Hydrogen Transport Modelling Near a Crack Tip in a Pressurized Tank

With the increasing interest in the use of hydrogen as an energy carrier, a better understanding of hydrogen embrittlement affecting materials is required. In addition, hydrogen tanks suffer fatigue processes due to stress variation in filling and refuelling operations. In this context, in order to simulate hydrogen transport inside the material, a sequence of subroutines has been developed within the commercial Finite Element software ABAQUS. Diffusion equations modified by the stress state and the by existence of microstructural traps have been implemented. Models used by previous authors have been improved by implementing a stress state dependent concentration as boundary condition. Once this numerical model is established and checked, a pressurized hydrogen vessel is simulated assuming a defect in the inner wall and cyclic stresses. The influence of internal pressure, load amplitude and frequency on hydrogen concentration near the crack tip is discussed.