Simulation And Experimental Research On Crack Propagation Of EA4T Axles Of Railway Vehicles

Axles as important component of railway vehicles,during the operation of the train,it not only has to bear the main weight of the vehicle,but also withstand the excitation from track irregularities.Axle fracture accident caused by injury will inevitably cause a huge disaster once it occurs.To ensure that it has good and reliable service performance during operation.At present,damage tolerance assessment methods based on fracture mechanics and regular flaw detection ensure the safety of axles in service.In order to formulate a scientific and reasonable ultrasonic inspection cycle for axles,this thesis takes EA4T axles as the research object to carry out crack propagation life research.The specific work is as follows:(1)To determine the fatigue crack growth life prediction model,aiming at the fatigue crack growth test of M(T)specimens under variable amplitude load conditions.Use Paris and NASGRO equations to estimate remaining life.The results show that the NASGRO equation can better predict the crack growth life under variable amplitude loading.(2)Create a finite element model of the wheel and axle.The influence of three different stress states on the crack propagation behavior at the unloading groove is studied.Finally,the NASGRO equation is used to predict the fatigue crack growth life of these three stress analysis models.Comparison of fatigue crack growth test results with fullscale EA4T axles.It is believed that considering the secondary stress can provide more accurate and conservative results for life prediction(3)In order to obtain the behavior characteristics of axle crack growth based on the conditions of the railway in my country.Adopt the above determined axle force analysis plan and life prediction model.Using a 2mm deep crack as the initial condition,predict the crack propagation life of the motor car axle in the measured line load spectrum.The results show that when the crack propagates to a depth of 4.2mm,all levels of load have an effect on the crack propagation.(4)The effects of different initial crack shape,depth and number of cracks on fatigue crack growth behavior and fatigue crack growth life are studied.This thesis considers the two influencing factors of the prediction model and the secondary stress state to realize the transferability of input parameters from small specimens to full-size axles,and improve the prediction accuracy of axle crack growth life.