Redesign of Dovetail Joints Based on Estimated Low Cycle Fatigue Life

 

Strain Posavljak,

Stevan Maksimović

 

Fatigue life behavior of the dovetail joint of aero engine axial compressors and its redesigned version were investigated in this work. It is shown how redesigned version increases low cycle fatigue life. It was assumed that elements of joints are made of steel 13H11N2V2MF of known cyclic properties and subjected to blocks of variable force. For the purpose of low cycle fatigue life estimation, the block of variable force was decomposed on the simple cycles. The stress-strain response at critical points, for all simple cycles, was determined using approximate Sonsino’s curve, cyclic stress-strain curve and Masing’s curve. Stress concentration factors needed for application of the mentioned Sonsino’s curve were determined using the finite element method. Palmgren-Miner’s rule was applied for damages and low cycle fatigue life estimation.

Key words: aero engine, compressor, fatigue life, low-cycle fatigue, life cycle, finite elements.