Analysis And Prediction Of Fatigue Life And Reliability For High Speed Train Wheel Axles

The axle is an important related component between the train and the wheel rail,and its safety is directly related to the safety of the train.The axle will be affected by the wheel-rail excitation load and the body load.When the load is applied for a long time,fatigue damage will occur on the axle and cause the axle to fail.In order to ensure the safety of the train,the fatigue life and reliability of the axles need to be analyzed.Based on the analysis of load spectrum data,this paper conducts research on fatigue life prediction and reliability analysis of wheel axles.The main focuses are the study of load calculation methods in different national standards,the correction of gray theory methods,the correction of cumulative damage models under multi-level loads,the analysis of load spectrum data characteristics,the estimation of the fatigue life of axles by modified cumulative damage models,the reliability of axles under variable amplitude loads,reliability research of axle and wheel for interference fit.The thesis mainly researches from the following aspects:(1)The different standards are compared,and the Japanese standard vertical load calculation method and the Chinese scholars' lateral load calculation method are determined to be as the axle analysis method.The modified gray-scale theory method is applied to the stress calculation of each position on the shaft to obtain the stress interval at the given position on the shaft.Through the analysis of the interval,the position prone to fatigue failure on the axle is determined.(2)The method of fatigue damage accumulation was modified based on the Corten-Dolann model and the Manson-Halford method.A cumulative damage model considering load sequence and load interaction force and small load reinforcement was established and verified by two cases.(3)The load spectrum signal was processed by using methods such as Romanovsky's outlier elimination method,nonlinear wavelet denoising method,and low-amplitude load filtering method.The processed data is used to plot the mean and amplitude histogram by using rain-flow counting method,and the mean probability distribution function and amplitude probability distribution function was fitted.Based on the analysis of train driving conditions,load data is extrapolated according to mileage,quantile extrapolation,and parameter extrapolation methods.Onedimensional program load spectrum of the axle load is constructed based on the extrapolated data,and the fatigue life of the axle is estimated.(4)Based on the stress-intensity distribution model,the reliability function of the axle is derived from the strength probability distribution function and the twodimensional joint probability density distribution function of the mean and amplitude.The reliability of the axle under cyclic load is analyzed according to the reliability function.(5)Based on the radial displacement function under the action of centrifugal force,A contact stress change model of the wheel-shaft interference fit was established.The change in contact stress of interference fit and the safety and reliability of wheel and axle combination was investigated.The research results in this paper provide a new method for the fatigue life prediction and reliability analysis of the axle,and provide a theoretical basis for the analysis of the safety of the interference fit of the axle under centrifugal force.