Research On Dynamics Of 30t Axle Load Heavy Haul Train On The Mengxi-central China Railway

With the rapid development of heavy haul railway,the longitudinal impulse problems become more and more prominent due to the increased mass of train and weight of axle load. In this thesis with a train longitudinal dynamics package TDEAS(Train Dynamics and Energy Analyzer/ Train Simulator). , a 21,000t train model with two 30t axle electric locomotives '1+1' marshalling mode is established primarily to simulate goods transporting and train energy consumption on the Mengxi-Central China Railway. Subsequently,a type 30t axle load locomotive model and the 13A type coupler system model are formulated with the commercial software SIMPACK, in which the locomotive structural characteristics,suspension parameters, wheel/rail matching, the friction surface of coupler tail and the buffer with the nonlinear hysteresis characteristics are taken into consideration. Then the'loco A+loco B+multiple cars' dynamic model of short marshalling train is established based on substructure method. On the basis of this model and the longitudinal impulse data,the tread board deformation of the middle locomotive is studied, and the lateral dynamic analysis of the locomotive is performed. Finally, the effect of track parameters and train parameters on the dynamics performance of heavy haul train is investigated based on a 21,000t train model with '1+1' marshalling mode and a 10,000t train model with '1+0'marshalling mode. The main conclusions are shown as follows:1. The 30t axle load locomotive's traction capacity can meet the application requirements of the Mengxi-Central China Railway. From Yan'an East Station to Yuncheng West Station, the average running speed of the train is 58km/h. The train is running at a speed greater than 40km/h in the 6‰ long and steep upgrades and can get through the-13‰ long and steep downgrades by several times cycle braking. During operation,locomotive traction force work done 13.17E10 J and recyle 8.57E10 J from dynamic braking. Priority to use the dynamic braking can recyle the huge gravitational potential energy of the Mengxi-Central China Railway.2. In the operation of the train, the maximum coupler forces occurs in the coupler connecting the middle locomotive and the neighboring car. The maximum coupler-pulling force is 1050kN and the maximum coupler-pressing force is 1000kN. The maximum coupler-pulling force often appears in the traction condition when the middle locomotive is located on the line of convex longitudinal profile. The maximum coupler-pressing force often occurs in the cycle braking condition when the middle locomotive is located on the line of concave longitudinal profile. The maximum longitudinal acceleration of the cars and locomotives occurs at the 180th vehicle, and the maximum value is less than 3m/s2. If properly manipulated, the longitudinal force and the vehicle acceleration are within the safe range.3. The simulation analysis of the tread board deformation of the middle locomotive of combined heavy haul train shows that the minimum distance between the center of the tread board and the end of the vehicle body will be less than the critical condition of 250mm, and the tread board will crush with the end of the vehicle body if the coupler-pressing force is greater than 1200kN when the curve radius is 800 meters. Under the longitudinal impulse of 1200kN for 5s, the dynamics performance of the middle locomotive can meet the safety requirements if the friction of coupler tail is in good condition.4. The dynamics simulation analysis of the key parameters of plane and profile show that: 1) The increase of curve radius has a small negative effect on the start-up traction of heavy haul train and a small promoting impact on the dynamic braking. 2) The locomotive with 13A type coupler system is capable for the longitudinal compressive forces with magnitude of 2250kN on the straight track. With the decrease of the curve radius, the safety capacity of the coupler system and the safety performance of the locomotive will reduce. 3)When applying emergency braking or conventional braking on the same ramp, the longitudinal impulse of heavy haul train is almost the same as that when it is on the flat track. 4) The longitudinal impulses are different caused by different initial position of the train related to point of gradient change. Take a 10,000t train under emergency braking as an example, the greatest impulse braking position is the approximate 2/5 length of the train just crossing the point of gradient change. The maximum coupler force is 1247kN, which is 1.52 times the flat track reference value. Therefore, in the actual operation emergency braking should be avoided in this initial position. 5) Changing the composition of difference gradients has almost no influence on the longitudinal impulse of train. As the difference gradients increases from 0 to 24 9‰, the maximum value of the coupler force is approximately linearly increased, and the value reaches 2.3 times the flat track reference level.5. The dynamics simulation analysis of the different key parameters of heavy haul train show that: 1) With the increase in traction mass, the longitudinal impulse of heavy haul train increased significantly. 2) With the same mass, increasing the axle load benefit to reducing the longitudinal impulse of the heavy haul train. 3) Comparing with the three kinds of power distribution modes of '2+0', '1+1' and '1+0+1',the longitudinal impulse of train with '1+1' marshalling mode is the smallest. 4) From the gap effect, with the increase of the coupler gap, the longitudinal impulse of the train increases obviously. The application of the traction rod in the cars can significantly reduce the longitudinal impulse of the train. While the effects of traction rod on the longitudinal impulse of the heavy haul multi-locomotive is negligible and in the large vertical pressure condition the traction rod would impose the great threaten to running safety of heavy haul multi-locomotive. 5) From the aspect of train operation and signal control, traction power or dynamic braking imposed by the faster,the train longitudinal impulse increase with a slight. Properly lowering the electric braking force during the cycle braking, can reduce the longitudinal impulse of the train. The longer the slave control locomotive signal hysteresis time, the greater the impulse of the train is it. With the application of ECP technique,the vertical impulse of the train can be significantly reduced and the emergency braking distance is decreased.