Load assumptions and strength analysis of tramway track components

Customer: Würzburger Straßenbahn GmbH, KÜNSTLER Bahntechnik GmbH, Germany

Project tasks

• Clarification of the intended track layout, speed restrictions and wheel/rail profile conditions
• Setup of appropriate multi body system (MBS) models of the tracks including the cross-sections of the switch blades as well as three types of existing tram vehicles
• Conduction of a variation of MBS simulation runs and extraction of loads acting on track components like e.g. rails, switch tongues; setup of related load assumptions
• Setup of a finite element model (FEM) e.g. of the switch tongues and the surrounding structure
• Fatigue strength assessment of the track component while applying the loads as gained from the MBS simulations
• Proposals of design improvements regarding the strength
• Meter gauge tram application
• Tracks including deep grooved switches

Our Approach

Running dynamics simulations have been performed to determine the wheel/rail loads, which are acting on the related track components. The specific conditions of WSB have been considered while conducting multi body system (MBS) simulations for all three types of vehicles in all relevant directions of travel through the triangular joint “Sanderring” as well as the tracks in front of the central railway station. As a result, load assumptions for the track components under assessment (e.g. switch tongues) have been extracted from the MBS simulations. A finite element model (FEM) of the component and the surrounding structure was set up. The wheel/rail load assumptions as derived from the MBS simulations have been applied to the FEM model. A fatigue assessment was conducted while analyzing the strength amplitude as deriving from the maximum strength. Based on the FEM results, specific design adjustments have been recommended to improve the strength.

Customer benefit

One major benefit is the minimization of the risk e.g. of occurrence of cracks. This is especially important, as new tram vehicles by tendency come along with higher axle loads and are thus more demanding regarding the strength of track components. Another benefit is the reusability of the load assumptions as well as the strength analysis for future tenders of similar track layouts under comparable conditions. Two of the three MBS vehicle models have already been setup in a former project for WSB. Thus, the benefit of reusability without initial modelling efforts was already used in this project.