A computer program was developed for treating transient hydrogen diffusion and elastoplastic coupling by combining a finite-element program with a general purpose finite element program for analyzing hydrogen diffusion. The hypothesis was that the hydrogen absorbed in the metal affected the yield stress of the metal. The effects of cyclic loading on the hydrogen concentration near to the crack tip were considered. An important finding was that the hydrogen concentration near to the crack tip depended greatly upon the loading frequency. This indicated that the fatigue lives of components in a hydrogen system depended not only upon the number of loading cycles but also upon the loading frequency.

Transient Hydrogen Diffusion Analyses Coupled with Crack-Tip Plasticity under Cyclic Loading. H.Kotake, R.Matsumoto, S.Taketomi, N.Miyazaki: International Journal of Pressure Vessels and Piping, 2008, 85[8], 540-9