How is the safety factor selected

Components of the fatigue measure
When you select Fatigue from the Quantity drop-down list, the Component drop-down list displays the components specific to that size. You can use this drop-down list to refine the definition of the measured variable even further. The options available in the drop-down list vary depending on the combination of design study, representation type, and size selected.
The following options are available from the Component drop-down list if you selected Fatigue:
• Log. Log Life - This option shows the estimated number of cycles before the model breaks. Due to the exponential nature of fatigue, it makes sense to express the fatigue strength logarithmically.
• Log. Log Damage - This option displays the relationship between accumulated fatigue cycles and the total number of cycles to failure. A value greater than one means failure. A value of 0.5 means, for example, a 50% reduction in the useful life of the model. Due to the exponential nature of fatigue, it makes sense to express the damage ratio logarithmically.
• Factor of Safety - This option displays the allowable safety factor for the input load. If the calculated fatigue strength of your model is greater than the target construction life cycle, the program performs a backward-looking calculation to determine the permissible safety factor for the load entered. This factor indicates how much the amplitude of the load can be increased without jeopardizing the target design life cycle.
• Confidence of Life - This option displays the relationship between the calculated life cycle and the target construction life cycle. Due to the statistical nature of the amount of fatigue, life expectancy should be as high as possible. Values ​​below one indicate failure. For life expectancy, values ​​greater than 3.0 are usually sufficient to achieve the desired construction life cycle.
You can plot life expectancy results with a three-color color area plot to get an idea of ​​where the model breaks first and where the model has a higher number of life cycles. The color red indicates a life cycle range from 0 to the number of cycles entered in the "Desired Endurance" text field in the Analysis dialog box (counts as 1x). The color yellow indicates a life cycle range from 1x to 3x (applies as a minimum cycle). The color green indicates any number of cycles above the minimum cycle (3x). The default is 3x. However, you can change this setting by editing the value of the sim_fatigue_safety_margin configuration option.
For fatigue analyzes, Creo Simulate reports results for all surfaces in the model, but not for the interior of the model.