The shaft shown is simply supported and rotates at constant

The shaft shown is simply supported, and rotates at
constant speed. The part exiting the bearing at A takes
only torsional loading. The normal force of contact on
the 7-in-diameter gear is 375 lb, and acts at a pressure
angle of 22°. Details of the shaft layout are shown at A top, and the gear is press fit onto segment B, as shown.

Find the diameter of segment B that would lead to infinite life with a safety factor of 1.5. Use DE-Gerber, and take Se as 25 ksi. Assume well-rounded fillets (Table 7-1), and that notch sensitivities q and qs are both 0.75. The shaft is machined from a material that has tensile strength Sut = 85 ksi, and yield strength Sy = 71 ksi.

A. 1.9 in
B. 1.3 in
C. 0.88 in
D. 0.94 in
E. None of the above

Solution

0.94in