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  • 1.
    Björkquist, Willand
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Janjua, Ismayil
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Evaluation and comparison of ballastless track systems with regards to system and performance characteristics2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As axle loads and speeds constantly increase in rail transport, new track systems are being developed. One such development is the ballastless track system. Today there are several types and variations of slab tracks, but how do they differ, and which one is the best? This thesis aims to answer these questions for given scenarios as each system has its unique set of strengths and therefore performs differently compared to the other systems for different projects. In this thesis, several existing ballastless track solutions have been studied. This was done viaballastless system manufacturer websites, brochures, other notable literature as well as multiple meetings with each of the system manufacturers. As a result, a descriptive list of nine different systems has been developed as well as a more detailed comparison in the shape of a table. To find out which one should be used and when, a model was developed for comparison of them. This model is based on a Multiple-criteria decision analysis (MCDA). This is a tool that can be used to compare different alternatives, based on several, often conflicting criteria. In the end, the VIKOR method was chosen. The choice was based on VIKOR’s user-friendliness, as well as implementation of auxiliary features, such as regret-value and compromise solutions. The MCDA based model was built in Excel and MATLAB and is expandable to the needs of the user. To test the model and whether it contains any bias, a sensitivity study was carried out. Ten hypothetical scenarios were set up and corresponding importance weights were assigned accordingly. The results were mixed and sparse for the different hypothetical scenarios and showed that no, or little, inherent biases were present in the model. Thus, the model proved to be successful in the end, and can therefore be a good addition to the selection process of a ballastless system alongside other studies, such as Life-cycle cost analysis (LCCA). There is however still some more development that could be done to improve the model. Finally, to demonstrate how the model is implemented for a rail project, a case study was carried out. The case study was conducted for a single hypothetical tunnel close to a city, assumed to be in Sweden. The background conditions were described, and the weighting process was illustrated and inserted to the model. For this particular case the ÖBB-Porr system from the Porr group proved to be the most suitable choice.

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  • 2.
    Casanueva, Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Alonso, Asier
    CAF I+D, Spain.
    Bernsteiner, Christof
    VIRTUAL VEHICLE Research Center, Austria.
    Czerwinka, Thomas
    Siemens AG, Austria.
    Gabriel, Daniel
    Stadler Rail Valencia, Spain.
    Gonzalez-Larrache, Xabier
    Siemens AG, Austria.
    Marte, Christof
    VIRTUAL VEHICLE Research Center, Austria.
    Muñoz, Jesús
    Stadler Rail Valencia, Spain.
    Orbegozo, Ane
    CAF I+D, Spain.
    Paar, Roland
    Siemens AG, Austria.
    Energy Prediction Benchmark for Universal CostModel Calculations2018Conference paper (Refereed)
    Abstract [en]

    Within the EU project Roll2Rail a Universal Cost Model (UCM) is being developed that accounts for different costs in the railway system affected by the design of the running gear. The objective of the methodology is not to calculate the global LCC of the entire vehicle (with all its components) but to boost the introduction of new technologies in the bogie by calculating the savings or incremental costs on the LCC that could be obtained between technological alternatives. The UCM will allow a more objective comparison of different bogie concepts, for instance in purchasing processes, and thus it includes a trustworthiness analysis that evaluates how accurate the calculations in the UCM are for a given study.

    When looking at the total life-cycle cost of a railway vehicle, energy consumption accounts for about 5% of the total expenditure. Within this UCM, a methodology has been proposed that allows the calculation of the energy consumption related to the bogie-technology of any railway vehicle. In order to ensure that all the calculation tools developed by the different partners are adequate, a benchmark simulation has been carried out. The benchmark studies a high-speed vehicle composed of two powered units and four non-powered ones, including six conventional bogies and three Jacobs bogies with both mechanical and ED brakes. In order to validate each simulation tool the share of energy consumed is then compared in different concepts, including in the fields of rolling resistance, curve resistance, unstable running resistance, gradient resistance, aerodynamic and turbulent resistance, inertia resistance and energy use of auxiliary elements. It should be stressed that the comparison and validation focuses on bogie-influenced energy consumption.

    In this paper, the overall UCM methodology is described, with special focus on the energy calculation methodology. The benchmark case is then presented and the energy calculation of all the partners is compared. A discussion on the calibration of the different partners' calculation tools is carried out, including a follow-updiscussion on the relative importance of the different energy consumption concepts in the final energy expenditure. Finally, the trustworthiness analysis is recalibrated according to these results. Closing remarks aregiven addressing the influence of these costs on the UCM.

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  • 3.
    Casanueva, Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Dirks, Babette
    Trafikverket.
    Tohmmy, Bustad
    Trafikverket.
    Rail Vehicle Dynamics Simulation-based decision support for novel block brake material implementation in Sweden2019In: THE 26TH IAVSD INTERNATIONAL SYMPOSIUM ON DYNAMICS OF VEHICLES ON ROADS AND TRACKS, 12-16 August 2019, Gothenburg, Sweden, 2019Conference paper (Other academic)
    Abstract [en]

    . The application of TSI Noise in Sweden needs decision support that can objectively state system-wide benefits and disadvantages, as there are issues with the introduction of novel block brakes: reduced braking performance and increased equivalent conicity. The Roll2Rail Universal Cost Model (UCM) is used to analyse Life Cycle Cost (LCC), as it was also conceived so that it could be used within the decision making processes of infrastructure managers. The simulated characteristics are mainly track Rolling Contact Fatigue (RCF) due to the worsened dynamic train-track interaction.

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  • 4.
    Casanueva, Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Krishna, Visakh V
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    System-wide impact of vehicle innovations: Evaluating track-friendliness during vehicle design2021In: Proceedings of the Resource Efficient Vehicles Conference - 2021 (rev2021), 2021Conference paper (Refereed)
    Abstract [en]

    The cost of maintenance of railway tracks due to vehicle passage is a major limiting factor to the competitiveness of railway sector in EU. For instance, in Sweden in 2017only, 2800million SEK was spent on track maintenance and reinvestment due to wear and tear caused by traffic. Considering this, there is a major incentive to operate track-friendly vehicles that also facilitate economically feasible maintenance strategies. In this context, the NEXTGEAR project aims to incorporate a track-friendliness module in the ‘Universal Cost Model 2.0’ that can estimate operating costs for a given set of operational parameters such as vehicle suspension design, energy usage, track geometry, etc. Such a tool could be useful in estimating the costs for a train operator for a given route and application. However, estimation of costs due to track damage is a complex cross-disciplinary task encompassing varying domains such as vehicle dynamics, tribology, economics, maintenance policy etc so that actual damage in the infrastructure can be linked to maintenance actions and thus costs. Currently there are two major diametrical approaches such as the ‘Bottom-up’ Engineering approach that seeks to create accurate engineeringmodels of vehicle, track, etc. Then there is the ‘Top-down’ Econometric approach that seeks to create statistical models linking the operating variables with historically recorded cost data. Also, track damage itself manifests in various forms such as wear RCF and settlement and it is extremely useful to understand the distribution of costs amongst them. Nowadays a Hybrid approach isbeingdeveloped that can bridge the limitations of the other two methods. Eventually all these models seek to calculate differential operating costs due to the introduction of vehicle innovations during the design stage, hence contributing to the overall economic feasibility of the railway system

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  • 5.
    Chen, Shaoyao
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Modified train wheel wear calculation for fast calculation2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, a modified wear calculation method is developed to calculate the train wheel wear, which can give less precise but faster results compared to the classic wear calculation method. This modified method is developed based on the classic wear calculation method developed by Jendel, which uses Hertz theory and Kalker’s simplified theory to calculate the contact variables and uses Achard theory to calculate the wear volume in an iterative manner. Compared with the classic method, this modified wear calculation method does not execute the multibody simulation (MBS) at each wear step, instead, it executes MBS by different strategies, for example, does MBS only at the first wear step or does it at every several wear steps. This way, a look-up table is utilised to store the contact variables from MBS and when no MBS is executed, the variables stored in the look-up table would be used to calculate the wear.In order to make the implementation of the modified wear calculation method possible, a contact point detection program is developed in this research. Significantly, this contact point detection program considers the material flexibility and can detect multiple contact points, which makes it very precise. It uses the pressure distribution calculated by Winkler theory as a weighting function to consider the material flexibility. In terms of multiple contact points detection, the gap between wheel and rail is regarded as a function, and the derivative relationship of the function is used to detect multiple contact points. Results from the modified wear calculation method are compared with results from the classic wear calculation method. The effects of different strategies are discussed, and the analysis of the error source is carried out in this work.This modified wear calculation method could be used for predicting the wear condition of the wheel when a quick result with only moderate precision is needed. 

