A peridynamics approach for modelling hydrogen- and oxidation-assisted fatigue crack growth

High performance superalloys, when exposed to gases such as hydrogen and oxygen, experience material embrittlement and a significant increase in the rate of fatigue crack growth, thereby reducing the service life of their structural components. In this study, a peridynamics model was developed to simulate fatigue crack growth in a nickel-based superalloy exposed to hydrogen and/or oxygen environments. The model leverages on the non-local characteristics of peridynamics theory to simulate the growth of fatigue cracks, while also accounting for hydrogen embrittlement and/or oxidation damage. The model’s capability and reliability were verified by comparing a series of simulation results with experimental data available in literature. Furthermore, this paper also explores the effects of loading frequency and degradation factor on the simulated results of fatigue crack growth. The peridynamics model provides an alternative and effective method for simulating and predicting fatigue crack growth in corrosive gas environment, which can be potentially applied to structural integrity assessment of gas turbine systems.