Investigation On Value Of Wheel-rail Vertical Dynamic Load

As the basis of driving,the track repeatedly bears the wheel-rail dynamic load.Accurately determining the wheel-rail dynamic load is an important basis for understanding the stress and deformation of each component of the track structure and performing track structure design,track strength check,maintenance and repair.In this paper,a vehicle-track coupling dynamics model is established by ANSYS LS-DYNA software.The track quality index(TQI)is used to quantitatively characterize the track quality status.The effects of vehicle speed,fastener stiffness,wheel set mass,car body mass,and track mass status on the statistical characteristics of wheel and rail forces is analyzed;the wheel-rail impact force caused by the wheels flat of the maximum length allowed by the current vehicle maintenance and repair regulations in China is caculated;the wheel-rail force statistical characteristic value of different grade railways under different track quality conditions is calculated.Based on the field test values of wheel and rail forces,the regression analysis method is used to study the changes of the field test values of the wheel and rail dynamic loads of the high-speed railway and passenger and freight railways along with the vehicle speed.By comparing and analyzing the field test values of wheel-rail force and the calculated values of simulation,the vertical dynamic load of wheelrail is finally determined.The following main conclusions are drawn:(1)The distribution range of wheel-rail force is positively correlated with vehicle speed,fastener stiffness,unsprung mass,and sprung mass;the average value of wheel-rail force hardly changes with vehicle speed and fastener stiffness,there are great changes with the unsprung mass and the sprung mass,but the amount of change is almost the same as the amount of change of the static weight;the standard deviation of wheel-rail force is positively related to vehicle speed,fastener stiffness,and unsprung mass,and hardly changes with the change of sprung mass;dynamic coefficient is positively correlated with vehicle speed and fastener Stiffness and unsprung mass,but slightly decrease as the sprung mass increases.As the track quality state deteriorates,the wheel-rail force distribution range increases,the average value is almost unchanged,the standard deviation increases,and the dynamic coefficient increases.(2)The decay rate of the wheel-rail impact force caused by the wheels flat slows down with the increase of P1 force.Under the excitation of the new flat scars,the CRH2 EMU have a maximum dynamic load coefficient of 2.95 at a speed of 100km/h;the 23 t axis heavy electric locomotive,under the excitation of new flat scars,has a maximum dynamic load coefficient of 3.66 at a speed of 160km/h.(3)The field test values of wheel and rail force on the ground have a large dispersion,and not all wheel and rail dynamic loads increase with the increase of vehicle speed.So the wheel and rail force measured by the ground test method is used to calculate the wheel weight reduction rate,Derailment coefficient and other parameters,and then to evaluate the overall safety of the track is not reasonable,the wheel-rail dynamic force measured by measuring wheel method is used to calculate the wheel weight reduction rate is advised.(4)The recommended speed coefficients of the high-speed railway,inter-city railway and passenger-cargo railway under different track quality conditions obtained in this paper can provide a certain reference for the strength check of high-speed railway,intercity railway and passenger-cargo railway in China;The recommended values of dynamic load coefficients of high-speed railway,intercity railway and passenger-cargo railway obtained in this paper can provide a certain reference for the design of track structure of high-speed railway,intercity railway and passenger-cargo railway in China.