Railway Dynamics and Wheel-Rail Contact. Simulations and Testing for Running Dynamics Behaviour Assessment

The aim of railway vehicle dynamics simulations is to optimize the vehicle and subsystems design (focus on bogie design) in order to fulfill the performances requested by the standards referred to (running dynamics safety criteria) and by other specific customer requirements related to the train acceptance (ride comfort, track damage, etc.). The simulations support the engineering process, starting with the concept study through the tender phase, preliminary and detailed engineering design and ending with the qualification and acceptance process. When allowed by the standard, the simulations are used also for virtual homologation, subject to validation of the model through tests. The simulations are frequently used also to support trouble-shooting in service and sometimes to support the design retrofit. With the advent of the extensive use of condition base monitoring (CBM), health monitoring and bogie monitoring systems (derailment detector, etc.), the simulations are the first step of the analysis to be done in order to define the high level specification of such systems, i.e. the specification of type of sensors and their placement on the train, the signal processing to be used, etc.

Concluding, the support of railway dynamics department is necessary during whole phases of the project, starting from the bid and ending with the follow-up in revenue service, as a relevant decision-making contributor through all project phases and as a support for testing and virtual homologation.

The methods, tools and processes used for vehicle dynamics simulations, the input data necessary to obtain reliable simulations, the tasks and simulations carried out, the output and the assessment quantities and the return on experience, are the content of the first section.

The second section provides an overview of standards and methods used for testing and assessment of the vehicle dynamics performances, i.e. for running behavior (running safety, ride quality and track loading) and for the ride comfort. The understanding of testing methods, instrumentation used and signal processing methods is essential also for the validation of simulation models. In some cases, such as the assessment of the crosswind stability or when the extension of the homologation via simulations is allowed, the validated models are used for the virtual homologation. Finally, the conditions and perspectives for virtual homologation in railway dynamics will be discussed.