Three identical fatigue specimens (denoted A, B, and C) are fabricated from a nonferrous alloy. Each is subjected to one of the maximum–minimum stress cycles listed in the following table; the frequency is the same for all three tests.
Specimen σmax (MPa) σmin (MPa)
A +450 -150
B +300 -300
C +500 -200
(a) Rank the fatigue lifetimes of these three specimens from the longest to the shortest.
(b) Now, justify this ranking using a schematic S-N plot.