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  • 6.
    Chen, Shaoyao
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Modified Wear Modelling for Fast Wear Calculation2022In: IAVSD 2021: Advances in Dynamics of Vehicles on Roads and Tracks II, Springer Nature , 2022, p. 561-571Conference paper (Refereed)
    Abstract [en]

    In this paper, a modified wear calculation method is developed, which can give less precise but faster results compared to the classic wear calculation method. Besides, a precise contact point detection program is developed to cooperate with this modified method.

  • 7.
    Damsongsaeng, Prapanpong
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Improvement of Steering Performance of a Two-axle Railway Vehicle via Look-up Tables Estimation2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A conceptual design of an innovative two-axle lightweight railway vehicle for commuter services is carried out at KTH Railway Group. An active wheelset steering is introduced to improve the curving performance of the vehicle, which is one of the critical performance requirements. This thesis aims to improve the steering performance of the active wheelset steering. Look-up tables for estimating time-varying wheel-rail contact parameters are introduced to supervise a simple PID controller of the active steering system in order to improve steering performance. The look-up table (LUT) estimation is focused on time-varying wheel-rail contact parameters, including creep coefficients and contact patch variables due to their direct influence on curving performance and lateral stability of the wheelset. As a result, the estimated longitudinal unit creep forces (UCF) have the potential to supervise the gains determination of PID controller because it can appropriately distinguish running conditions. The estimation of longitudinal UCF is achieved by the combination of the results from the LUT of creep coefficients and the LUT of contact patch variables. The result from longitudinal unit creep force estimation is shifted to the first quadrant to use as critical gain in the Ziegler-Nichols tuning method for the PID controller. The critical oscillation period for PID tuning can be expressed as a function of vehicle speed. Consequently, the PID controller for the active steering system uses time-varying gains with real-time tuning. The proposed control system for active wheelset steering is validated with nine running conditions using SIMPACK and MATLAB/Simulink co-simulation. The proposed control system provides a stable wheelset lateral displacement control regardless of the running condition. The active steering system significantly reduces wheel-rail wear, which demonstrates the effectiveness of the proposed active steering system.

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  • 8.
    Dang, Ngoc Thúy Vy
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    The Effect of High Wheel Impact Load on the Rail Reliability - a Case Study at Bodsjön2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study focuses on the reliability of railway track in the relation with high loads resulted from wheel damages, where higher (dynamic) vertical wheel loads are expected from trains with damaged wheels. The Swedish Transport Administration (Trafikverket) has monitored and recorded data of rail defects and breaks. This data is important for the risk evaluation and management process, in order to obtain a balance between the maintenance costs and availability and quality of service for the railway transportation. To detect wheel damages in advance, Wheel Impact Loads (WIL) are measured and recorded by Wheel Impact Load Detectors (WILD), which are installed along the Swedish railway network, currently at 29 locations. Additionally, to detect defects and breakages in rails, Ultrasonic Testing (UT) is a common non-destructive testing method used by Trafikverket. In this project, a case study is conducted to examine statistically the frequency of rail defects and rail breaks after trains with high WILs, which exceed 350 kN, continued to operate in a defined area during the winter of 2019/20 at Bodsjön. The case study compares the data of WILD at Bodsjön and UT of the nearby track sections, 211 and 212, over a period of five years, from 2016 to 2020. Rail reliability levels are examined based on the absolute frequencies of rail defects detected by UT and the normalised ones per kilometre of UT-checked track, as well as the severity levels of those rail defects. The severity levels are denoted from the highest to the lowest, as 1a/ 1v/ 1m, 2b and 3i, based on the derailment risks and the priority of maintenance. It is observed that the extremely high WILs in the winter 2019/2020 has coincided with the more severe rail defects found by the following UT in 2020. Furthermore, the dominant rail defect type is found as squats. By studying the frequency of squats and their locations along the defined track sections, it is shown that there is a similar trend in the frequencies of squats and the high WILs. While, the effect of the high WILs’ magnitudes onto the occurrence of squats is undefined. However, the correlation between the frequencies and magnitudes of high WILs and the rail reliability levels could not be determined from this case study due to the limitations in the data collections. The current way of data collections for WILs, wheel damage types and rail defects are discussed for future works. Lastly, the statistics shows that the level of rail reliability of the area defined in the case study is considered as acceptable, considering the recent national levels that have been reported in the annual reports on rail defects. This gives the basis for the possibility of reviewing the permissible power level and proposing a new alert limit value of WIL. Nevertheless, considering the recommendation of The International Union of Railways (UIC) for the international railway sections, the implementation of the increased alert limit of WIL shall be examined carefully, with a future pilot study in railway sections that are not used for international traffic.

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  • 9.
    de Leeuw, Bente
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Improving the validation of a railway vehicle model in the virtual certification process2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Before vehicles can be placed in service it has to complete an authorisation process. At the moment,this process is largely depended on tests. This is, however, an expensive and long process. With new technologies and improved simulations this process can be shortened and the costs can be lowered. The validation of a vehicle model, however, is often limited by the available data. Often the measured rail profiles are not available and thus a new UIC60 profile is used for the simulations. The railway track often has been used and showssigns of wear and damages, therefore research has been done to investigate the influence of the rail profiles on the validation of a railway vehicle model. The current methods of validation in the European norm are used to compare simulated values with forces and accelerations available from vehicle measurements. In the first step,25 track sections with different curve radii have beensimulated with a measured rail profile every 100 meters. In the next step, the same sections have been simulated by using the standard UIC60 rail profile. The results show that the use of measured rail profiles does have a positive influence on the outcome of simulation.

    In the final step, one single narrow curve has been simulated to show the effect of standard and worn rail profiles. Four different wear stages of the rail profile are simulated and compared to the available vehicle measurements available. These simulations show that the use of a medium worn rail profile gives the most accurate value.

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  • 10.
    Ding, X.
    et al.
    National Engineering Research Centre of Railway Vehicles, CRRC Changchun Railway Vehicle Co. Ltd., No.435 Qingying Road, Changchun, 130062, China.
    Ai, X.
    National Engineering Research Centre of Railway Vehicles, CRRC Changchun Railway Vehicle Co. Ltd., No.435 Qingying Road, Changchun, 130062, China.
    Li, Y.
    National Engineering Research Centre of Railway Vehicles, CRRC Changchun Railway Vehicle Co. Ltd., No.435 Qingying Road, Changchun, 130062, China.
    Wang, J.
    National Engineering Research Centre of Railway Vehicles, CRRC Changchun Railway Vehicle Co. Ltd., No.435 Qingying Road, Changchun, 130062, China.
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Monitoring and analysis of dynamic behaviour of high-speed trains in long-term service using an unattended test system2019In: International Journal of COMADEM, ISSN 1363-7681, Vol. 22, no 3, p. 45-50Article in journal (Refereed)
    Abstract [en]

    Dynamic behaviour and its evolution are concerns for those operating high-speed trains. In this paper, a cloud server is applied to establish a connection between the vehicle-mounted equipment and users to decrease the influence of network instability. To ensure the accuracy and consistency of data transmission, MQTT (Message Queue Telemetry Transport) protocol is used to transfer data measured from the vehicle. The paper discovers the vibration transfer characteristic and the evolution of the dynamic behaviour of several types of high-speed trains, along with wheel wear under several operation conditions, over time. The turbulence caused by high-order wheel polygonalization formed during long-term service, which cannot be weakened by the suspended system sufficiently, is harmful to the ride quality of high-speed trains. The results confirm the operational reliability of the high-speed trains in China and provide useful references for the optimisation and maintenance of high-speed trains. 

