Research On Life Modification And Accelerated Test Method Of Aviation Bearing For High Purity 8Cr4Mo4V

As a key component of the aero engine and transmission part,the aero-engine main shaft bearing has an important impact on the performance,service life and reliability of the aero-engine.Therefore,accurate prediction of bearing life and exploring the distribution law of bearing life are important The maintenance and performance improvement of aero engines are of great significance.At present,domestic theoretical research on bearing life is insufficient,lack of correction coefficients for bearing life of new bearing materials,lack of theoretical guidance for bearing fatigue testing,and lack of statistical analysis methods for bearing life.In response to the above problems,this paper established a bearing life calculation method based on internal load distribution,designed and guided the standard bearing fatigue test to obtain the 8Cr4Mo4 V bearing material correction coefficient,and carried out research on the accelerated life test method of long-life aviation bearings on this basis.The life prediction and life determination methods of aero-engine main shaft bearings provide experimental guidance and theoretical support.Aiming at the current difficulties in life prediction of aviation bearings in my country,this paper is based on Lundberg-Palmgren’s rolling bearing fatigue life prediction theory,and considers the stress state of the bearing surface and subsurface by many factors such as aviation bearing structure design,manufacturing process,assembly conditions,and service conditions.The influence of the distribution,the basic rating life of the bearing is revised,and the calculation method of the bearing life based on the internal load distribution is proposed,which provides a more accurate analysis method for the prediction of the basic rating life of the rolling bearing under the actual working conditions.Taking the 7208 AC angular contact ball bearing as an example,the influence of different factors on the internal load distribution and the basic rated fatigue life of the bearing is analyzed,which provides a basis for the follow-up standard bearing life assessment and material life correction coefficient.According to the four-level evaluation system of my country’s aviation bearing performance test,the current 8Cr4Mo4 V material used in domestic aviation bearings has improved performance relative to the GCr15 material in the LP theory.Based on the Weibull distribution theory,the standard is designed to increase the test confidence and shorten the confidence interval.The bearing fatigue test program and guide the bearing test,obtained multiple sets of standard bearing fatigue life statistical data,used the maximum dictated estimation method and the studentized residual method to fit the basic rated life of the bearing,and obtained the 8Cr4Mo4 V material life correction coefficient.Furthermore,a method for calculating and analyzing the fatigue life of aviation bearings made of 8Cr4Mo4 V was established,and a software for predicting and analyzing the life of aviation bearings was developed,which provided a theoretical basis and technical means for the life prediction and life determination methods of aviation bearings in my country.Aiming at the full-condition simulation assessment and verification of fatigue life of long-life aviation bearings in my country,a research on equivalent accelerated life test methods for aviation bearings has been carried out.The influence of stress level and the number of test samples on the fitting accuracy of Weibull distribution is studied,a multistress level equivalent accelerated life test model is established,a long-life bearing accelerated life test program design method is proposed,and the equivalent accelerated life test steps are formulated,combined The case analysis proves the validity of the method used in this paper,and provides analysis theory and design guidance for the accelerated life test of long-life aviation bearings.