Fatigue Testing - starting load 1

[will123]

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

 

[NickE]

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!

 

[arunmrao]

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?

 

[EdStainless]

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.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm