Ahmed Shabana

Biography:

Ahmed Shabana is the Richard and Loan Hill Professor of Engineering and a University Distinguished Professor in the Mechanical and Industrial Engineering Department at the University of Illinois at Chicago. He received his B.Sc. degree from Cairo University in 1974, his M.Sc. degree from Ain Shams University (Egypt) in 1978, and his Ph.D. degree from the University of Iowa in 1982. He is internationally known for his research contributions in the areas of large-scale computations as applied to dynamic systems, specifically multi-body systems such as vehicles, machines, and robots. He has been conducting research in railroad vehicle dynamics for 10 years with support from the Federal Railroad Administration. Dr. Shabana has published more than 130 papers, presentations and technical reports, and is the author of four books including his most recent entitled, "Railroad Vehicle Dynamics; A Computational Approach". He received an Honorary Doctorate Degree from the Lappeenranta University of Technology in Finland in 2004, was recognized as a Fellow of the Association of Mechanical Engineers in 1996, received a Fulbright Scholar Award in 1997 and a Humboldt Prize in 1995.

He teaches courses on Multi-Body Dynamics and Computer Analysis and received the UIC Award for Excellence in Teaching. He has supervised 30 Ph.D. students, 30 M.S. students and 25 visiting scholars and postdoctoral fellows. Dr. Shabana has served on the editorial Boards of the Journal of Multibody System Dynamics, Journal of Nonlinear Dynamics, Journal of Sound and Vibration, IMECHE Journal of Multibody Dynamics, ASME Journal of Mechanical Design, ASME Journal of Computational and Nonlinear Dynamics and the Journal of the Franklin Institute.

Abstract:

The integration of finite element (FE) and multibody system (MBS) algorithms is necessary for accurate modeling of railroad vehicle systems. This presentation discusses how such integration can be used to develop computational methods for the computer simulation and virtual prototyping of complex railroad vehicle systems. The three-dimensional formulations that can be used to predict online the locations of the wheel/rail contact points are first discussed in order to explain the need for accurate geometry description. It is explained how the normal wheel/rail contact forces can be determined and used to determine the creep tangential forces. The contact formulations employ fully nonlinear creepage expressions that account for the rail movements and deformations. Flexible body modeling capabilities are necessary in many railroad vehicle simulation scenarios. The floating frame of reference (FFR) and the absolute nodal coordinate (ANCF) formulations that can be used in the deformation and geometry analysis of railroad vehicle systems are implemented in a general purpose computer program that allows for modeling tracks with complex geometry as well as rail, tank car, pantograph/catenary system flexibility. The MBS numerical procedures developed in this study ensure that the constraint equations are satisfied at the position, velocity, and acceleration levels. The sparse matrix implementation of the nonlinear equations of motion will be discussed, and numerical examples presented in order to demonstrate this computer implementation.

Finite Element/Multibody System Algorithms for Railroad Vehicle System Dynamics

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