Analyses to be performed at the various locations of the shaft to determine the minimum shaft diameters



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Step # 1 - Select Materials for the Shafts

Assume the basic shaft diameters and make a first trial material selection for each shaft

Hint: For strength based designs, shafts having diameters less than 3.5" are usually made from a cold drawn steel in order to resist fatigue


For D 3.5" Cold Drawn (CD) Material - better surface finish and easily machinable

For D 3.5" Hot Rolled (HR) or preferably Quenched & Treated (Q&T) - generally rough surface but low cost


Step # 2 - Perform Static & Fatigues Analyses

Static Analyses/Assumptions

Fatigue Analyses - eqn. (18-39)

d3 - using eqn. (18-12)

d2 - using eqn. (18-12)

d1 = 0.8 d2

d4 = 0.8 d3

d2 - Fillet Location (Sharp)

d3 - Keyseat Location

d4 - Fillet Location (Sharp)