This paper investigates the effect of hydrogen diffusion on stable crack propagation by using numerical finite element simulations based on the cohesive model. The model with its two common parameters, cohesive strength, T 0 , and critical separation, δ 0 , and its two additional parameters for stress corrosion cracking, the effective diffusivity, D eff , and a material parameter, α, which represents the reduction of the cohesive strength, is described. This model is then employed to predict the stable crack propagation in C(T) specimens made from a high strength structural steel which were tested under hydrogen charging conditions in rising displacement tests using various deformation rates. It is shown that, in general, the prediction of stable crack propagation is promising, but may be further improved by the use of a more sophisticated diffusion equation. Finally, the influence of variations of the effective diffusivity and the cohesive strength reduction on the thus simulated crack growth resistance curves is studied.

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We investigate numerically the shape of cracks obtained in hydraulic fracturing at constant pressure using a square lattice beam model with disorder. We consider the case in which only beams under tension can break, and discuss the conditions under which the resulting cracks may develop fractal patterns. We also determine the opening volume of the crack and the elastic stress field in the bulk, quantities which are accessible experimentally.

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To rationalise the results of stress corrosion cracking tests on smooth tensile specimens of a magnesium alloy, performed as constant extension rate tensile tests, a mesoscale fibre bundle model is employed in which the material being tested is represented by a bundle of parallel fibres The effect of hydrogen embrittlement oil the stress-Strain curves measured at various strain rates is simulated by assuming that the hydrogen is generated in localised corrosion pits and subsequently diffuses into the bulk. thereby reducing the strain-to-failure of individual fibres. The stress-strain curves obtained from these simulations show the same strain rate effect as was experimentally observed