Study of hydrogen concentration dependent growth of external annular crack in round tensile specimen using cohesive zone model

• Modelling of growth of eccentric circumferential crack by 2-dimensional FEM.
• Evaluation of effects of exclusion of hydrostatic stress from diffusion calculations.
• Analytical and FD solution for diffusion in round specimen with external crack.
• Coupled diffusion analysis with FE study of crack growth.

A hydrogen concentration dependent cohesive zone model is presented for analysis of growth of external annular crack in round tensile specimen under internal and external hydrogen supply. A scheme is given to reduce three-dimensional problem for analysis by two-dimensional approximation. The results show significance of exclusion of hydrostatic stress from diffusion calculations. The predicted stress intensity factors corresponding to the maximum loads in the presence and absence of hydrostatic stress compare well with experimental data. The lowest stress intensity factors obtained through tests and analysis are close to the lower range of published data on threshold stress intensity factors.