Computational predictions of hydrogen-assisted fatigue crack growth.

A new model is presented to predict hydrogen-assisted fatigue. The model combines a phase field description of fracture and fatigue, stress-assisted hydrogen diffusion, and a toughness degradation formulation with cyclic and hydrogen contributions. Hydrogen-assisted fatigue crack growth predictions exhibit an excellent agreement with experiments over all the scenarios considered, spanning multiple load ratios, H 2 pressures and loading frequencies. These are obtained without any calibration with hydrogen-assisted fatigue data, taking as input only mechanical and hydrogen transport material properties, the material's fatigue characteristics (from a single test in air), and the sensitivity of fracture toughness to hydrogen content. Furthermore, the model is used to determine: (i) what are suitable test loading frequencies to obtain conservative data, and (ii) the underestimation made when not pre-charging samples. The model can handle both laboratory specimens and large-scale engineering components, enabling the Virtual Testing paradigm in infrastructure exposed to hydrogen environments and cyclic loading. [Display omitted] • A new phase field-based model for hydrogen-assisted fatigue crack growth is presented. • Model predictions are compared against fatigue crack growth experiments in H 2. • An excellent agreement is attained across H 2 pressures, loading ratios and frequencies. • The impact of hydrogen pre-charging the samples is quantified. • The sensitivity to frequency is elucidated, mapping regimes of conservative testing. [ABSTRACT FROM AUTHOR]