Research On Dynamic Performance And Parameters Optimization Of An Export Broad-gauge Freight Locomotive

With the rapid development of the railway transport industry around the world,the increasing demand of railway vehicles brings great opportunity for the export of locomotives in China.However,there exist great differences in rail gauge,wheel-rail profile,and railway-related standards in different countries and regions due to historical and technical reasons.Besides the relevant dynamic performance tests of export locomotives are difficult to carry out due to the limitation of railway track conditions,which brings great challenges to the export of railway vehicles.Therefore,it is of great significance to carry out theoretical research on the dynamic performance of export broad-gauge locomotives.Emphasis on the running safety and ride comfort of a certain type of broad-gauge locomotive,the effect of the key suspension parameters,and wheel profile on the dynamic performance of the locomotive are studied,which intends to provide guidance for the optimization of the locomotive.In this thesis,the structural characteristics of a certain type of export broad-gauge locomotives are described first.Then,two locomotive models with different axle loads are established using the multi-body system dynamics software SIMPACK.Meanwhile,indexes which are used to evaluate running safety and ride comfort of the locomotive in Russian railway standards and Chinese railway standards are introduced.The critical speed,running safety,and ride comfort of the locomotive adopting original parameters are evaluated according to Russian railway standards and Chinese railway standards,respectively.The research results indicate that all the dynamic performance indices of the broad-gauge locomotive adopting original parameters are within the limitations of the Chinese railway standard.However,the ride comfort of the locomotive exceeds the limitation of the Russian railway standard when the vehicle running on a tangent track at a high speed.And the dynamic load coefficient of secondary suspension exceeds the limited value as well when the locomotive passing through the curves.It is necessary to optimize the parameters of broad-gauge locomotive.To improve the dynamic performance of the locomotive,the effect of the key suspension parameters(the stiffness of primary and secondary suspensions and the damping of secondary lateral damper)on the locomotive are revealed through the Russian railway standards,and a set of optimized suspension parameters are proposed and further evaluated according to the Russian railway standards and Chinese railway standards,respectively.According to the simulation results,the longitudinal stiffness of primary suspension has little influence on the dynamic performances of the locomotive.It is revealed that reducing the lateral stiffness of the primary suspension and horizontal stiffness of secondary suspension can contribute to improving the lateral dynamic performance of locomotives.Both the running safety and ride comfort indices of the locomotive increase with increasing vertical stiffness of primary and secondary suspensions.Besides,appropriate reduction of the damping of secondary lateral dampers can effectively improve the lateral ride comfort of the locomotive.Based on a comprehensive assessment of the dynamic performance of the locomotive,the lateral stiffness of the primary suspension,and the horizontal and vertical stiffness of secondary suspension are optimized to be 3 MN/m,0.1 MN/m,2 MN/m,respectively.And the damping of the secondary lateral damper is recommended to reduce to60% of its original value.The dynamic simulation results indicate that all the dynamic performance indices of the locomotive adopting optimized are within the limitations of the Russian and Chinese railway standards.Moreover,the influence of different wheel profiles on wheel-rail contact geometry,locomotive dynamics performance,and wheel-rail wear are investigated by simulations.The results shows that comparing to the locomotives adopting the Russian ДМЕеТИ ЛБ profile,the locomotives with the Chinese JM3 profile have slightly better lateral dynamic performance,but the wheel-rail wear is relative severer.The ДМЕеТИ ЛБ profile is recommended to be used.