Repeat Problem 6–20 but with an alternating torsional stress of 15 kpsi and a steady bending stress of 15 kpsi. Problem 6–20 A bar of steel has the minimum properties  kpsi,  kpsi, and  kpsi. The bar...

Repeat Problem 6–20 but with an alternating torsional stress of 15 kpsi and a steady bending stress of 15 kpsi.

Problem 6–20

A bar of steel has the minimum properties
 kpsi, kpsi, and
 kpsi. The bar is subjected to a steady torsional stress of 15 kpsi and an alternating bending stress of 25 kpsi. Find the factor of safety guarding against a static failure, and either the factor of safety guarding against a fatigue failure or the expected life of the part. For the fatigue analysis use:

Goodman criterion.

Gerber criterion.

Morrow criterion.