Validation of three-dimensional multi-body system approach for modelling track flexibility

Abstract

The objective of this investigation is to examine the results and demonstrate the validity of a proposed multi-body railroad vehicle system formulation that accounts for the dynamic coupling between three-dimensional (3D) contact parameters and the rail structural flexibility. This formulation allows building complex track models that include significant details at a finite-element preprocessing stage. The data of the detailed track model can be used as an input to a general purpose flexible multi-body computer program for a non-linear analysis that accounts for the dynamic coupling between the track flexibility, 3D wheel—rail contact, and the vehicle dynamics. The simulations are performed using the methods of multi-body system dynamics that employ 3D wheel—rail contact methodology capable of finding the wheel—rail contact points online. The effect of the structural flexibility of the rails is included in the equations of motion using the finite-element floating frame of reference formulation. While this formulation allows for an arbitrary reference displacement for the track, this reference displacement is constrained in order to be able to compare the results with those results obtained using simplified approaches. The results obtained by applying the proposed multi-body system/finite-element formulation to a simple railroad vehicle travelling on a deformable tangent track are compared with the results of a moving load on a Winkler foundation. In addition to the simple moving load model used, a second model that accounts for the effect of the vehicle inertia is also used in this study. The comparative study presented in this article shows a good agreement between the results obtained using the two different methods. Furthermore, the results obtained in the case of a flexible track are compared with the results obtained using a rigid track in order to examine the effect of the track structural flexibility on the non-linear dynamics of the rail system.