The strain-life approach applied to welded joints: Considering the real weld geometry

Fatigue assessment of welded joints is a challenging task. Various codes and guidelines provide assessment procedures with specific ranges of application. If an approach is applied, which requires numeric calculations, the modelling of the weld profile is critical. In the contribution at hand, the combination of the real weld geometry obtained by 3D laser scanning and the strain-life approach is investigated. By doing so, the effect of additional stress concentration from the weld profile itself can be studied, leading to predictions of fatigue lifetime, which take into account the individual features of the weld. By taking into consideration the strain-life concept, different methods for mean stress and plasticity correction are available. Therefore, fatigue lifetimes resulting from different combinations of the aforementioned procedures are compared to the ones obtained experimentally. Depending on the combination of mean stress, as well as plasticity correction and material data, the predicted fatigue lifetimes vary from being unrealistic to pretty accurate. The results are very sensitive to material input data, for which base material properties are assumed in this contribution. Further investigations are necessary to verify the potential of this procedure, preferably with the application of experimentally determined material properties for the heat affected zone and the weld material. The location of crack initiation has been predicted with high accuracy.