Efficient models and techniques for the computational analysis of railway vehicles in crosswinds

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Efficient models and techniques for the computational analysis of railway vehicles in crosswinds

Carrarini, Antonio

Nowadays, crosswind stability is a key topic for the homologation of railway vehicles and thus it is a pivotal boundary condition in their design process. In most countries, the safety proof is based on the numerical multibody simulation of the driving behaviour of the vehicle assuming a worst case wind scenario. The conservativeness of this approach is aggravated by the uncertainties in the parameters of the simulation models. In this work, some possible improvement of the safety proof are discussed mainly concerning the computational model of the vehicle. An alternative approach based on reliability techniques is then presented and discussed, leading to a more efficient assessment of the risk, and thus to a reduction of the safety factors. The analysis of the crosswind stability of railway vehicles can be extended and made more efficient and accurate by dedicated computational model and enhanced analysis techniques. Simpler vehicle models than the conventional full multibody ones allow the computational effort to be reduced and possibly stochastic wind scenarios instead of deterministic ideal gusts to be used. In this respect, automatic linearisation of the multibody model seems to be practicable and convenient. A dramatic increase m the accuracy and plausibility of the risk assessment can be reached by the introduction of reliability techniques. Such techniques allow the consideration of the well known but still poorly documented uncertainties in the aerodynamic models. The computational effort is increased but as the risk analysis has to be performed only once in the life of a vehicle, this can be accepted.