Rail vehicle design optimization for operation in a mountainous railway track

The use of reliable computational tools and of validated vehicle and track models allow studying the railway vehicle performance in realistic operation conditions. The use of such advanced tools permits performing the so-called virtual homologation, which means that most of the criteria defined in the standards and regulations for vehicle acceptance can be verified numerically. This approach reduces the need of the expensive and long on-track tests, and also permits performing design optimization of several vehicle components, namely, the suspension elements, to improve its operational performance in terms of running safety, ride quality and track loading. The realism of the numerical simulations depends strongly on the model assumptions. In this work, all the mechanical elements that compose the rail vehicle are modeled properly using advanced methodologies. Then, a realistic and fully three-dimensional track, containing the measured track irregularities, is used. Finally, for a realistic running representation of the vehicle in the track, a prescribed motion of the motor wheel sets is adopted to adjust the vehicle speed as function of the track characteristics, namely, its curvature, cant angle and grade. The aim of this research is to develop a methodology to optimize the design of a rail vehicle in a mountainous track based on virtual homologation procedure. For this purpose, an optimization method is used to run the numerical simulations in batch mode and the dynamic performance of the rail vehicle is quantified based on the safety and ride quality indices defined in the standards. In addition, the optimization procedure uses a penalty term that penalizes cases where the vehicle presents an unacceptable dynamic behavior. The design variables considered are the suspension characteristics. This work provides an optimal design tool for the rail vehicle performance that leads to optimal dynamic performance in terms of running safety and ride quality.