Finite Element Analysis And Fatigue Life Prediction Of An Aero-engine Turbine Shaft

As the power source of aircrafts, aero-engines have received much attention, and their stability and reliability will influence the normal usage of aircrafts directly. The main shaft of an aero-engine mainly includes: fan shaft, high-pressure and low-pressure turbine shafts, and so on. The main shaft is responsible for connecting the surrounding components and transferring the working loads. Under working conditions, the turbine shaft operates under high temperatures, and bears high cycle fatigue loads and low cycle fatigue loads along with the changing of flight status. Because of the poor working conditions, the turbine shaft has become the critical fracture part of aero-engines. Therefore, fatigue life of turbine shaft often limited the normal use of an aero-engine directly, and its failure often leads to serious accidents. To improve the safety and working life of an aero-engine and provide guidance on maintenance and replacement of turbine shafts, its fatigue has been widely studied. Thus, this thesis aims to investigate the fatigue life of an aero-engine turbine shaft based on Finite Element Analysis(FEA). The content mainly includes:Firstly, based on the analysis of working, structure, and assembling conditions of turbine shafts, the constraint condition in FEA, high cycle fatigue loads and low cycle fatigue loads are analyzed, such as axial force, torque and bending moment. According to the aircraft flight status analysis, its working cycles are determined, and the external loads and loading positions are analyzed according to its working conditions. Then, ANSYS Workbench software is used to build and simplify the finite element model of the turbine shaft. To simulate its actual working status, the working loads and boundary conditions should be set properly. Based on finite element analysis, the stress-strain distribution and dangerous parts of the turbine shaft can be obtained under different working conditions.Secondly, the combined cycle fatigue life prediction model based on the critical plane method and local stress-strain method, are introduced respectively. Then, these methods are used to predict fatigue life of the dangerous parts of turbine shaft using finite element analysis results. The estimated fatigue lives are compared with each other.Finally, to verify the accuracy of fatigue life prediction results of the turbine shaft, the loads and scheme of fatigue test are investigated. Then, under the experimental condition, the finite element analysis of turbine shaft is carried out. Then, fatigue life of dangerous parts is calculated to verify the accuracy of fatigue life tests.