Change search
Refine search result
1 - 34 of 34
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Arun, Arora
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Passive Components in Active Suspension System2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The concept of active technology in rail vehicles has been studied theoretically and experimentally for several decades and has now reached the stage of implementation. Active Lateral Suspension (ALS) is the active technology that leads the development in active secondary suspensions if carbody tilting is disregarded.

    Active suspension systems may have an influence on running safety of the vehicle. The requirements to fulfil are related to forces between wheel and rail. The safety must be assured by the manufacturer by a safety assessment, which must be sent to the authorities before entering service. An important part of the assessment is to show that the active system, under all conditions, is part of a vehicle that runs safely on the track. The passive components in the vicinity of the active system have an important role in assuring that even a defective active system fulfils the required safety.

    This master thesis aims to set requirements on the passive suspension components for the failed ALS.

    The study has been conducted by varying various parameters of the vehicle with different running conditions and failure cases. The study highlights that the secondary lateral bumpstop is the most important parameter for the vehicle safety.

    With soft bumpstop (low stiffness) the vehicle runs within safe limits for all studied conditions, and the effect of varying other parameters, running conditions and failure cases, is marginal. For somewhat higher stiffness (medium bumpstop), the effect of other parameters plays a critical role in ensuring safe run. For hard bumpstop, the track shift forces are above the limit values, independently of the passive component settings.

    High vertical forces have been observed for certain cases with medium bumpstop, due to primary vertical bumpstop contact, which can be prevented by increasing the primary vertical damping or by increasing the vertical play. Reduction in track shift forces has been observed with the increase of primary vertical damping. The reason for the effect is not known and is proposed for further study.

  • 2.
    Borinder, Daniel
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Track forces of iron ore wagons- Comparison Between Strain Gauge Based Measurements and Calculated Results2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Iron ore trains run from the mine in Kiruna to Narvik and Luleå. These trains are subject to wear and have to be maintained. The wheel-­‐rail interface is a major cost-­‐driver in the maintenance. In Narvik, Norway  and  Sävast  outside  Luleå,  Sweden  there  are  measurement  stations  that  can  indirectly measure the forces that arise in this interface using strain gauges. However, it would save money if the wear could be predicted. It is therefore desirable to be able to predict the forces that arise in this interface.  For  this  purpose  a  model  of  two  coupled  iron  ore  wagons  has  been  developed  for simulations  in the Swedish multi body software Gensys. The aim of this master thesis was to take existing  measurement  station  results  from  Sävast  and  compare  them  with  simulations  of  trains running pn the same track section in order to evaluate and validate the model. To get as close to the measurement  station  results  as possible  several  different  parameters  such  as wheel  profiles,  rail profiles and friction coefficient were varied. Vertical Q forces, lateral Y forces as well as the Y/Q ratio were  evaluated  and  compared.  Longitudinal  X  forces  were  also  evaluated  in  the  simulations  for better   understanding   of   the   dynamics.   Comparisons   show   fairly   good   agreement   between simulations  and  measurements.  Calculated  Q  forces  end  up  in  the  mid  to  upper  spectrum  of measured forces. Y forces display good agreement with measured forces on all wheels except for the leading outer wheel. Measured Y/Q ratio is far above the calculated ratio.

  • 3.
    Brabie, Dan
    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.
    Dynamic simulation of derailments and its consequences2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, no Suppl 1, p. 652-662Article in journal (Refereed)
    Abstract [en]

    This article describes the necessary prerequisites and methodology in progress for studying train vehicle derailments and means of minimising the risk of catastrophic consequences. A comprehensive model has been developed and used in the multi-body system (MBS) simulation software for studying pre- and post-derailment vehicle behaviour. An axle-mounted brake disc and vertically extended bogie frames have shown empirically, as well as by MBS simulations, a potential to favourably influence the sequence of events in case of wheel flange climbing derailments. The MBS simulation methodology has been presented. Examples of how critical geometrical parameters affect the ability of these mechanisms to act as substitute guidance are presented. Further, a finite element (FE) model is developed for studying the impact phenomenon between a rail vehicle wheel and concrete sleepers. In particular, the proposed FE model will be used for obtaining hysteresis data for the wheel-sleeper force as functions of concrete indentation, for further development of the MBS simulations technique.

