Tolerable longitudinal forces for freight trains in tight S-curves using three-dimensional multi-body simulations

Abstract

With the need for increasing length of freight trains, the longitudinal train dynamics and its influence on the running safety become a key issue. Longitudinal train dynamics is a complex issue with contributions from both the vehicle and the operating conditions such as infrastructure design, braking regimes, etc. Standards such as the UIC Code 530-2 and EN-15839 detail the procedure for on-track propelling tests that should be conducted to determine the running safety of a single wagon. Also, it only considers a single S-curve and specifies neighbouring wagons and buffers. Hence, the resulting longitudinal train dynamics would not be able to judge the effects of various heterogeneities in the train formation such as the adjacent wagons, buffer types, carbody torsional stiffnesses, curvatures, etc. Here, there is a potential of using three-dimensional multi-body simulations to develop a methodology to judge the running safety of a train with regard to its longitudinal dynamic behaviour, subjected to various heterogeneities. In this study, a tool based on three-dimensional multi-body simulations has been developed to provide longitudinal compressive force limits and tolerable longitudinal compressive force for wagon combinations passing through S-curves of varying curvatures, and the sensitivities of the various heterogeneities present in the train are assessed. The methodology is applied to open wagons of the ‘Falns’ type on tight S-curves by calculating the corresponding tolerable longitudinal compressive force, and the effect of various parameters on the same is discussed.

An integrated numerical framework to investigate the running safety of overlong freight trains

“…A detailed description of the modeling procedure, methodology, and the critical heterogeneities that influence the derailment risk of a wagon due to additional lateral forces when it passes through infrastructure bottlenecks such as flat S-curves was discussed by Krishna et al. 15…”

“…Therefore, a smaller three-wagon train with static LCF applied on either ends is simulated in the 3D simulation tool. The tool was introduced and applied for coal wagons of the wagon class Falns by Krishna et al 15 The two force quantities would help judge the safety of the long freight train operation. However, it is not possible to account all possible combinations of trains and track infrastructure points as will be seen in the next subsection.…”

“…17 The calculation of the tolerable LCF, however, considers a three-wagon train, inspired by the UIC 530-based simulation methodology developed in a previous study. 15 The methodology focuses on heterogeneities from a more local inter-wagon interaction level as illustrated by Figure 2. The previous study identified the high influence of carbody torsional stiffness, horizontal track curvatures, loading patterns, and wagon arrangements on the tolerable LCF.…”

“…The 3D MBS tool for the calculation of tolerable LCF values was developed by KTH in the GENSYS 18 environment. A detailed description of the modeling procedure, methodology, and the critical heterogeneities that influence the derailment risk of a wagon due to additional lateral forces when it passes through infrastructure bottlenecks such as flat S-curves was discussed by Krishna et al 15 The simulation methodology to calculate tolerable LCF draws inspiration from the UIC 530-2 and the EN 15839 based on-track propelling tests. The empty test wagon is surrounded by two loaded barrier wagons, resulting in a height difference between the side-buffers.…”

Methodology to Admit New Freight Trains to International Traffic According to the Uic

“…The experimental tests according the UIC Leaflet 530-2, see also [22], are the starting point for the determination of the permissible LCF, even if it is possible to compute permissible values by means of trusted computer packages or by means of extrapolations as in [21].…”