Non‐local stress approach for fatigue assessment based on weakest‐link theory and statistics of extremes

ABSTRACT In the present paper a non‐local stress approach for fatigue assessment based on weakest‐link theory and statistics of extremes is presented. It is a non‐local stress approach in the sense that it takes the complete stress field into account rather than just the highest local stress. The statistical distribution of fatigue strength data from smooth standard specimens serves as a starting point for the computation of the probability of fatigue failure of a mechanical component under cyclic loading. The probability of fatigue failure can be obtained by post‐processing results from a standard finite element stress analysis. It is shown that the non‐local stress approach can be linked to the probability of finding the fatigue critical defect in the most highly stressed volume of the component. A numerical procedure is presented that is fully compatible with the results from a standard finite element stress analysis. It is further shown how the fatigue strength distribution can be transformed into a fatigue life distribution by using Basquin's equation. Finally, the non‐local stress approach is used for predicting the fatigue limit of several specimens and predictions are compared with test results.