Multibody model of railway vehicles with weakly coupled vertical and lateral dynamics

Abstract

In the field of railroad dynamics, multibody models used for on-board state observation, parameter identification and track geometry measurement must ensure a high computational efficiency, particularly when real-time simulations are required. In this paper, a simplified model based on the assumption of weakly coupled lateral and vertical dynamics is proposed. Generalized forces included in the equations of motion are obtained using symbolic computations and the wheel-rail contact is modeled using knife-edge contact constraints and the concept of equivalent conicity. Resulting contact constraint equations can be solved analytically allowing the solution of ODE equations of motion in terms of independent coordinates. This general model considers arbitrary-geometry tracks including rail centerline irregularities. With the aim of showing the accuracy of the proposed model for the simulation of railways vehicle dynamics, a comparative study with a full 3D coupled dynamic model has been carried out for different vehicles and track geometries. The comparative study shows that the proposed simplified model in this work provides acceptable results for many applications. The model greatly improves the computational effort and it is applicable to real-life situations requiring a reduced set of parameters