In this paper, a very efficient risk assessment procedure for crosswind stability analysis of ground vehicles has been introduced. It is based on (1) a random variable gust model derived from level crossing theory of Gaussian processes; (2) a constrained simulation technique that allows us to focus on extreme wind events; (3) variance reducing Monte Carlo simulation techniques such as subset simulation and LS and analytical methods such as FORM in order to evaluate the failure probability efficiently; (4) the Poisson process approximation in order to compute failure probabilities on time intervals or track sections. The developed procedure is an interesting alternative to the stochastic simulation approach proposed in Appendix G of [Railway applications aerodynamics, part 6; requirements and test procedures for cross wind assesment, CEN/TC 256, European Norm, 2008]. Besides risk assessment, the procedure allows us to discuss many important aspects of vehicles under crosswind influence. Especially, in this paper the importance of turbulent fluctuations, track irregularities and the friction coefficient between wheel and road has been clarified. It has been shown that for vehicles on wet roads and low mean wind speeds, lateral deviation leads to failure, while for higher mean wind speeds, the whole vehicle rolls over. Moreover, local and global parameter sensitivity studies are possible. The proposed procedure relies on a decomposition of the wind process into a low frequency part (the random gust model) and a high frequency part (the turbulence). Besides this, the transfer of the wind velocity into loads on the vehicle can be modelled with more or less details, for example, by considering also fluctuations of the resulting angle betaw. It is still an open question how this would affect the probability of failure. The simulations in this paper were restricted to straight tracks. However, the extension to curved tracks does not lead to additional difficulties. The method offers the possibility of computing failure probabilities for specific connections. If these failure probabilities are related to probabilities of having an accident with a given severity, a comparison with other risks becomes possible. It seems also to be possible to extend the method to bicycles and motorbikes on wind-exposed terrain. Also, the influence of crosswind on pantograph detachments can be investigated by means of the proposed procedure.
A probabilistic approach for assessing the crosswind stability of ground vehicles
Ein probabilistisches Verfahren zur Bewertung der Seitenwindstabilität von Bodenfahrzeugen
2010
18 Seiten, 21 Bilder, 1 Tabelle, 35 Quellen
Aufsatz (Konferenz)
Englisch
Anwendung im Fahrzeugbau , CEN (Kommission Europäische Norm) , Seitenwind , Eisenbahnfahrzeug , Kraftfahrzeug , Querstabilität , Monte-Carlo-Simulation , Fahrzeugdynamik , Risikobewertung , Empfindlichkeitsanalyse , Wahrscheinlichkeitsrechnung , Rechnersimulation , Reibbeiwert , Fahrbahnkraftschluss , Bodenhaftung , Fahrbahngriffigkeit , Windgeschwindigkeit , Fahrzeugsicherheit , Fahrzeugaerodynamik , Seitenwindverhalten , Seitenstabilität
A probabilistic approach for assessing the crosswind stability of ground vehicles
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