Originally Posted by
NWA SLF
Fatigue is induced by stress cycles. I haven't even touched on thermal cycles. How do you manage to design for this? Is it by overdesign or by realization there will be a failure at some point, predict the safe limit, and replace the critical component at that point?
NWA,
Components can be designed to operate at below fatigue inducing stress levels and, therefore, not fatigue fail. However, where circumstances require, components that have to operate inside their fatigue vulnerability are given a "safe life" that requires replacement before likely failure. Unfortunately, the combination of defects or unplanned loads can corrupt both strategies of component integrity. Consequently, the fact that the Fan hub has obviously failed on the remains of this engine does not confirm the type of failure or, even that the Fan hub is the cause of the incident.
