Reliability analysis of multiaxial low cycle fatigue life for turbine disk

Multiaxial low cycle fatigue is the main failure mode of aeroengine turbine disks. The fatigue life of a turbine disk is predicted by equivalent strain models and critical plane models. The predicted lives are compared with the life evaluated by fatigue tests of real turbin disks, and it is discovered that the equivalent strain models will give overestimated results and the errors are too big, but that the critical plane models have good precision; in particular the error of the SWT model is less than 10%. Furthermore, the reliability analysis of fatigue life for the turbine disk is completed with the SWT model. As the multiaxial fatigue test is complex and costly, the fatigue parameters are randomized and expressed as functions of a standard random variable based on uniaxial fatigue test data, and the predicted life with reliability of 0.998 7 is close to the technical life based on test evaluation.