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Fatigue design: basis of the Soderberg relation In fatigue/dynamic loading design, the Soderberg line uses which material property on the static-stress axis (unlike other relations that often use ultimate strength)? Choose the correct property.

Difficulty: Easy

Ultimate tensile strength
Yield strength
Proof stress (0.2%)
True fracture strength

Correct Answer: Yield strength

Explanation:

Concept
The Soderberg criterion is a linear fatigue design relation that limits mean stress using the yield strength (not the ultimate strength), paired with the fatigue limit for alternating stress.

Comparison
Goodman and Gerber relations use ultimate tensile strength on the mean-stress intercept; Soderberg is more conservative by using yield strength.

Final Answer
Yield strength

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