Study of creep–fatigue behavior in a 1000 MW rotor using a unified viscoplastic constitutive model with damage

A unified viscoplastic constitutive model with damage is presented to describe creep–fatigue deformation behavior. Creep and fatigue tests under different temperature and loading conditions were conducted to validate the material model. Good agreement was achieved between the simulated and measured values. The material model was further applied to a specific part of a steam turbine rotor for numeric investigation of the creep–fatigue behavior. The multiaxial mechanical behavior of the rotor was studied in detail in terms of temperature, von Mises stress, equivalent strain, accumulated plastic strain, and damage. The results illustrate that the stress is concentrated on the notch of the groove. In addition, although the accumulation of damage at the rotor locations is dominated by creep behavior, the results actually disclose that the combination of creep and fatigue deformation behavior further accelerate the damage.