  • 11. Dou, W.
    et al.
    Zhang, L.
    Chen, G.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    A boundary-condition-transfer method for shell-to-solid submodeling and its application in high-speed trains2020In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 177, article id 105542Article in journal (Refereed)
    Abstract [en]

    The boundary-condition-transfer method for a shell-to-solid submodeling is fundamental for analyzing local or weak regions of a complex structure accurately. In this paper, a novel method is presented for transferring displacement boundaries based on hypothetical nodes. By considering the invariable volume of an element as a constraint, the interpolation through conventional methods using 6-degrees-of-freedom (DOFs) nodal translations and rotations is converted into a 3-DOF translational interpolation at the cut boundary of a submodel. To demonstrate this method, a radial basis function (RBF) was employed for interpolation. For validating the accuracy of the proposed method, a square plate with a hole under tensile and bending load were designed as examples. By considering global and local errors, three typical kernel functions with respect to mesh density ratios were analyzed to fix the optimal parameter in RBF. The examples showed that the proposed method significantly improves the accuracy in shell-to-solid submodeling problems compared to conventional solutions such as ANSYS. For structural analysis of a high-speed train car body under combined mechanical and aerodynamic loads, the submodeling method was implemented on the solid-element-based local model with a welding seam, with which a more detailed stress state was obtained compared with that computed by shell elements. The accurate and reliable results illustrate that the proposed method is the core for the global–local analysis of large complex structures, which also is used for the design and evaluation of the mechanical properties.

  • 12.
    Flodin, Jesper
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Investigate the track gauge widening on the Iron-ore line and suggest maintenance limits2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Iron ore export remains a major player in the Swedish economy to date, with 90% of all iron ore produced in Europe stemming from the relatively small northern country. A large amount of this ore is transported from the mines to harbours for world-wide freight on railways. On such railway is the SwedishIron-ore Line running from Kiruna to Riksgränsen, connecting to the Norwegian Ofoten line which continues to Narvik. The line has the highest permissible axle-load in Europe at 30 tonnes, which poses challenges in its own. Historically, damage on the high rail of curves have been problematic, butremedies introduced in the form of wear adapted rail profiles has brought light to a new issue. Lowrail spalling damage, caused by rolling contact fatigue (RCF) has been problematic on the line, as it reduces the life of the rails and increases maintenancecosts. It is believed that a major factor to this damage is the track gauge width. The current limit values for maintenance of the track gauge is set at 1450mm, a figure derived from empirical studies. It is therefore the wish of the infrastructure manager Trafikverket to investigate the effect the gaugewidth has on this RCF induced damage, in order to review current maintenance practices. By applying current state of the art in rail vehicle dynamics simulations and contact mechanics, the current maintenance limit has been investigated.The outcome of said investigation has yielded a foundation of support for the current maintenance limit, as it closely aligns with where damage is calculated to form at a significantly higher rate than at lower gauges.

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  • 13.
    Fraschini, Daniele Mario
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Dynamic Modelling of the KTH Roller Rig2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Rail Vehicle Research group at Kungliga Tekniska Högskolan (KTH) is on the path to design and build a scaled test rig called roller rig for research and educational purposes. A roller rig is a device simulating the track with rollers on which the test subject (a wheelset, bogie or even a full vehicle) canbe placed.This thesis report is part of a bigger project involving several team members and it explores the applicability of track irregularities on a scaled roller rig by means of computer simulations. A scaled roller rig model, capable of simulating track irregularities, is generated using the multibody simulation softwareSIMPACK. Track irregularity data, represented as Power Spectral Densities (PSD), are applied to the model created. The model created and implementation of track irregularities are assessed in order to validate the modelling steps.Comparison with a reference vehicle model is carried out to verify if results obtained on the test rig are representative of a vehicle running on track, taking into account roller rig intrinsic errors. Results obtained aim to support the design of the roller rig’s mechanical components from a dynamical standpoint.

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  • 14.
    Fu, Bin
    et al.
    Politecn Milan, Dipartimento Meccan, Milan, Italy..
    Hossein-Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Bruni, Stefano
    Politecn Milan, Dipartimento Meccan, Milan, Italy..
    Wheel Wear Evolution of Solid-Axle Wheelset with Active Steering2022In: ICRT 2021 - Proceedings of the 2nd International Conference on Rail Transportation / [ed] Zhai, W Wang, KCP Zhu, S, American Society of Civil Engineers (ASCE) , 2022, p. 24-32Conference paper (Refereed)
    Abstract [en]

    Active steering is an attractive technology to improve vehicle curving performance. It can reduce the track shift force and wear index in curves, but it is still unknown how much material removal across the wheel profile can be reduced and how it would affect the wheel wear evolution, which is crucial to motivate the implementation of active steering. This paper studies the wheel profile evolution under the presence of active steering. An iterative wear calculation approach is applied based on Archard's wear model. Two practical steering control strategies are proposed. The wheel wear simulations are performed in three different scenarios, considering different rail cants and proportions of curves. The simulation results reveal the wear pattern of the actively steered vehicle and verify the reduced material removal across the wheel profile especially on the wheel flange. The two control strategies are also compared and evaluated for the future application of the active steering system.

  • 15.
    Geiberger, Philipp
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Monitoring energy efficiency of heavy haul freight trains with energy meter data2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this MSc thesis, it is investigated what parameters are relevant for describing energy consumption of heavy haul freight trains and how these can be used to develop key performance indicators (KPIs) for energy efficiency. The possible set of KPI is bounded by data available from energy meters used in electric IORE class locomotives hauling iron ore trains in northern Sweden. Furthermore, the analysis is only concerned with energy efficiency at the rolling stock level, excluding losses in the electric power supply network.

    Based on a literature study, parameters of interest describing driver, operations and rolling stock energy efficiency have been identified. By means of simulation, a parametric study is performed, simulating a 30 ton axle load iron ore train with 68 wagons. Train modelling input is obtained from technical documentation or estimated through measurements and statistical analysis. A multi-particle representation of the train is used to calculate gradient resistance for the simulation, which is also applied to determine the curve resistance. 

    Results show that the motion resistance is simulated quite accurately, while the lack of a driver model in the simulation tool leads to overestimation of energy consumption. Taking this into account, the importance of the driver for energy efficiency can still clearly be showcased in the parametric study. Especially on long steep downhill sections, prioritising the electric brakes over mechanical brakes is demonstrated to have a huge influence on net energy consumption, as has the amount of coasting applied. With the same driver behaviour in all simulations, the savings in specific energy from increasing axle load to 32.5 tons is estimated. Moreover, a comparison of increased train length and axle load points towards higher savings for the latter.

    In the end, parametric study results are used to recommend a structure for a monitoring system of energy efficiency based on a set of KPIs. With a sufficiently high sampling rate of energy meter data, it is adequate for calculating driver related KPIs and some additional KPIs. More KPIs can be tracked with access to additional data, e.g. cargo load.

