at a machined shaft shoulder the small diameter d is 1.100 in, the large diameter d is 1.65 in, and the fillet radius is 0.11 in. the bending moment is 1260 lbf ? in and the steady torsion moment is 1100 lbf ? in. the heat-treated steel shaft has an ultimate strength of sut 5 105 kpsi and a yield strength of sy 5 82 kpsi. the reliability goal for the endurance limit is 0.99. (a) determine the fatigue factor of safety of the design using each of the fatigue failure criteria described in this section. (b) determine the yielding factor of safety