Analysis Of High-speed Wheel-rail Transient Rolling Contact In Turnout Frog Area

High speed railway turnout,as the main structure of train transfer line,has a strong impact on it when the train crosses the track at high speed,which seriously affects the service life of the turnout.The high-speed frog area has the most obvious impact because of its more complex geometric structure.In order to adapt to the situation of increasing speed of high-speed rail,it is necessary to explore the change law of wheel-rail transient rolling contact during the wheel transition in the frog zone.In this paper,the research is fixed on static and dynamic wheel/rail contact states while a wheel is over the turnout based on models of wheel with LMA worn surface and the No.18high-speed turnout,and ANSYS / LS-DYNA is used to establish a three-dimensional wheel-rail transient rolling contact finite element model considering the true wheel-rail profile of the frog zone.The model takes into account the elastic-plastic constitutive relation of the material and reflects the wheel-rail rolling contact behavior of the wheel through the frog zone in the real situation in the time domain.The main work and conclusions are as follows:When the wheel crosses the frog zone at a speed of 300 km/h,the wheel load transition begins at 24.2 mm of the top width of the heart rail and completes at 38.2 mm of the top width of the heart rail.The wheel-rail load reduction will occur when the wheel passes through the deflection point of the center line of the wing rail in frog area,and the ratio of the wheel-rail force,contact stress,equal effect force and the area of the wheel-rail contact sliding zone decreases accordingly.The equivalent plastic strain only appears after the top width of 26.2mm of the point rail.The plastic strain gradually increases during the wheel load transition,and reaches a maximum value of 0.0135 when the wheel load transition is completed,but no plastic strain appears in the wing rail.The vertical displacement of the wing rail reaches a maximum of 1.5 mm when the wheel reaches steady rolling,and the displacement of the wing rail decreases after passing the deflection point of the center line of the wing rail.The vertical displacement of the point rail reaches a maximum value of 1.7mm when the wheel load transition is completed.The greater the speed of the wheel crossing,the closer the wheel load transition position on the point rail,the more obvious the impact between the wheel and rail,and the contact stress and plastic strain of the wheel and rail are increased accordingly.The vertical displacement of the point rail and the wing rail decreases with the increase of the bifurcation speed of the wheel,but the difference is not big.When the wheel crosses the turnout at a lower speed,the adhesion performance of the point rail wheel rail is better,which is conducive to reducing the wear and impact of the frog area.The greater the stiffness of the frog fastener system,the later the wheel load transition occurs,but it has little effect on the wheel rail force and contact stress.Comparing the equivalent stress and plastic strain,it is found that when the stiffness of the wing rail and the point rail fastener system is 25 k N/mm and 30 k N/mm,respectively,the wear on the point rail of the vehicle passing through the frog area is the least.The greater the stiffness of the fastener system,the smaller the displacement of the point rail and the wing rail during the wheel load transition in the frog area.When the wheels cross over with different traction coefficients,they have little effect on the wheel-rail vertical force,wheel-rail contact stress,and rail vertical displacement.The wheel-rail longitudinal force,equivalent stress,equivalent plastic strain,the distribution range of plastic strain above 0.01 and the area proportion of the contact spot sliding area on the point rail are all increased due to the increase of the traction coefficient,so the vehicle acceleration bifurcation will aggravate the wear of the rail.