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  • 16.
    Giossi, Rocco Libero
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Persson, Rickard
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Improved curving performance of an innovative two-axle vehicle: a reasonable feedforward active steering approach2020In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159Article in journal (Refereed)
    Abstract [en]

    A mechatronic rail vehicle with reduced tare weight, two axles and only one level of suspension is proposed with the objective of reducing investment and maintenance costs. A wheelset to carbody connection frame in composite material will be used both as structural and as suspension element. Active control is introduced to steer the wheelsets and improve the curving performance. A feedforward control approach for active curve steering based on non-compensated lateral acceleration and curvature is proposed to overcome stability issues of a feedback approach. The feedforward approach is synthesised starting from the best achievable results of selected feedback approaches in terms of wheel energy dissipation and required actuation force. A set of 357 running cases (embracing 7 curves, 17 speeds per curve and 3 conicities) is used to design the controller. The controller is shown to perform well for conicity and track geometry variations and under the presence of track irregularities.

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  • 17.
    Giossi, Rocco Libero
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Persson, Rickard
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Gain Scaling for Active Wheelset Steering on Innovative Two-Axle Vehicle2020In: Lecture Notes in Mechanical Engineering, 2020Conference paper (Refereed)
    Abstract [en]

    Within the Shift2Rail project Run2Rail, an innovative single axle running gear with only one suspension step is proposed. A composite material frame shall be used both as structural and as suspension element. To improve curving performance active wheelset steering control is introduced. The selected control aims to minimize the longitudinal creepage by controlling the lateral wheelset position on the track. A two-axle vehicle is created in the MBS program SIMPACK and co-simulation is established with Simulink. The control strategy used is a simple PID control. A set of run cases with different curves and speeds is selected to verify the performance. The control gain optimal for high non-compensated lateral acceleration (NLA) tends to produce unstable results for low speeds. Control gain scaling is introduced based on vehicle speed and online estimation of the curvature. The proposed gain scheduling approach maintains the simple control formulation still solving the instability problem. Gain scheduling allows use of optimal control gains for all combinations of curve radii and vehicle speed and thereby taking the full advantage that the active wheelset steering brings to a vehicle with single axle running gears. 

  • 18.
    Karlsson, Henrik
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Qazizadeh, Alireza
    TÜV SÜD Sverige AB Stockholm Sweden.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Condition Monitoring of Rail Vehicle Suspension Elements: A Machine Learning Approach2020In: Lecture Notes in Mechanical Engineering, Springer , 2020, p. 119-127Conference paper (Refereed)
    Abstract [en]

    With an increasing demand for safe and efficient rail transportations with high availability, there is an interest to apply condition based maintenance on railway systems to increase the total system reliability. A condition based maintenance system utilizes data collecting, data processing and decision making to schedule maintenance based on the actual condition of components. In this paper a rail vehicle is simulated at varying operational conditions, and with degraded dampers in the primary and secondary suspension. A large database of simulations is generated and is used to train and test classification algorithms to detect upcoming damper faults, introduced as a fault factor multiplied with the damper coefficients. Frequency response functions between accelerometer signals in the carbody, bogieframes and axles are used as fault indicators, predictors, fed to the classification algorithms. The algorithms are evaluated for a varying number of included frequency response functions, as well as varying operational conditions in the training datasets. The linear Support Vector Machine and 1-Nearest-Neighbour classifier both indicate high capability of correctly classifying damper degradations.

  • 19.
    Krishna, Visakh V
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Evolution of wheel-rail kinematic coupling due to RCF and natural & maintenance-induced wear using vehicle dynamic simulations2021In: Proceedings of the 26th International Congress of Theoretical and Applied Mechanics (ICTAM2020+1), Milan (Italy), August 2021., 2021Conference paper (Refereed)
    Abstract [en]

    The wheel-rail interaction constitutes a complex kinematic coupling that evolves over time due to various factors such aswear, rolling contact fatigue and periodic maintenance activities, that determine the rail service life. The state of the rail surface after aspecified traffic and tonnage passing reflects the track-friendliness of the vehicles. This is particularly helpful in guiding track accesspricing strategies for different vehicle designs based on the amount of damage they cause to the track. A complex and highly non-linearmulti-body simulation environment is set up and iterative vehicle dynamics calculations are performed, along with the implementationof recently developed wheel-rail contact models, damage models and maintenance procedures over a 100 MGT tonnage period.

  • 20.
    Krishna, Visakh V
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Trummer, Gerald
    Virtual Vehicle Research GmBH.
    Six, Klaus
    Virtual Vehicle Research GmBH.
    Rail RCF damage quantification and comparison for different damage models2021In: Railway Engineering Science, ISSN 2662-4745Article in journal (Refereed)
    Abstract [en]

    There are several fatigue-based approaches that estimate the evolution of Rolling Contact Fatigue (RCF) on rails over time, built to be used in tandem with Multi-Body Simulations of vehicle dynamics. However, most of the models are not directly comparable with each other since they are based on different physical models even though they shall predict the same RCF damage at the end. This article studies different approaches to quantifying RCF and puts forward a measure for the degree of agreement between them. The methodological framework studies various steps in the RCF quantification procedure within the context of one another, identifies the ‘primary quantification step’ in each approach and compares results of the fatigue analyses. In addition to this, two quantities - ‘similarity’ and ‘correlation’ have been put forward to give an indication of mutual agreement between models. Four widely used surface-based and subsurface-based fatigue quantification approaches with varying complexities have been studied. Different operational cases corresponding to a metro vehicle operation in Austria have been considered for this study. Results showed that the best possible quantity to compare is the normalized damage increment per loading cycle coming from different approaches. Amongst the methods studied, approaches that included the load distribution step on the contact patch showed higher similarity and correlation in their results. While the different approaches might qualitatively agree on whether contact cases are ‘damaging’ due to RCF, they might not quantitatively correlate with the trends observed for damage increment values. 

  • 21.
    Krishna, Visakh V
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Jobstfinke, Daniel
    Melzi, Stefano
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    An integrated numerical framework to investigate the running safety of overlong freight trains2020In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017Article in journal (Refereed)
    Abstract [en]

    Long freight trains up to 1500 m in length are currently not in regular operation in Europe. One of the important reasons for the same is high inter-wagon forces generated during the operation, especially when pneumatic (P-type) brake systems are used. For long trains with multiple locomotives at different positions along the train, radio communication with necessary fail-safe mechanisms can be used to apply the brakes. Long freight train operation on a given line is subjected to various attributes such as braking/traction scenarios, loading patterns, wagon geometries, brake-block materials, buffer types, track design geometries, etc., which are referred to as heterogeneities. The complex longitudinal train dynamics arising in the train due to various heterogeneities play a major role in determining its running safety. In this context, the maximum in-train force refers to the maximum force developed between any two wagons along the train during operation. The tolerable longitudinal compressive force is the maximum compressive force that can be exerted on a wagon without resulting in its derailment. Here, the authors adopt a bottom-up approach to model pneumatic braking systems and inter-wagon interactions in multibody simulation environments to study the complex longitudinal train dynamics behavior and estimate maximum in-train forces and tolerable longitudinal compressive forces, subjected to various heterogeneities. These two force quantities intend to facilitate a given freight train operation by providing guidelines regarding the critical heterogeneities, that currently limit its safe operation. In doing so, the authors propose the notion to have an operation-based approval for long freight trains using the simulations-based tool.

