Investigation of creep-fatigue interaction in steam turbine rotor

In this research, the strength analysis and life evaluation of a steam turbine rotor were studied. The effects related to low cycle fatigue and creep were investigated according to ASME BPVC SECTION III-NH. For this purpose, numerical analyses were performed considering transient and steady-state thermal and mechanical loadings. Transient response was used to obtain temperature, stress, and strain distributions as functions of time in low-cycle fatigue analysis, and steady-state response was used for the evaluation of creep effects. Finally, the number of allowed Equivalent Operating Hours (EOH) was determined. Using this method, the turbine start-up curves were modified in such a way that the life provided for the turbine is in the safe area and the fastest possible start-up occurs.