Elasto-plastic Stochastic Finite Element And Structural Reliability Analysis Of Turbine Discs Under Uncertainty

As the power device of airplane,aero engine has shown a decisive impact on the performance of aircraft flight capability and safety.Harsh working condition makes most of engine components bear complicated working loads,which means that while increasing the thrust-to-weight ratio of aircraft engine,specific fuel consumption and the overall performance of the aircraft engine,the reliability of the major parts have to be paid enough attentions.As one of fatigue critical components of aircraft engines,high pressure turbine(HPT)disc works under high rotational speeds and high temperatures.Once it appears micro cracks,it may lead to immeasurable disastrous consequences for the aircraft.In order to ensure that the engine can operate safely,high reliability and considerable performance of the HPT disc are desired.Considering the issues mentioned-above,in this thesis,researches on an HPT disc have been carried out:1)Uncertainty quantification in fatigue life prediction of turbine disk.Engine hot section components like the HPT discs withstand complex loadings under multi-source uncertainties.The influence of these uncertainties on structural response of HPT discs cannot be ignored during its fatigue life and reliability assessment.In this study,seversal FE simulations are established to quantify the influence of material variability and load variations by using the Latin hypercube sampling.In particular,material response variability is modeled by combining the Chaboche model with Manson-Coffin equation.2)Probabilistic fatigue life prediction and structural reliability analysis of the HPT disc.In practice,engine component like HPT discs is frequently subjected to complex multiaxial loadings.Therefore,the Fatemi-Socie(FS)damage criterion is used to predict the fatigue life of the HPT disc.From the results of FE analysis of the HPT disc,probabilistic fatigue life of the HPT disc is calculated,based on which,the structural fatigue reliability and sensitivity analysis of the HPT disc under multiple sources of uncertainty has been carried on.3)Nonlinear cumulative damage model considering the influence of loading sequences.Usually the HPT disc is subjected to variable amplitude loading during service time.Considering that the accuracy and applicability of the Miner’s rule under variable amplitude loadings is not ideal,a new nonlinear fatigue damage accumulation model is proposed based on the isodamage curves.Through introducing a lot of test data and some commonly used prediction models,the accuracy of the proposed model is verified.4)Fatigue life prediction and reliability analysis of turbine disk based on cumulative damage.In order to consider the influence of the amplitude variation of loading and the loading sequences,the proposed damage accumulating model is used to predict the fatigue life of an HPT disc,and its structural fatigue reliability is also studied.