Displayed SN-curve summary

[Jorgemendozaesp]

The information displayed in the top-right of the figure is very useful.
I believe Delta Sigma refers to the stress range predicted by the model given N=2e6 cycles. So, I believe that Sigma is a typo. Some standards such as IIW refer to this parameter to Fatigue life. Thus, I would call it: Stress range at N=2e6 (Fatigue life):

Some additional information would be useful:

• Intercept C is expressed in number of cycles. I can understand much faster the information as log10(Intercept C) since the scatter doesn't happen in the order of 100 of units but in units.
• Std. Dev. refers to the standard deviation of the log10(N). I would either call it Std. Dev. of log10(N) OR Std. Dev. of model
• I would add units to the stress range, i.e. MPa or N/mm2.
• I would like to see a small comment on how the design curve is defined, e.g. if it is defined by 2*Std. Dev. This is an important aspect and it would be interested to test different definitions, since this program is typically use for small databases where the statistical uncertainty is large.

[simon-ball]

Regarding the exact definition of the design curves: this is complicated, because I do not have access to their formal specifications.

The calculations have been ported from the VB6 based Edna program, and validated to give the same results (as per the project specification). I cannot provide a full audit of how or why the values are calculated as they are.