The shaft in Figure P16.7 is supported in flexible bearings at A and D, and two gears B an...

The shaft in Figure P16.7 is supported in flexible bearings at A and D, and two gears B and C are attached to the shaft at the locations shown. The gears are acted on by tangential forces as shown by the end view. The shaft is made of SAE 1040 steel (σu = 830 MPa, Y = 660 MPa, and σam = σL = 380 MPa). If the shaft is rotated under constant load an indefinitely large number of times, determine the diameter of the shaft for a factor of safety SF = 2.0 for the initiation of fatigue failure.

FIGURE P16.7