  • 4.
    Brabie, Dan
    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.
    On minimizing derailment risks and consequences for passenger trains at higher speeds2009In: 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 6, p. 543-566Article in journal (Refereed)
    Abstract [en]

    The first part of this article deals with the possibility of preventing wheel climbing derailments after an axle journal failure by implementing mechanical restrictions between the wheelsets and the bogie. A multi-body system (MBS) computer model is developed to account for such an axle failure condition, which is successfully validated by comparing the pre-derailment sequence of events with two authentic cases. An extensive parameter analysis on the maximum vertical and longitudinal play between the wheelset and the bogie, required to prevent a highspeed power or trailer car to derail, is performed for various combinations of running conditions in curves. Once an actual derailment has Occurred on conventional passenger trains at 200 km/h, extensive MBS simulations are performed on the feasibility of utilizing alternative substitute guidance mechanisms, such as low-reaching parts of bogie frame, axle box, or brake disc, as means of minimizing the lateral deviation. Results are presented in terms of geometrical parameters that lead to a successful engagement with the rail for a total of 12 different derailment scenarios. These are caused by an axle journal failure, an impact with a small object on the track, or a high rail failure. Minimizing the lateral deviation is also investigated by means of restraining the maximum Coupler yaw angle and altering the bogie yaw stiffness. Time-domain simulations are also performed in terms of lateral track forces and derailment ratio when negotiating a tight horizontal 'S-curve'. Further, the articulated train concept is investigated in terms of the post-derailment vehicle behaviour after derailments on tangent and curved track at a speed of 200 km/h. In this respect, a trainset consisting of one power car and four articulated passenger trailer cars is modelled in the MBS software. Results in terms of lateral deviation and maximum carbody roll angle are presented as a function of different inter-carbody damper characteristics and running gear features. The feasibility of these damper characteristics is also tested in terms of lateral track forces and derailment ratio when negotiating a tight horizontal S-curve.

  • 5.
    Casanueva, Carlos
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Alonso, Asier
    CEIT and TECNUN, University of Navarra, Spain.
    Eziolaza, Ibon
    R&D Department, Construcciones y Auxiliar de Ferrocarriles, S.A., Spain.
    Giménez, José Germán
    TECNUN, University of Navarra and R&D Department, Construcciones y Auxiliar de Ferrocarriles, S.A., Spain.
    Simple flexible wheelset model for low-frequency instability simulations2014In: 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 2, p. 169-181Article in journal (Refereed)
    Abstract [en]

    As a general rule, the multi-body simulation models used by railway vehicle designers consider the wheelsets to be fully rigid, thus leading to possible errors when calculating the critical speed of the vehicle under study. This article suggests a wheelset model that takes into account wheelset flexibility for the study of dynamic stability. The model is simple to implement, easily parameterised, and can be applied to both conventional and variable gauge wheelsets. The parameters corresponding to wheelset flexibility that most influence the critical speed of high-speed and variable gauge vehicles are also analysed.

  • 6.
    Chaar, Nizar
    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, Railway Technology.
    Dynamic wheel-rail force measurements and simulations of a high-speed train running on two tracks with different flexibility and irregularitiesArticle in journal (Other academic)
  • 7.
    Chaar, Nizar
    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, Railway Technology.
    Simulation of vehicle-track interaction with flexible wheelsets, moving track models and field tests2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, no Suppl., p. 921-931Article in journal (Refereed)
    Abstract [en]

    Vehicle-track dynamic interaction emerged as a key multi-aspect subject following the development in high-speed and high axle-load trains. In this context. wheelset structural flexibility and track flexibility are the two main factors that contribute to high frequency content of the wheel-rail forces and influence the vehicle-track damage. Appropriate wheelset and track flexibility models are hence of great importance in pertinent numerical simulations. The present study comprises vehicle-track dynamic simulations considering wheelset structural flexibility and advanced moving track models. Simulated wheel-rail forces are then validated against measured data. The effects of the wheelset structural flexibility and track flexibility on the wheel-rail forces are investigated in the frequency range 0-150 Hz. The influence of track modelling and pertinent data on the simulation results is particularly assessed through a set of moving track models. Measured track data, i.e. irregularities, roughness and flexibility support the simulations. It is confirmed that track flexibility with appropriate modelling and data is important when examining the vehicle-track interaction. In the present case study, the influence of wheelset structural flexibility on the lateral wheel-rail forces is quite significant too.

