Unless I'm misunderstanding the diagram, it does not look like fatigue at all but rather yielding from shear loading. The definition of fatigue is a small crac

Unless I'm misunderstanding the diagram, it does not look like fatigue at all but rather yielding from shear loading. The definition of fatigue is a small crack (in fact microscopic in the beginning) that grows through the application of cyclical loading (typically about 10k cycles is the lower bound for high cycle fatigue, which does not involve macro yielding). Thus a fatigue failure would look like a fully ruptured part , usually with two distinct zones of the fracture face: one smooth zone from crack growth ( sometimes with characteristic "beach marks") and the final sudden rupture which is usually rough. https://en.m.wikipedia.org/wiki/Fatigue_(material) https://en.m.wikipedia.org/wiki/Fatigue_(material)