The shaft shown in the figure is machined from AISI 1040 CD steel. The shaft rotates at 1600 rpm and is supported in rolling bearings at A and B. The applied forces are $F_1 = 1,900$ lbf and $F_2 = 2850$ lbf. Determine the minimum fatigue factor of safety based on achieving infinite life. If infinite life is not predicted, estimate the number of cycles to failure. Also check for yielding.
What is the value of the moment at the critical section?
he value of the moment at the critical section is $\boxed{}$ lb-in.