  • 8.
    Chaar, Nizar
    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, Railway Technology.
    Vehicle-track dynamic simulations of a locomotive considering wheelset structural flexibility and comparison with measurements2005In: Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, ISSN 0954-4097, Vol. 219, no 4, p. 225-238Article in journal (Refereed)
    Abstract [en]

    Wheelset structural flexibility, that is the elastic deformation of the wheelset as a structure, can significantly influence the vehicle-track dynamic interaction. In this paper on-track simulations considering flexible wheelsets, modelled through eigenmodes derived from a finite element model, are presented and compared with on-track measurements. The effects of the wheelset structural flexibility on track forces, in the frequency range 0-100 Hz, are investigated. Results from parametric studies are also presented. The present application is a Swedish Rc7 locomotive having rather slender wheelsets. It is shown that both lateral and vertical track forces are significantly influenced by the wheelset flexibility and that the agreement with measurements is fairly good. The wheelset flexibility increases the lateral track forces. The track representation in the present context is important and the used so-called moving track model needs improvements.

  • 9.
    Diedrichs, Ben
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Studies of Two Aerodynamic Effects on High-Speed Trains: Crosswind Stability and Discomforting Car Body Vibrations Inside Tunnels2006Doctoral thesis, comprehensive summary (Other scientific)
  • 10.
    Diedrichs, Ben
    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, Railway Technology.
    Stichel, S.
    Krajnovic, S.
    Vehicle dynamics of a high-speed passenger car due to aerodynamics inside tunnels2007In: 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 4, p. 527-545Article in journal (Refereed)
    Abstract [en]

    High train speeds inside narrow double-track tunnels using light car bodies can reduce the ride comfort of trains as a consequence of the unsteadiness of the aerodynamics. This fact was substantiated in Japan with the introduction of the series 300 Shinkansen trains more than a decade ago, where the train speed is very high also in relatively narrow tunnels on the Sanyo line.

    The current work considers the resulting effects of vehicle dynamics and ride comfort with multi-body dynamics using a model of the end car of the German high-speed train ICE 2. The present efforts are different from traditional vehicle dynamic studies, where disturbances are introduced through the track only. Here disturbances are also applied to the car body, which conventional suspension systems are not designed to cope with.

    Vehicle dynamic implications of unsteady aerodynamic loads from a previous study are examined. These loads were obtained with large eddy simulations based on the geometry of the ICE 2 and Shinkansen 300 trains.

    A sensitivity study of some relevant vehicle parameters is carried out with frequency response analysis (FRA) and time domain simulations. A comparison of these two approaches shows that results which are obtained with the much swifter FRA technique are accurate also for sizable unsteady aerodynamic loads. FRA is, therefore, shown to be a useful tool to predict ride comfort in the current context.

    The car body mass is found to be a key parameter for car body vibrations, where loads are applied directly to the car body. For the current vehicle model, a mass reduction of the car body is predicted to be most momentous in the vicinity of 2 Hz.

  • 11.
    Diedrichs, Ben
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Krajnovic, Sinisia
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    On the aerodynamics of car body vibrations of high-speed trains crusing inside tunnels2008In: ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUID MECHANICS, ISSN 1994-2060, Vol. 2, no 1, p. 51-75Article in journal (Refereed)
    Abstract [en]

    Aerodynamically induced car body vibrations of high-speed trains inside tunnels have for approximately two decades been recognized as a problem in Japan, while other nations' high-speed rail services have not reported similar problems. In order to shed light on this contradiction the scope of the present paper is to primarily explore tail car vibrations of Deutsche Bahn AG's high-speed train ICE 2 and Japan Railways series 300 Shinkansen train. Despite similarities of these two trains the problems are reported only for the latter. Several large eddy simulations are carried out to predict the aerodynamics around simplified and smooth models of the above mentioned trains inside tunnels. The results focus on the ability to resolve PPD (propagating pressure disturbances) generated alongside the bodies, unsteady aerodynamic forces and their corresponding frequencies. Mesh refinement studies are undertaken for both train models, where mesh independence is quite a challenge for this type of application. Affordable meshes appropriate for LES could only be achieved for models confined to a typical car length. For smooth models and for a model with three generic inter-car gaps, the high spatial frequency of the resolved PPD does not make them sufficient to upset the ride quality of a car. A low frequency mode that strongly affects the forces of the tail of the Shinkansen models is described, which is caused by the confinement of the tunnel walls. A study of the implications of the lateral distance to the wall is further investigated. The findings reveal that the effects of the low frequency mode intensify with a narrow wall clearance, corresponding to the nominal lateral position of the train.

