Study on the Irregularity under Urban Railway Vehicle Passing through a Frog

Irregularity of the fixed frog affects the passage velocity and the comfort of urban railway vehicles. To reveal this irregularity, based on the Finite Element Method (FEM) computational models were set up. The models included the contact between the worn tread wheel of Dalian tram and the 50kg/m rail as well as the different sections of No. 9 fixed frog. The results were used to find the laws of the contact states, the equivalent stress of the frog and the laws of the irregularity under the vehicles passing straightly through it. The results show the biggest value of the irregularity is located near the trip of the point rail. The elastic deformation of the wheel and frog doesn´t produce a deeply effect on the regularity in crossing zone. The equivalent stress in the contact area of frog is so great that it goes far beyond the yield limit, which would lead to the serious wear of the wheel and frog. The theoretical basis is provided for the rational design of structures and the profiles optimization of turnouts.