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  • 51.
    Enblom, Roger
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Impact of non-elliptic contact modelling in wheel wear simulation2008In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 265, no 9-10, p. 1532-1541Article in journal (Refereed)
    Abstract [en]

    Advances in simulation of railway wheel wear in the sense of material removal have drawn the attention to the importance of wheel–rail contact modelling. As a further step of enhancing the used simulation procedure in direction of increased generality and reduced need for application-dependent calibration, the focus of this investigation is the influence of non-elliptic contact models on the wheel wear rate and profile shape. To facilitate evaluation the semi-Hertzian contact procedure Stripes, developed by INRETS in France, has been implemented.

    To investigate the capabilities of Stripes to assess the contact area and pressure, shape comparisons have been made with other numerical methods for a set of wheel–rail contact situations. The referenced results are based on the linear elastic half-space assumption, elastic finite element analysis, and elastic–plastic finite element analysis. For reference also the elliptic contact area according to Hertz is shown as given by the contact data table of the multi-body simulation code.

    After exploring the properties of the Stripes procedure with respect to contact area estimation and pressure distribution, the focus is moved to the influence on wear rate, being the principal objective of this investigation. First the wear distribution over the contact patch is studied and compared to results using the elliptic model from the MBS code Gensys and the non-elliptic approach with Kalker's code Contact. Finally the evolution of the wheel profile is simulated for a few typical cases.

    This investigation of wear distributions over non-elliptic patches under different operating conditions indicates significant differences compared to both Contact and the applied Hertzian approach. The expansion from single contact occasions to complete simulations indicates comparable material removal rates but relocation towards the flange side. This tendency is apparent in all of the cases shown, however limited to initial wear in tangent run or reasonably mild curve negotiation.

  • 52.
    Enblom, Roger
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Proposed procedure and trial simulation of rail profile evolution due to uniform wear2008In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 222, no 1, p. 15-25Article in journal (Refereed)
    Abstract [en]

    A procedure for numerical simulation of rail wear and the corresponding profile evolution has been formulated. The wear is assumed to be uniform in the sense that the profiles remain constant along the track portion to be investigated. A simulation set is selected defining the vehicles running on the track, their operating conditions, and contact parameters. Several variations of input data may be included together with the corresponding occurrence probability.

    Simulation of multi-body dynamics is used to calculate contact forces and positions, and Archard's wear equation is applied for the calculation of wear depth. Wear coefficients as a function of contact pressure and relative sliding velocity are collected from different test results.

    Trial calculations of four non-lubricated and two lubricated curves with radii from 303 to 802 m show qualitatively reasonable results in terms of profile shape development and difference in wear mechanisms between gauge corner and rail head. The wear rates related to traffic tonnage are, however, overestimated and the lubrication efficiency underestimated.

    It is expected that model refinements in terms of environmental influence and contact stress calculation are useful to improve the quantitative results.

  • 53.
    Enblom, Roger
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Industrial implementation of novel procedures for the prediction of railway wheel surface deterioration2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, no 1-2, p. 203-209Article in journal (Refereed)
    Abstract [en]

    Adequate performance of the wheel-rail interface is essential for satisfactory operation of a railway system in terms of quality of service and maintenance effort. Pertinent requirements on efficiency tend to push the operation conditions towards higher loads and increased speed while the wheel-rail contact remains a small and highly stressed area. Dominating modes of deterioration due to high normal and tangential stresses are wear and rolling contact fatigue. Both kinds lead to surface material loss, in the former case as a slow rate profile geometry change with consequences to the dynamic performance and in the latter case different crack patterns and eventually spalling or shelling requiring reprofiling. In this paper the implementation of emerging technologies for the prediction of wheel surface deterioration in an engineering environment is summarised. Methods for the prediction of wear and profile geometry evolution as well as for the assessment of the risk for the onset of rolling contact fatigue are described. Example results from recent applications are given. In general it may be concluded that the implemented methods are becoming useful for the prediction of profile alterations, for instance hollow wear linked to conicity increase, and flange wear. The fatigue assessment methods are less mature and need further calibration but are still capable of indicating location and significance of risk for damage.

  • 54.
    Enblom, Roger
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Industrial implementation of novel railway wheel damage prediction procedures2009In: 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, 2009Conference paper (Refereed)
    Abstract [en]

    Adequate performance of the wheel-rail interface is essential for satisfactory operation of a railway system in terms of quality of service and maintenance effort. Pertinent requirements on efficiency tend to push the operation conditions toward higher loads and increased speed while the wheel-rail contact remains as a small and highly stressed area. Dominating modes of deterioration due to high normal and tangential stresses are wear and rolling contact fatigue. Both kinds lead to surface material loss, in the former case as a slow rate profile geometry change with consequences to the dynamic performance and in the latter case different crack patterns and eventually spalling or shelling requiring reprofiling.

    In this paper the implementation of emerging technologies for wheel damage prediction in an engineering environment is summarised. Methods for prediction of wear and profile geometry evolution as well as for assessment of the risk for onset of rolling contact fatigue are described. Example results from recent applications are given.

    In general it may be concluded that the implemented methods are becoming useful for prediction of profile alterations, for instance hollow wear linked to conicity increase and flange wear. The fatigue assessment methods are less mature and need further calibration but are still capable to indicate location and significance of risk for damage.

  • 55. Evans, J.
    et al.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Challenges in simulation of rail vehicle dynamics2009In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 47, no 8, p. 1023-1048Article in journal (Refereed)
    Abstract [en]

    Rail vehicle dynamic simulation has progressed a long way from its origins as a research tool. Modern multibody software packages are used as an essential part of the design process for new vehicles and for investigating service problems with existing vehicles. Increasingly, simulation is being used as part of the vehicle acceptance process in place of on-track testing. This state of the art paper for the 21st IAVSD Symposium in Stockholm in August 2009 surveys the current applications for rail vehicle dynamic modelling. The process of reducing a complex mechanical system to a mathematical representation is invariably subject to compromise and open to individual interpretation. The level of detail and choice of idealisation of suspension components will depend on the application, and in the real world it also depends on the availability of information about the system. This paper discusses appropriate modelling choices for different applications, and comments on best practice for the idealisation of suspension components, wheel/rail contact conditions and modelling inputs such as track geometry. The validation of simulation results is increasingly important, and this paper discusses recent trends in this area. Finally, the paper takes a brief look forward to future simulation issues.

  • 56.
    Favre, Tristan
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Diedrichs, Ben
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Efraimsson, Gunilla
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aeroacoustics.
    Detached-Eddy Simulations Applied to Unsteady Crosswind Aerodynamics of Ground Vehicles2010In: PROGRESS IN HYBRID RANS-LES MODELLING, Berlin: SPRINGER-VERLAG , 2010, Vol. 111, p. 167-177Conference paper (Refereed)
    Abstract [en]

    Crosswind stability is an important safety issue for manufacturers of cars, buses and rail vehicles. Since side wind conditions are unsteady phenomena they require time-dependent techniques to simulate the flow. In this study, a hybrid RANS-LES methods, Detached-Eddy Simulation, is applied to evaluate headwind and unsteady crosswind situations for a simple model of car. A grid refinement study is carried out to evaluate the accuracy of the calculations. Convergence in the force coefficients while refining the grid suggests that a certain level of grid convergence is reached. A similar conclusion is drawn from the unsteady simulations.

