Probabilistic Fatigue Life Prediction And Reliability Analysis Of Aeroengine Turboshaft

As the "heart" of an aircraft,the performance of an aero engine plays a decisive role in the overall performance of the aircraft,and it is a key research object of all major aviation countries in the world.The constituent materials of aero engines are special,the manufacturing process is complicated,and the difficulty factor is high.There are many components of the aero engine,and the working conditions are bad,which will lead to the reduction of the reliability of the aero engine.How to maintain the safe and reliable operation of aeroengines has become an important research topic under the current situation of increasing requirements for aeroengine performance.The turbine shaft is an important component that connects the rotating parts of the aero engine,used to support various components and transmit torque.The main failure mode of the turbine shaft is fatigue failure,which is specifically manifested as mechanical fatigue,creep fatigue and thermomechanical fatigue according to the effect of different external loads.In view of the characteristics of turbine shaft failure,this paper starts from quantifying the uncertainty of materials and working conditions,and studies the random characterization method of the uncertainty of turbine shaft material performance parameters,fatigue life,and fatigue life and reliability considering the effects of creep.The main research work of this paper is as follows:(1)Through the analysis of fatigue life theory,several material performance parameters that affect the fatigue life of the turbine shaft are determined.The statistical method is used to process the sample data of the material performance parameters,and the random distribution of the material performance parameters is determined by means of hypothesis testing and parameter fitting.The influence of the window width and kernel function on the parameter estimation accuracy in the kernel density estimation is analyzed.The progressive integration mean square error method is used to find the optimal window width and the random distribution of material performance parameters is estimated.(2)The load condition of the turbine shaft is studied,and the stress and strain of the turbine shaft is analyzed by finite element analysis to obtain the stress and strain value at the weak link.The local stress-strain method and the Paris formula are used to analyze the crack initiation and propagation life of the turbine shaft.Combined with ABAQUS software,the method of solving the shape factor of irregularly-shaped cracked body is analyzed.The probability representation method of life is studied,the fatigue reliability modeling methods under different reliability indexes are analyzed,and the first-order second-moment method and Monte Carlo method are used to analyze the turbine shaft fatigue reliability.(3)Considering the effect of creep on fatigue failure,the fatigue reliability modeling and calculation under the interaction of creep fatigue are analyzed.Based on the life model,the interaction between creep fatigue failure is analyzed using Copula theory.A nonlinear cumulative damage theory is used to establish a fatigue reliability model for coupled multiple damages,and the Monte Carlo method is used for calculation.Finally,the sensitivity of various factors affecting fatigue life is analyzed.