Keywords: railway dynamics, variability, stochastic, virtual certification.

The track-vehicle system contains several sources of variability: variability of the mechanical parameters of a train among a class of vehicles (mass, stiffness and damping of different suspensions), variability of the contact parameters (friction coefficient, wheel and rail profiles) and variability of the track design and quality. This variability plays an important role on the security, on the ride quality, and thus on the certification criteria. When using the simulation for certification purposes, it seems therefore crucial to take into account the variability of the different inputs.

A method to take into account the inputs' variability in the railway dynamic modelling is proposed: the first step is to characterize and to model the input variability. The track-vehicle system being very non-linear, the mean value and the deviation of the outputs cannot be computed directly: the variability has to be propagated through the model. The second step is therefore to generate samples of the input vectors for which the deterministic simulations will be raised. Finally an analysis of the stochastic content is achieved.

This methodology is applied to the analysis of the variability of the contact. The wheel and rail profiles are fully parameterized based on analytical functions. A set of measured profiles are rebuilt and the parameters distributions and dependencies determined. The input characteristics are propagated through the deterministic multi-body model and the stochastic content of the certification criteria are analysed.

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