  • 22.
    Krishna, Visakh V
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Wu, Qing
    Central Queensland University.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Spiryagin, Maksym
    Central Queensland University.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Long freight trains and long-term rail surface damage: A systems perspective2022In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, p. 1-24Article in journal (Refereed)
    Abstract [en]

    In this work, the authors present a detailed train-track interaction model of a long freight train operation to predict long-term rail surface damage. In addition to vehicles and track, intermediate maintenance actions in the form of cyclic grinding passes have also been modelled according to European standards to realistically represent the evolving wheel-rail interface. The influence of longitudinal train dynamics in the form of inter-vehicle interactions, traction, braking, gradients, etc is also included in this method to reflect their effect on damage evolution. The authors demonstrate that the novel ‘Train-track interaction’ formulation is more complete and therefore better suited to study long-term rail surface damage as opposed to existing ‘vehicle-track’ formulations since the former brings the system dynamics at play, significantly altering the wheel-rail interaction. A key highlight of this work is that the rail surface damage is expressed in the form of evolving rail profiles over a large tonnage passing and by depicting RCF-affected zones. This framework can be tuned into a digital twin to guide infrastructure managers regarding the condition of rail surface as a function of tonnage passage. This can in turn facilitate predictive maintenance of track depending on traffic and operation.

  • 23.
    Kulkarni, Rohan
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Berg, Mats (Contributor)
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Carlsson, Ulf (Contributor)
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.
    Stichel, Sebastian (Contributor)
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Vehicle running instability detection algorithm (VRIDA): A signal based onboard diagnostic method for detecting hunting instability of rail vehicles2021In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017Article in journal (Refereed)
    Abstract [en]

    In recent years, significant research transpired on onboard monitoring of various phenomena arising in dynamic vehicle-track interaction. One key issue being monitoring of vehicle hunting instability. Current hunting detection standards are appropriate for certification tests of vehicles, but incapable to monitor the health of the vehicle and track subsystems influencing the hunting instability. This paper proposes a signal based procedure for accurately triggering Hunting/No-Hunting alarm by conforming to requirements of onboard monitoring. A new method is conceived to reveal coherence among lateral and longitudinal accelerations during vehicle hunting. Furthermore, an index which amalgamates phase and amplitude information of lateral and longitudinal axlebox accelerations is introduced to detect coupled modes in lateral and yaw directions, i.e. hunting modes. Several simulations based pragmatic case studies are performed to assess the efficacy of the proposed procedure. The proposed method outperforms traditional hunting detection procedures by detecting more Hunting/No-Hunting occurrences. The proposed method contributes towards digitalization of rail vehicles through condition-based and predictive maintenance.

  • 24.
    Kulkarni, Rohan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Qazizadeh, Alireza
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Identification of vehicle response features for onboard diagnosis of vehicle running instability2022In: 2022 IEEE International Conference on Prognostics and Health Management (ICPHM) / [ed] Jason W Rupe, Institute of Electrical and Electronics Engineers (IEEE) , 2022, p. 52-57Conference paper (Refereed)
    Abstract [en]

    Condition Monitoring (CM) of dynamic vehicle track interaction is an important research topic in rail vehicle dynamics. The most cost-effective method for CM is through carbody floor mounted accelerometers because this is most safe and reliable location for onboard accelerometers onboard inservice train. However, the dynamic response of carbody is influenced not only by excitations coming from track but also by various nonlinearities such as wheel-rail interface and vehicle suspension elements. Thus, it is very challenging to accurately monitor track subsystems via carbody floor accelerations. In this article, two feature extraction algorithms are proposed with the objective of obtaining crucial information on the stability of vehicle using carbody floor accelerations. The first algorithm is based on spectral analysis and the latter is on adaptive signal processing technique. The first algorithm calculates transfer function between track irregularities and carbody floor acceleration using Multiple Input Multiple Output (MIMO) system identification method. The later method analyses the carbody floor accelerations with Empirical Mode Decomposition followed by Singular Value Decomposition (EMD+SVD). These algorithms are evaluated on simulated carbody floor accelerations obtained with vehicle dynamic simulations. In this investigation, it is observed that the first method extracts more crucial information from carbody floor acceleration in comparison to EMD+SVD method. These features are planned to be used in future research to develop machine learning based intelligent fault identification algorithm for identification of root cause of vehicle running instability occurrence.

  • 25.
    Kulkarni, Rohan
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Qazizadeh, Alireza
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Dirks, Babette
    Department of Technology & Environment, Swedish Transport Administration, Västertås, Sweden.
    Ingemar, Persson
    Investigating the effect of the equivalent conicity function's nonlinearity on the dynamic behaviour of a rail vehicle under typical service conditions2022In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 60, no 10, p. 3484-3503Article in journal (Refereed)
    Abstract [en]

    Generally, the equivalent conicity function (ECF) is denoted by equivalent conicity at 3mm (λ3mm) and a Nonlinearity Parameter (NP). NP describes the nonlinearity of the ECF and its influence on a vehicle design is explored thoroughly, however, NP’s role in vehicle and track maintenance is not researched yet. This paper investigates the influence of track maintenance actions on vehicle dynamics with help of NP vs λ3mm scatter plots of ECF database. The ECF database is constructed by combining measured worn wheel and rail profile pairs of the Swedish high-speed vehicle and rail network, respectively. The ECF database revealed an inverse relationship between λ3mm and NP, i.e., NP is negative for larger λ3mm values. The combination of negative NP and high λ3mm causes reduction in the vehicle’s nonlinear critical speed and vehicle often exhibit the unstable running on the Swedish rail network. Thus, the occurrence of ECF with negative NP and high λ3mm is undersirable and the undesirable ECF can be converted into desirable ECF by grinding the rail, which converts ECF’s into positive NP and low λ3mm combinations. Thus, the NP parameter along with the λ3mm must be considered in track maintenance decisions.

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  • 26.
    Kulkarni, Rohan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Qazizadeh, Alireza
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Fault detection and isolation method for vehicle running instability from vehicle dynamics response using machine learning2019In: Proceedings of 11th International Conference on Railway Bogies and Running Gears (BOGIE'19) / [ed] Prof. István ZOBORY, Budapest, 2019Conference paper (Refereed)
    Abstract [en]

    In this paper, a Fault Detection and Isolation (FDI) method is proposed for monitoring the vehicle running stability in a high-speed railway bogie. The objective is to detect and isolate the different faults of bogie components which are critical to vehicle stability, especially degraded yaw dampers and high equivalent conicity caused by wheel wear. The proposed method has two steps; firstly, signal features sensitive to the characteristics of running instability are extracted based on frequency domain and time domain analysis of lateral accelerations of bogie frame and axlebox; then these features along with vehicle speed are fed into machine learning based fault classifiers. The supervised machine learning based fault classifier are trained to identify the cause of observed running instability among yaw damper degradation and wheel-rail profile pair with high equivalent conicity. The Support Vector Machine (SVM) classifier with Linear and Gaussian kernels are trained by k-fold crossvalidation method and the hyperparameters are optimized with a bayesian optimization algorithm to minimize the classification error. These fault classifiers are trained and tested with an extensive database generated from numerical experiments performed by multibody simulation (MBS) software. The performance of Linear and Gaussian SVM fault classifiers is compared with each other to identify the best performing classifier. The results underline the ability of machine learning based fault classifiers to be used for FDI of vehicle running instability and outline the possibility of detecting and isolating bogie faults critical to the vehicle stability based on onboard measurement of vehicle dynamic response.

