For the problem specified in the table, build upon the results of the original problem to determine the minimum factor of safety for fatigue based on infinite life. The shaft rotates at a constant speed, has a constant diameter, and is made from cold-drawn AISI 1018 steel.

Problem 3-77, A torque T = 100 N · m is applied to the shaft EFG, which is running at constant speed and contains gear F. Gear F transmits torque to shaft ABCD through gear C, which drives the chain sprocket at B, transmitting a force P as shown. Sprocket B, gear C, and gear F have pitch diameters of a = 150, b = 250, and c = 125 mm, respectively. The contact force between the gears is transmitted through the pressure angle φ = 20°. Assuming no frictional losses and considering the bearings at A, D, E, and G to be simple supports, locate the point on shaft ABCD that contains the maximum tensile bending and maximum torsional shear stresses.

Combine these stresses and determine the maximum principal normal and shear stresses in the shaft.

aA T 100 N m d 30 mm f= 250 mm ,-125 mm | e= 75 mm c 125 mm b-250 mm a 150 mm View a-a