  • 57.
    Forsberg, Tobias
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Condition Monitoring of Train Ride Stability2007In: Proceedings of the 7th International Conference on Railway Bogies and Running Gears, BOGIE'07, Budapest, September 3-6, 2007, 2007, p. 271-280Conference paper (Refereed)
  • 58.
    Fröidh, Oskar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Transport planning.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Framtida trafikeringskostnader och utveckling av persontågsparken: Slutrapport2019Report (Other academic)
    Abstract [sv]

    Syftet med projektet och rapporten är att beräkna och redovisa trafikeringskostnader med typtåg som underlag för ASEK 7.0 i Trafikverkets kommande nationella trafik- och infrastrukturplanering, och att göra en bedömning av vilka framtida tågtyper som kan rulla på spåren.

    Projektets resultat är främst val av typtåg och de trafikeringskostnader för typtågen som presenteras i rapporten.

    En äldre modell för att beräkna trafikeringskostnader i persontrafik har uppdaterats och vidareutvecklats vid KTH till Costmodel PT. Denna modell har använts att beräkna kostnader för framtida typtåg. I vissa fall saknas motsvarande tågtyp i Sverige idag och det har också varit svårt att få tillgång till aktuella data genom kommersiell sekretess. Trots det har den kalibrering som gjorts mot tillgängliga verkliga värden visat på en relativt god överensstämmelse.

  • 59.
    Fröidh, Oskar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Kottenhoff, Karl
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Green Train concept and interior design2014In: International Journal of Rail Transportation, ISSN 2324-8378, Vol. 2, no 1, p. 28-39Article in journal (Refereed)
    Abstract [en]

    In the Green Train research programme, the objective is to develop an attractive trainconcept in the form of a concept proposal based on economic assessments. Green Trainis to be an attractive express train for both business and leisure-time travellers. Highstandards of comfort can be motivated by passengers’ willingness to pay. One fundamentalidea is the wide carbody for services in Scandinavia to achieve lower total costsfor train traffic than a carbody with a normal, quite narrow European continentalprofile. The trains are thereby made shorter and 2 + 3 seating arrangements areoptimised for optimal comfort. Another principle is that the train must be designedto allow punctual station stops, also during periods of peak load. Boarding andalighting must take place within very tight margins, which means that doors, entrancesand luggage racks must be in well-considered locations and correctly dimensioned.

  • 60.
    Gao, Shigen
    et al.
    Beijing Jiaotong Univ, State Key Lab Rail Traff Control & Safety, Beijing 100044, Peoples R China..
    Hou, Yuhan
    Beijing Jiaotong Univ, State Key Lab Rail Traff Control & Safety, Beijing 100044, Peoples R China..
    Dong, Hairong
    Beijing Jiaotong Univ, State Key Lab Rail Traff Control & Safety, Beijing 100044, Peoples R China..
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Ning, Bin
    Beijing Jiaotong Univ, State Key Lab Rail Traff Control & Safety, Beijing 100044, Peoples R China..
    High-Speed Trains Automatic Operation with Protection Constraints: A Resilient Nonlinear Gain-based Feedback Control Approach2019In: IEEE-CAA JOURNAL OF AUTOMATICA SINICA, Vol. 6, no 4, p. 992-999Article in journal (Refereed)
    Abstract [en]

    This paper addresses the control design for automatic train operation of high-speed trains with protection constraints. A new resilient nonlinear gain-based feedback control approach is proposed, which is capable of guaranteeing, under some proper non-restrictive initial conditions, the protection constraints control raised by the distance-to-go (moving authority) curve and automatic train protection in practice. A new hyperbolic tangent function-based model is presented to mimic the whole operation process of high-speed trains. The proposed feedback control methods are easily implementable and computationally inexpensive because the presence of only two feedback gains guarantee satisfactory tracking performance and closed-loop stability, no adaptations of unknown parameters, function approximation of unknown nonlinearities, and attenuation of external disturbances in the proposed control strategies. Finally, rigorous proofs and comparative simulation results are given to demonstrate the effectiveness of the proposed approaches.

  • 61.
    Gourdeau, Sarah
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Energy balance of a vehicle2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Simulation has become a very useful tool to predict the characteristics of a system and perform analysis of parameters without having to run too many tests. The advanced system engineering team of Continental Automotive uses a 0D simulation program, AMESim, to realize simulations of vehicle models. These simulations are used e.g. to predict the fuel consumption and CO2 emissions.

    A tool has been developed over the course of previous internships to realize the energy balance of AMESim vehicle models, which goal is to check the consistency of the models (no creation or loss of energy) and simplify their analysis. In this thesis, this tool has been further improved and developed through a comprehensive analysis. The computations have been checked and corrected to fit best with the AMESim results and obtain a consistent energy balance. The program has been adapted to hybrid vehicles and combustion losses computations were introduced. The program is coded in Matlab for the computations and in HMTL and JavaScript for the display.

    After the program was validated, it was used to realize a study on CO2 emissions. Three vehicle models were used. The influence of some parameters on the CO2 emissions was analyzed: the mass, aerodynamic resistance, rolling resistance, frictions and electric load. The aim of the study was to assess which parameters had the most influence on the CO2 emissions reduction in the perspective of the 95 g/km goal by 2020 set by the European Union. It was shown that the parameters have different effects on the vehicles CO2 emissions and that this effect varied from one vehicle to another. Substantial CO2 reduction can be achieved by improving some parameters, which makes it possible for the diesel vehicles to reach the 95 g/km in 2020 target set by the European Union. However, to achieve this goal with gasoline vehicles, the resort to hybridization will probably be needed. To assess the possible benefits of hybridization, a fourth vehicle model featuring mild hybridization was used.

    However, the decrease of CO2 emissions enabled by this type of hybrid vehicle would still not be sufficient to meet the 95 g/km target with gasoline vehicles.

  • 62.
    Hedberg, Ann-Sofie
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Economic evaluation of old and new locomotives2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Like any other business, a train operator is expected to make a profit and to make that profit as large as possible. The transportation market is highly competitive and it is therefore hard to increase the price of the transportation service. In order to maintain the profit margins focus needs to be on keeping the costs down. Therefore, in this thesis the cost side of freight train operation will be investigated. The main focus will be on the costs inflicted by the choice of locomotives. Locomotives are expensive and the capital cost usually makes up a significant portion of the total cost. It can therefore be tempting to buy older locomotives with lower capital cost. However, even though reducing the capital cost, using older locomotives might inflict other costs, such as higher maintenance costs.

    The aim of this thesis is to find the main cost drivers in freight train operation that is related to the choice of locomotive and to use that information to build a software tool that calculates if using old or new locomotives is more cost efficient for different scenarios.

    In order to identify the different factors that affect the cost of the railway operation, interviews were conducted with experts in different railway transportation fields. To complement the information from the experts, a literature survey was performed. Also, statistical data of the actual costs related to different locomotives was used.

    It was found that capital cost, energy, maintenance and repair, planning and administration, delays, infrastructure and drivers were important factors that affect the cost.

    Whether it is more cost efficient to use old or new locomotives depends mainly on the transportation service that should be provided. The marginal cost per kilometre is lower for new locomotives, however their capital cost is higher. This makes modern locomotives more suitable for transportation tasks that require that the locomotive runs long distances every year, whereas older locomotives are more suitable when shorter transportations are needed.

