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  • 1. Bucca, Giuseppe
    et al.
    Carnevale, Marco
    Collina, Andrea
    Facchinetti, Alan
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Adoption of different pantographs' preloads to improve multiple collection and speed up existing lines2012In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 50, no SUPPL. 1, p. 403-418Article in journal (Refereed)
    Abstract [en]

    The current collection using more than one pantograph is needed in railway operation to provide power to non-electrically connected traction units and, in some cases, to reduce current density on the collector strips that heavily influences the wear on the contacting bodies. The multiple current collection may become a critical condition due to the mechanical disturbances produced on the trailing pantographs by the interaction between the first pantograph and the catenary. The present-day evolution of pantograph preload regulating systems, exploiting pressure-controlled servo-valves driven by electronic units, allows a diversification of the preloads of front and rear pantographs. In this work, a suitable solution to improve multiple pantograph collection quality is analysed by the use of a lower mean force on the leading pantograph aimed at reducing the oscillations of contact wire the trailing pantograph is subjected to. This would improve the current collection quality of the trailing pantograph, and could be pursued even admitting a slight worsening of front pantograph's performances.

  • 2. Bucca, Guiseppe
    et al.
    Carnevale, Marco
    Collina, Andrea
    Facchinetti, Alan
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Jönsson, Per-Anders
    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.
    Differentiation of pantographs’ preloads as a mean to improve multiple collection and speed upexisting lines2011In: Proceedings of 22nd Symposium of the International Association for Vehicle System Dynamics / [ed] Simon Iwnicki, 2011Conference paper (Refereed)
  • 3.
    Casanueva, Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Doulgerakis, Emmanouil
    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.
    Influence of switches and crossings on wheel profile evolution in freight vehicles2014In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 52, no SI, p. 317-337Article in journal (Refereed)
    Abstract [en]

    Wheel reprofiling costs for freight vehicles are a major issue in Sweden, reducing the profitability of freight traffic operations and therefore hindering the modal shift needed for achieving reduced emissions. In order to understand the damage modes in freight vehicles, uniform wear prediction with Archard's wear law has been studied in a two-axle timber transport wagon, and simulation results have been compared to measurements. Challenges of wheel wear prediction in freight wagons are discussed, including the influence of block brakes and switches and crossings. The latter have a major influence on the profile evolution of this case study, so specific simulations are performed and a thorough discussion is carried out.

  • 4.
    Casanueva, Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Jönsson, Per-Anders
    Tikab Strukturmekanik AB.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    influence of switches and crossings on wheel profile evolution in freight vehicles2013In: Proceedings of the 23nd IAVSD Symposium on Dynamics of Vehicles on Roads and Tracks / [ed] Simon Iwnicki, Taylor & Francis, 2013Conference paper (Refereed)
  • 5.
    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.

  • 6.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Dynamic Vehicle-Track Interaction of European Standard Freight Wagons with Link Suspension2007Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The link suspension is the most prevailing suspension system for freight wagons in Central and Western Europe. The system design is simple and has existed for more than 100 years. However, still its characteristics are not fully understood. This thesis investigates the dynamic performance of freight wagons and comprises five parts:

    In the first part a review of freight wagon running gear is made. The different suspension systems are described and their advantages and disadvantages are discussed.

    The second part focuses on the lateral force-displacement characteristics of the link suspension. Results from stationary measurements on freight wagons and laboratory tests of the link suspension characteristics are presented. To improve the understanding of various mechanisms and phenomena in link suspension systems, a simulation model is developed.

    In the third part the multibody dynamic simulation model is discussed. 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, a new simulation model is presented and validated against 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 on the behaviour of the wagon, on tangent track and in curves, is discussed. Finally, suggestions for improvements of the system are made.

    A majority of the traffic related track deterioration cost originates from freight traffic. With heavier and faster freight trains the maintenance cost is likely to increase. In the fourth part the possibility to improve ride comfort and reduce track forces on standard freight wagons with link suspension is discussed. The variation of characteristics in link suspension running gear is considerable and unfavourable conditions leading to hunting are likely to occur. Supported by on-track tests and multibody dynamic simulations, it is concluded that the running behaviour of two-axled wagons with UIC double-link suspension as well as wagons with link suspension bogies (G-type) can be improved when the running gear are equipped with supplementary hydraulic dampers.

    Finally in the fifth part the effects of different types of running gear and operational conditions on the track deterioration marginal cost — in terms of settlement in the ballast, component fatigue, wear and RCF — is investigated. Considerable differences in track deterioration cost per produced ton-km for the different types of running gear are observed. Axle load 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.

  • 7.
    Jönsson, Per-Anders
    KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
    Freight Wagon Running Gear - a review2002Report (Other academic)
    Abstract [en]

    This review covers firstly the development of the three running gear standardized by the UIC and the conventional three-piece bogie. The different suspension systems are described and their advantages and disadvantages are discussed. Five improved three-piece bogies and twelve recently developed running gear are also presented.

