Marin Factors | Corrected Endurance Limit | Fatigue Stress Concentration

Here several corrections to the endurance limit are presented and discussed, as well as fatigue stress concentrations and their relation to theoretical stress concentration factors via notch sensitivity factors. An example is completed in which a non-rotating hot-rolled rectangular plate with a hole is subjected to fully-reversed bending. A fully-corrected endurance limit is found by applying Marin factors, including a surface finish factor, a size factor (including an accounting for non-rotating bending using an equivalent diameter technique), a loading factor, a temperature factor, and a reliability factor. A fatigue stress concentration factor (Kf) is computed from the theoretical stress concentration factor (Kt) by computing the Neuber constant (sqrt(a)) to then compute a notch sensitivity factor (q). The nominal stress in the plate is computed and the fatigue stress concentration factor is applied to determine the maximum stress. The fatigue factor of safety for infinite life is determined by taking the ratio of the fully corrected endurance limit to the maximum stress.

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This lecture was presented on February 2, 2018. All retainable rights are claimed by Michael Swanbom.

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