Numerical modelling of fatigue crack initiation of martensitic steel

Numerical simulation of micro-crack initiation that is based on Tanaka-Mura micro-crack nucleation model is presented. Three improvements were added to this model. Firstly, multiple slip bands where micro-cracks may occur are used in each grain. Second improvement deals with micro-crack coalescence by extending existing micro-cracks along grain boundaries and connecting them into a macro-crack. The third improvement handles segmented micro-crack generation, where a micro-crack is not nucleated in one step like in Tanaka-Mura model, but is instead generated in multiple steps. Numerical simulation of crack-initiation was performed with ABAQUS, using a plug-in that was written specially for ha…