Research On Fatigue Crack Propagation And Fatigue Lifetime Prediction Of GH4133B Superalloy Used In Turbine Disk Of Aero-engine

GH4133B is a nickel-base superalloy modified by adding Zr and Mg on the basis of GH4133.The material is mainly used in the turbine disk between the combustion chamber and the tail nozzle whose temperature is above 600? and below 1000?.Because turbine disks play an important role in the performance of aircraft engines,and to construc their materials is a top priority.This paper based on the fatigue test and crack propagation test conducted by GH4133B,and combines the knowledge of probability theory and mathematical statistics to analyze the test data.Numerical analysis software R language and MATLAB and Bayesian analysis software WinBUGS are also used.For the fatigue life test of GH4133B,this paper analyzes the fatigue life of different stress amplitudes with different probability models.With computer software Matlab and R language doing numerical fitting about the normal distribution,two-parameter Weibull distribution,three-parameter Weibull distribution and logarithm-based these three probability distributions under different stress amplitudes are fitted.Combined with the goodness-of-fit analysis,the three probability models were compared to provide a reference for different survival probabilities of the fatigue life of GH4133B at normal temperature.The results show that the logarithm-based distribution can be good to reflect the fatigue life probability distribution Relatively speaking,the three-parameters Weibull distribution can be fit better.For the crack growth test of GH4133B,this paper first calibrates the test data of this material with Paris test.Combined with Bayesian theory and Markov chain Monte Carlo method(MCMC),and using no priori information obtain the posterior distribution of model parameters.The Bayesian modelling and the least-squares fitting analysis of the Paris formulae were performed using Winbugs software and R language.The model parameters under these two methods were compared and a new idea was provided for the parameter optimization of the model.In the Walker model that stress ratio,intensity factor and the crack growth rate are considered simultaneously,Bayesian theory is analyzed using by the same method.