Eurocode 3’s standard curves and Theory of Critical Distances to estimate fatigue lifetime of steel weldments

This paper reports on the use of the Modified Wöhler Curve Method (MWCM) applied along with the Theory of Critical Distances (TCD) to estimate fatigue lifetime of steel welded joints subjected to both uniaxial and multiaxial cyclic loading. In a recent work [1] we have proved that the above engineering method is highly accurate when calibrated by using standard fatigue curves characterised by a probability of survival equal to 50%. In order to better check its accuracy and reliability, in the present study our approach is systematically applied to a large amount of experimental data by calibrating it using standard fatigue curves having a probability of survival equal to 97.7%. This exercise allowed us to prove that the in-field application of such an engineering procedure results in estimates which fully comply, from a statistical point of view, with Eurocode 3’s recommendations. This result strongly supports the idea that our approach can safely be employed to perform the fatigue assessment of real mechanical assemblies, with the advantage over other existing methods that fatigue lifetime under any kind of fatigue loading can be estimated by simply post-processing linear-elastic Finite Element Models