Analysis Of High-speed Wheel-rail Loads And Axle Dynamic Stresses Including Extreme Conditions

As an important load-bearing component of high-speed trains,wheel-axle plays an important role in the safe operation of the vehicle.Studying the actual load and dynamic stress characteristics of the vehicle can provide an important reference for structural design,optimization,and service life prediction.This article takes the wheel-axle of a high-speed EMU as the research object,relies on the wheel-axle load and dynamic stress data of the typical working conditions of the Daxi Passenger Dedicated Line,and combines the wheel flat impact,turnout passing and combined working condition simulation models,studies the characteristics of axle load and dynamic stress under different working conditions from the perspective of line measurement and numerical simulation.The specific research contents are as follows:(1)According to the patch principle and scheme of the instrumented wheelset,This paper completes the static loading calibration test of the wheel axle,processes and analyzes the static calibration data under different working conditions,analyzes the influence between the load applied in different directions,and obtains the vertical and lateral stress-load transfer coefficient of the wheel-axle.(2)This paper uses the stress-load transfer coefficient to process the measured data of the line,extracts the stress/load time history of different speed straight line conditions and different radius curve conditions,compile the corresponding load spectrum and stress spectrum,and analyzes the wheel-rail load and axle dynamic stress distribution characteristics under these typical conditions.The results show that under straight-line conditions,the speed has little effect on the wheel-rail main frequency load and the axle main frequency stress,and the load / stress change interval will increase as the speed increases;Under the curve conditions,the wheel-rail load and the axle stress are significantly offset.The degree of offset is closely related to the curve radius and super elevation.The specific manifestation is that the greater the difference between the equilibrium speed of the curve and the actual running speed of the train,the wheel-rail load and axle stress are more clearly deviated from the linear operating conditions.(3)Using the multi-body dynamics simulation tool SIMPACK,a rigid-flexible coupled vehicle system dynamics model is established according to the parameters of the EMU.In order to accurately study the wheel-axle load and dynamic stress characteristics,consider the flexibility of the wheel-axle;According to the turnout model of the high-speed passenger dedicated line,the No.42 movable nose rail single turnout is selected,and the straight-through and side-through turnout models are established by extracting the critical section data and interpolating non-critical sections;The wheel flat is considered as local out-of-roundness on the wheel circumference,the models of different sizes are established.(4)Through numerical simulation,the wheel-rail load and dynamic stress of the key nodes of the axle under the wheel flat impact,turnout passing and combined extreme conditions are obtained,and the influence characteristics of these extreme conditions on the wheel rail-load and the dynamic stress of the axle are analyzed.The results show that the length of the wheel flat has obvious influence on the wheel rail load and the dynamic stress of the axle,with the increase of the speed,the vertical load of the wheel-rail and the stress of the key section of the axle increase first and then decrease,under the condition of low speed,the impact of flat scar will seriously affect the fatigue life of the axle;There will be significant wheel-rail impact when passing through the switch area and the frog area;When the wheel flat passes through the turnout at high speed,the wheel/rail force is accompanied by repetitive high-frequency impact,and the vertical force of the wheel/rail in the switch area is mainly caused by wheel flat impact,while the frog area is mainly caused by turnout impact.The wheel/rail forces and dynamic stress peaks generated by the combined conditions are larger than those generated by the single working condition.Figure 86,table 12,reference 102.