Question

Write goodmann equation

Answer 1

{\displaystyle \sigma _{\text{a}}=\sigma _{\text{fat}}\left(1-{\frac {\sigma _{\text{m}}}{\sigma _{\text{ts}}}}\right).}

Where {\displaystyle \sigma _{\text{a}}}\sigma _{{\text{a}}} is the equivalent fatigue limit for combined alternating and mean stress, {\displaystyle \sigma _{\text{m}}}\sigma _{{\text{m}}} is the mean stress, {\displaystyle \sigma _{\text{fat}}}\sigma _{{\text{fat}}} is the fatigue limit for completely reversed loading, and {\displaystyle \sigma _{\text{ts}}}\sigma _{{\text{ts}}} is the ultimate tensile strength of the material. The Goodman line connects {\displaystyle \sigma _{\text{ts}}}\sigma _{{\text{ts}}} on the abscissa and {\displaystyle \sigma _{\text{fat}}}\sigma _{{\text{fat}}} on the ordinate.