Strain energy gradient-based LCF life prediction of turbine discs using critical distance concept

For aeroengine components with geometrical discontinuities like notches, low cycle fatigue (LCF) life prediction is critical for ensuring the engine structural integrity. In this regard, a concept of strain energy gradient is elaborated and a general procedure combining this concept with theory of critical distance is established for LCF life prediction of notch components, which relates its life with the strain energy distributed within the effective damage zone. For GH4169 and TC4 notched specimens as well as a case study of a high pressure turbine disc, the proposed procedure provides better life correlations than models of Fatemi-Socie and Smith-Watson-Topper.