A phase field model for hydrogen-assisted fatigue

We present a new theoretical and numerical phase field-based formulation for predicting hydrogen-assisted fatigue. The coupled deformation-diffusion-damage model presented enables predicting fatigue crack nucleation and growth for arbitrary loading patterns and specimen geometries. The role of hydrogen in increasing fatigue crack growth rates and decreasing the number of cycles to failure is investigated. Our numerical experiments enable mapping the three loading frequency regimes and naturally recover Paris law behaviour for various hydrogen concentrations. In addition, Virtual S–N curves are obtained for both notched and smooth samples, exhibiting a good agreement with experiments. •A phase field formulation for hydrogen-assisted fatigue is presented.•Fatigue crack nucleation and growth is predicted for arbitrary loading patterns, geometries, and environments.•Paris’ law behaviour, and the role of hydrogen on it, is naturally recovered.•The influence of the loading frequency is quantified and the resulting regimes mapped.•Virtual S–N curves are obtained, showing a good agreement with experiments.