  • 27.
    Kulkarni, Rohan
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Rosa, Anna De
    Qazizadeh, Alireza
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Vehicle Dynamics.
    Gialleonardo, Egidio Di
    Faccinetti, Alan
    Bruni, Stefano
    Monitoring of Alignment Level (AL)and Cross Level (CL) track geometry irregularities from onboard vehicle dynamics measurements using probabilistic fault classifier2021In: Lecture Notes in Mechanical Engineering, Budapest: Springer Science and Business Media Deutschland GmbH , 2021, p. 479-487Conference paper (Refereed)
    Abstract [en]

    Condition monitoring of track geometry irregularities from onboard measurements of vehicle response is a cost-effective method for surveilling qual-ity of track irregularities on daily basis. The monitoring of Alignment Level (AL)and Cross Level (CL) track irregularities is challenging due to the nonline-arities of the contact between wheels and rails. Recently, the authors proposed a signal-based method in combination with a machine learning (ML) fault classi-fier to monitor AL and CL track irregularities based on bogie frame accelerations. The authors concluded that the Support Vector Machine (SVM) fault classifier outperformed other traditional ML classifiers. Thus, an important question arises: Is the previously reported decision boundary an optimal boundary? The objective of this research investigation is to obtain an optimal decision boundary according to theory of probabilistic classification and compare the same against the SVM decision boundary. In this investigation, the classifiers are trained with results of numerical simulations and validated with measurements acquired by a diagnostic vehicle on straight track sections of a high-speed line (300 km/h). A fault classi-fier based on Maximum A Posterior Naïve Bayes (MAP-NB) classification is developed. It is shown that the MAP-NB classifier generates an optimal decision boundary and outperforms other classifiers in the validation phase with classifi-cation accuracy of 95.9±0.2% and kappa value of 80.4±0.6%. Moreover, the Lin-ear SVM (L SVM) and Gaussian-SVM (G SVM) classifiers give similar perfor-mance with slightly lower accuracy and kappa value. The decision boundaries of previously reported SVM based fault classifiers are very close to the optimal MAP-NB decision boundary. Thus, this further strengthens the idea of imple-menting statistical fault classifiers to monitor the track irregularities based on dynamics in the lateral plane via in-service vehicles. The proposed method con-tributes towards digitalization of rail networks through condition-based and pre-dictive maintenance.

  • 28.
    Lei, Lei
    et al.
    Southwest Jiaotong University.
    Dongli, Song
    Southwest Jiaotong University.
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Xiao, Xu
    Southwest Jiaotong University.
    Zejun, Zheng
    Southwest Jiaotong University.
    Displacement Identification by Computer Vision for ConditionMonitoring of Rail Vehicle Bearings2021In: Sensors, E-ISSN 1424-8220, Vol. 21, no 6, article id 2100Article in journal (Refereed)
    Abstract [en]

    Bearings of rail vehicles bear various dynamic forces. Any fault of the bearing seriouslythreatens running safety. For fault diagnosis, vibration and temperature measured from the bogieand acoustic signals measured from trackside are often used. However, installing additional sensingdevices on the bogie increases manufacturing cost while trackside monitoring is susceptible toambient noise. For other application, structural displacement based on computer vision is widelyapplied for deflection measurement and damage identification of bridges. This article proposesto monitor the health condition of the rail vehicle bearings by detecting the displacement of boltson the end cap of the bearing box. This study is performed based on an experimental platform ofbearing systems. The displacement is monitored by computer vision, which can image real-timedisplacement of the bolts. The health condition of bearings is reflected by the amplitude of thedetected displacement by phase correlation method which is separately studied by simulation. Toimprove the calculation rate, the computer vision only locally focuses on three bolts rather thanthe whole image. The displacement amplitudes of the bearing system in the vertical direction arederived by comparing the correlations of the image’s gray-level co-occurrence matrix (GLCM). Forverification, the measured displacement is checked against the measurement from laser displacementsensors, which shows that the displacement accuracy is 0.05 mm while improving calculation rate by68%. This study also found that the displacement of the bearing system increases with the increase inrotational speed while decreasing with static load

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  • 29.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Bustad, Tohmmy
    Trafikverket, Borlänge, Sweden.
    Review of the existing energy labelling systems and a proposal for rail vehicles2021In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 235, no 4, p. 518-528, article id 095440972092636Article, review/survey (Refereed)
    Abstract [en]

    Improving energy efficiency and reducing CO2 emissions are becoming very essential worldwide. To encourage the development and application of energy-efficient and low-emission technologies and to increase people's awareness of energy-saving, many energy labelling systems are developed and utilized in most countries. Since energy labelling systems have a significant impact, more and more sectors are developing their energy labelling systems to have their products included. Globally, the transport sector consumes a great proportion of energy and is responsible for considerable CO2 emissions. Although rail vehicles have relatively high energy efficiency, a labelling system has not been developed in the railway sector, whereas other modes of transport have developed energy efficiency indicators or energy labelling systems. Therefore, it is necessary to develop an energy labelling system for rail vehicles to promote rail transport and develop the technology of rail vehicles. First, this paper gives a review of the existing energy labelling systems. Second, it summarizes the rail needs and rail stakeholders’ interests regarding energy efficiency and corresponding labelling. Last but not least, a proposal for an energy labelling system for rail vehicles is given.

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  • 30.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Ekmark, Anders
    Trafikverket, Kruthusgatan 17, SE-41104 Gothenburg, Sweden.
    Investigation of Power Peak Reduction in Rail Freight Transport2021In: Proceedings of the 2nd International Conference on Rail Transportation, 2021Conference paper (Refereed)
  • 31.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Ekmark, Anders
    Trafikverket, Kruthusgatan 17, SE-41104 Gothenburg, Sweden .
    Study of the Dynamic Performance of Pantograph at Speeds Close to the Critical Speed on Soft Catenary System2021In: Proceedings of the 2nd International Conference on Rail Transportation, 2021Conference paper (Refereed)
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  • 32.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Schick, Bastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Study of the Dynamic Performance of PantographRunning Close to Critical Speedon Soft Catenary System2021In: Proceedings of the 2nd International Conference on Rail Transportation, 2021Conference paper (Refereed)
  • 33.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Vehicle Dynamics.
    Overview of technology and development of maglev and hyperloop systems2022Report (Other academic)
    Abstract [en]

    Guided transport has higher transport capacity and energy efficiency in operation than other modes of transport, so there has been fast development of guided transport all over the world in the past decades. Although rail transport is the most successful guided transport system, there are still some limitations to the further development of rail transport, e.g. long travel time for long-distance travel, noise and vibration in urban areas, and rail-wheel wear and adhesion. In response, maglev and hyperloop systems which do not rely on the rails and wheels have been proposed and developed. 

    In maglev and hyperloop systems the vehicles are levitated and propelled from the guideway by magnetic forces. There is no direct physical contact between the moving train and the guideway during operation. To achieve very high-speed operation, hyperloop systems are supposed to run inside low-pressurized tubes to reduce aerodynamic drag. In the world, there are many different types of technology developed to realize maglev and hyperloop systems. However, the technology of maglev and hyperloop systems is relatively new and still under development. Now there are only five low-speed maglev systems and one high-speed maglev system in commercial operation in the world. 

    The maglev and hyperloop systems have different features compared to the well-developed rail transport, so it is needed to look into their core technology and follow their latest development for future development in the transport sector. In response, this work gives an overview of the maglev and hyperloop systems with respect to their history, technology and applications in the world. This work summarizes the development history of different maglev and hyperloop systems, explain the core technology used in hyperloop systems and three types of maglev systems, and describe the applications of six commercial maglev systems. This work also compares the features of different systems based on statistics. In the end, some conclusions are drawn and future work plans are sketched.

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  • 34.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Rønnquist, A.
    A Numerical Study on Pantograph Raising and Lowering in Multi-Pantograph Operation2017In: The international Journal of railway technology, ISSN 2049-5358, E-ISSN 2053-602X, Vol. 6, no 3, p. 51-69, article id 3Article in journal (Refereed)
    Abstract [en]

    Multi-pantograph operation is a convenient and efficient way to operate railway rolling stock and infrastructure, but the influence between the pantographs makes the system more sensitive and vulnerable than a single-pantograph system. When a train passes through special sections, or falls into an emergency condition, it is necessary to lower one, or all, of the pantographs and then raise them up again. In these circumstances, the motion of the pantographs can introduce a sudden impact to the catenary that may change the configuration of the pantograph combination and its dynamic performance. To address the dynamic performance during pantograph raising and lowering, a numerical study on a multi-pantograph operation is performed with the help of a three-dimensional pantograph-catenary finite element (FE) model and an artificial beam along the catenary is used to guide the motion of the pantograph to describe the pantograph raising-lowering operation. The paper studies the following conditions: the relationship between spacing distance and the span length, various pantograph raising-lowering orders, and different operating positions in a span. The results show that the leading pantograph is little influenced by the raising and lowering movement of any pantograph behind it. However, the trailing pantograph is heavily affected by any operation ahead of it. The dynamic performance of the system depends on the pantograph spacing distance and the operational speed but is little affected by the operating position in a span. To study auxiliary-pantograph operation, where the leading pantograph works as an auxiliary pantograph, this paper shows how an optimal setting of the leading pantograph benefits the trailing pantograph and suggests specifying the speed where the leading pantograph gets into, or out of, service to avoid disruption and to skip unfavourable working conditions.

