| With the rapid development of aeronautics,higher requirements have been put forward for the aircraft engine and its main components,the turbine blades.The aero engine is the heart of the aircraft,its life and reliability must be guaranteed runs throughout life cycle of the aircraft,turbine blades as the main power output component,which guarantee the strength and fatigue life under high temperature,high pressure and high speed airflow,the prediction of fatigue damage of turbine blade and calculation of fatigue life are the key issues.Due to its complex working environment,its load and material are uncertain to some extent,in order to more accurately evaluate the fatigue life of turbine blades,the calculation of fatigue reliability of turbine blade is an important technical means to ensure the reliability of aero-engine system.In this paper,based on the actual situation that turbine blades are in high temperature working environment for a long time,the turbine blade structure model with internal cooling channels is built.Based on this,the strength analysis and fatigue life calculation of turbine blades are carried out,and the fatigue reliability of the aero-engine turbine blade is studied considering the randomness of the load.(1)Taking a certain type of turbine blade as the engineering background,the finite element model of the turbine blade and the internal and external flow fields are established.The real working environment of the turbine blade is simulated,and the flow field is analyzed and calculated,the results of flow field analysis are taken as input to carry out the unidirectional coupling calculation of flow-heat-solid of blades.The temperature distribution cloud diagram and pressure distribution cloud diagram of turbine blades are given,and the maximum stress and maximum deformation during the operation of the turbine blade are analyzed.(2)According to the working characteristic of aeroengine,considering the fatigue behavior of turbine blades when centrifugal load,temperature load and aerodynamic load are combined under various working cycle conditions,the fatigue life and fatigue damage value of the turbine blade under different working conditions are obtained.According to Miner linear theory,the total damage of the turbine blade and the fatigue life of turbine blade are calculated.(3)Taking the rotational speed,gas temperature and coolant temperature as random input variables,the damage value of the blade was calculated as output response by finite element method,and the response surface method was used to establish the response surface equation of the fatigue damage of turbine blade structure.Combining the modified Second-Moment method to calculate the failure probability of the turbine blade.The Monte-Carlo method is used to verify the analysis results,and the influence of multiple variability of random variables on the fatigue reliability of the turbine blade are discussed. |
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