    Since the newer locomotives have higher tractive force and better slip control they can pull heavier trains. Therefore, depending on the mass of the train, fewer new than old locomotives can be used to pull the trains. In those cases it will be more cost-efficient to use new locomotives.

  • 63.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    An Investigation of the Iron-Ore Wheel Damages using Vehicle Dynamics Simulation2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Maintenance cost is one of the important issues in railway heavy haul operations. For the iron-ore company LKAB, these costs are mainly associated with the reprofiling and changing of the wheels of the locomotives and wagons. The main reason for the wheel damages is usually surface initiated rolling contact fatigue (RCF) on the wheels.The present work tries to enhance and improve the knowledge of the vehicle-track interaction of the Swedish iron-ore freight wagons and locomotives used at Malmbanan. The study is divided into two parts. Firstly, it is tried to get into the roots of RCF using the simulation model of the iron ore wagon (Paper A). Secondly, the study is focused on predicting wear and RCF on the locomotive wheels also via a dynamic simulation model (Paper B).In the first paper, some key issues of the dynamic modelling of the wagons with three piece bogies are first discussed and then parameter studies are carried out to find the most important reasons of wheel damages. These parameter studies include track design geometry, track irregularities, wheel-rail friction level, cant deficiency and track stiffness. The results show a significant effect of the friction level on the amount of RCF risk.As the locomotive wheel life is much shorter than that of the wagons, LKAB has decided to change the locomotive wheel profile. Two final wheel profiles are proposed; however, one had to be approved for the field tests. In the second paper, the long term evolution of the two profiles is compared via wear simulation analysis. Also, the RCF evolution on the wheel profiles as a function of running distance is discussed. The process is first carried out for the current locomotive wheel profiles and the results are compared with the measurements. Good agreement is achieved. Finally, one of the proposed profiles is suggested for the field test because of the mild wear and RCF propagation.

  • 64.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    On Heavy-Haul Wheel Damages using Vehicle Dynamics Simulation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Maintenance cost is one of the important issues in railway heavy-haul operations. In most of the cases, these costs are majorly referring to reprofiling and changing the wheels of the locomotives and the wagons. The main reason of the wheel damages is usually severe wear and/or surface initiated rolling contact fatigue (RCF).This work tries to enhance and improve the knowledge of the wheel wear and RCF prediction models using dynamic simulations. While most of the contents of this study can be generalised to other operational networks, this study is focused on the locomotives and wagons of the Swedish iron-ore company LKAB. The trains are operating on the approximately 500 km long IORE line from Luleå to Narvik in the north of Sweden and Norway respectively.Firstly, a literature survey of dynamic modelling of the wagons with various three-piece bogie types is presented. Then, with concentrating on the standard three-piece bogies, parameter studies are carried out to find out what the most important reasons of wheel damages are. Moreover, the long-term stability of wheel profiles of the IORE wagons is analysed. This is done by visualising the wear and RCF evolution on the wheel profiles over 150,000km of simulated running distance.Most of the calculations for the wagons are repeated for the locomotives. However, traction and braking are also considered in the simulation model and their effects on wheel damages are briefly studied. To improve the accuracy of the wheel damage analysis, a newly developed algorithm called FaStrip is used to solve the tangential contact problem instead of FASTSIM. The damage prediction model developed in the thesis is used to study the effects of increasing axle load, correcting the track gauge, limiting the electro-dynamic braking and using a harder wheel material on the wheel life. Furthermore, a new method is developed to predict the running distance between two consecutive reprofilings due to severe surface initiated fatigue. The method is based on shakedown analysis and laboratory tests.Most of the research works in wear calculation are limited to two approaches known as wear number and Archard methods. The correlation between these two methods is studied. The possibility of using the relation between the two methods for the wear calculation process is investigated mainly to reduce the calculation time for wheel profile optimisation models.

  • 65.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Fast Wear Calculation for Wheel Profile Optimization2015In: 10th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, Colorado Springs, August 30 - September 3, ​2015, 10th Contact Mechanics Conference , 2015Conference paper (Refereed)
  • 66.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Prediction of RCF  and Wear Evolution of Iron-Ore LocotomotiveManuscript (preprint) (Other academic)
  • 67.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Sichani, M. S.
    Prediction of rolling contact fatigue (RCF) for iron-ore locomotive wheels; comparison of an alternative contact algorithm with FASTSIM2018In: The Dynamics of Vehicles on Roads and Tracks, CRC Press/Balkema , 2018, p. 835-840Conference paper (Refereed)
    Abstract [en]

    In this article, a model to estimate the evolution of surface initiated Rolling Contact Fatigue (RCF) is developed and applied to a heavy haul locomotive. To consider the changes in the wheel profile due to wear, a methodology based on Archard’s wear calculation theory is used. The method is based on the load collective concept, which determines a set of dynamic time-domain simulations as representative for the line. For RCF calculations a shakedown based theory is applied locally, using the FaStrip algorithm to estimate the tangential stresses instead of FASTSIM. The differences between the two algorithms regarding damage prediction models are studied. The differences are due to the accumulation of the FASTSIM error in the long-term process. The simulated crack locations and their angles are compared with a five-year field study and good agreements are achieved.

  • 68.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Jönsson, Per-Anders
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Wheel damage on the Swedish iron ore line investigated via multibody simulation2014In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 228, no 6, p. 652-662Article in journal (Refereed)
    Abstract [en]

    The Swedish iron ore company LKAB uses freight wagons with three-piece bogies to transport iron ore from its mines in Kiruna and Malmberget to the ports at Lulea and Narvik. A simulation model of the freight wagon is built using the multibody simulation code GENSYS. The objective is to investigate possible sources of rolling contact fatigue (RCF) of the wheels given the high level of observed damage. A parameter study is performed on the effects of vertical track stiffness and viscous damping that occur as a result of seasonal variations of the track condition. Another parameter study is carried out on the influence of the wheel/rail friction coefficient as in winter time the climate is very dry along most parts of the Malmbanan line. The impact of track gauge, track quality and cant deficiency on RCF is also studied. Comparing the calculated and observed RCF locations on wheels, attempts are made to find a relation between wear number and RCF damage. To detect the surface-initiated fatigue a so-called shakedown map is used. It is shown that RCF occurs on the tread of the inner wheels while negotiating curves with below an approximately 450 m radius. It is also shown that cant deficiency can be helpful for the vehicles to negotiate curves and to reduce the risk of RCF, however, on the other hand it may increase the track forces and in severe cases result in flange climbing. Lateral track irregularities and a large track gauge result in small contact areas and can lead to a higher risk of RCF. In cold dry climate conditions, as the water content in air drops significantly, the wheel/rail friction coefficient increases and when the material in the wheel begins to behave in a brittle manner, the risk of RCF is significantly increased, especially when the wear rate is not high enough to remove the initiated cracks.

