Modelling and simulation of fatigue crack initiation in welded joints based on crystal plasticity

In the present study a numerical model to simulate the initiation growth of fatigue cracks in welded joints is shown. The developed model is based on a polycrystalline microstructure with potential slip bands whose directions are dependent on the grain orientations. Considering transgranular crack growth, the crack propagation direction at the grain boundaries is determined by the potential slip directions in the neighboring grain and an energy-based criterion. Subsequently, a statistic analysis of different computed crack path provides a distribution of the number of cycles up to a pre-defined crack length which is as an incipient crack important for many fracture mechanics evaluation concepts.