Abstract
Probabilistic safety assessment is an effective method to improve the conservative safety factors on low cycle fatigue life of turbine blades used in jet engines. This paper focuses on uncertainties of low cycle fatigue design life result from small samples and surface finishes. Improvement of uncertainty of design fatigue life, reflected from small sample tests, by use of inspection data is verified through Bayesian update and virtual inspection data. Furthermore, tension-compression low cycle fatigue tests on Inconel 718 were conducted with the specimens, of which surfaces were finished Ra 0.8, Ra 6.3, and Ra 12.5. The results indicates strain-amplitude dependence of the influence of surface finishes on low cycle fatigue life. In order to investigate the effect of surface finishing on low cycle fatigue life, local misorientations of surface layer of specimens are measured by EBSD.