  • 69.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    S. Sichani, Matin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Wheel life prediction model – an alternative to the FASTSIM algorithm for RCF2018In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, no 7, p. 1051-1071Article in journal (Refereed)
    Abstract [en]

    In this article, a wheel life prediction model considering wear and rolling contact fatigue (RCF) is developed and applied to a heavy-haul locomotive. For wear calculations, a methodology based on Archard's wear calculation theory is used. The simulated wear depth is compared with profile measurements within 100,000km. For RCF, a shakedown-based theory is applied locally, using the FaStrip algorithm to estimate the tangential stresses instead of FASTSIM. The differences between the two algorithms on damage prediction models are studied. The running distance between the two reprofiling due to RCF is estimated based on a Wohler-like relationship developed from laboratory test results from the literature and the Palmgren-Miner rule. The simulated crack locations and their angles are compared with a five-year field study. Calculations to study the effects of electro-dynamic braking, track gauge, harder wheel material and the increase of axle load on the wheel life are also carried out.

  • 70.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Prediction of RCF and Wear Evolution of Iron-Ore Locomotive wheels2015In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 338-339, p. 62-72Article in journal (Refereed)
    Abstract [en]

    Locomotives for the iron ore line in northern Sweden and Norway have a short wheel life. The average running distance between two consecutive wheel turnings is around 40,000 km which makes the total life of a wheel around 400,000 km. The main reason of the short wheel life is the severe rolling contact fatigue (RCF). The train operator (LKAB) has decided to change the wheel profiles to get a better match with the rail shapes in order to decrease the creep forces leading to RCF. Two wheel profiles optimised via a genetic algorithm were proposed. They have, however, not been analysed for long term wear development. There is a risk that the optimised profiles might wear in an unfavourable way and after a while cause even higher RCF or wear than the original one. This study predicts wheel profile evolution using the uniform wear prediction tool based on Archard’s wear law. RCF evolution on the surface of the wheel profiles is also investigated. The impact of wear on polishing the wheel surface and avoiding the RCF cracks to propagate is considered via introducing a correction factor to the calculated RCF index. Traction and braking are also considered in the dynamic simulation model, where a PID control system keeps the speed of the vehicle constant by applying a torque on the loco wheels. The locomotives are also equipped with a flange lubrication system, therefore the calculations are performed both for lubricated and non-lubricated wheels. The simulation results for the wheel profiles currently in use, which are performed to validate the model and the simulation procedure, show a good agreement with the measurements. It is also concluded that the lubrication system partly does not perform as expected. Comparison between the proposed optimised profiles for their long term behaviour suggests that one of them produces less RCF and wear compared to the other one.

  • 71.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Nordmark, Thomas
    STUDY OF THE LONG TERM EVOLUTION OF LOW-RCF WHEEL PROFILES FOR LKAB IRON-ORE WAGONS2015Conference paper (Refereed)
  • 72.
    Hossein Nia, Saeed
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Jönsson, Per-Anders
    Nordmark, Thomas
    Bogojevic, Nebojsa
    Can Simulation Help to Find the Sources of Wheel Damages?: Investigation of Rolling Contact fatigue on the Wheels of a Three-Piece Bogie on the Swedish Iron ore Line via Multibody Simulation Considering Extreme Winter Condition2013In: Proceedings of the 10Th International Heavy Haul Association Conference IHHA, 2013, p. 357-363Conference paper (Refereed)
    Abstract [en]

    The Swedish iron ore company LKAB uses freight wagon with three-piece bogie to transport iron ore from the mines in Kiruna and Malmberget to Luleå and Narvik. A simulation model of the freight wagon has been built at KTH Rail Vehicles using the Multibody simulation code GENSYS. The purpose is to investigate possible sources of rolling contact fatigue (RCF) of the wheels given the high level of damage, particularly in the winter.The wooden sleeper track has recently been replaced by a stiffer track with concrete sleeper. After the change, the frequency of RCF increased. Therefore, both track models are implemented. A parameter study is performed on vertical track stiffness and viscous damping regarding the seasonal variations of the track conditions. Another parameter study is carried out on the influence of the wheel-rail friction coefficient because in winter time the climate is very dry along most parst of the Swedish iron-ore line. The impact of new and worn wheel profiles on RCF is investigated. The wear number is calculated and compared with the RCF probability.The shakedown map is used to study the influence of an increase in track forces on RCF. It is shown that RCF happens on the tread of the inner wheels while negotiating curves below approximately 450 m radius. And in cold dry climate conditions when the wheel-rail friction coefficient significantly increases and when the wheel material behaves more brittle, the risk of RCF is significantly increased while the wear rate is not high enough to wear out the initiated cracks. It is proven that using concrete sleepers and vertically stiffer track might increase the track forces but it cannot be the main reason for severe RCF during winter.

  • 73.
    Iwnicki, Simon
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Bezin, Yann
    Orlova, Anna
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Schelle, Henning
    The "SUSTRAIL" High Speed Freight Vehicle: Simulation of Novel Running Gear Design2013Conference paper (Refereed)
    Abstract [en]

    As part of the European Commission project ‘SUSTRAIL’ the authors together with other industry and academic partners are designing a freight vehicle optimised for the carriage of high value, low density, time sensitive products. A review of potential engineering innovations has been carried out and a vehicle is being designed based on optimised parameters for this combination of innovative technologies including radial steering, disk braking and optimised bogie frame structure. The results of the selection and optimisation of the running gear are presented heretogether with an assessment of the potential improvement in running behaviour and its impact on the railway system.

  • 74.
    Jans Bertilsson, Marcus
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Verication of simulated wheel-rail forces with measured data2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The purpose of this thesis was to verify the simulated wheel-rail forces from the simulation soft-ware Simpack by comparing the results with on-track measurements. The report constitutes a literature study on wheel-rail contact modelling and techniques for measurements of track forces and track irregularities. Furthermore, it describes the verification procedure itself and how the model was set up, and subsequently presents the results from the actual comparisons. Three versions of Simpack have been compared that utilize different types of contact models. Investigations on alternative ways of filtering track irregularities were conducted, and how the simulated forces were influenced by using worn wheel and rail profiles was also studied.The method was to realistically model the track sections in nine test cases with varying curve radii, considering the nominal track geometry and track irregularities. A vehicle model for the Regina 250 train was used for the simulations, which were then compared with the correspond-ing on-track measurements. Time histories and frequency contents were compared.It was found that the simulated wheel-rail forces correspond well to the measurements, at least for frequencies up to 5-10 Hz, and that no considerable deviations could be found when comparing the contact models. However, the simulation times differed and the discrete contact model introduced in Simpack 9.8 was particularly time demanding.The results shows that it is beneficial to filter the track irregularities before conducting simula-tions, since it saves simulation time while retaining an adequate accuracy of the track forces.The use of worn wheel and rail profiles could in this report not be shown to have any ma-jor impact on the wheel-rail forces, which is in contradiction with the hypothesis. However, it should be noted that the scope for this part was narrow and it merits a more thorough investigation.

  • 75. Jönsson, Per-Anders
    et al.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    On the Influence of Freight Traffic Operational Conditions on Track Deterioration Cost2009In: International Journal of COMADEM, ISSN 1363-7681, no 2, p. 3-9Article in journal (Refereed)
    Abstract [en]

    In order to increase the understanding of the running behaviour of freight wagons and the interaction between vehicles and track, a research project was started at KTH in 1996. The background to the initiation of the project were plans to increase axle load, loading gauge and speed of freight trains to make freight traffic on rail more competitive. In the present paper, the effect of different types of running gear and operational conditions on the track deterioration marginal cost in terms of settlement in the ballast, component fatigue and wear and RCF are investigated. Considerable differences in track deterioration cost per produced ton-km for the different types of running gear are observed. Axleload is an important parameter for settlement and component fatigue. Also the height of centre of gravity has significant influence on track deterioration, especially on track sections with high cant deficiency or cant excess.

