| Wheel wear not only affects the safety of train operation,but also increases vehicle maintenance costs.Because the locomotive has to take on the role of traction and braking,the wheel wear of the locomotive is more serious than that of the conventional vehicle.For the freight locomotive running on the Sichuan-Tibet Railway,the locomotive needs to face the cold climate,complex curved lines and large terrain drop.Therefore,the wheel wear behavior of the locomotive is more complicated than that of the ordinary freight locomotive.Taking the Sichuan-Tibet Railway under construction as the background,this thesis systematically studies the wheel wear behavior characteristics and influencing factors of freight locomotives in the alpine and large-slope environment,and provides a reference for the operation and maintenance strategies of the Sichuan-Tibet Railway locomotives.In this thesis,based on the analysis and correction of the basic resistance of the locomotive in the plateau climate environment,the tractive force of the freight locomotive on the high-cold ramp is calculated,and the tractive force is input into the dynamic model of the HXD1 electric locomotive established in the SIMPACK multi-body dynamics software.Combined with FASTSIM algorithm,Braghin wear model,wavelet filter smoothing method and wheel tread update strategy,a wheel wear simulation program is written to realize the prediction simulation of freight locomotive wheel wear.The wheel wear behavior and wear life under different operating modes are predicted,and the influence of wheel wear on the wheel-rail contact geometry and vehicle dynamics is analyzed.Finally,the key factors affecting the wheel wear of locomotives are studied.The main results and conclusions obtained are as follows:(1)The basic resistance of the train is affected by the atmospheric pressure(altitude)and temperature of the line environment.The increase in altitude reduces the atmospheric pressure,resulting in a decrease in air resistance,while the decrease in temperature increases air resistance and mechanical resistance.Compared with the climatic environment in the plain area,the influence of altitude change on the basic resistance of freight trains along a domestic railway is about 30%,while the influence of temperature changes on the basic resistance of freight trains is about 15%.(2)Among different operation modes,the wheel wear of the locomotive is the most serious in the re-removal and re-return mode.In this mode,the repair and wear life of the locomotive wheel segment is 500,000 km.At the same time,during the entire wear life cycle,the uphill,downhill and straight road wear contributes were 47.4%,28.4% and 24.2%.(3)With the increase of running mileage,the wheel-rail contact area becomes narrower,and the number of multi-point contacts increases significantly,resulting in the reduction of the critical speed of the locomotive from 318km/h to 215km/h.With the continuous wear of the wheels,the derailment coefficient of the locomotive shows an upward trend,the wheelset lateral force shows a downward trend,and the change of the wheel unloading rate is not obvious.Wheel wear has a greater impact on lateral stability and lateral maximum acceleration,and has less impact on vertical stability and vertical maximum acceleration.(4)Wheel wear decreases as the radius of the curve increases,and increases as the slope of the line increases.The wheel wear in the uphill condition is more serious than that in the downhill condition.When the line gradient increases from 0‰ to 10‰,the wear area increases by 4.19 times,while the wear area increases only by 1 time when the slope is-10‰.Wheel wear increases with operating speed and decreases as wheel-rail friction coefficient decreases,so friction modifiers can be used to improve locomotive wheel wear.On a line with slopes and curves at the same time,the smaller the curve radius,the more obvious the effect of the slope on wheel wear.Therefore,large-radius curves should be designed as far as possible for large-slope road sections. |
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