S-N Curves for Plastics?

Wow that was fast.

Unfortunately, it turns out that fatigue data is hard to get.  You can have it measured, but

its expensive.  I figured I'm probably not the first person to need this kind of information,

and find it odd that generic curves for some of the more popular commodity plastics aren't

readily available.

What is "Moldflow"?

SW, as you know, has a few built in but they appear to be exclusively for metals.

I'll dig around Campus, but its like finding a needle in a haystack.

Thanks all.

Anthony,

Thanks -- that reaffirmed some of my suspicions.  I did manage to find a curve for polycarbonate, however

unreliable that might be.  This may be sheer coincidence, but based on the strains in my static analysis,

"gut feel" told me this part might last about 10,000 actuations (order of magnitude).

It is a simple cantilever snap -- granted a bit big -- but still a simple cantilever in plastic.

I used the curve for PC.. again, this might be just a strange coincidence, but Simulation predicts

approximately 14,000 cycles to failure.

I really just went through the paces as a learning exercise at this point.  What I did find curious, however,

is that the fatigue analysis only gave what seem to be reasonable results with fully reversible loading.

Zero-based loading (such as this snap would see), always reported the max life cycles that my S-N

contained (10^8), even though stress in the static analysis is uncomfortably close to yield.

At any rate, thanks again to all who responded.

-Tony