Sharma et al. 2015. Int. J. Vehicle Structures & Systems, 7(1), 1-9 International Journal of Vehicle Structures & Systems Available online at www.maftree.org/eja ISSN: 0975-3060 (Print), 0975-3540 (Online) doi: 10.4273/ijvss.7.1.01 © 2015. MechAero Foundation for Technical Research & Education Excellence 1 Challenges in Rail Vehicle-Track Modeling and Simulation Sunil Kumar Sharma a , Rakesh Chandmal Sharma b , Anil Kumar c and Srihari Palli d a Centre for Transportation Systems, Indian Institute of Technology Roorkee, India Email: sunilsharmaiitr@gmail.com b Mech. Engg. Dept., Maharishi Markandeshwar University, Mullana, India Corresponding Author, Email: drrcsharma@mmumullana.org c Mech. Engg. Dept., Indian Institute of Technology Roorkee, India Email: kumara.iitr@gmail.com d Mech. Engg. Dept., Aditya Institute of Technology and Management, Tekkali, India Email: srihari.palli@gmail.com ABSTRACT: Rail vehicle-track modeling and simulations, in past many years is developed a long way from its origins as a research tool. This paper presents an overview of the current features and applications for components of rail vehicle-track dynamic modeling and few challenges which these applications find while doing the simulations. This paper discusses appropriate modeling choices for different applications and analyse the best practice for the optimum performance of suspension components, wheel-rail contact conditions and modeling inputs such as track geometry. KEYWORDS: Vehicle dynamics; Modeling and simulation; Rail vehicle; Suspension components; Track models CITATION: S.K. Sharma, R.C. Sharma, A. Kumar and S. Palli. 2015. Challenges in Rail Vehicle-Track Modeling and Simulation, Int. J. Vehicle Structures & Systems, 7(1), 1-9. doi:10.4273/ijvss.7.1.01. 1. Introduction Railway vehicle running along a track is one of the most complex dynamical systems in engineering. It has many degrees of freedom and the study of rail vehicle dynamics is a difficult task. The interface between the surfaces is established at contact points between the wheels and rail surface, therefore the vehicle/track physical, geometric and mechanical parameters greatly influence the vehicle dynamic behaviour [46]. Most modern passenger-carrying railway vehicles have the configuration shown schematically in Fig. 1. The railway vehicle in general comprises a car body supported by two bogies one at each end. Bolsters are the intermediate members between the car body and each bogie frame and is connected to car body through side bearings. The bogie frame supports the weight of the car body through a secondary suspension located between the car body and the bogie frame. Each bogie usually consists of two wheel axle sets that are connected through the primary suspension to the bogie frame. In addition, the wheels are usually tapered or profiled to provide a self-centering action as the axle traverses the track. In passenger rail vehicles, the bogie frame is quite rigid. The primary and secondary suspensions are designed to achieve good ride quality, safe curve negotiation and good dynamic behaviour on tangent track. The wheel axle sets are connected to the bogie frame by elastic and energy dissipative suspension elements. These elements may include coil springs, air springs, or elastomeric pads. The primary suspension allows the wheel axle sets to move in relation to the bogie frame and helps to reduce the transmission of vibrations to the car body. Hydraulic dampers are generally used in both primary and secondary suspensions. The bogie frame also has an anti-roll bar to minimise the car body roll, especially in curves. Fig. 1: Simplified view of a passenger rail vehicle [5, 6 and 10] A freight rail vehicle is different from a passenger rail vehicle in the following ways:  The bogie frame is relatively less rigid,