Guest Editorial

Railroad Vehicle Dynamics—A Roadmap to High Speed Trains PUBLIC ACCESS

[+] Author and Article Information
José L. Escalona, Tae-Won Park, Khaled E. Zaazaa

J. Comput. Nonlinear Dynam 7(4), 040301 (Aug 10, 2012) (1 page) doi: History: Published August 10, 2012; Online August 10, 2012

In densely populated areas, the railway transportation is a realistic alternative to airway transportation for long distances. Traveling by train is fast, safe, comfortable, and environmentally friendly. Moreover, passengers have come to prefer the train, as these four qualities have further improved. Mathematical modeling, dynamic analysis, and computer simulation play an essential role in railway design, analysis, and performance evaluation. This Special Issue of the Journal of Computational and Nonlinear Dynamics includes the most recent research and advancements in the field of railroad vehicle system dynamics.

Some derailment criteria that remain relevant in the mechanical design and analysis of the railway system need to be reevaluated using more comprehensive nonlinear approaches and more sophisticated computer software that do not employ simplifying assumptions. This scientific evaluation allows for better understanding the range of applicability and limitations of these criteria. For example, for many years, Nadal’s formula has been used as the basis for derailment criteria, while the equivalent conicity concept has been used as a valid parameter for the lateral dynamics of railway vehicles. The simplicity and the practical experience with these methods are undoubtedly positive features, which can be overlooked by the scientific research community. Modern techniques in modeling and simulation of railway vehicles can accurately reproduce their dynamics, resulting in to the abandonment of certain methods or, on the contrary, providing a scientific basis for what has been experimentally validated.

Railway vehicle modeling and simulation are vibrant research areas in the computational and nonlinear field. All international conferences in multibody dynamics now include symposia or sessions specifically devoted to railways. Multibody formulations and algorithms developed for the dynamic analysis of constrained mechanical systems are not directly applicable to railway vehicle systems. In modeling such systems, one must address the two important issues of geometry and wheel/rail contact. Rolling contact between wheels and rails requires specific treatment for the calculation of normal and tangential contact forces as well as for the accurate prediction of the location of contact points. The modeling of the track geometry in multibody system (MBS) algorithms requires a special description that is not normally covered by the standard MBS kinematic equations. The length and complex geometry of the track structure require the use of specially designed preprocessors. Such a predefined geometric description has a significant effect when the rail flexibility is considered. Furthermore, the motion description of other components of the railway vehicle may require the use of additional coordinate systems such as trajectory frames that facilitate the analysis and allow for conveniently defining specified motion trajectories.

The study of railway dynamics has led to interesting research issues in the area of nonlinear dynamics. The lateral stability of the railway vehicle dynamic system requires eigenvalue analysis when using simple models. However, detailed MBS models transform the analysis of hunting motion in the search of periodic orbits, which are no longer unstable. Continuation techniques developed in nonlinear dynamics may fail when dealing with railway systems due to its complexity and non-smoothness. While developing more appropriate nonlinear dynamics methods, the more comprehensive kinetic approach based on nonlinear numerical simulations is sometimes preferred.

These interesting dynamic problems are addressed in this special issue. To this end, we have selected papers from active and internationally recognized researchers in computational and nonlinear dynamics of railway vehicles. We would like to thank all authors and reviewers who contributed to this special issue. Thanks also to Ms. Tara Smith for her excellent work in the professional production of this special issue. Special thanks are due to Dr. Ahmed Shabana for his patient and continuous support during the edition of this special issue.

Copyright © 2012 by American Society of Mechanical Engineers
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