fatigue which include chemical environment

[mkrajci]

Hi,

Is possible modeling fatigue analysis which include chemical environment ? For example: fatigue of tooth, where acts Chemical substances.

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[unickque]

Usually the environment is accounted for via an extra stress factor. But this is very tricky business. You cannot just say that a certain chemical has a factor of X. The factor will be different for different concentrations of the chemical, and will have different effects on different materials. So I don't think anyone has ever dared to create an overview of such factors. Perhaps some studies have been done to your particular case of interest. Otherwise you probably need to do some extensive (and expensive) testing.

[mkrajci]

Where can I define extra stress factor ?

[unickque]

Depends on your tools. How are you currently calculating fatigue?

[mkrajci]

over fatique analysis. We are partner PTC , we have all extension..

[unickque]

I do not have that luxury, so I have to go on what i read and see.

You could (ab)use the surface finish and try different settings, and then compare it to test results. But this is sort of a black box with only discrete settings.

Another option may be what they call the "failure strength reduction factor Kf". That way you have more control over the actual reduction numbers, and you can tune your model more precisely to the test results.

In any case it will be difficult to get good results. But you will have the same trouble with other software or hand calculations. The influence of environment on fatigue is just difficult to predict.