Analysis of Damage and Stress Fields of a Mode I Creep Crack in Steady-State Growth

Elaboration of the asymptotic stress and damage fields of a mode I creep crack in steady-state growth are analyzed by employing the continuum damage mechanics and semi-inverse method. The damage evolution equation are expressed as a power function of the equivalent stress, the maximum principal stress and the hydrostatic stress. Analytical relations among the exponent p of the stress singularity of the asymptotic stress field and the exponents n, m and q of the power creep constitutive law and the power creep damage law are obtained for plane strain state. Based on the results of the analysis, the conditions for the damage evolution equation required to obtain a non-singular crack -tip stress were discussed. For Kachanov-type damage evolution law, more precise numerical results are derived for both the plane stress and plane strain states. The effects fo the shape of damage distribution on the stress singularity are also discussed.