Research On Probability Life Prediction Of Blade Vibration Fatigue

Blades are the core components of aero-engines and play an important role in compressing air and generating thrust.The periodic resonance caused by the excitation of the external air flow is one of the main forms of fatigue failure of the blade.The structural strength of the blade directly affects the safety and reliability of the engine.This paper studies the establishment method and flow of blade vibration fatigue probabilistic life prediction model,and proposes a more simple blade vibration fatigue probability life prediction model.Based on the actual crown-deep-rooted aero-engine blades,a simulated blade with crown-deep root plate was established,and the prediction of the first-order and higher-order vibration fatigue life of the blade was studied.The research content and main conclusions of this paper are as follows:In this paper,we studied the analysis and summarization of the classical one-dimensional stress field method and the three-dimensional space vector stress field strength method(CTSVM)based on the classical one-dimensional stress field method.Based on this,the two methods were used to calculate and analyze the cyclic bending load.The field-strength equivalent stress at the dangerous point of the notched round bar specimen shows that the CTSVM method has higher calculation accuracy and more stable calculation results.In this paper,the establishment method and process of the predictive model of blade vibration fatigue life is studied,and the corresponding calculation flow diagram is given.For the problem of long computation time of the combinatorial model,this paper establishes a modified model 1 and an improved model 2 based on the dual maximum entropy quantile function,which is based on the pairwise incomplete probability maximum entropy quantile function and coefficient weighting.Three kinds of models were used to predict the first-order vibration fatigue life of the gap simulated blade,and compared with the results of the literature [39].The results show that the improved model 2 has good calculation accuracy and short calculation time.Because the real aero-engine blades are not nicked,this paper has established a simulated blade with deep-rooted flat plate.In this paper,improved model 2 is used to predict the first-order and higherorder bending fatigue life of blades with crown-deep root plate.The results show that: first-order and higher-order vibration fatigue probabilistic life-time maximum entropy quantile function curves and gaps The same simulation of the blade shows that the improved model 2 is effective and feasible for predicting the fatigue life of the first-order and higher-order bending fatigue of the blade with deep crown plate.In this paper,the three-dimensional space stress field strength method(CTSVM)is used to successfully calculate the equivalent stress at the critical point of the first-order and higher-order bending vibrations of simulated blade with crown and deep root plate,indicating that the threedimensional space stress field method(CTSVM)is suitable for Calculate the field-strength equivalent stress at high-order vibrations of flat-blade blades.