Research On Probabilistic Fatigue Life Prediction And Reliability Evaluation Method Of Aero-engine Turbine Shaft

As a primary power source of aviation industry,the aero-engine's reliability is an important guarantee for aviation safety.The develop state of aero-engine reflects the level of a country's national economy,scientific and technological innovation and comprehensive national strength,and plays a vital role in national strategic security.With the rapid development of manufacturing,the design of aero-engine is gradually developing towards high thrust to weight ratio and high performance.In addition,the service condition of aero-engine is more stringent,which causes the reliability design of aero-engine meets higher challenge.As one of the most important transmission components of aero-engine,turbine shaft plays an important role in connecting the core components such as turbine disk and turbine blade and transmitting power.In order to improve the fatigue performance of turbine shaft,the fatigue test of turbine shaft and labyrinth is carried out,which is easy to bear a variety of axial loads during flight,so it is also of great value to improve the fatigue life of turbine shaft.In addition,there are a lot of uncertainties in the process of studying the fatigue life of turbine shaft,mainly from material performance parameters,structural geometric dimension parameters,load parameters borne in work and life prediction model parameters.When studying the fatigue life and reliability of turbine shaft,fully considering the influence of uncertain factors is more in line with the actual requirements of engineering.It is of great significance to improve the accuracy of fatigue life prediction and reliability evaluation of turbine shaft and ensure the normal operation of aero-engine.In view of this,this thesis studies the probabilistic life prediction and reliability evaluation method for aero-engine turbine shaft.The main research contents are as follows:(1)Considering the influence of average stress,an improved Gerber life prediction model is proposed.Combined with finite element simulation,the fatigue life prediction method of turbine shaft is established,which is verified by the bending fatigue test results of turbine shaft of an aero-engine.(2)Establish the probabilistic fatigue life prediction framework of turbine shaft.Determine the main sources of uncertainty factors of turbine shaft in geometric modeling,finite element analysis and fatigue life prediction,obtain the distribution of random variables on this basis,obtain the sample data of turbine shaft random variables through sampling algorithm,calculate a large number of turbine shaft fatigue life data based on the established life prediction method,and fit the turbine shaft life distribution.(3)The reliability model of turbine shaft is established based on the stress strength interference model.Combined with the fatigue life distribution and fatigue cumulative damage distribution of turbine shaft calculated by the probabilistic life prediction framework,the curve of turbine shaft reliability with design life is solved.(4)Based on the research on fatigue life and reliability of turbine shaft,combined with the existing guidelines of life determination,compile the design process and specification for fatigue reliability of turbine shaft.