  • 76.
    Jönsson, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Nilsson, Cecilia
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    CaPaSIM statement of methods2015In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, no 3, p. 341-346Article in journal (Refereed)
    Abstract [en]

    In the present paper, the method for calculation of the dynamic pantograph-catenary interaction developed by the Royal Institute of Technology and the Swedish National Rail/Road administration (Trafikverket) is described and the results of the benchmark exercise are discussed. The method is based on the commercial Finite Element software ANSYS. The geometry of the catenary and pantograph is defined in a pre-processor, BARTRAD, developed by Trafikverket, and is automatically translated into an ANSYS model. Basically all types of catenary systems could be handled as well as different types of non-linearity. There are both 2D and 3D versions of the code existing. The results achieved in this first stage of the benchmark are well in line with the results from the other partners in the benchmark study

  • 77.
    Jönsson, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Persson, Ingemar
    AB DEsolver, Östersund.
    New Simulation Model for Freight Wagons with UIC Link Suspension2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, no Suppl. S, p. 695-704Article in journal (Refereed)
    Abstract [en]

    The Previous freight wagon model developed at KTH is able to explain many of the phenomena observed in tests. In some cases. however, simulated and measured running behaviour differ. Therefore, in this paper, a new simulation model is presented and validated with on-track test results. The performance of standard two-axle freight wagons is investigated. The most important parameters for the running:behaviour of the vehicle are the suspension characteristics. The variation in characteristics between different wagons is large due to geometrical tolerances of the components, wear, corrosion, moisture or other lubrication. The influence of the variation in suspension characteristics and other Parameters oil the behaviour of the wagon on tangent track and in curves is discussed. Finally, suggestions for improvements of the system are made.

  • 78. Kabo, Elena
    et al.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Ekberg, Anders
    A simplified index for evaluating subsurface initiated rolling contact fatigue from field measurements2011In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 271, no 1-2, p. 120-124Article in journal (Refereed)
    Abstract [en]

    A previous simplification of the Dang Van equivalent stress measure for assessment of subsurface initiated rolling contact fatigue (RCF) related to wheel-rail contact is modified. The new criterion is intended for real-time assessment of subsurface RCF from measured wheel-rail contact forces. The only needed parameters in the new expression for the equivalent stress are the vertical force and the wheel and rail radii. Comparisons between the new and the original criterion are carried out and show good agreement for the studied cases of tangent track operations. By employing principles of vehicle dynamics the criterion is further extended to the case of operations in curves. Reasonable consistency was found for curve radii down to approximately 2000 m.

  • 79.
    Kabo, Elena
    et al.
    Chalmers Tekniska Högskola, Göteborg.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Ekberg, Anders
    Chalmers Tekniska Högskola, Göteborg.
    Assessing risks of subsurface initiated rolling contact fatigue from field measurements2009In: Proceedings of the 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems, 2009, p. 355-361Conference paper (Refereed)
    Abstract [en]

    A previous simplification of the Dang Van equivalent stress measure for cases of wheel–rail contact is modified. The new criterion is suited for real-time rolling contact fatigue assessment of measured wheel–rail contact forces. The only parameters in the new expression for the equivalent stress are the vertical force and the wheel and rail radii.Comparisons between the new and the original criterion are carried out and show good agreement for the studied cases of tangent track operation. By employing principles of vehicle dynamics the criterion is further extended to the case of operations in curves. Finally the influence of transient loads on the growth of RCF cracks in wheels was investigated. It was demonstrated that transients need to be spaced closer than roughly 10 meters to give any substantial increase in crack growth rates.

  • 80.
    Kahnert, Pascal
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Development and Optimisation ofInnovative Running Gear Conceptsfor an Ultra-High-Speed Train2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Since the last ten to 15 years, railway operators have to face new challenges which are an increased demand on comfort and high safety requirements, increased energy costs and the high competitive market situation. German Aerospace Center, DLR is designing a novel concept of an ultra-high-speed train with distributed propulsion system—the Next Generation Train (NGT). It consists of two Power units and eight powered intermediate cars. The intermediate cars are characterised by powered single-wheel single running gears supporting the low-floor concept within the whole train, re-sulting in both effective usage of the inner space but less space for the run-ning gears itself. Additionally, the traditional guiding system with wheel-sets cannot be applied.  The first goal of this Master’s thesis is the analysis of the state of the art for unconventional running and driving gears to get an overview of possi-ble and operating technologies. Based on this research and previous spec-ifications for the train, a technical specification for the running gear was created. This led to the development of a number of different concepts un-der consideration of the available space and an optimised arrangement of relevant components. After a conclusion and evaluation of these concepts, a CAD implementation of the relevant structural elements of the selected variant is the final goal of this thesis. Additionally to the technical specifi-cations, the focus lies on lightweight design to support the stringent weight concept of the NGT. However, the accessibility for assembling and mainte-nance is considered, too. The result is a CAD model of only one of doubtless more than a dozen possible variants. Hence, possible changes at specific parts are addressed; advantages and disadvantages were discussed. Finally, the concept was evaluated on the basis of the underlying technical specification.

  • 81.
    Karis, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Analysing the correlation between vehicle responses and track irregularities using dynamic simulations and measurementsManuscript (preprint) (Other academic)
  • 82.
    Karis, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Analysing the correlation between vehicle responses and track irregularities using dynamic simulations and measurements2019In: 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]

    Track irregularities play a key role in vehicle response, but it is not uncommon to find irregularities with similar statistical characteristics giving very different vehicle behaviour. It is therefore important to find a consistent way of describing track irregularities, which better matches the vehicle behaviour to facilitate an efficient track maintenance and vehicle acceptance testing. Various proposals have been made to resolve this issue, although with limited success. In the present paper, a methodology to break down the track–vehicle interaction into steps, by analysing the irregularity–response correlation in detail, is applied to both the measured and simulated data of a passenger coach. The results show a very good agreement and a high correlation coefficient between the vertical axle box acceleration and the second spatial derivative of the vertical track irregularities when analysing the simulated data, but not for the measured data. Parameter variations are carried out through simulations, in which the vertical track stiffness, vehicle unsprung mass, vertical primary suspension and different combinations of track irregularities are varied. The results show that track stiffness mainly affects the axle box acceleration whereas the primary vertical suspension stiffness and unsprung mass predominantly affect the vertical wheel–rail forces. Therefore, it is important to understand the influence of track stiffness, especially with the help of the measured data, and the methods that reduce its influence should be investigated in future works.

