Reply To: A significant concern regarding the fatigue tool.

[Elizabeth White]

Hello,

If you have S-N curves available for specific mean stress levels, such as zero mean stress, 100 MPa, and 200 MPa, but the actual mean stress in your analysis is different (e.g., 500 MPa), you would typically select one of the mean stress correction theories provided in the fatigue analysis tool, rather than choosing 'none.'

Mean stress correction theories aim to adjust the S-N curves to account for the influence of mean stress on the fatigue behavior of a material. These theories provide mathematical models or correction factors that can be applied to the S-N curves to estimate the effect of the actual mean stress on the fatigue life.

The appropriate mean stress correction theory to use depends on the specific fatigue analysis tool you are using and the available options within that tool. Common mean stress correction theories include the Goodman, Gerber, and Soderberg criteria, among others. These theories have different mathematical formulations and assumptions regarding the influence of mean stress on fatigue life.