Time Domain Identification Method Of Wheel-rail Force Based On Finite Element Model

Wheel-rail system is the main form of railway and urban rail transit in our country,but there are still many problems in the health status of wheel-rail system.Among them,many dynamic indexes related to driving safety,such as derailment coefficient,wheel weight and load reduction rate,are closely related to wheel-rail contact force.The vibration,noise and stress of track structure caused by wheel-rail impact load seriously affect the driving safety and the service life of wheel and track.Therefore,the accurate measurement of wheel-rail force is of great significance in both theoretical research and engineering practice.The wheel-rail force data collected by ground equipment can provide a basis for real-time monitoring of train condition and dynamic performance evaluation.Through the real-time measurement and data acquisition of wheel-rail force,the dynamic performance and status of vehicle system are evaluated,which is one of the important means and ways to implement the vehicle conditionbased maintenance.Based on this,the main contents of this paper include the following aspects:(1)In this paper,a Newmark-α method for time domain identification of moving loads(wheel-rail force)based on track dynamic response is presented,and the transfer matrix equations with displacement response and strain response are derived,the ill-conditioned problem is solved effectively by using the least squares method and the regularization method.(2)Based on the displacement and strain response,the identification of single moving load and multi-wheelset moving load is demonstrated respectively.The results of the load transfer matrix equations are compared with those obtained by the least squares method and the regularization method,at the same time,the influence of measurement noise,vehicle speed and sampling frequency on the load identification method and the advantages and disadvantages of the solution method are analyzed.The results show that the regularization method is more accurate than the least squares method,and has better effect on reducing the noise error,so the regularization method is used to solve the following models.(3)Through the measured strain data,the wheel-rail force is compared with the wheel-rail force calculated by the wavenumber domain method,and the wheel-rail force is basically matched with the wavenumber domain normal wheel-rail force in each frequency,it is shown that the method is accurate and reliable in identifying wheel-rail force.Finally,the main vibration frequency is obtained by the spectrum analysis of the wheel-rail force identification.(4)A more precise three-dimensional discontinuous track structure model is built by ANSYS software,and the complex K,M,C matrix is solved by ANSYS platform,the feasibility of wheel-rail force identification on complex discontinuous track structure is proved.At the same time,through the analysis of the identification results of the moving load at different measuring points and different frequencies,it is found that when the moving load is transmitted to the base under the rail,the higher the frequency of the moving load is,the more difficult it is to transfer down,the effect of identifying wheel-rail contact load directly by measuring point on rail is the best.