Simulation Analysis And Experimental Research On Contact Between Wheelset And Fixed Frog

In recent years,with the rapid development of China’s economy,heavy-duty freight railroad technology has also made great progress.While the train load increases,the contact damage between the wheelset and the fixed frog becomes a problem to be solved.Due to the discontinuous track surface of fixed frogs,when trains pass through the fixed frogs,not only the wear damage exists between the wheel frogs,but also the vertical dynamic performance of the wheelsets will change drastically,causing serious impact damage to the fixed frogs,which affects the smoothness of trains passing the frogs and the service life of the fixed frogs.Therefore,it is important to systematically study the contact relationship between wheel frogs and summarize the change law of vertical dynamic performance of wheelsets passing fixed frogs under different working conditions to mitigate frog damage and reduce frog operation and maintenance costs.In this paper,the contact problem between wheelset and fixed frog is studied by both simulation and experiment.The finite element model of wheelset-fixed frog elastic-plastic contact and dynamics model are established for simulation and calculation analysis.Self-developed wheelset-fixed frog test bench conducts experimental research on heavy-duty wheelset and fixed frog taken from actual line operation sites.In-depth analysis of the wheelset and fixed frog contact problem,the main research work and conclusions are as follows:(1)The wheel and rail profile measuring instrument was applied to measure the wheel and fixed frog profiles,and the LM wheel treads with different wear levels and the 60-9 fixed frog profiles with different positions and wear levels were collected respectively.Comparative analysis was carried out to determine the wear status of the measured wheel treads and to conduct a preliminary study on the wear pattern of the fixed frogs at different locations.(2)The finite element model of contact between wheelsets and fixed frogs at different positions were established by actual measured wheel and fixed frog type surfaces,and the change law of contact spot,normal contact force and equivalent force of wheel frog with different degree of wear under 25 t axle weight is studied.The results show that the contact area of frog nose rail edge near 400 mm from the theoretical tip is smaller and the equivalent force is larger,which will lead to plastic flow and wear damage of frog material.(3)The simulation model of wheelset-fixed frog dynamics with different wear degree is established to analyze the changes of vertical displacement,vertical velocity,vertical acceleration and vertical force of wheelsets with different axle weights passing fixed frogs,and to investigate the influence of the above indicators on the smoothness of wheelsets passing frogs and damage of fixed frogs.The results show that the wear zone of fixed frog is900 mm from the theoretical tip to the core rail side,and the vertical contact performance of wheelset passing fixed frog in this zone changes greatly,which seriously affects the smoothness of wheelset passing frog.(4)A full-size wheelset-fixed frog test bench was developed to conduct wheel-frog contact position test and wheelset through frog vertical displacement test.The position and width of the contact zone between the wheelset and the fixed frog when the wheelset passes the frog at different traverse amounts,and the vertical displacement of the wheelset when it passes the frog at different speeds,axle weights and traverse amounts are analyzed.The results show that the maximum vertical displacement of the wheelset in contact with the nose rail is located between 600 mm and 450 mm from the theoretical tip,and the maximum vertical displacement in contact with the wing rail is located between 300 mm and 200 mm from the theoretical tip on the nose rail side.The results of the simulation analysis and experimental research in this paper can provide some reference for improving the smoothness of wheelsets passing through fixed frogs and slowing down the injury and damage of fixed frogs,as well as providing a basis for determining the maintenance and inspection cycles of fixed frogs and the design of fixed frog profiles.