Stress-Based Fatigue Analysis High Cycle Fatigue

So far, we have examined fatigue from a phenomenological point of view, describing the sequence of events that take place in metals from the early submicroscopic damage that precedes microcracks formation and eventually leads to the macrocrack generation. It has also been discussed what are those factors, other than stresses, that affect fatigue strength or life of metals and have something to do with their surface layer, so important in the fatigue process. We shall now address the issue of high cycle fatigue design looking at stresses that, for the moment, are considered elastic and of equal amplitude, though with possible mean value larger than zero.