FATIGUE ANALYSIS OF A GAS TURBINE ROTATING BLADE WITH THERMAL BARRIER COATING

Useful life estimation of a gas turbine moving blade made of IN738LC was carried out under uniaxial and multiaxial fatigue criteria. The fatigue analysis was done from a previous 3D finite element analysis where thermal and mechanical stress calculation at high temperatures was done. The simulations considered steady and transient state during normal start ups and shutdowns. Several load histories with different cooling conditions producing different stresses and strains in the blade were considered in the numerical simulations. A thermal barrier coating was also considered in contrast to simple blade without such coating. The effect of high temperatures on the blade material calculations is shown in this study as in the stress analysis as in the fatigue calculations. This study is mainly focused on two different critical zones in the blade: the leading edge at the middle of the height and an inner cooling channel, where high stresses were found. Such critical zones found in numerical analysis are the same found during the service life. The benefit of the presence of a coating in the blade in the fatigue life estimation is shown.