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Fatigue Testing - starting load

Fatigue Testing - starting load

Fatigue Testing - starting load

(OP)
I am going to start carrying out some fatigue testing on a number of ferrous and non-ferrous alloys to produce S/N curves. Test parameters: tension-compression, fully reversed, Kt=1.
Could you please give me some advice on how to decide on which loads I should consider testing at considered to the material's tensile strength.

I thank you in advance for your assistance

RE: Fatigue Testing - starting load

Well that all depends on the material and what you are looking for. I do harmonic testing on simple cantilever beams, usually I try to use enough peak to peak travel to get >105% of the published endurance limit of the material. Although I'm doing accelerated testing to compare different steels or processing methods.

It seems to me that to build an S-N curve you will need lots and lots of samples. Then you would test them at different stresses. Tehn plot stress vs CTF and at 10^7 cycles consider the DNF condition.

Nick
I love materials science!

RE: Fatigue Testing - starting load

will, what is the time frame you have to construct the S-N curves for different alloys and under different conditions.Is it for academic interest?

RE: Fatigue Testing - starting load

Estimate the fatigue life from similar materials.  Often you can use a percentage of the yield strength.  Then select a load that will give you your first failure in a reasonable time, say a day or two.  Then you can work either up or down from there.

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