  • 12.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    On Simulation of Uniform Wear and Profile Evolution in the Wheel - Rail Contact2006Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Numerical procedures for reliable wheel and rail wear prediction are rare. Recent development of simulation techniques and computer power together with tribological knowledge do however suggest computer aided wear prediction as possible. The present objective is to devise a numerical procedure able to simulate profile evolution due to uniform wear sufficiently accurate for application to vehicle dynamics simulation. Such a tool should be useful for maintenance planning, optimisation of the railway system and its components as well as trouble-shooting. More specifically, the field of application may include estimation of reprofiling frequency, optimisation of wheel – rail profile match, optimisation of running gear suspension parameters, and recognition of unfavourable profile evolution influencing the dynamic response of the vehicle.

    The research contribution accounted for in this thesis includes, besides a literature review, modelling of the wheel – rail interface, benchmarking against traditional methods, and validation with respect to full-scale measurements.

    The first part addresses wheel – rail contact conditions in the context of wear simulation as well as tribological environment and tractive forces. The current approach includes Archard’s wear model with associated wear maps, vehicle dynamics simulation, and railway network definition. One objective is to be able to include variations in operation conditions in the set of simulations instead of using scaling factors. In particular the influence of disc braking and varying lubrication conditions have been investigated. Both environmental factors like moist and contamination and deliberate lubrication need to be considered. As part of the associated contact analysis the influence of tangential elastic deformation of the contacting surfaces has been investigated and found to be essential in case of partial slip contact conditions. The influence on the calculated wear of replacing the Hertzian contact by a non-elliptic semi-Hertzian method has been investigated, showing relocation of material loss towards increased profile curvature.

    In the second part comparisons have been carried out with traditional methods, where the material loss is assumed to be directly related to the energy dissipated in the contact. Attention has been paid to the understanding of the principle differences between the investigated methods, comparing the distribution of friction energy, sliding velocity, and wear depth. As a prerequisite, contact conditions with dependence on wheelset guidance and curving performance as well as influence of tractive forces have been investigated.

    In the final part validation of the developments related to wheel wear simulation is addressed. Disc braking has been included and a wear map for moist contact conditions based on recent tests has been drafted. Good agreement with measurements from the reference operation, is achieved. Further a procedure for simulation of rail wear and corresponding profile evolution has been formulated. A simulation set is selected defining the vehicles running on the track to be investigated, their operating conditions, and contact parameters. Trial calculations of a few curves show qualitatively good 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. The impact of the model improvements accounted for in the first part of the thesis has been investigated, indicating directions for further development.

  • 13.
    Gely, Pierre
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    High frequency vehicle-track interactionsimulation: Coupling of an advanced track model with a multi-bodysystem2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The forces caused by the high frequency vehicle-track interaction have a great impact on thetrack maintenance. They should be represented in vehicle-track models in order to predicttheir impact. As a result, a multi-body system (MBS) should be extended with an advancedtrack model. The MBS represents the vehicle and the wheel-rail contact with a great accuracy.The track will be modeled in two different ways: a moving track model and a continuous trackmodel which is a finite element modeling (FEM). The first one will be a lumped-mass model.The most advanced system will be the second one, which is a MBS-FEM representation andoffers a great precision to represent the high frequency dynamical properties. The system willbe used to simulate pertinent phenomena such as a wheelflats, corrugations and rail joint.Based on the literature and the measurements, the model is validated in a wider frequencyrange than the one currently used (0-20Hz). The results given by both models are close tothe literature and the measurement.

  • 14.
    Gustafsson, Michael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Running Dynamics for a Maintenance Railway Vehicle2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    BS Verkstäder has developed a new railway maintenance vehicle, MTR2000, which is in the process of authority approval. A part of the approval is the running dynamics of the vehicle which for maintenance vehicles following SS‐EN 14033‐1 can be evaluated using a simulation model of the vehicle, which is verified by comparing simulation results to measurements from a vehicle test. The testing, assessment values and limit values for running dynamics follow EN 14363.

