Effect of the Uncorrelated Profile of Rails on Train-Track-Ground Induced Vibrations

Abstract

In predicting the track-ground vibrations induced by moving trains, it is generally assumed that the irregularities of two rails of a track are identical and fully correlated. This assumption leads to identical contact forces at the contact point of wheels and rails. In the present paper, the uncorrelated profile of the two rails is considered to investigate their influence on the train-track-ground vibrations. For this purpose, a three-dimensional (3D) finite element model capable of simulating interactions between a 3D train and track by using a nonlinear Hertz contact method is developed. Nonlinear Hertz contact is represented by the tensionless stiffness between the wheels and rails. The rails are modeled as 3D Euler-Bernoulli beam elements. Solid brick elements represent the model components, such as the track (other than rail) and ground. A detailed description of an iterative numerical algorithm is presented to establish the integrations of the train and track system. This iterative numerical algorithm can calculate the responses and forces at the interaction point between each wheel and rail to incorporate the uncorrelated profile of two rails, instead of only considering the interaction at the centroid of the wheelset axle and the center of the track. A comparative study is conducted by considering various train speeds and three different track cases. The results show that an increase in train speed causes an increase in ground vibration in the case of uncorrelated profiles of two rails of a track. Moreover, the effects of correlated and uncorrelated profiles of two rails of a track are investigated in terms of the train-track-ground responses.