The S-N Curve and High-Cycle Fatigue

Stress-controlled fatigue tests and the properties generated by these tests are useful for HCF analysis where elastic strains are dominant. One 

The Basquin equation can be reformulated as Equation 4.9 to show the mathematical relationship between HCF and elastic strain  

The Basquin equation can also be remodified as Equation 4.10 to include the effect of mean stress. 

For example, shot peening introduces residual compressive stress on part surface, lowers the mean tensile stress, and therefore improves part s fatigue life. 

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