Two different approaches for the computation of the dynamic interaction between the pantographs and railway overhead lines are compared in this paper. On the one hand, a finite element model has been developed and presented. The approach followed by this paper is to map the initial equilibrium configuration obtained using the method proposed in [3] to provide a finite element mesh, using beam elements for contact and messenger wires and truss elements for droppers. On the other hand, a simplified model of the catenary-pantograph interaction based on mass-spring systems, originally presented in [2], is provided. In this model, the catenary is described by equivalent mass, damping and stiffness of a one degree-of-freedom system while the pantograph is considered a two degree-of-freedom lumped system.

The main purpose of this comparison is the analysis of the suitability and limitations of these different methods considering European validation standards as reference criteria. The examination against the European Standard EN50318:2002 [1] reveals another original contribution of this paper, since the scientific literature does not include many validated models. Thus, the dynamic interaction must be carried out at two different train speeds, 250 and 300 km/h. If the results obtained at the two central spans and frequency range of interest were within the limit values set forth in EN50318, the simulation method could be validated.

To summarize, both models presented show quite similar general tendencies of the catenary-pantograph contact forces. However the finite element (FE) model, as well as being more comprehensive and accurate to the real phenomenon, is able to compute the propagation of the contact wave along the contact wire. As it is pointed out in certain results (especially the displacement evolution of the contact wire), wave propagation provides the FE model with a much better simulated behaviour. In fact, the FE model almost fulfils all the EN50318 validation criteria, what probably could be successfully achieved deeping into the numerical methods used for integration. Nevertheless, a CPU time comparison reveals that for fast or massive computations (for example for optimization) wherein very accurate results are not required, the simplified model is suitable.

1

EN50318:2002, "Railway applications. Current collection systems. Validation of simulation of the dynamic interaction between pantograph and overhead contact line", European Standard, 2002.

2

O. Lopez-Garcia, A. Carnicero and J.L. Maroño, "Influence of stiffness and contact modelling on catenary-pantograph system dynamics", Journal of Sound and Vibration, 299, 806-821, 2007. doi:10.1016/j.jsv.2006.07.018

3

A. Carnicero, O. Lopez-Garcia, V. Torres and J.R. Jimenez-Octavio, "An Algorithm Based on the Finite Element Method and the Catenary Equation to Compute the Initial Equilibrium of Railway Overhead", in Proceedings of the Eighth International Conference on Computational Structures Technology, B.H.V. Topping, G. Montero and R. Montenegro, (Editors), Civil-Comp Press, Stirlingshire, United Kingdom, paper 96, 2006. doi:10.4203/ccp.83.96

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