A PC-Based Modeling Tool for Creep, Fatigue, and Creep-Fatigue Interactions Using a Viscoplasticity Theory

Computational results for modeling one-dimensional stress relaxation, creep, fatigue, and creep-fatigue interaction phenomena of metals at elevated temperatures using a unifying thermodynamic theory of viscoplasticity are presented. The theory incorporates in a nonequilibrium formulation the idea of a “concealed” parameter α, originally due to Bridgman (1950), where the constitutive equations are governed by 1) a thermodynamic potential such as the Helmholtz free energy function F with an explicit dependence on α, and 2) a prescription for α˙, the time rate of change of α, such that α˙ is proportional to −Fα, the negative of the partial derivative of F with respect to α. Significance of the results and a comparison with other modeling tools in the literature are discussed.