Keywords: virtual homologation, pantograph-catenary dynamics, standards, uncertainty, homologation map, frequency band analysis, multiple units.

This paper addresses the use of numerical simulations to extend the physical pantograph homologation to virtual processes. Until today, the evolution of the railway system, especially the pantograph or overhead contact line (OCL), followed an empirical process based on prototypes tested in commercial operating conditions. This method is costly, time consuming and becomes inconsistent with the increase of the traffic load and with cross-border operation encouraged by free competition.

Numerical simulation can significantly reduce the number of iterative design tests by predicting accurately the system behaviour. The work described in this paper arise from European partners discussions during the PantoTRAIN project, about scientific and numerical developments based on current computing technologies and railway standards for certification purposes. This challenging project aims at cutting global costs and duration of a pantograph catenary couple homologation by developing a virtual homologation procedure.

All results presented in this paper were performed using OSCAR©, the SNCF's software, a fully three-dimensional finite element software that can model any kind of catenary system (classical and high speed lines). It takes into account all non-linearities present in the system: bump stops, friction elements in the pantograph; and non-linear droppers in the catenary; contact losses at the interface.

The methodology presented here aims to guarantee full confidence in the virtual homologation procedure and at ease the final homologation decision. This procedure, partially described in this paper, consists of three steps. The first step of the procedure, called "validation", consists in assessing that both the software and the numerical models are accurate enough to reproduce the real system behaviour with respect to the requirements of current European standards. An enhanced validation tool called frequency bands analysis (FBA) to improve the pertinence of current indicators is proposed and described. The second step "modification" intends to assess minor changes mandatory to adapt design characteristics of pantographs to the gauge imposed by the network or by the national rules. The third step "extension" has the aim of building a new pantograph or overhead line couple by merging ones previously validated and by assessing numerically the homologation criteria in order to virtually homologate the current collection quality.

To obtain the maximum of confidence, several kinds of irregularities are applied to the numerical models such as contact wire height or aerodynamic forces. Their impact on spectral components is studied highlighting the different operating conditions that can be encountered considering realistic maintenance tolerances and physical variability. To obtain more simplicity and to help the final homologation decision, a new mapping tool based on current standards criteria is detailed with its associated acceptance criterion. The methodology is finally applied to single and multiple unit(s) to demonstrate the advantages of the numerical tool in terms of understanding, assessment, optimisation and homologation of the complex pantograph-catenary dynamic behaviour.

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