A 6.4 mm (.25 in) diameter cylindrical rod fabricated from a 2014 -T6 aluminum a
ID: 1853510 • Letter: A
Question
A 6.4 mm (.25 in) diameter cylindrical rod fabricated from a 2014 -T6 aluminum alloy is subjected to reversed tension compression load cycling along its axis. If the maximum tensile and compressive loads are + 5340 N ( + 1200 lbs) and -5340 N (-1200 lbs) respectively, determine its fatigue life. Assume that the stress plotted in figure is stress amplitude. sigma a = sigma r / 2 = sigma max - sigma min / 2 = 5,340 (1,200lb) - (-5,340)(1,200) / 2 sigma = 10,680N(2,400lbs) / 2 [ sigma a = 5,340 (1,200lbs)]Explanation / Answer
Fatigue Life Number of cycles of fluctuating stress and strain of a specified nature that a material will sustain before failure occurs. Fatigue life is a function of the magnitude of the fluctuating stress, geometry of the specimen and test conditions. An S-N diagram is a plot of the fatigue life at various levels of fluctuating stress.