Calculation of the Wohler (S-N) curve using a two-scale model

This paper deals with the initiation of a short crack and subsequent growth of the long crack in a type of carbon steel under cyclic loading, concluded with the estimation of the complete lifetime represented by the Wailer (S-N) curve. A micro-model containing the microstructure of the material was generated by using the Finite Element Method followed by the calculation of respective non-uniform stress distribution. The number of cycles needed for crack initiation was estimated on the basis of the stress distribution in the microstructural model and by applying the physically-based Tanaka-Mura model. The long crack growth was examined by using the Paris law. The analysis yielded good agreement with experimental results from the literature.