Fatigue damage
Fatigue and fracture mechanics of light-alloy parts

Experience shows that repeated stress cycles modify and degrade the properties of light alloys, and can eventually lead to part failure.

In aeronautics, fatigue of light alloy parts generally occurs without overall plastic deformation, but with very localized plastic deformation around form anomalies (notches, bores, connection fillets, etc.).

If we take a close look at a fatigue-stressed structure (figure 3), we can quickly identify numerous microcracks within the grains that make up the metal (microcrack initiation phase) [1].

When the number of cycles applied is sufficiently high, we notice that a certain number of grains are completely penetrated by such microcracks. This phase is known as microcrack nucleation.