Strain-based approach to fatigue crack initiation and propagation in welded steel joints with arbitrary notch shape

•A novel strain-based approach for fatigue strength modelling of welded steel joints.•Actual geometry, arbitrary crack growth, and material microstructure are considered.•Fatigue life predicted with the approach is in line with the experimental results.•The approach can describe the different crack growth periods of the fatigue life.•For smooth weld notch, the short crack growth period has a significant influence.

In this paper, a novel strain-based approach for the fatigue strength modelling of welded steel joints is introduced. The actual weld notch geometry and the variation in the microstructure characteristics of the material are considered, and thus, the approach enables the fatigue crack growth simulation from the crack initiation to the critical crack length before the final fracture. The predicted fatigue strength is in line with the experimental results. By considering the crack tip plasticity and stress triaxiality, the approach is able to describe the different crack growth periods of the fatigue life: the short crack, long crack, and tearing-related long crack growth periods. For a welded joint with a smooth notch shape, the short crack growth period is observed to be dominant and to have a significant influence on fatigue life.