Elastic-Plastic Analysis on the Contact of Wagon Wheels and Heavy Haul Frogs

The phenomenon of spallings on the frog used in the heavy haul railway occurs easily, which reduced the service life of frog. The worn profiles of No.12 unmovable frog with 75 kg/m rail and wagon wheels used in Datong-Qinhuangdao have been measured. They are used to established an elastic-plastic finite element model to study the contact problem of wheel and frog at different location. The contact patches, the equivalent Von Mises stress and the variation of contact path have been analyzed. The results indicate that the contact patch on the nose rail is near the center line of top surface when the wheel contact with the standard frog and it is on the edge of nose rail when the wheel contact with the worn frog. The equivalent Von Mises stress exceeds the yield limit into the plastic deformation stage. When the wagon passes the standard frog, the wheel contacts with the wing rail, then transits to the nose rail gradually. However, when the wheel runs over the worn frog, the contact point shifts from wing rail to nose rail and then moves to the wing rail again. The contact status of wheel and frog changes between one point contact and two point contact, which causes the variation of equivalent Von Mises stress of the wing and nose rail. Besides, the wheel displacement has a great effect on the equivalent Von Mises stress and therefore it should be taken into consideration when designing the match of wheel and frog. The research provides a theoretical basis for the design of wheel and frog profiles used in the heavy haul railway.