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 σ_max (mpa) σ_min (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.
stress (s) - no. of cycles (n) plot: