A bar of steel has the minimum properties Se 5 40 kpsi, Sy 5 60 kpsi, and Sut 5 80 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: (a) Modified Goodman criterion. (b) Gerber criterion. (c) ASME-elliptic criterion.

Factor of safety guarding against static failure = 1.66

Factor of safety guarding against static failure using Modified Goodman = 1.05

Factor of safety guarding against static failure using Gerber criterion = 1.31

using ASME-elliptic criterion = 1.315

Explanation:

Attached is the detailed solution of using the given criterion as required by the question firstly we calculate the Maximum stress in the bar using Von Misses stresses for the two stress elements for static failure before proceeding with other criterion