Extrapolation of probabilistic fatigue S-N curves on 16MnR steel weld joint

This paper extended the commonly probabilistic curves of 16MnR steel weld joint into long life regime by 2m-1 exponent method according to the fatigue test data in different test conditions. The curves are constructed by Basquin relations, consisting of survival probability-based curves, confidence-based curves, and survival probability and confidence-based curves. These curves fit the test data well in original regime, can predict the long life regime approximately. The extrapolated effects, which fit into the test data of 16MnR steel weld joint, reveal that the method acts approximately as the function of extrapolation, and it is more reasonable than direct method, which extends original S-N curves into long life regime directly. The results show that the method is feasible.