علي كشكولي

Today, in order to maintain the position of the railway industry in the transportation market, increasing the speed of trains has been considered. Ride comfort is one of the most important criteria for eva‎luating the dynamic performance of a railway vehicle. Vibrations an‎d accelerations to the train under the influence of various factors play a very important role in this area. The braking process is one of the important factors that affects the longitudinal dynamics of the train an‎d track. One of the issues that has been addressed very little in previous research is the effect of the braking process on train ride comfort indicators. Since this issue has not been studied under the influence of various parameters an‎d also for high speeds; therefore, in this research, we try to investigate the aforementioned research gap by applying light braking to a railway passenger car. Among the parameters that have been examined in this thesis; The initial speeds, braking force, track irregularity amplitude at different intensities, an‎d vertical damping ratios of primary an‎d secondary suspension systems can be mentioned. The Sperling index (Wz) was also used to eva‎luate the ride comfort. The numerical simulation of the wagon an‎d track was carried out using a software based on multibody dynamics an‎d in the Universal Mechanism (UM) software. The validity of the dynamic model developed in this study was also examined with the dynamic model of Dhanasekar (2011). The results showed that by applying light braking forces with a constant an‎d uniform magnitude, the comfort in the vertical direction at speeds of 150 to 175 km/h an‎d above, compared to the no-braking condition, is significantly reduced, which is exacerbated by increasing the irregularity intensity. For example, in conditions with soft irregularity an‎d at a speed of 250 km/h, comfort decreased by 35.4% an‎d for conditions with moderate irregularity by 36%. In addition, the best damping ratio of the secondary suspension system in unbraked conditions for speeds of 150 km/h an‎d above was 0.06. Also, at high speeds an‎d for braking conditions, the best damping ratio of the secondary suspension system increased slightly with increasing braking force. In addition, changes in the damping ratios of the primary suspension system in both unbraked an‎d braked conditions had a smaller effect than the secondary suspension system on the values of the ride comfort index.

راحتي سفر , ترمزگيري , شاخص اسپرلينگ , الگو‌سازي , شتاب‌هاي بدنه واگن

Ride comfort , Braking , Sperling index , Modeling , Wagon body accelerations

Ali Kashkoli

Saeed Reza Massah