[prabeshlohani]

Sorry for the confusion again. I have uploaded an image that shows the cross section of the assembly. Hope this helps. Please follow this link to see the drawing:

http://geocities.com/prabeshlohani/temp/spring.JPG

Thanks for the help.

 

[israelkk]

As I understand these type or ring springs are usually grinded or even polished to achieve low coefficient of friction. Therefore, the surface factors for fatigue analysis should be similar to the factors for rotating bending or tension fatigue samples. As to loades, deflection, stresses, etc. you can look at Mechanical Springs 2nd edition 1963 by A.M. Wahl pages 204-210 and/or Spring Design A Practical Treatment 1961 by W.R. Berry pages 262-266.

http://israelkk.googlepages.com/home

 

[unclesyd]

Here is an article on "Ring-Springs or Friction Springs" made by RingFeder. These might lead to more information.

http://www.ringfeder.com/PDF/Friction Springs in New Millenium.pdf

http://www.ringfeder.com/PDF/Damping Technology catalog 2002 Rev1.pdf