Vibration Fatigue Probabilistic Life Prediction Model and Method for Blade

Vibration fatigue is one of the main failure modes of blade. The vibration fatigue life of blade is scattered caused by manufacture error, material property dispersion and external excitation randomness. A new vibration fatigue probabilistic life prediction model (VFPLPM) and a prediction method are proposed in this paper. Firstly, as one-dimensional volumetric method (ODVM) only considers the principle calculation direction, a three-dimensional space vector volumetric method (TSVVM) is proposed to improve fatigue life prediction accuracy for actual three-dimensional engineering structure. Secondly, based on the two volumetric methods (ODVM and TSVVM), the material C-P-S-N fatigue curve model (CFCM) and the maximum entropy quantile function model (MEQFM), VFPLPM is established to predict the vibration fatigue probabilistic life of blade. The VFPLPM is combined with maximum stress method (MSM), ODVM and TSVVM to estimate vibration fatigue probabilistic life of blade simulator by finite element simulation, and is verified by vibration fatigue test. The results show that all of the three methods can predict the vibration fatigue probabilistic life of blade simulator well. VFPLPM & TSVVM method has the highest computational accuracy for considering stress gradient effect not only in the principle calculation direction but also in other space vector directions.