Study on Creep-Fatigue Combined Damage of a GT Superalloy Blade

For quantification of Low - cycle Fatigue (LCF) of a gas turbine blade made of superalloy material, a finite element analysis was carried out. Centrifugal force (CF), aerodynamic (AE) and thermal (TM) loads were taken from a typical load cycle of one F class gas turbine blade . After thermal boundary conditions were quantified in a 3D thermal model, all loads were applied to the 3D ANSYS model. The subsequent lifetime analysis for LCF damage was conducted during normal start - up and shut - down conditions for each of the individual loads, i.e. CF, aero and thermal, as well as for the total stress distribution. At the same time, a creep damage analysis of 150,000OH was carried out. The resulting combined creep - fatigue damage was counted to the total damage. The results show that the superalloy blade is able to meet the requirements of the GT even in areas of superimposed significant LCF and creep damage mechanisms. The calculation provides a reference for safe blade design and shows the detrimental effects of the individual load contributions towards the overall lifetime consumption