Finite element model of wheel – Rail impact due to flat spot

Abstract

Mechanics of wheel-rail interaction is one of the most important research topics in railway engineering. It helps in determining the wheel impact response, track vibration, and track safety. Recently, Dedicate Freight Corridor Corporation of Indian Ltd. (DFCCIL) has started laying out the Dedicated Freight Corridor (DFC), which has made it possible for the freight car axles to carry higher loads and travel at higher speeds than previously possible. It leads to high contact stress on the rail-wheel interface. Under these loads, any defect in the wheel structure leads to wheel-rail impact forces that can lead to significant losses for track owners through damage to rails and sleepers beneath. These imperfections can be wheel flats, irregular wheel profiles, rail corrugations, and differences in the heights of rails connected at a welded joint. Wheel-flats form due to unintentional locking of the wheel-set during emergency braking, which leads to the sliding of the wheel. It leads to the formation of a chord on the circumference of the wheel. A wheel flat can cause a sizeable dynamic impact force, as high as four times higher than regular wheels, and produce high-frequency vibrations, which can damage the track structure. Finite Element Method is an excellent tool for analysing contact stresses between complex geometries in wheel-rail interactions. In this paper, wheel-rail interaction dynamics for a flat wheel is modelled through a three-dimensional finite element (FE) method using Finite Element Analysis (FEA) software package ANSYS. Models used in the simulation are generated according to the Indian Railways standard. The impact force was studied thoroughly, to find the evolution of the contact patch of the wheel rail interface and effect of the impact force in the cross section of the wheel.