Flexible Track Models in Railway Dynamics Using a Finite Element Formulation

The dynamic analysis of railway vehicles involves the construction of three independent models: The vehicle model; the track model; and the wheel-rail contact model. In this paper, a finite element methodology is proposed to create detailed three-dimensional track models, which includes the flexibility of the rails and of the substructure. In this approach, the rails are modelled as beams supported in a discrete manner by spring-damper systems that represent the flexibility of the pads, sleepers, ballast and subgrade. A multibody formulation with Cartesian coordinates is used to describe the kinematic structure of the rigid bodies and joints that constitute the vehicle model. The inclusion of flexible track models is very important to study the dynamic behaviour of railway vehicles in realistic operation scenarios, especially when studying the impact of train operations on the infrastructure and, conversely, the damages on vehicles provoked by the track conditions. This topic has a significant economic impact on the vehicles maintenance and also affects the life cycle costs of tracks. The wheel-rail contact formulation used here allows obtaining, online during the dynamic analysis, the contact points location, even for the most general three-dimensional motion of the wheelsets with respect to the track. The methodology proposed to build flexible track models is validated here by comparing the results obtained with this new approach with those obtained with ANSYS. Furthermore, the methodology is demonstrated by studying the dynamic behaviour of the Alfa Pendular railway vehicle.