    An overview of the guiding mechanisms for a wheelset is made. The running gear in this study are grouped into three categories according to their primary suspension and principle for wheelset guidance:

    Stiff wheelset guidance.

    Soft wheelset guidance.

    Soft wheelset guidance with inter-axle linkage.

    and in case of bogie running gear in two categories according to the frame design:

    Horizontally stiff frame.

    Horizontally lozenging frame.

    Advantages and disadvantages, as far as known, with the different principles are discussed.

  • 8.
    Jönsson, Per-Anders
    KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
    Modelling and laboratory investigations on freight wagon link suspensions with respect to vehicle-track dynamic interaction2004Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    The link suspension is the most prevailing suspension system for freight wagons in central and western Europe. The system design is simple and has existed for more than 100 years. However, still its characteristics are not fully understood. This thesis emphasizes freight wagon dynamics and comprises three parts:

    In the first part a review of freight wagon running gear is made. The different suspension systems are described and their advantages and disadvantages are discussed. The review covers the running gear standardized by UIC and the conventional so-called three-piece bogie. Additionally five improved three-piece bogies and twelve novel running gear designs are presented.

    The second part focuses on the lateral force-displacement characteristics in the link suspension. Results from stationary measurements on freight wagons and laboratory tests of the link suspension characteristics are presented. To improve understanding of the various mechanisms and phenomena in link suspension systems a simulation model is developed. Link suspension systems have strongly nonlinear characteristics including a hysteresis loop. The loop exhibits usually three characteristic sections with different tangential stiffnesses. The actual contact geometry of the links and end bearings has a significant influence on the characteristics. By wear in ordinary service - as well as by geometric tolerances on new components - the contact geometry may deviate considerably from nominal geometry. Further, it seems that elastic deformation in the contact surfaces has considerable effects on the suspension characteristics, in particular on the initial rolling stiffness for small displacements. Also, flexibilities in links and end bearings influence the characteristics. It is also observed that new components after a short period of dynamic testing can exhibit a very low amount of energy dissipation, a phenomenon that is also indicated in some stationary measurements on wagons.

    To summarize the second part, it appears that the link suspension characteristics are very sensitive to several factors being hard to control in the real world of freight wagon operations. The various stiffnesses and hysteresis loops have a considerable variation and may have a strong influence on the ride qualities of vehicles. As long as the characteristics can not be controlled within closer limits than found in this study, there is a strong need for sensitivity analysis to be made, both in predictive multibody simulations of vehicle dynamics, as well as in verification and acceptance tests.

    In the third part a study on the possibility to improve ride qualities of freight wagons with link suspensions is presented. Parametric studies with multibody dynamic simulations on freight wagons equipped with link-suspension bogies are performed. The effect of supplementary friction and hydraulic damping is investigated under various running conditions: speed, loading, tangent and curved track, wheel-rail contact geometry, track gauge and track irregularities. Substantial improvements of the lateral running behaviour of wagons with link suspension bogies can be achieved - both at ordinary speeds and at increased speeds - by using a proper combination of supplementary hydraulic dampers. Speeds up to 160 km/h could be realistic.

  • 9.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Multibody simulation model for freight wagons with UIC link suspension2007Report (Other academic)
    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 on the behaviour of the wagon on tangent track and in curves is discussed. Finally, suggestions for improvements of the system are made.

  • 10.
    Jönsson, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Experimental and Theoretical Analysis of Freight Wagon Link Suspension2006In: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit, ISSN 0954-4097, E-ISSN 2041-3017, Vol. 220, no 4, p. 361-372Article in journal (Refereed)
    Abstract [en]

    Link suspension is the most prevailing suspension system for two-axle freight wagons and still frequently used for four-axle freight wagons in central and western Europe. The system design is simple and has existed for more than 100 years. However, still, the characteristics are not fully understood. This article focuses on the lateral characteristics of the link suspension. First, results from stationary measurements on freight wagons and laboratory tests on single links are presented. Then, a simulation mathematical model is proposed. Finally, the influence of various parameters on the link characteristics is investigated. With the developed simulation model, many of the stability problems of link suspension running gears can be explained, but further research is needed to fully understand the characteristics and to be able to recommend improvements. From the tests, it also becomes obvious that the characteristics of different links can vary significantly from each other depending on age and maintenance status.

  • 11.
    Jönsson, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Influence of link suspension characteristics variation on two-axle freight wagon dynamics2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, no Supplement 1, p. 415-423Article in journal (Refereed)
    Abstract [en]

    The link suspension is the most prevailing suspension system for freight wagons in central and western Europe. Link suspension systems have strong non-linear characteristics including a hysteresis loop. The loop exhibits usually three characteristic sections with different tangential stiffnesses. The actual contact geometry of the links and end bearings has a significant influence on the characteristics. By wear in ordinary service. the contact geometry changes considerably, thus causing the characteristics to change. In summary, it appears that the link suspension characteristics are very sensitive to several factors. being hard to control in the real world of freight wagon operations. The various stiffnesses and hysteresis loops are found to have a strong influence on the ride qualities of vehicles. This paper presents non-linear multibody simulations investigating these matters. As long as the characteristics cannot be controlled within closer limits than found in this study, there is a strong need for the sensitivity analysis to be made, both in predictive multibody simulations of vehicle dynamics as well as for verification and acceptance tests.

