Gigacycle fatigue of metallic aircraft components

According to the Paris–Hertzberg crack growth law, an analytical model shows that cracks grow from a flaw very quickly from the short to the long cracks regime, during gigacycle fatigue. The location of the initiation, at the surface or inside, has a small effect. This means that the key problem is the nucleation of the crack around the flaws as it is shown by Lukas et al. and Mughrabi and Stanzl [Lukas P, Kunz L, Svoboda M, Bokuvka O. Fatigue behaviour of ultra fine-grain copper in VHCF regime. In: VHCF4, Ann Arbor; 2007. p. 265–70, ; Mughrabi H, Stanzl S. Fatigue damage evolution in ductile single phase FCC metals in the UHCF regime. In: VHCF4, Ann Arbor; 2007. p. 75–82, ]. This approach is applied to a PM Ni alloy which is used for aircraft turbine. It is concluded that the damage tolerance concept is to be applied with cautiousness for VHCF prediction, in PM alloys.