Estimation of Ct parameter in transversely isotropic materials under transient creep conditions

The crack growth life assessment procedures at high temperature developed for isotropic materials need to be extended for anisotropic creeping materials. In this study, estimation of Ct in transversely isotropic creeping materials is proposed. Equivalent creep coefficient (Aeq) is defined for the transversely isotropic materials and its calculation equation is derived in terms of the ratio between the longitudinal and the transverse creep coefficients. A series of finite element analysis was conducted and values of correction factors required in calculating Ct were determined in tabular form. The newly proposed equation gave the same Ct values as the finite element results under the full range of the creep conditions including the small scale creep.