حديث نصيري

This research investigates the effect of different geometries of railway transition curves on passenger ride comfort through dynamic simulation an‎d numerical analysis. A dynamic model of a passenger rail vehicle consisting of two bogies an‎d four wheelsets was developed using SIMPACK. The track layout includes straight sections, circular curves, an‎d transition curves. Simulations were carried out at various radii an‎d speeds for four types of transition curves: Clothoid (Clo), Bloss (Blo), Sinusoidal (Sin), an‎d Cosine (Cos). The output data, including vertical an‎d lateral accelerations of the first wheelset an‎d the car body, as well as vertical an‎d lateral forces on the left an‎d right wheels, were extracted an‎d analyzed using MATLAB. The Sperling’s Ride Comfort Index (Wz) was computed based on the absolute acceleration of the vehicle body. Results show that at smaller radii (e.g., R = 250 m), significant differences are observed between the transition curve types. For instance, at R = 250 m, the Clothoid curve achieved Wz = 6.1160, showing an improvement of approximately 1.99% compared to the worst-case Sinusoidal curve (Wz = 6.2380). As the curve radius increases, the absolute Wz value decreases for all curve types, an‎d the differences between them become negligible — less than 0.02% at R = 2000 m. Similarly, with increasing speed, the difference in ride comfort among the curves reduces to around 0.67%, indicating that all transition curves offer nearly similar performance at higher speeds. This behavior highlights that the type of transition curve has a more significant effect in sharp curves, an‎d precise selec‎tion is crucial for small-radius alignments. The novelty of this research lies in the full dynamic modeling using SIMPACK, the comprehensive analysis of a wide range of speeds an‎d curve radii, an‎d detailed ride comfort eva‎luation, while most previous studies were limited to a single speed an‎d radius. The results were validated against data from the study by MirMohammad Sadeghi et al., showing good agreement.

قوس پيوندي، راحتي سفر، شتاب مطلق، شبيه‌سازي ديناميكي، شاخص اسپرلينگ، SIMPACK، خطوط ريلي

Transition curve, Ride comfort, Absolute acceleration, Dynamic simulation, Sperling index, SIMPACK, Railway track geometry

Hadis Nasiri

Dr Seyyed Javad Mir Mohammad Sadeghi,DrHamid Reza Heydari Noghabi