Haibach correction

Figure 5.15 shows this bi-linear S-N diagram obtained with the Haibach correction. The Basquin line provides the simplest way to build the S-N diagram, provided that the slope b is known. However, it must be remembered that only the elastic component of the stress amplitude enters in the Basquin Eq. (5.22). 

Note that the surface finish factor has been considered only to correct the fatigue limit and not Ss since we know that surface finish does not have any effect on low cycle fatigue. New points A and B are shown in Fig. 5.21. Let s evaluate the Haibach correction using (5.35). From (5.21) it can be inferred the slope b for line A B ... 

S-N curve under completely reversed (dotted line, R = —1) and released tension (full R = 0) conditions and Haibach correction for the gear material... 

Note that it has not been considered the Haibach correction as in the previous problem, but it should. The number of allowable blocks is... 

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