Overturning assessment of railway vehicles under cross winds

The overturning issues in a strong wind are extremely critical to the railway vehicles, which have attracted a great deal of attention over the years. To address such problems, this paper introduces a dynamic reliability approach to evaluate the overturning risk of vehicles in crosswinds. Starting from the aerodynamic model, a novel prediction formula of unsteady crosswind forces with a consideration of the complete turbulent field effect is derived. Using the pseudo-excitation method (PEM), the power spectrum of vehicle responses is then calculated by the established vehicle model, and finally the corresponding results are used to assess the probabilistic overturning of vehicles in terms of the dynamic reliability analysis. It is found from the calculations that the time-dependent failure probability curves are related to the vehicle speed, wind speed, and crosswind direction, and the probabilistic characteristic wind curves (PCWCs) at different failure probabilities are more useful and reasonable for evaluating the overturning risk in comparison with the traditional characteristic wind curves (CWCs) in previous investigations. Furthermore, the probabilistic characteristic wind surface (PCWS) that considers the effect of crosswind direction, is developed, and it reveals that the vehicle is most vulnerable at a condition of perpendicular crosswind direction.