  • 35.
    Niedecken, Timon
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Optimized maintenance budget planning for DB Cargo locomotives2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Deutsche Bahn Cargo AG (DB Cargo) is a German line haul provider for the European Rail Transport Market. The more than 1500 locomotives owned by the company receive frequent maintenance for all their components. The many components of course have many different life cycles, costs and time needed for maintenance in the workshop. One of the tasks for the department “Operative Locomotives and Budget Planning Germany” (L.CBA 22) is to create a budget plan for the locomotive maintenance with a high quality of prediction. Because a change in maintenance procedures is currently ongoing, the budgeting process needs to be adjusted to keep the quality of prediction high without exceeding available time needed to create the budget plan.To do so, a tool consisting of excel files with queries, macros, in cell calculations as well as pivot table visualization is being created. Although not finished until now, it already facilitates some processes of the budgeting procedure.

  • 36.
    Niewalda, Tobias
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Deep Learning Based Classification of Rail Defects Using On-board Monitoring in the Stockholm Underground2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this work is to find out if an artificial neural network can be useful purpose of this work is to find out if an artificial neural network can be useful in order to detect rail squats with the existing Quiet Track Measurement System (QTMS). Squats are surface-initiated rail defects which arise due to rolling contact fatigue. The monitoring system, installed on seven trains running on the green line in the Stockholm underground, aims to improve the maintenance process. The early detection and surveillance of defects helps to extend the service life of the tracks and reduce operating costs. An artificial neural network is used to analyse the the continuously recorded measurements, which consist of vertical bogie acceleration and surrounding noise, each sampled with a frequency of 22 kHz.In particular, the power spectral density as input for multi-layer Fully-connected Neural Network (FNN) has proven to be promising for accurate squat predictions. The supervised learning was carried out according to the one-vs-all principle, i.e. squats versus all other events. A two-hidden-layer FNN has finally been chosen to complement the QTMS. The usage of the full available frequency range from almost DC up to 11kHz, but minimum 7 kHz, allows good prediction with only low false prediction rates. When concatenating all six measurement channels to a single classifier input, an accuracy of over 96% for the squat class and up to 99.98% can in total be achieved. The chosen network type also showed high stability despite quite strong parameter variations and a massive under-representation of squat observations in the measurement data.However, since limited maintenance information about actual squats is available for labelling and testing, more evaluation is needed. The correct identification of mis-labelled squats indicates the high potentials of artificial neural networks.

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  • 37.
    O'Reilly, Ciarán J.
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Boij, SusannKTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.Casanueva, CarlosKTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.Göransson, PeterKTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.Jerrelind, JennyKTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Vehicle Dynamics.Karlsson Hagnell, MathildaKTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.Rothhämel, MalteKTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.Rumpler, RomainKTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics, Marcus Wallenberg Laboratory MWL.Wennhage, PerKTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Proceedings of the Resource Efficient Vehicles Conference - 2021 (rev2021)2021Conference proceedings (editor) (Other academic)
    Abstract [en]

    rev2021 was the first edition of the conference on Resource Efficient Vehicles, held online on 14-16 June 2021. This vehicle-centric conference aims to bring together participants from academia, industry and public agencies to discuss research from all relevant fields connected to resource efficiency in all motorised modes of transport and interdependent surrounding systems. 

    The theme of this multidisciplinary conference is Resolving Functional Conflicts in Vehicle Design, a theme explored through topics including modelling for multifunctional design; making trade-offs; efficient use of materials and space; integrating new solutions; transforming the product system; transforming the vehicle-transport system; sustainable design; and early-stage design. 

    The 2021 edition of the conference consisted of 40 selected papers for presentation at the conference, complemented with four workshops, five keynote lectures from invited speakers, and a concluding panel discussion with four invited participants. It was organised by the Centre for ECO2 Vehicle Design at KTH Royal Institute of Technology in Stockholm.

    Download full text (pdf)
    rev2021_proceedings
  • 38.
    Persson, Rickard
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Giossi, Rocco Libero
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Possible reduction of energy consumption with single axlerunning gears in a metro train2021Conference paper (Refereed)
    Abstract [en]

    Running gears form a significant part of the weight of a railway vehicle, and if the weight of these could be reduced, this would affect the vehicle’s energy consumption, especially for services with many stops. In the project RUN2Rail, a part of the EU-funded initiative Shift2Rail, a single axle running gear was proposed for metro vehicles. Active suspensions were suggested to overcome deficiencies in terms of ride comfort and wheelset steering, which are well known for such vehicles. The concept has been further developed in the project NextGear, also part of Shift2Rail, where the material of the running gear frame has been changed from steel to composite to further reduce the weightand the wheelset guidance updated to decrease the running resistance in curves. Prototypes of frame and wheelset steering actuator will be built and tested in the laboratory to validate the performance.The present study is comparing a reference vehicle from Metro Madrid with the proposed vehicle in terms of energy consumption for simulated service on Metro Madrid Line 10 with curvature, gradients, stops and speed profiles considered. Only parameters with relation to the weight, curving performance and auxiliary energy consumption for the active system are assumed different for the vehicles. The vehicles are further assumed to use regenerative braking, hence the energy needed to accelerate the vehicle will be regenerated when braking, but there will be transformation losses with relation to the weight. The simulation results show that the very innovative NextGear vehicles will reduce energy consumption by 8% compared to the reference vehicles. The lower weight and the decreased running resistance in curves contribute about as much to the savings.

  • 39.
    Prifer, David
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Dynamic Simulation and Suspension Optimization for a Heavy Duty Railway Bogie2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A multi-body simulation study was undertaken to investigate the running behavior of a rail grinder vehicle with newly developed Ganz bogies. The main purpose of the simulations was to forecast and support the vehicle acceptance tests and support the ongoing development.

    A multi-body model was built in Simpack and the most critical force elements were isolated and validated by tests. Derailment safety was assessed based on both European and Australian standards. The vehicle's running stability was carried out for both standard (1435mm) and broad gauge (1676mm) versions. Vehicle sway characteristics were determined through the calculation of flexibility coefficient both numerically and analytically.

    A parametric study for primary vertical damper was undertaken to assess the empirically selected dampers and optimize the performance. The results show that the damping coefficient can be greatly reduced while maintaining acceptable running behavior, thus the lifetime of dampers can be increased. Based on stability investigations, yaw damper installation is not necessary, though the bracketry for the possibility of later installation will remain on the prototype bogie.

