Effect of Multiple Overloads on Fatigue Crack Propagation in 2024-T3 Aluminum Alloy

The effect of multiple overloads on subsequent fatigue crack propagation in 2024-T3 aluminum alloy specimens was studied, and 1, 2, 10, 100, 1000, and 5000 overload cycle tests were run. Typical tests consisted of running constant ΔK tests where $ΔK=15ksiin.(16.5MN/m3/2)$ and $λ=1.05(λ=Kmax/ΔK)$⁠. The maximum overload level was 50 percent ΔK or $Kmax=22.5ksiin.(24.7MN/m3/2)$⁠. The usefulness of closure concepts in aiding the understanding of fatigue crack propagation due to overloads is considered. Evidence is given to demonstrate the general applicability of closure concepts for analysis of fatigue crack propagation results.