  • 83.
    Karis, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Li, M.
    Trafikverket, Borlange, Sweden..
    Thomas, D.
    SNC Lavalin, Bromma, Sweden..
    Dirks, B.
    Bombardier Transportat, Vasteras, Sweden..
    Correlation of track irregularities and vehicle responses based on measured data2018In: The Dynamics of Vehicles on Roads and Tracks, Vol 2 / [ed] Spiryagin, M Gordon, T Cole, C McSweeney, T, CRC Press/Balkema , 2018, Vol. 2, p. 1285-1290Conference paper (Refereed)
    Abstract [en]

    Track geometry quality and dynamic vehicle response are closely related, but do not always correspond with each other in terms of maximum values and standard deviations. This can often be seen to give poor results in analyses with correlation coefficients or regression analysis. Measured data from the EU project DynoTRAIN is used in this paper to evaluate track-vehicle response. A single degree of freedom model is used as inspiration to divide track-vehicle interaction into three parts, which are analysed in terms of correlation. One part, the vertical axle box acceleration divided by vehicle speed squared (z(w)/v(2)) and the second spatial derivative of the vertical track irregularities (z(t)''), is shown to be the weak link with lower correlation coefficients than the other parts. Future efforts should therefore be directed towards investigating the relation between axle box accelerations and track irregularity second derivatives, while also including more vehicles.

  • 84.
    Karis, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Li, Martin
    Trafikverket.
    Thomas, Dirk
    SNC-Lavalin.
    Dirks, Babette
    Bombardier Transportation.
    Correlation of track irregularities and vehicle responses based on measured data2018In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, no 6, p. 967-981Article in journal (Refereed)
    Abstract [en]

    Track geometry quality and dynamic vehicle response are closely related, but do not always correspond with each other in terms of maximum values and standard deviations. This can often be seen to give poor results in analyses with correlation coefficients or regression analysis. Measured data from both the EU project DynoTRAIN and the Swedish Green Train (Gröna Tåget) research programme is used in this paper to evaluate track–vehicle response for three vehicles. A single degree of freedom model is used as an inspiration to divide track–vehicle interaction into three parts, which are analysed in terms of correlation. One part, the vertical axle box acceleration divided by vehicle speed squared ((Formula presented.)) and the second spatial derivative of the vertical track irregularities ((Formula presented.)), is shown to be the weak link with lower correlation coefficients than the other parts. Future efforts should therefore be directed towards investigating the relation between axle box accelerations and track irregularity second derivatives.

  • 85.
    Karlsson, Henrik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Monitoring Vehicle Suspension Elements Using Machine Learning Techniques2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Condition monitoring (CM) is widely used in industry, and there is a growing interest in applying CM on rail vehicle systems. Condition based maintenance has the possibility to increase system safety and availability while at the sametime reduce the total maintenance costs.This thesis investigates the feasibility of using condition monitoring of suspension element components, in this case dampers, in rail vehicles. There are different methods utilized to detect degradations, ranging from mathematicalmodelling of the system to pure "knowledge-based" methods, using only large amount of data to detect patterns on a larger scale. In this thesis the latter approach is explored, where acceleration signals are evaluated on severalplaces on the axleboxes, bogieframes and the carbody of a rail vehicle simulation model. These signals are picked close to the dampers that are monitored in this study, and frequency response functions (FRF) are computed between axleboxes and bogieframes as well as between bogieframes and carbody. The idea is that the FRF will change as the condition of the dampers change, and thus act as indicators of faults. The FRF are then fed to different classificationalgorithms, that are trained and tested to distinguish between the different damper faults.This thesis further investigates which classification algorithm shows promising results for the problem, and which algorithm performs best in terms of classification accuracy as well as two other measures. Another aspect explored is thepossibility to apply dimensionality reduction to the extracted indicators (features). This thesis is also looking into how the three performance measures used are affected by typical varying operational conditions for a rail vehicle,such as varying excitation and carbody mass. The Linear Support Vector Machine classifier using the whole feature space, and the Linear Discriminant Analysis classifier combined with Principal Component Analysis dimensionality reduction on the feature space both show promising results for the taskof correctly classifying upcoming damper degradations.

  • 86. Knothe, Klaus
    et al.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Dietz, Stefan
    Konzept für einen Betriebsfestigkeitsnachweis aufgrund gekoppelter FE-MKS-Simulationsrechnungen1996In: Konstruktion, Vol. 48, p. 35-39Article in journal (Refereed)
  • 87.
    Krishna, Visakh V
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    FR8RAIL Y25 running gear for high tonnage and speed2019In: Proceeedings of the International Heavy Haul Association STS Conference 2019 / [ed] P.O. Larsson-Kråik, A. Ahmadi, Narvik, 2019, p. 690-697Conference paper (Refereed)
    Abstract [en]

    The rolling stock in railway freight transport has traditionally been mainly characterised by lowcost, long lifetime of the fleet, and relatively low requirements on running behaviour. However, the sector inEurope has acknowledged that in order to be competitive there is a need to develop more advanced wagons thatenable to maximise payload and speed in different scenarios, while reducing the overall system costs, includingwheelset and track deterioration. In the Shift2Rail project FR8RAIL, a consortium of wagon manufacturers,wheelset manufacturers, and research centres has worked to develop a new generation of the widely used robustY25 freight running gear, that minimises maintenance costs both on the vehicle and the track by improving thecurving performance and hunting stability. The dynamic behaviour of the proposed solutions has been studiedwith simulations-based EN14363 tests up to 30 tons/axle, and their expected impact on wheel wear and fatiguehas also been predicted, with satisfactory results regarding both damage modes.

  • 88.
    Larsson, Kristina
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Wheel damage and maintenance of SCA Skog wagons2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the SCA Skog wagon fleet run by Hector Rail, wheel damages are a serious problem all year. The goal of this work is to find out why, and what changes can be made to decrease them. For comparison, Hector Rail does run the same sgnss type wagons for two other customers (Stora Enso and SCA Logistics), and those are much less damaged. This makes it possible to compare the different attributes of the customers’ wagon traffics to single out the influencing factors. The SCA Skog damages are almost only wheel flats. In Stora Enso there are a few wheel flats while in SCA Logistics there is almost none. Wheel flats can only occur if a wheelset is blocked in a moving vehicle. That could however be due to a few different reasons.

    Studying data from workshops and automatic detectors, it was found that most flats occur in the ends of the trains. Some other patterns were that the inner wheelsets on wagons had less flats, and Stora Enso wagons temporarily moved to the SCA Skog network had less flats too. Therefore, the similarities and differences between these networks are studied and classified regarding their influence on wheel damage, and several different actions are suggested afterwards to decrease the number of flats. For the flats in the ends of the train is the remedy to teach the drivers the second, but better, driver valve RHZE2. Another remedy for the same purpose is to implement an end-of-train device that measures air pressure in the end of the train. That the inner wheelsets cope better is probably because one of two brake blocks there cannot freeze to the wheel. Therefore one action is to prevent running with frozen brake blocks by for example moving the train back and forth at red light. Lastly, when it comes to the Stora Enso wagons they probably break free from ice easier as they are heavier, so an extra wall added on the SCA Skog wagons might improve the situation.

  • 89. Li, M. X. D.
    et al.
    Berggren, E. G.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Assessment of vertical track geometry quality based on simulations of dynamic track-vehicle interaction2009In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 223, no 2, p. 131-139Article in journal (Refereed)
    Abstract [en]

    A study assessing vertical track geometry quality based on simulations of dynamic track-vehicle interaction is presented in this article. The dynamic model is composed of track, vehicle, and wheel-rail contact with moving irregularities and is solved in the frequency domain by fast Fourier transform or in the time domain by constructing a filter function based on system identification. Frequency-dependent stiffness and loss factor of railpads are used in this study. Numerical simulations are carried out for a 120 km long track to demonstrate the potential benefits of enhancing track quality assessment by calculating wheel-rail forces.