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  • 40.
    Rosa, Anna De
    et al.
    Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy.
    Kulkarni, Rohan
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Qazizadeh, Alireza
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Gialleonardo, Egidio Di
    Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy.
    Faccinetti, Alan
    Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy.
    Bruni, Stefano
    Department of Mechanical Engineering, Politecnico di Milano, Milan, Italy.
    Monitoring of lateral and cross level track geometry irregularities through onboard vehicle dynamics measurements using machine learning classification algorithms2020In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017Article in journal (Refereed)
    Abstract [en]

    In recent years, significant studies have focused on monitoring the track geometry irregularities through measurements of vehicle dynamics acquired onboard. Most of these studies analyse the vertical irregularity and the vertical vehicle dynamics since the lateral direction is much more challenging due to the non-linearities caused by the contact between the wheels and the rails. In the present work, a machine learning-based fault classifier for the condition monitoring of track irregularities in the lateral direction is proposed. The classifiers are trained with a dataset composed of numerical simulation results and validated with a dataset of measurements acquired by a diagnostic vehicle on the straight track sections of a high-speed line (300 km/h). Classifiers based on decision tree, linear and Gaussian support vector machine algorithms are developed and compared in terms of performance: good results are achieved with the three algorithms, especially with the Gaussian support vector machine. Even though classifiers are data driven, they retain the essence of lateral dynamics.

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    Accepted_Version
  • 41.
    Schick, Bastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    A Digital Test Bench for Pneumatic Brakes2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master’s thesis covers the structuring and implementation of a digital testbench for the air brake system of freight trains. The test bench will serveto further improve the existing brake models at Transrail Sweden AB. Theseare used for the optimised calculation of train speed profiles by the DriverAdvisory System CATO. This work is based on the research of the technicalbackground, as well as the methodical approach to physical modelling anda modular implementation of the test bench. It gives full flexibility for thesimulation of customised train configurations using the European UIC brakesystem. Train length and vehicle arrangement can be adapted to the user’sspecific needs. For example, the test bench could be used for the simulation ofa train with distributed power. The system parameters are stored in a vehiclelibrary for the convenient generation of train configurations. This vehiclelibrary is freely expandable.The simulation is based on an equivalent electric circuit model which iscompleted with nozzle flow modelling. This model involves monitoring themain pipe, brake cylinder and reservoir pressure. Linear approximation is usedto obtain braking forces for the individual wagons and for the whole train. Thedepiction of the brake system behaviour is mostly accurate in the operationalscenarios, which is validated with measurement data. Additional calibrationis required for further reduction of the simulation errors and an extension ofthe model’s domain of validity. The test bench is developed by incrementaland iterative modelling and prepared for further improvements and variations,for example the adaption to the American AAR system variant.The presented work can also be used as a basis for similar implementationssuch as driving simulators. The methods are transferable to other applicationsof modular simulation.

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  • 42.
    Schick, Bastian
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Modelling Pantograph-Catenary Dynamic Interaction of Swedish Catenary Systems for High-Speed Operation2021Conference paper (Refereed)
  • 43. SJ Smith, Andrew
    et al.
    Odolinski, Kristofer
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Iwnicki, Simon
    Wheat, Phill
    Estimating the marginal maintenance cost of different vehicle types on rail infrastructure2021In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017Article in journal (Refereed)
    Abstract [en]

    In this paper, we combine engineering and economic methods to estimate the relative maintenance cost of different types of damage on the Swedish rail infrastructure. The engineering method is good at predicting damage from traffic, while the economic method is suitable for establishing a relationship between damage and cost. We exploit the best features of both methods in a two-stage approach and demonstrate its applicability for rail infrastructure charging, based on a sample of 143 track sections comprising about 11,000 km of track. The paper implements for the first time the method previously proposed in Smith et al., whilst also enhancing the method in several respects. We demonstrate how the estimated relative maintenance costs related to different damage mechanisms can be used to calculate the marginal cost of different vehicle types. The results are relevant for infrastructure managers in Europe who wish to differentiate their track access charges such that each vehicle pays its short run-marginal damage cost, which can support more efficient use of the rail infrastructure and influence vehicle design to minimize system costs.

  • 44. Song, Yang
    et al.
    Liu, Zhigang
    Rönnquist, Anders
    Navik, Petter
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Contact Wire Irregularity Stochastics and Effect on High-Speed Railway Pantograph-Catenary Interactions2020In: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 69, no 10, p. 8196-8206Article in journal (Refereed)
    Abstract [en]

    In high-speed rail operations, contact wire irregularity (CWI) in a catenary is a common disturbance to the pantograph-catenary interaction performance, which directly affects the quality of current collection. To describe the pointwise stochastics of CWI, the power spectral density (PSD) function for CWI is proposed, and its effect on the pantograph-catenary interaction is investigated. First, a preprocessing procedure is proposed to eliminate the redundant information in the measured irregularities based on the ensemble empirical mode decomposition (EEMD). Then, the upper envelope of the irregularity, which contains all the information regarding the dropper positions on the contact wire, is extracted. A form of the PSD function is suggested for contact wire irregularities. A methodology is proposed to include the effect of random irregularities in the assessment of the interaction performance of a pantograph-catenary. A developed target configuration under dead load (TCUD) method is used to calculate the initial configuration of the catenary, in which the dropper points on the contact wire are placed on their exact positions. Finally, the effect of the random contact wire irregularities on the contact force is investigated through 500 numerical simulations at each operating speed. The present results indicate that random irregularities have a direct impact on the pantograph-catenary contact, including an increment in the dispersion of the contact force statistics. The stochastic analysis shows that over 70% of the results with irregularities are worse than the ideal result without irregularities.

  • 45. Xu, Yan
    et al.
    Yang, Caijin
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Zhang, Weihua
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Long-Term High-Speed Train-Track Dynamic Interaction Analysis2021In: Proceeding of the 27th IAVSD Symposium on Dynamics of Vehicles on Roads and Tracks, 2021Conference paper (Refereed)
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  • 46.
    Zarov, Filipp
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Rail Vehicles.
    Life Cycle Cost of Smart Wayside Object Controller2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In a regional railway signalling system, object controllers are the devices responsible for controlling Track Side Equipment and act as interfaces for TSE with the interlocking computer and the Traffic control system. However, associated cabling (signal and power cabling) and civil works pose a major capital investment and it is a source of significant Capital and Operational expenses, particularly in rural areas, where accessibility andconnectivity to power grid and to the interlocking are a problem. Furthermore, cables/signalling equipment are exposed to sabotage and theft in such areas. This can increase the total Life Cycle Cost even further. The Shift2Rail research programme, which was initiated by the European Union and railway stakeholders, tries to address this issue, and revamp the Object Controller concept through the project “TD2.10 Smart radio connectedwayside object controller”, where the aim is to develop a Smart Wayside Object Controller (SWOC). A SWOC is capable of wireless communication between central interlocking and TSE as well as decentralization of interlocking logic. These innovations can reduce the cabling required, increase the availability of diagnostic data, thus reducing maintenance and operational costs and can lead to power saving by utilizing local power sources. The most important impact of the SWOC is a significant reduction of CAPEX, OPEX and of total LCC for an installation utilizing SWOCs, instead of typical OCS. 

    This work focuses on estimating the LCC of a SWOC system and to compare it with a conventional OCS by developing an LCC model that covers both cases, as well as to use this model to examine when it is more profitable to implement a SWOC, instead of an OCS system. This is done by utilizing LCC analysis and combining a variety of methods in a parametric study. To that extend, a thorough analysis of a modern regional railway signalling system, as well as the basis for LCCA are being discussed. At the same time, both OC and SWOC systems are being described and factors affecting their cost discussed. 

    The methodology is comprised of the LCC modelling part as well as the collection of methods and techniques used to calculate the LCC of OC/SWOC systems and to estimate the costs of different sub-models and parameters of the process. For the modelling process, the station of Björbo was chosen, which operates under ERTMS-R system, but for the sake of the analysis it is assumed that the typical base system in place is an OCS and together with the existing track layout and equipment it is used as the basis of the analysis. Finally, the formed LCC model is being used in a parametric study to examine how the LCC is affected by using OC or SWOC as well as how LCC responds to changes in parameters such as number of OC/SWOC, traffic density and local power installation cost for the Björbo station.

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