Microstructure sensitive fatigue life prediction and size effects in notched specimens: application to Ni-based superalloy GH4169

• A multiscale fatigue life prediction model for notched components is developed. • The model accounts for the combined influence of notch and microstructure. • The model links macroscopic FE simulations with microscopic CP-FFT modeling. • The fatigue life of Ni superalloy GH4169 in C- and V-notched specimens under stress control is predicted. Fatigue behavior of Ni-based superalloy GH4169 is significantly influenced by the microstructural characteristics and the presence of notches. In this study, a statistically based microstructure sensitive multiscale modelling framework is developed to analyze the fatigue behavior of Ni-based superalloy GH4169 notched components. At the macroscale, notched specimens are simulated with the FE method under applied stress range using the Chaboche cyclic plastic model. At the microscale, the local strain range tensor on the notch tip is used as input of FFT-based homogenization with the crystal plasticity model, allowing to capture the grain-level mechanical response under cyclic loading. Fatigue life prediction is done at the microlevel using the FIPs extracted from the CP-FFT simulation. To explore the probabilistic dispersion of fatigue failure, FIPs obtained from multiple microstructural realizations are analyzed using Gumbel distribution and statistical assessments are conducted to evaluate fatigue life distribution. Finally, the notch effect associated with variations in the dimensions of the stress-affected zones around the notch is considered. The predicted results are compared with experimental data, demonstrating the reliability of the proposed methodology in estimating the fatigue life of notched specimens in a probabilistic manner.