1. A 6.4 mm (0.25 in.) diameter cylindrical rod fabricated from a 2014-T6 aluminum alloy (Figure 8.34) is subjected to reversed tension- compression load cycling along its axis. If the maximum tensile and compressive loads are +5340 N (+1200 lbf) and -5340 N (-1200 lbf), respectively, determine its fatigue life.Assume that the stress plotted in Figure 8.34 is stress amplitude.
2. A 15.2 mm (0.60 in.) diameter cylindrical rod fabricated from a 2014-T6 aluminum alloy (Figure 8.34) is subjected to a repeated tension- compression load cycling along its axis. Compute the maximum and minimum loads that will be applied to yield a fatigue life of 1.0 X 108 cycles. Assume that the stress plotted on the vertical axis is stress amplitude, and
(a) Make an S-N plot (stress amplitude versus logarithm cycles to failure) using these data.
(b) Determine the fatigue strength at 4 X 106 cycles.
(c) Determine the fatigue life for 120 MPa.