  • 12.
    Jönsson, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    On the influence of Freight Traffic Operational Conditions on Track Deterioration Cost2007In: Proceedings of the International Heavy Haul Conference, pp. 445-452, Kiruna, June 11-13, 2007, 2007, Vol. 12, no 2, p. 445-452Conference paper (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.

  • 13.
    Jönsson, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Improving Ride Comfort in Freight Wagons with Link Suspension Running Gear using Hydraulic Dampers2007In: ZEV Rail Glasers Annalen, ISSN 1618-8330, Vol. 131, no Suppl., p. 230-240Article in journal (Refereed)
    Abstract [en]

    A majority of the traffic related track deterioration cost originates from freight traffic, With heavier and faster freight trains the maintenance cost Is likely to increase. The present paper focuses on the possibility to improve ride comfort and reduce track forces on standard freight wagons with link suspension. The variation of characteristics in link suspension running gear is considerable and unfavourable conditions leading to hunting are likely to occur. Supported by on-track tests and multibody dynamic simulations it is concluded that the running behaviour of two-axle wagons with UIC double-link suspension as well as wagons with link suspension bogies (G-type) can be improved when the running gear are equipped with supplementary hydraulic dampers.

  • 14.
    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

  • 15.
    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.

  • 16.
    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.

  • 17.
    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.

  • 18.
    Liu, Zhendong
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Jönsson, Pär-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Ronnquist, Anders
    On the implementation of an auxiliary pantograph for speed increase on existing lines2016In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 54, no 8, p. 1077-1097Article in journal (Refereed)
    Abstract [en]

    The contact between pantograph and catenary at high speeds suffers from high dynamic contact force variation due to stiffness variations and wave propagation. To increase operational speed on an existing catenary system, especially for soft catenary systems, technical upgrading is usually necessary. Therefore, it is desirable to explore a more practical and cost-saving method to increase the operational speed. Based on a 3D pantograph–catenary finite element model, a parametric study on two-pantograph operation with short spacing distances at high speeds shows that, although the performance of the leading pantograph gets deteriorated, the trailing pantograph feels an improvement if pantographs are spaced at a proper distance. Then, two main positive effects, which can cause the improvement, are addressed. Based on a discussion on wear mechanisms, this paper suggests to use the leading pantograph as an auxiliary pantograph, which does not conduct any electric current, to minimise additional wear caused by the leading pantograph. To help implementation and achieve further improvement under this working condition, this paper investigates cases with optimised uplift force on the leading pantograph and with system parameter deviations. The results show that the two positive effects still remain even with some system parameter deviations. About 30% of speed increase should be possibly achieved still sustaining a good dynamic performance with help of the optimised uplift force.

  • 19.
    Stichel, Sebastian
    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.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Is there a Future for Freight Wagon with Link Suspension?2009In: Proc. of the 9th International Heavy Haul Conference, IHHA´09, 2009Conference paper (Refereed)
  • 20.
    Stichel, Sebastian
    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. TIKAB Strukturmekanik AB.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Hossein Nia, Saeed
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Modeling and simulation of freight wagon with special attention to the prediction of track damage2014In: The international Journal of railway technology, ISSN 2049-5358, E-ISSN 2053-602X, Vol. 3, no 1, p. 1-36Article in journal (Refereed)
    Abstract [en]

    This paper gives an overview of the state of the art of modelling and simulation of freight wagons. The main focus of the paper is to analyse the impact of freight wagons operation on track and wheel damage. Especially experiences of more than 15 years of modelling and simulation of a variety of freight wagons at KTH Royal Institute of Technology are summarized. Different models for the dry friction suspension elements are presented. The challenges of validation arising e.g. from the strong non-linearities and non-smoothness in vehicle models are discussed. Possibilities to use simulation results to predict wheel and track damage like wear, rolling contact fatigue and track settlement are introduced. It is concluded that it is possible to develop simulation models that give relevant results, even though it is more difficult than for passenger vehicles. The results, however, are very sensitive to small changes in the input parameters; therefore a sensitivity analysis regarding some key parameters should always be included in the validation phase of a model.

  • 21. True, H.
    et al.
    Hoffmann, M.
    Jönsson, Per-Anders
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    The design and performance of the European freight wagon standard suspensions2005In: Am Soc Mech Eng Rail Transp Div Publ RTD, 2005, p. 9-18Conference paper (Refereed)
    Abstract [en]

    In the paper we present the three most common European standard freight wagon suspensions. It is characteristic for the European suspensions that they are all primary suspensions without a bolster. The design and the function of their single elements are described. New results on the nature of dry friction and its influence on the damping characteristics are presented. Finally a few theoretical investigations of the dynamics of European freight wagons are surveyed with emphasis on the calculations of the critical speed. The results are compared with corresponding results for American wagons.

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