    The goal of this work was to create a simulation model of the vehicle in the software Gensys and to verify the model with vehicle tests. Using the verified model, simulations were then performed corresponding to the test conditions defined in the standard for approval of running behaviour. The model was also used to investigate how the vehicle’s running behaviour could be improved. The results of the verification showed that the model gave a good representation of the vehicle up to the frame, while attempts to have similar good representation for the cabin were not successful. There were also other aspects of the verification process which could question the validity of the model.

    With the verification only being partly successful all further simulations were done with focus kept on results up to the frame were the verification had given the best results.

    The results of these latter simulations showed that the vehicle would most likely pass an authority approval process in its current configuration. Simulations performed to try to improve the vehicle running behaviour showed that a decrease of 50% in damper constant for the vehicle’s hydraulic dampers would lead to decreased acceleration levels and lower wheel‐rail guiding forces.

  • 15.
    Iwnicki, Simon
    et al.
    Manchester Metropolitan University.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Elements.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Wheel-rail contact mechanics2009In: Wheel-rail interface handbook / [ed] Roger Lewis, Ulf Olofsson, Cambridge, UK: Woodhead Publishing Ltd , 2009, p. 58-92Chapter in book (Refereed)
  • 16.
    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.

  • 17.
    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.

  • 18.
    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.

  • 19.
    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.

  • 20.
    Karis, Tomas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Track Irregularities for High-Speed Trains: Evaluation of their correlation with vehicle response2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 21.
    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)
  • 22.
    Khan, M. Shafiguzzaman
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Sundström, J.
    Vibration measurements in Swedish Inter-city trains: Evaluation of discomfort values2005Conference paper (Refereed)
    Abstract [en]

    Passenger surveys on Swedish trains have revealed that a majority of the passengers are occupying themselves with reading or writing during their train journeys. Other studies have shown that whole-body vibrations severely affect the ability to read and write. Therefore, in this study vibration measurements were performed on three types of Swedish passenger trains in order to determine the vibration discomfort. Acceleration measurements were made at a typical passenger seat, above the car bogie during normal running conditions, at five points namely seat-pan, backrest, armrest, table and floor. The vibration data was weighted and evaluated in accordance with the ISO 2631-1 standard and the older German (Sperling) Ride Index Wz. The results of the ISO and Wz-weightings did not reveal any significant discomfort in any of the trains. On the other hand, a concurrent questionnaire study on the same trains and tracks showed that about two thirds of the passengers felt moderate difficulties while performing a hand-writing task. This means that even low levels of vibration can make writing difficult. A general trend was that the vertical axis (z) had relatively higher contribution to the vibration discomfort (ISO & Wz) for all measurement points except at the backrest. For the backrest it was the longitudinal axis (x) that gave the highest vibration level. Vibration levels were more pronounced on the seat cushion, backrest and table whereas vibrations on armrest and floor were less pronounced.

  • 23.
    Khan, Shafiquzzaman
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Sundström, Jerker
    Effects of vibration on sedentary activities in passenger trains2007In: Journal of Low Frequency Noise Vibration and Active Control, ISSN 0263-0923, Vol. 26, no 1, p. 43-55Article in journal (Refereed)
    Abstract [en]

    The effects of vibration on train passengers' sedentary activities were investigated with a questionnaire survey as well as onboard vibration measurements. Three types of Swedish inter-regional trains were studied on four different lines. 330 passengers were randomly selected for the questionnaire survey. The vibration measurements were made at five positions around a passenger seat above the bogie during normal service. The vibration data were weighted according to ISO 2631-1 and the older German (Sperling) Ride Index Wz. Two-thirds of the passengers reported difficulties in performing sedentary activities such as reading and writing due to vibration and shocks. However, the standardized measurements did not reveal any severe discomfort values due to the vibration. This reveals that ISO and Wz standards do not evaluate vibrations effect on sedentary activities correctly. This also indicates that even low levels of vibration can reduce the ability to perform sedentary activities. Both chair and table produced more vibration than the floor. The spectral analysis showed that the chair had nearly the same frequency content as the floor, below 10 Hz. This range is critical since it coincides with the most vulnerable range for reading and writing as well as the perception of ride comfort.

