Mean Stress Effect on Fatigue Limit of Notched Members

1 Mean Stress Effect on Fatigue Limit of Notched Members 

A generic point B will move to B in which the peak stress would reasonably be equal to the stress in A for the unnotched specimen. Beyond point C in Fig. 7.17 the theoretical stress concentration factor k, loses its validity. It is interesting to see how experimental data obtained on notched and unnotched specimens of aluminum alloy of 570 MPa ultimate strength and SAE 4130 steel of 807 MPa behave with respect to the safety domain of Fig. 7.17. This is shown in Fig. 7.18 [21].The behavior of the two alloys is completely different from each other and from that of Fig. 7.17. The unnotched specimens of aluminum alloy seem to follow the Goodman line while those of SAE 4130 steel the Gerber parabola as in Fig. 7.17. But differences do not finish with that. The notched specimens behavior of 

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