Investigation of Rail Track Vibration Due to Fractured Sleepers

In this paper, the effects of fractured sleepers on rail track vibration under moving wheelset have been investigated. Two parallel rails of the track have been modeled as Euler-Bernoulli beams mounted on rail pads acting as elastic points. Moreover sleepers have been modeled as visco-elastic Euler-Bernoulli beams. It is assumed that, some sleepers under the rail track have been fractured and modeled by two beams. The wheelset has 5 DOF which are longitudinal, vertical and lateral movements plus roll and axial rotations. To determine normal contact force between the wheel and the rail, relative position of the wheel and the rail has been determined at each instant. Using the coordinate of each wheel point in the rail coordinate system, the penetration of the wheel into the rail has been determined. In order to investigate rail-wheel contact forces, Hertzian nonlinear contact theory and Kalker theory have been applied. A computer program has been developed that numerically solves the equations of motion of the system for different operating conditions using RungeKutta Cash-Karp computation method. Using this model the effects of wheel-set velocity, wagon weight, number of fractured sleepers and fracture location on rail track vibration have been investigated.