Research On The Identification Method Of Wheel-Rail Force Of Rail Vehicle Based On Structural Dynamics Theory

In recent years,large mechanical structural systems have become more and more complex while engineering structural design requirements have been continuously improved.The vibration problems of mechanical systems have received more and more attention,and the acquisition of dynamic loads acting on system structures is also a hot issue.It is very important to judge the safety performance of the vehicle during the running of the wheel and rail force.The wheel-rail force identification of the rail vehicle during the running process by using the dynamic load identification technology is not only important for the research of the key technology for the high-speed train,but also one of the hot topics in the research.In this paper,the load identification method is applied to the rail vehicle system.Based on the structural dynamics theory,the load identification model of multi-degree-of-freedom vibration system for the rail vehicle system is established to identify the vertical and lateral forces of the rail vehicle.Then the vehicle operation safety is analyzed according to the identification results.(1)A method for dynamic load identification of a single-degree-of-freedom vibration system is derived by using Duhamel integration in the time domain.The equation of motion of a multi-degree-of-freedom vibration system is decoupled by modal coordinate transformation,and then the load identification model for the multi-degree-of-freedom vibration system is established.Two examples are verified to prove the correctness of the identification method.(2)The multi-degree-of-freedom vibration system load identification model is applied to the vehicle track system.By simplification of the vehicle vertical vibration and lateral vibration model,the vehicle wheel-rail force identification model is established combined with the relevant vehicle motion equation.On the premise of ensuring the correct simulation results of the SIMPACK dynamic model,the vertical force and the lateral force of the vehicle wheel-rail are identified respectively by taking the displacement of axle box connection point as the input of the identification model.And then they are compared with the simulation results in both the time domain and the frequency domain.The correctness of the identification model and the accuracy of the results are proved by the identification results at 100km/h and 250km/h.(3)By analyzing the force of the wheelset during the running of the vehicle,the vertical force of the wheel is calculated according to the vertical force and the lateral force of the vehicle wheelset obtained from the identification model.The wheel is regarded as a single-degree-of-freedom vibration system,and the lateral force of the wheel is identified rapidly according to the relative displacement of the connection point between the wheelset and the frame axle box.The derailment coefficient and load reduction rate of wheels are calculated based on the identification results of vertical force and lateral force of wheels.By comparing the calculated results with the simulation results,it is concluded that the trends are consistent.So,it is shown that the results obtained by the load identification model can provide a reference for the safety performance evaluation of rail vehicles in the process of operation.