Sharif University of Technology Scientia Iranica 1026-3098 16 6 2009 12 01 New Dynamics Model for Rail Vehicles and Optimizing Air Suspension Parameters Using GA 3135 EN H. Sayyaadi Department of Mechanical Engineering,Sharif University of Technology N. Shokouhi Department of Mechanical Engineering,Sharif University of Technology Journal Article 2010 05 12 In this paper, a complete four axle rail vehicle model with 70 Degrees Of Freedom (DOFs) is addressed, which includes; a carbody, two bogies and four axles. In order to include track irregularity eects on vehicle behavior, a simplied track model for a straight line is proposed. As the performance of the suspension components, especially for air springs, has signicant eects on rail-vehicle dynamics and the ride comfort of passengers, a complete nonlinear thermo-dynamical air spring model which is a combination of two dierent models is introduced and then implemented in the complete rail-vehicle dynamics. By implementing the Presthus formulation [1], the thermo-dynamical parameters of an air spring are estimated and then tuned, based on the experimental data. Eects of air reservoir volume and connecting pipe length and diameter on system performances are investigated. For improving passenger comfort during their trips, air suspension parameters of the modeled rail vehicle are tuned to minimize the Sperling ride comfort index. Results showed that by modication of air suspension parameters, passenger comfort is improved and the ride comfort index is reduced by about 10%. The Genetic Algorithm (GA) optimization method is also used to optimize air suspension parameters. Results showed that improved air suspension congurations are more practical, compared to optimized ones. https://scientiairanica.sharif.edu/article_3135_00f6618e0b3a583481cf484c2ff57e1f.pdf