Strength Analysis And Life Prediction Of Aeroengine Turbine Blade

The research of turbine blade fatigue life has been a hotspot in the field of aeroengine structural strength. With the continuous improvement of engine performance, the working temperature of turbine blade is higher and higher, bear the loads more and more complicated, The probability of fatigue failure is also becoming more and more big, In order to ensure the stability and reliability of the airplane and engine when they are in service, an accurate analysis of the strength and the fatigue life for the turbine blade is needed imminently. With the way of theory analysis and computer simulation, the strength and life of the civil aeroengine turbine blade are deeply studied. The main contens and results of this paper are as follows:(1)For the seven actual flight cyclic load datas,the peak valley value cyclic number of speed cyclic spectrum is counted by amplitude method, and the duration of each temperature range of exhaust temperature spectrum is counted by interval method. When analyzing the impact of the partial loading cycles on the life of the engine, the high frequency and little damage loads of the partial loading cycles are removed as invalid value, finally, the working load spectrum is obtained. This load spectrum is the foundation for the engine strength analysis and life prediction.(2)For more real reflecting the stress of turbine blade,the thermal-mechanical coupling calculation of turbine blade is conducted by using software ANSYS12.0, then the stress and strain distribution rules of turbine blade are obtained under the combined three kinds of the centrifugal load and the role of the heat load. The calculation results show that the suction surface of the blade root is the dangerous point, and the stress and strain of the blade are meet the design requirements. The calculated results prepare the conditions for the turbine blade fatigue life prediction.(3)Due to the complexity of the contact stress, the contact analysis between blade rabbet and disc mortise is conducted. The results show that the influence of the friction coefficient on the contact stress is not strong, but for the tangential stress is great, and shows a trend of increase. the friction coefficient should be controlled.(4)Through the analysis of turbine blade loading environment, It concludes that the fatigue life of turbine blade is refer to the low cycle fatigue life. In the case of fully considering life influence factors, the Morrow correction formula for the coefficient of fatigue strength and fatigue strength index is amended and the low cycle fatigue life prediction model of turbine blade is established. Depend on the stress-strain analysis results and the material’s fatigue characteristics, we select S-N curve method and low cycle fatigue life prediction method respectively to calculate the turbine blade fatigue life under various working states, by using two different life calculation methods which are mentioned above, the same results show that the low cycle fatigue life model stablished is reliable and reasonable. At the same time, based on the low cycle fatigue life prediction model and creep equations, the fatigue/creep life of the five check points selected on turbine blade is researched. The results show that the minimum life of turbine blade exists on blade inlet side and it is 13114 working cycles,so the blade inlet side should be the focus inspection, repair parts of turbine blade.