  • 24.
    Le Bars, Theo
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Investigation of the behaviour of return collectors on Paris’ subway MP05 (Line 1)2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Return collectors are predominant organs for rubber-tyred subways to operatesince they ensure both the track circuit shunt and the traction current return. Po- sitioned at the interface between the track and the rolling stock, they are subjected to the disruptions linked to the train movement and the track irregularities. One of the most critical steps is the crossing of a switch nose.This study aims at determining the collector position during this crossing by means of a quasi-static analysis of the system. Two approaches are investigated. The first one brings into play a rigid contact and geometrical angles. It enables to model the crossing until the contact with the crossing nose. The diving capability of the collector is also taken into account. The second one is a standard  approach of the contact. A slight penetration is considered, which allows to grasp the contact with  the crossing nose. The second advantage  is to prepare the ground for a complete dynamical analysis. Both approaches are then implemented on Matlab to solve the equations. Finally the study of the switch crossing in nominal conditionsand a parametric analysis are achieved for a specified switch.

  • 25. Mazzola, Laura
    et al.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Secondary suspension of railway vehicles - air spring modelling: Performance and critical issues2014In: 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 3, p. 225-241Article in journal (Refereed)
    Abstract [en]

    This paper shows the importance of modelling the components of the suspension when performing dynamics simulations of a railway vehicle. Focusing on the air spring secondary suspension, a process to define an accurate component model is proposed based on a combination of laboratory tests and model identification techniques. Six models for the air spring secondary suspension are discussed and assessed based on comparison with experiments.

  • 26.
    Polach, Oldrich
    et al.
    Bombardier Transportation, Switzerland.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Iwnicki, Simon
    Manchester Metropolitan University, UK.
    Simulation2006In: Handbook of Railway Vehicle Dynamics / [ed] Simon Iwnicki, Taylor & Francis Group, 2006, p. 359-421Chapter in book (Refereed)
  • 27.
    Schär, Raphael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Active Control of the Pantograph-Catenary Interaction in a Finite Element Model2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work analyzes the implementation of an active train pantograph in a full finite element model in the program Ansys. As controller design method, the H∞ method was taken in order to cope with the different uncertainties in the given system. The focus lies on the contact force between the pantograph and the catenary. The goal was the reduction of the contact force standard deviation in order to allow higher train speeds on existing lines. An additional goal is the use of multi train configurations. This means that two coupled trains with a distance between the two pantographs of 100 meters can run with high speed on existing lines. Current regulations limit the distance to 200 meters. In addition to the active solutions, different modifications of the given pantograph were investigated.

    The simulations showed that the desired speed of 280 km/h is achieved on existing lines in multi train configuration. For only one train, a speed of up to 300 km/h can be reached. More important, by using an estimator, the standard deviation values for these speeds were still below the limitations and hence, it is possible to implement this solution in a real system.

  • 28.
    Sh. Sichani, Matin
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology. 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), Aeronautical and Vehicle Engineering, Railway Technology. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Comparison of non-elliptic contact models: Towards fast and accurate modelling of wheel-rail contact2014In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 314, no 1-2, p. 111-117Article in journal (Refereed)
    Abstract [en]

    The demand to investigate and predict the surface deterioration phenomena in the wheel-rail interface necessitates fast and accurate contact modelling. During the past 20 years, there have been attempts to determine more realistic contact patch and stress distributions using fast simplified methods. The main aim of the present work is to compare some of these state-of-the-art, non-elliptic contact models available in the literature. This is considered as the first step to develop a fast and accurate non-elliptic contact model that can be used on-line with vehicle dynamics analysis. Three contact models, namely STRIPES, Kik-Piotrowski and Linder are implemented and compared in terms of contact patch prediction, as well as contact pressure and traction distributions. The evaluation of these models using CONTACT software indicate the need for improvement of contact patch and pressure estimation in certain contact cases.