  • 90. Li, M. X. D.
    et al.
    Berggren, E. G.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Persson, I.
    Assessing track geometry quality based on wavelength spectra and track-vehicle dynamic interaction2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, no Suppl. S, p. 261-276Article in journal (Refereed)
    Abstract [en]

    This paper presents a study of assessing track geometry quality (longitudinal level and alignment) by the use of dynamic track-vehicle simulations and wavelength spectra analysis. Two simulation models are developed: one is based on the software package GENSYS, which provides realistic simulations of the nonlinear dynamic behaviour of a vehicle running on real track. and (he other one is based on a newly developed linear track-vehicle model. which is Suitable for effectively calculating wheel-rail forces for very long track sections. The linear model. first proposed in 11,21 to assess vertical track geometry quality (longitudinal level), is extended in the present paper to simulate lateral track-vehicle dynamic interaction and, thus, to assess lateral track geometry quality (alignment) as well. Numerical results are presented to compare the simulation results with online measurement and to demonstrate the possibilities of enhancing track quality assessment and maintenance by simulations of track-vehicle interaction.

  • 91. Li, Martin
    et al.
    Persson, Ingemar
    Spännar, Jan
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    On the use of second-order derivatives of track irregularity for assessing vertical track geometry quality2012In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 50, no SUPPL. 1, p. 389-401Article in journal (Refereed)
    Abstract [en]

    This paper studies the use of second-order derivatives of track irregularities (longitudinal level, LL) for assessing vertical track geometry quality. Both a single-degree-of-freedom and a three-DOF vehicle-track model are investigated in order to explain theoretically why from the aspect of vehicle-track dynamic interaction it is relevant to consider not only the amplitudes of LL but also their second-order derivatives (LL2). Simulation results are then presented to demonstrate that dynamic vertical track forces are more correlated with the second-order derivatives (LL2) than to the amplitudes (LL) themselves. A comparison of the power spectral density (PSD) spectra for typical track reveals that it is more convenient to use the PSD spectra for the second-order derivatives than for the amplitudes, as the curves for the second-order derivatives are flat within the short wavelength range. Finally, the practical use of derivatives within the maintenance management system in order to achieve improved assessment of track geometry quality is also discussed.

  • 92.
    Li, Y.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Sichani, M.S.
    Influence of an alternative non-elliptic contact model on wheel wear calculation2018In: The Dynamics of Vehicles on Roads and Tracks, CRC Press, 2018, Vol. 2, p. 937-943Conference paper (Refereed)
    Abstract [en]

    The contact model between wheel and rail is significant for predicting wear of the wheel profile with help of multi-body dynamics simulation. Among the contact models, Hertz’s theory and Fastsim algorithm are widely used in MBS software due to high computational efficiency and acceptable precision. But with respect to wear, the accuracy of such a contact model is insufficient, especially for predicting the wear distribution. A new non-elliptic contact model called ANALYN/FaStrip with fast calculation speed has been proposed to improve the precision for both normal and tangential solutions. This paper investigates the influence of this new contact model on the wear calculation by comparing with Hertz/Fastsim in terms of contact pressure and creep forces, and finally indicates the difference of wear depth calculated by the two contact models. The results illustrate that significant improvements can be gained by implementing ANALYN/FaStrip into the wheel wear prediction.

  • 93.
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Measures to Enhance the Dynamic Performance of Railway Catenaries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The pantograph-catenary system is used in railways to transfer electric power from infrastructure to trainset. As the pantograph slides against the catenary, the contact between the two surfaces is not stable due to stiffness variation, propagating wave and other environmental perturbation, especially at high speeds or in multi-pantograph operation. Heavy oscillation can result in poor power-transmission quality, electromagnetic interference, severe wear or even structural damage. So the pantograph-catenary dynamics has become one of the key issues which limits the operational speed and determines the maintenance cost. There are many types of catenary systems in Sweden, which are relatively soft and sensitive compared with the systems in other countries. They work well at low operational speed and have strict limitations to multi-pantograph operation. It is possible to achieve an operational speed of 350 km/h on newly-built high-speed lines, but there is still a large demand for higher operational speed and more capacity on the existing lines.

        Many researchers and engineers have made progress to improve its dynamic performance. From the research aspect, many numerical models have been built up to demonstrate the dynamics of the pantograph-catenary system and to unveil the key influencing factors. There have been many applications developed in recent years. Regarding the catenary, high-tensile loads on the catenary and low-stiffness-variation designs are widely used to improve the dynamic performance. Regarding the pantograph, aerodynamic-friendly designs and active-control technique contribute to the development of high-speed pantograph. But all these methods need not only large investment but long out-of-service. Considering the large scale and heavy service duty of the existing lines, it becomes almost impossible to completely upgrade the existing pantograph-catenary systems. So it is necessary to find practical and efficient methods to exploit the potentials of the existing systems to enhance their dynamic performances.

        This thesis investigates the dynamic behaviour of the Swedish pantograph-catenary systems and proposes methods for better usage. A numerical study on multi-pantograph operation is performed and the relationships between dynamic performance and some key parameters is established. By studying the multi-pantograph operation at short spacing distance, a method to use the leading pantograph as auxiliary pantograph is proposed to increase the operational speed on the soft catenary system. To ensure operational safety in abnormal conditions, numerical studies on pantograph raising/lowering processes and in catenary overlap sections are performed. By studying the influence of the lumped-mass on the dynamic performance, it shows that it is even possible to implement some artificial tuned-masses on the catenary for dynamic optimization.

  • 94.
    Liu, Zhendong
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Numerical study on multi-pantograph railway operation at high speed2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Multi-pantograph operation allows several short electric multiple unit (EMU) trainsets to be coupled or decoupled to adapt to daily or seasonal passenger-flow variation. Although this is a convenient and efficient way to operate rolling stock and use railway infrastructure, pantographs significantly influence each other and even significantly change the dynamic behaviour of the system compared to single-pantograph operation in the same condition. The multi-pantograph system is more sensitive and vulnerable than the single-pantograph system, especially at high operational speeds or with pantographs spaced at short distances. Heavy oscillation in the system can result in low quality of current collection, electromagnetic interference, severe wear on the contact surfaces or even structural damage. The mechanical interaction between the pantograph and the catenary is one of the key issues which limits the maximum operational speed and decides the maintenance cost.

        Many researchers have paid a lot of attention to the single-pantograph operation and have made great progress on system modelling, optimizing, parameter studies and active control. However, how the pantographs in a train configuration affect each other in multi-pantograph operation and which factors limit the number of pantographs is not fully investigated. Nowadays, to avoid risking operational safety, there are strict regulations to limit the maximum operational speed, the maximum number of pantographs in use, and the minimum spacing distance between pantographs. With the trend of high-speed railways, there are huge demands on increasing operational speed and shortening spacing distance between pantographs. Furthermore, it is desirable to explore more practical and budget-saving methods to achieve higher speed on existing lines without significant technical modification.

