A Creep Rupture Time Model for Anisotropic Creep-damage of Transversely-isotropic Materials

Anisotropic creep-damage modeling has become an increasingly important prediction technique in both the aerospace and industrial gas turbine industries. The introduction of tensorial damage mechanics formulations in modeling tertiary creep behavior has lead to improved predictions of the creep strain that develops due to anisotropic grain structures and the induced anisotropy that occurs with intergranular damage. A number of isotropic creep-damage rupture time prediction models have been developed in literature; however, few rupture time prediction models for tensorial anisotropic creep-damage are available. In this paper, a rupture time model for anisotropic creep-damage of transversely isotropic materials is derived. Comparison with the Larson-Miller parameter, Monkman-Grant relation, and Kachanov-Rabotnov continuum damage mechanics (CDM) approach shows improved creep rupture time predictions for multiaxial conditions and material rotations. A parametric study of the rupture time predicted under various states of equivalent stress and material orientations is performed to demonstrate the robustness of the new formulation.