  • 29. Sundström, Jerker
    et al.
    Khan, Shafiguzzaman
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Influence of stationary lateral vibrations on train passengers' ability to read and write2008In: Applied Ergonomics, ISSN 0003-6870, E-ISSN 1872-9126, Vol. 39, no 6, p. 710-718Article in journal (Refereed)
    Abstract [en]

    Recent studies on train passengers’ activities found that many passengers were engaged in some form of work, e.g. reading and writing, while traveling by train. A majority of the passengers reported that they were disturbed by vibrations or motions during their journey. A laboratory study was therefore set up to study how stationary low-frequency lateral vibrations influence the difficulty to read and write. The study involved 48 subjects (24f+24m) divided into three age groups. Two levels of sinusoidal vibrations were applied at nine discrete frequencies (0.8–8.0 Hz). Subjects performed both reading and writing tasks under two sitting positions (leaning against the backrest and leaning over a table). The judgments of perceived difficulty to read and write were rated using Borg's CR-100 scale. The results showed significant differences between the tasks and postural conditions. The subjects reported greater difficulty while reading and writing on the table than while leaning back. The frequencies up to 5 Hz had a particular influence on the perceived difficulty.

  • 30. Sundström, Jerker
    et al.
    Khan, Shafiguzzaman
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Train passengers' ability to read and write during lateral vibration transients2006Conference paper (Refereed)
    Abstract [en]

    In a passenger survey aboard Swedish Intercity trains a majority of the passengers reported disturbances due to vibration and shocks. Subsequent laboratory studies revealed that the difficulty of reading and writing displayed non-linear frequency characteristics for stationary vibrations in the lateral direction. In the present study a train mock-up was used to investigate the effect of lateral vibration transients on passengers' ability to read and write. The subjects sat leaning against the backrest with the work material placed on their lap during the exposures. In order to limit the influence of anthropometric differences, 21 subjects were recruited according to predefined body measures. The study consisted of three experimental parts (A, B, C). Part A and B comprised of six discrete sinusoidal frequencies (1.25 - 5.0 Iiz) with a stationary amplitude of 0.3 m/s2. Each frequency was superimposed with transient peaks of three amplitudes (0.7, 1.0, 1.4 m/s2). The transient peaks were one oscillation period long and had a sinusoidal shape. Each peak appeared randomly three times during the 25 s long sequences. The test subjects rated their experienced difficulty to read and write due to each transient vibration, using Borg's CR-I00 scale. In part C, nine amplitude levels (0.43 - 0.7 m/s2) were used for three frequencies (1.25, 2.0, 4.0 Hz). In this part the test subjects were instructed to press a button whenever their reading was disturbed by a vibration transient. The results showed that occasional vibration transients cause lower levels of difficulty than stationary vibrations. Further did, only 35% of the shocks at 0.7 m/s2 cause a disturbance while reading.

  • 31. 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.

  • 32.
    Venkatasalam, Nachiyappan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Crosswind assessment of trains on different ground configurations2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cross wind analysis is one of the important safety measures for rail vehicle certification. The objective of this study is to identify which vehicle certification ground setup, true flat ground (TFG) or single track ballast and rail (STBR) represents a more realistic ground setup with atmospheric boundary layer (ABL) wind inlet and also to represent an embankment scenario. A streamlined high speed train ICE3 and a conventional Regional train are taken for the analysis to represent both categories. CFD is used as a tool for calculations. The best practice recommended by the AeroTRAIN project is used for the CFD approach. The analysis is done for various configurations including STBR, TFG, embankments, ground roughness, moving ground, non-moving ground, block profile inlet, ABL inlet, model scale and full scale setups.

    The Regional train shows higher roll moment coefficient about lee rail (Cmx,lee) compared to the ICE3 train, whereas the ICE3 train has a higher lift force coefficient than the Regional train. STBR setup shows a higher force and moment coefficient compared to TFG. The STBR setup represents the more realistic setup of moving rough ground with ABL wind inlet and also the realistic embankment scenario.

  • 33. Ågren, Jan
    et al.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Flash Temperature in Wheel/Rail contact and Martensite Formation: A Review2006In: Proc. of the 7th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems (CM2006), 2006Conference paper (Refereed)
  • 34.
    Östlund, Stefan
    et al.
    KTH, School of Electrical Engineering (EES), Electrical Machines and Power Electronics (closed 20110930).
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Railway Technology.
    Kottenhoff, Karl
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Traffic and Logistics.
    Efficient Passenger Trains for the Future1999In: Proceedings of the WCRR99, 1999Conference paper (Refereed)
1 - 34 of 34
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf