Research On Probabilistic Fatigue Lifetime Of GH4133B Superalloy Used In Turbine Disk Of Aero-engine

The turbine engine of an aero-engine is in a harsh environment and often needs to operate in a high-temperature and high-pressure environment,so its requirements for strength and quality are also very demanding.In this paper,the GH4133B alloy material of a certain type of aero-engine turbine disk is taken as the research object,and the fatigue life test is carried out,and the relationship between fatigue life and life is studied.The main content is:1.A brief introduction to the research of probability and mathematical statistics and the research progress of the probabilistic fatigue life of nickel-base superalloys.Introduced the theoretical basis of fatigue life analysis and the distribution function commonly used in mathematical statistics.2.The fatigue life data of GH4133B alloy obtained by fatigue experiment under different stress amplitudes?_a were analyzed.The theoretical fatigue life values under different survival probabilities are calculated and analyzed.It is found that the theoretical life and test life are the highest when P=50%.When P=90%and 95%,the theoretical life reliability is compared high.3.The S-N curve was studied on the small sample fatigue data obtained from the fatigue test.The fatigue test data is extended by the median S-N curve,and the Weibull distribution function is used to analyze and obtain the weighting matrix,Then the weighted least squares fit is applied to the expected value to obtain the fatigue life expression and its corresponding S-N curve.The undisturbed least squares fit is performed by expanding the fatigue data to obtain an unweighted S-N curve.The comparative analysis of the weighted S-N curve and the unweighted S-N curve and the median S-N curve shows that the theoretical fatigue life and the experimental fatigue fatigue life are better calculated according to the weighted S-N curve and the unweighted S-N curve.Under the lower stress amplitude,the theoretical fatigue life obtained from the weighted S-N curve agrees well with the experimental fatigue life value.Under the higher stress amplitude,the predicted fatigue life value is slightly higher than the experimental fatigue life value.4.Correlate analysis of the high temperature fatigue life of the GH4133B alloy obtained from the test.It is found that the fatigue lifeN_f decreases first and then increases with the increase of the stress ratio R,and the fatigue lifeN_f decreases with the increase of the maximum stress R.The fatigue life equation is used to analyze the data.It is found that the three-parameter power function can more accurately express the relationship between stress level?andN_f.By using the derived fatigue life equation,the experimental data is analyzed to obtain the fatigue lifeN_f-the stress amplitude?_a-the average stress?_m.After comparing the graph and the error data,it can be seen that when estimating the fatigue lifeN_f under different?_a and?_m,the number of cores under the assumption of creep fatigue interaction is used.The creep fatigue life equation derived forn?=k?_m?~m _a~nN is more accurate;theN_f under different survival probabilities are calculated,and the probabilistic life analysis is carried out.It is found that the relationship between the fatigue life and the stress used in the previous description is different.The survival probability is better expressed,and the greater the survival probability,the greater the N_f reliability.