= = A bar of steel has the minimum properties S. 40 kpsil Sy = 60 kpsi, and Sut 80 kpsi. The bar is subject to a steady (mean) torsional stress of 15 kpsi, an alternating torsional stress of 10 kpsi, and an alternating bending stress of 12 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 park. Use the modified Goodman criterion.