Long-term rail profile damage in a railway crossing: Field measurements and numerical simulations

Railway crossings are subjected to a severe load environment leading to a degradation of rail profiles due to wear and accumulated plastic deformation. This damage is the result of the high magnitudes of contact pressure and traction generated in the wheel–rail contact during each wheel transition between wing rail and crossing nose. An extensive measurement campaign has been carried out at a test site in Austria in a particularly severely loaded crossing manufactured from an explosion depth hardened (EDH) manganese steel grade. For an accumulated traffic load of 65 Mega-Gross-Tonnes (MGT), the evolution of profile degradation for 16 cross-sections along the crossing rail has been recorded on multiple occasions. The results from the measurement campaign are used to validate a previously presented multidisciplinary and iterative simulation methodology for the prediction of long-term rail damage. It is shown that the predicted rail profile degradation exceeds the measured degradation for some of the cross-sections but generally a good qualitative agreement is observed. Possible reasons for the higher predicted damage are the uncertain distribution of traffic at the test site and differences in material properties between the crossing in the field and the test specimens used for calibration of the cyclic plasticity model. The influence of the frequency of updating the rail profiles in the iterative simulation methodology, and the compromise between computational cost and the number of load cases accounted for in the applied load sequence, are addressed

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Zsfassung in engl. Sprache22

Simplified Damage Assessment Tool for Rails and Crossings Based on Standard Wear and RCF Models

A numerical tool is proposed to simultaneously assess various damage mechanisms that are driven by contact loading. The tool transfers loads to the contact-patch level using three contact parameters: the maximum contact pressure (pmax), the creepage (c) and the contact length (2a). The local wear and RCF predictions are implemented based on existing models from the literature. The load input can originate from numerical vehicle–track simulations or manual input of the user. The assessment tool is applied for a finite element analysis of a fixed manganese crossing nose to prove its validity. The algorithm is implemented via an automated Python code, which, on the one hand enables damage prediction for track components based on standard damage models. On the other hand, knowledge of novel local contact damage models can be transferred to the scale of track components

Simplified Damage Assessment Tool for Rails and Crossings Based on Standard Wear and RCF Models

A numerical tool is proposed to simultaneously assess various damage mechanisms that are driven by contact loading. The tool transfers loads to the contact-patch level using three contact parameters: the maximum contact pressure (pmax), the creepage (c) and the contact length (2a). The local wear and RCF predictions are implemented based on existing models from the literature. The load input can originate from numerical vehicle–track simulations or manual input of the user. The assessment tool is applied for a finite element analysis of a fixed manganese crossing nose to prove its validity. The algorithm is implemented via an automated Python code, which, on the one hand enables damage prediction for track components based on standard damage models. On the other hand, knowledge of novel local contact damage models can be transferred to the scale of track components

Calibration of a model for dynamic vehicle – track interaction in crossing panels to comprehensive field measurements

A so-called Whole System Model (WSM) for railway switches and crossings (S&C) is currently under development within the European research program Shift2Rail. The objective of the WSM is that it should allow for holistic simulation-based evaluation of S&C designs and ultimately provide input for Life Cycle Cost analysis and virtual homologation. At the centre of the WSM is a multibody simulation (MBS) model that evaluates the dynamic vehicle-track interaction for a given S&C design and traffic situation and generates wheel-rail contact quantities and structural responses for the following damage calculations. This paper is focused on the MBS model and present developments for a finite element track model of an S&C crossing panel. The developments concern the model itself and a calibration to measurement data from a comprehensively instrumented S&C demonstrator installed as a part of Shift2Rail activities in the Austrian railway network. The presented track model demonstrates an overall good agreement between measurements and simulation after minor and physical track parameter adjustments. A very good agreement is obtained at the center of the crossing panel at the crossing transition while discrepancies are found across the track along the sleeper that goes underneath the crossing transition. It is hypothesized that this discrepancy is due to variations in ballast stiffness distribution under the investigated sleeper. It is concluded that the presented track model can represent the track dynamics well enough to fulfil its function within the Whole System Modelling scheme

The life cycle energy demand and greenhouse gas emissions of high-capacity urban transport systems: A case study from Vienna\u27s subway line U2

This article calculates the impact of three measures in order to reduce the global warming potential (GWP) and cumulative energy demand (CED) of Vienna\u27s subway line U2. Results show that the increase of the train occupancy rate has the highest reduction impact (–30%/–30%), followed by new rolling stock (–26%/–34%), and a change in energy mix (–8%/–4%). The total reduction to be achieved with all measures combined is around –55% for GWP and CED, leading to a GWP of 91 [g] and 1.653 [MJ] per passenger kilometer traveled (PKT). With all these measures applied, the subway has lower GWP and CED than other modes of transport presented in the literature