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 3-76, Repeat the analysis of Prob. 3€“74 for shaft AB. Assume that bearing A carries the thrust load.
In the figure, shaft AB transmits power to shaft CD through a set of bevel gears contacting at point E. The contact force at E on the gear of shaft CD is determined to be (FE)CD = €“92.8i €“ 362.8j + 808.0k lbf. For shaft CD: (a) draw a free-body diagram and determine the reactions at C and D assuming simple supports (assume also that bearing C carries the thrust load), (b) draw the shear-force and bending-moment diagrams, (c) for the critical stress element, determine the torsional shear stress, the bending stress, and the axial stress, and (d) for the critical stress element, determine the principal stresses and the maximum shearstress.

6.50 in3 in 3.88 in- 2.50 in 0.88-in dia. 1.30 in 3.63 in 1.13-in dia.