Research On Dynamic Performance Of Lightweight Sub-frame Bogies

High speed and heavy haul are the development direction of freight wagons in the future.The development of high-speed and heavy-haul can effectively improve the efficiency of railway cargo transportation and provide guarantee for the rapid development of society and economy.However,the increasing in axle load and running speed will increase the action force between wheels and rails,also the wheel and rail wear will increase.Using radial bogies can effectively improve the curving performance,reducing wheel and rail wear,and improving the running quality of the vehicle.The lightweight sub-frame bogie is a radial bogie with a 27t axle load which is used for freight wagons with heavy haul and the bogie is improved on the basis of the type DZ3 bogie.The bogie uses integrated braking equipment on the basis of the DZ3 bogie,and the lightweight design of the wheelset and radial devices reduces the unsprung mass of the bogie and further improves the bogie’s dynamic performance.Based on the lightweight sub-frame bogie,this paper explores the influence of the flexibility of the sub-frames,the installation position of the crossed connection rods,and the longitudinal and lateral stiffness of the primary suspension device on the vehicle dynamic performance.This paper briefly describes the dynamics theory and modeling method of multi-rigid body and rigid-flexible coupling for rail vehicle systems.Using SIMPACK and ANSYS software,the rigid-flexible coupled dynamic model of a type C₈₇ gondola car with considering the flexibility of the sub-frames and the multi-rigid body dynamics model without considering the sub-frames’flexibility are built.According to the GB/T 5599-1985 standard,this paper analyzes the dynamic performance of the two models under the conditions of empty and heavy loads.The results show that the flexibility of the sub-frames will cause the vehicle’s stability to deteriorate on the straight-line,the curving performance to become better,and the performance will be more obvious under the condition of empty load.Sub-frames’flexibility will affect stability index of the vehicle.When the vehicle runs at a high speed,the flexibility of the sub-frames will be stimulated to cause the stability of the vehicle to deteriorate.In order to facilitate the installation of integrated braking equipment,a lightweight bogie with the sub-frames placed down was designed.In order to ascertain the effects of the longitudinal and lateral stiffness of the primary suspension and the position of the crossed connection rods of the sub-frames on the dynamic performance of the vehicle,the paper studies the above-mentioned problems based on the lightweight bogie with the sub-frames placed down.The results show that increasing the longitudinal or lateral stiffness of the primary suspension can improve the vehicle’s stability on the straight lines,but the excessive positioning stiffness of the primary suspension will reduce the vehicle’s curving performance;Comprehensive consideration,it is recommended that the lateral stiffness of the primary suspension on each bearing saddle is 2.0MN/m and the longitudinal stiffness is 2.3MN/m;The wheel load reduction rate of the wheel is greatly affected by the installation height of the crossed connection rods,When the rods are installed at a too high or too low position,it will reduce the vehicle’s dynamic performance;According to the calculation results,it is recommended to set the installation height of the crossed connection rods near 200mm from the centerline of the axle,which can meet the requirements of sub-frames’lower installation and have excellent dynamic performance.