Effect of Exposure Time on the Fatigue Crack Growth Behavior of Aircraft Skin Material

The objective of this research project is to identify the effects of service exposure on aircraft materials. The senior author participated in the KC-135 Corrosion Prevention Program conducted by the University of Utah, Salt Lake City. Data from this research program was analyzed to compare the fatigue crack growth rates of aged aircraft materials with those of virgin materials. 2024-T3(clad) Middle Tension (M(T)) specimens were machined from the fuselage and upper wing skins of a retired aircraft. Fatigue crack growth rate (da/dN) and mode 1 stress intensity factor range (Δ K) plots were generated for both sets of data. The aged materials exhibited fatigue crack growth rates that were 2-5 times higher than those of the new materials