Monte Carlo simulation of fatigue crack initiation at elevated temperature

In this paper, a novel way that simulated the micro-crack initiation due to void nucleation under thermal fatigue was proposed using the combination of finite element modeling and Monte Carlo method. A 3D model that simulated the dynamic void nucleation process was constructed using the commercial FEA software ANSYS. The strain and thermal energies of the model due to the applied loads at elevated temperature are calculated. After manually including the grain structures, surface and bonding energies, a number of vacancies were randomly generated and they moved and nucleated according to the energy distributions of the model. To consider the problem at microscopic scale while still maintaining acceptable accuracy, two models are constructed, namely a real-sized full model and a micro-scale sub-model that included the microstructure. The impurities and the residue stresses that may affect the void nucleation process were included in the sub-model as well. The simulation results showed that the vacancies tended to nucleate at the "weak spots".