Fatigue of polymers

[Muzialis]

I have the need to come up with some fatigue caculations on NR/SBR polymers.
Is there anything like a cumulative damage rule for polymers?
Otherwise what is the most common point of view on polymers fatigue?

Thank you

[Jorgen]

The current state of the art with respect to fatigue predictions of polymers is unfortunately far from well developed. There have been some interesting work, for example, on understanding and modeling fatigue of rubbers by Dr. Will Mars et al. One interesting and somewhat unintuitive feature is that the fatigue life can increase with increasing mean cyclic strain.

Another complication is that the fatigue life can be strongly dependent on the applied frequency due to thermal heating.

I believe that Ward's book (An Introduction to the Mechanical Properties of Solid Polymers) has some discussion about fatigue. There are also numerous journal articles on the subject.

- Jorgen

[Muzialis]

Jorgen,

thank you for your answer: I will certainly look for the book you mentioned.
Just a final curiosity:do you think an endurance limit exist for elastomers?We have done extensive testing at fixed strain and no failures were recorded in 10^8 cycles for strains below 12%: nevertheless some researchers believe this is not sufficient for defyning an endurance limit, as the behaviour at varying strains, even if all below 30%, is still unpredictable.

Thank you very much in advance:if you indicated another couple of titles of books or articles I would be greatly obliged.

Marco

[Roham]

Marco,

You can also check out the work done by C. Bathias. He has done a great job on farigue and failure of NR and SBR. It might help.