Berechnung der Dauerschwingfestigkeit unter Berücksichtigung der spannungsmechanischen und statistischen Stützziffer

Fatigue Limit and Geometrical and Statistical Size Effect The ratio of the fatigue limit of an unnotched specimen to that of a notched one, the fatigue notch factor K_f, is usually smaller than the theoretical stress concentration factor K_t. With the assumption of a plastic cyclic deformation ?_apW at the level of the fatigue limit the fatigue limit for a notched specimen can be calculated. According to formula (4) this fatigue limit σ_naD is a function of K_t, ?_apW, the notch stress amplitude σ_a, the cyclic strengthening exponent n′ and the fatigue limit of a smooth specimen σ_W. Moreover, taking into account the statistical size effect with the known “weakest link concept”, see flow chart Fig. 9, the calculation is in a good agreement with 77 test results for steel.