These factors must be taken into account to adjust the fatigue limit. Surface finish, stress concentatrations, etc. We haven't mentioned modifying factors that affect fatigue limit.It is a fit of scattered data and can lead to inexact results.

As mentioned earlier, the S-N curve is not exact.While we have described the basic method of fatigue life under alternating stress, there are additional considerations. For example, any point to the left of both the Goodman and yield lines could be considered safe, while a point between the Goodman and yield line is not safe because of yielding. The calculation is done based on the simplified approach that the linear cumulative damage (Palmgren-Miner) rule applies, and that fatigue strength is. The fatigue life curves used under ASME VIII-2 to calculate the permitted cycle life of a vessel are based on a large factor of safety compared with actual cycle life curves. This is used in conjunction with the Goodman and Gerber lines when yielding is a criterion of failure. The life of a vessel under cyclic service is related to the intensity of the alternating stress and the number of cycles it experiences. FEM for fatigue strength Structural strength assessment Fatigue strength. Yield A line from yield strength on the y-axis to yield strength on the x-axis. From set square and calculation assessment to Excel for fatigue and endurance. Any point to the left of both the Gerber line and the yield line is the safe region. The multiaxial fatigue method, and the mean stress model is then used to calculate the effective stress for each paired subcycle. Gerber A parabolic line from fatigue limit on the y-axis to ultimate strength on the x-axis. Any point to the left of both the Goodman line and the yield line is the safe region. The Weibull model can be applied in a variety of forms (including 1-parameter, 2-parameter, 3-parameter or mixed Weibull). Goodman A line from fatigue limit on the y-axis to the ultimate strength on the x-axis. In fact, life data analysis is sometimes called 'Weibull analysis' because the Weibull distribution, formulated by Professor Waloddi Weibull, is a popular distribution for analyzing life data. Any point to the left of the line is the safe region. Soderberg A line from fatigue limit on the y-axis to the yield strength on the x-axis. Each failure criterion is drawn according to:

Fatigue life calculation excel