Thermo-Mechanical Fatigue Life Assessment of a Gas Turbine Rotor Through Reliability Approach

Turbine rotor is a critical and life-limiting component in gas turbine engines. The thermo-mechanical fatigue (TMF) life of a turbine rotor was studied using reliability method. The fatigue life was estimated using (a) Marrow’s model and (b) Smith–Watson–Topper model. The creep life was estimated based on Larson Miller equations and finite element analysis. The cumulative fatigue–creep damage was estimated, and the turbine rotor TMF life was estimated against the data variation. The reliability approach takes care of material property variations, load variations and geometrical variations. These variations bring out the scatter in component stress–strain and further into life. The scattered life spells out the component reliability. The TMF life was modeled as Weibull distribution, and the reliability was estimated. The component was tested for structural integrity through hot cyclic spin test, and the results were compared with the predictions. The blade growth and strain estimations using Marrow and SWT–creep methods were found in good agreement with the test values.