Very High Cycle Fatigue Crack Initiation Mechanism in Nugget Zone of AA 7075 Friction Stir Welded Joint

Figure 8

Analysis on fatigue crack initiation from the surface defect: (a) distribution of fatigue crack initiation sites in the NZ; (b) relationship between defect size and fatigue life; (c) calculated results of fatigue life considering applied stress and welding defect.

(a)

(b)

(c)