        In addition to a literature survey of the dynamics of pantograph-catenary systems, this thesis carries out a numerical study on multi-pantograph operation based on a three-dimensional pantograph-catenary finite element (FE) model. In this study, the relationship between dynamic performance and other parameters, i.e. the number of pantographs in use, running speed and the position of the pantographs, are investigated. The results show that the spacing distance between pantographs is the most critical factor and the trailing pantograph does not always suffer from deterioration of the dynamic performance. By discussing the two-pantograph operation at short spacing distances, it is found that a properly excited catenary caused by the leading pantograph and the wave interference between pantographs can contribute to an improvement on the trailing pantograph performance. To avoid the additional wear caused by poor dynamic performance on the leading pantograph and achieve further improvement at high speeds, it is suggested to use the leading pantograph as an auxiliary pantograph, which does not conduct any electric current and optimize the uplift force on the leading pantograph. After a brief discussion on some system parameter deviations, it is shown that a 30% of speed increase should be possible to achieve while still sustaining a good dynamic performance without large modifications on the existing catenary system.

  • 95.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Rønnquist, Anders
    Dep artment of Structural Engineering, NTNU Norwegian University of Science and Technology, Norway.
    Implications of the operation of multiple pantographs on the soft catenary systems in Sweden2015In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 53, no 3, p. 341-346Article in journal (Refereed)
    Abstract [en]

    Trains operating with several pantographs are used in Sweden and other countries. The more complex operational conditions, however, cause additional difficulties, i.e. low quality of current collection, increased mechanical wear and electromagnetic interference, due to the poor dynamic behaviour of the system. In order to address these problems, a three-dimensional model for the computational analysis of the interaction between catenary and pantograph is presented and validated in this paper, and the dynamic behaviour of the multi-pantograph system, based on Swedish soft pantograph/catenary systems, is analysed. Parametric studies are performed to investigate cases with different distances between pantographs and with up to three pantographs in use. The relationship between dynamic performance and other parameters, i.e. the number of pantographs in use, running speed and the position of the pantographs, is studied. The results show that an appropriate distance between pantographs and a given type of catenary allow operation on the existing infrastructure with up to three pantographs while maintaining an acceptable dynamic performance at the desired speed.

  • 96.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Rønnquist, Anders
    Dep artment of Structural Engineering, NTNU Norwegian University of Science and Technology, Norway.
    Possible speed increase on soft catenary system with help of auxiliary pantograph2016In: The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics, IAVSD 2015, CRC Press, 2016, no 3, p. 927-936Conference paper (Refereed)
    Abstract [en]

    Stiffness variations and wave propagation in the catenary system cause high dynamic variations in the contact force between pantograph and catenary at high operating speeds. In order to increase the operational speed on an existing catenary system, especially on soft catenary systems, technical upgrading is usually required to keep the current collection quality within an acceptable range. Therefore, it is desirable to explore a more practical and costsaving method to achieve higher operational speed. With the help of a 3D pantograph-catenary finite element (FE) model, a parametric study on two-pantograph operation at short spacing distances is carried out. Results show that although the leading pantograph suffers from deterioration of dynamic performance, the trailing pantograph achieves a better dynamic behaviour by using a proper spacing distance between pantographs. To avoid the additional wear caused by poor dynamic performance on the leading pantograph, it is suggested to use the leading pantograph as an auxiliary pantograph, which does not conduct any electric current. In this way, the operational speed of the existing system can be increased while still sustaining a good dynamic performance without large modifications on the existing catenary system.

  • 97.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Rønnquist, Anders
    NTNU Norwegian University of Science and Technology.
    Application of tuned-mass system on railway catenary to improve dynamic performanceIn: Article in journal (Other academic)
    Abstract [en]

    Finding a simple and practical method to improve the dynamic behaviour of a specific structure is always desirable in civil and mechanical engineering. The railway catenary system is the overhead power line above the track, interacting with the train-based pantograph to transfer electric power. Due to vertical stiffness variation and a propagating wave along the catenary, the fluctuation of the contact force becomes significant with operational speed increasing. Therefore, this has become one of the key factors which limits the operational speed and service life of key components. Wire misalignment, structural errors and uneven mass distribution of the catenary can further deteriorate the contact stability. In order to achieve a higher speed on existing lines, the catenary needs large-scale modification implying long out-off-service time. From the designing aspect, all components directly fixed to the catenary, like clamps, steady arms and other fittings, are made as light and small as possible to minimize disturbances. However, in other engineering applications, some well-designed additional mass systems are adopted aiming to improve their dynamic performance. In order to take advantage of these unavoidable masses on the catenary, an investigation on lumped-mass distribution in single-pantograph and multi-pantograph operations is performed with help of a 3D pantograph-catenary finite element (FE) model. The results show that a rightly-tuned mass, here the implementing location and the elasticity of its connection, can positively change the dynamic performance without implementing large-scale modification to the existing system. Through a brief discussion on the mechanism of this positive effect, this paper proposes that applying some artificial tuned-mass system can be a possible method to overcome unfavourable working conditions or even allow speed increase on existing lines.

  • 98.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Rønnquist, Anders
    NTNU Norwegian University of Science and Technology.
    Dynamic optimization of railway catenary system by turning unwanted lumped-mass into tuned-mass2018In: Dynamic optimization of railway catenary system by turning unwanted lumped-mass into tuned-mass, CRC Press/Balkema , 2018, Vol. 2, p. 675-680Conference paper (Refereed)
    Abstract [en]

    The railway catenary is suspended to its supports with droppers, clamps and oth-er fittings. These lumped-masses are made light and small to minimize disturbances. The mass-es cannot be completely removed but can be adjusted during maintenance. In other technical systems, artificial mass is used to improve the dynamic behaviour. Therefore, in this study the relationship between the lumped-mass distribution and its dynamic behaviour is investigated. Based on a 3D pantograph-catenary finite element (FE) model, a parametric study on the lumped-mass distribution on the Swedish soft catenary system is performed by applying addi-tional lumped-mass to different positions. It is shown that the mass distribution affects the dy-namic performance and in some cases, can improve the dynamic performance. The influence becomes stronger in multi-pantograph operation. Installing these masses on the messenger wire can avoid hard-point effects. In this way, the artificial mass can be used to improve the dynamic performance or correct some structural defects.

  • 99.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Rønnquist, Anders
    Dep artment of Structural Engineering, NTNU Norwegian University of Science and Technology, Norway.
    Numerical study on pantograph raising and lowering in multi-pantograph operationIn: The international Journal of railway technology, ISSN 2049-5358, E-ISSN 2053-602X, no 3Article in journal (Other academic)
    Abstract [en]

    Multi-pantograph operation is a convenient and efficient way to operate railway rolling stock, 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 in 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 pantograph configuration, then disrupting the dynamic stability. To address the dynamic performance during pantograph raising and lowering, a numerical study on multi-pantograph operation is carried out with help of a 3D pantograph-catenary finite element (FE) model under the conditions: up to three pantographs, 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, any trailing pantograph is significantly affected by any operation taking place 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.

  • 100.
    Lukaszewicz, Piotr
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    A simple method to determine train running resistance from full-scale measurements2007In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 221, no 3, p. 331-338Article in journal (Refereed)
    Abstract [en]

    This article proposes a simple method to determine train running resistance. The resistance is determined by calculating the change in kinetic and potential energy of a coasting train between successive measurement positions. The strength of this method is that the measuring equipment needed is kept at a minimum and it is not limited to a track having a constant grade, thus making this method suitable, in particular, for long freight trains running in mountain areas. An error analysis is performed for this method and the probable error sources are discussed.

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