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  • 1.
    Andreasson, Johan
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Bünte, T
    Global Chassis Control Based on Inverse Vehicle Dynamics Models2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, no supplement s, p. 321-328Article in journal (Refereed)
    Abstract [en]

    This work proposes to approach global chassis control (GCC) by means of model inversion-based feedforward with allocation directly on the actuator commands. The available degrees of freedom are used to execute the desired vehicle motion while minimizing the utilization of the tyre's grip potential. This is done by sampled constrained least-squares optimization of the linearized problem. To compensate for model errors and external disturbances, high-gain feedback is applied by means of an inverse disturbance observer. The presented method is applied in a comparison of eight vehicles with different actuator configurations for steer, drive, brake and load distribution. The approach shows a transparent and effective method to deal with the complex issue of GCC in a unitized way. It gives both a base for controller design and a structured way to compare different configurations. In practice, the transparency supports automatic on-board reconfiguration in the case of actuator hardware failure.

  • 2.
    Andreasson, Johan
    et al.
    KTH, Superseded Departments, Vehicle Engineering.
    Laine, L
    Driving Dynamics for Hybrid Electric Vehicles Considering Handling and Control Architecture2004In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, p. 497-506Article in journal (Refereed)
  • 3. Apezetxea, I. S.
    et al.
    Perez, X.
    Casanueva, Carlos
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Alonso, A.
    New methodology for fast prediction of wheel wear evolution2017In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 55, no 7, p. 1071-1097Article in journal (Refereed)
    Abstract [en]

    In railway applications wear prediction in the wheel–rail interface is a fundamental matter in order to study problems such as wheel lifespan and the evolution of vehicle dynamic characteristic with time. However, one of the principal drawbacks of the existing methodologies for calculating the wear evolution is the computational cost. This paper proposes a new wear prediction methodology with a reduced computational cost. This methodology is based on two main steps: the first one is the substitution of the calculations over the whole network by the calculation of the contact conditions in certain characteristic point from whose result the wheel wear evolution can be inferred. The second one is the substitution of the dynamic calculation (time integration calculations) by the quasi-static calculation (the solution of the quasi-static situation of a vehicle at a certain point which is the same that neglecting the acceleration terms in the dynamic equations). These simplifications allow a significant reduction of computational cost to be obtained while maintaining an acceptable level of accuracy (error order of 5–10%). Several case studies are analysed along the paper with the objective of assessing the proposed methodology. The results obtained in the case studies allow concluding that the proposed methodology is valid for an arbitrary vehicle running through an arbitrary track layout.

  • 4.
    Blanco, Blas
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. University of Navarra, Spain.
    Alonso, A.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Gil-Negrete, N.
    Gimenez, J. G.
    Distributed support modelling for vertical track dynamic analysis2018In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, no 4, p. 529-552Article in journal (Refereed)
    Abstract [en]

    The finite length nature of rail-pad supports is characterised by a Timoshenko beam element formulation over an elastic foundation, giving rise to the distributed support element. The new element is integrated into a vertical track model, which is solved in frequency and time domain. The developed formulation is obtained by solving the governing equations of a Timoshenko beam for this particular case. The interaction between sleeper and rail via the elastic connection is considered in an analytical, compact and efficient way. The modelling technique results in realistic amplitudes of the pinned-pinned' vibration mode and, additionally, it leads to a smooth evolution of the contact force temporal response and to reduced amplitudes of the rail vertical oscillation, as compared to the results from concentrated support models. Simulations are performed for both parametric and sinusoidal roughness excitation. The model of support proposed here is compared with a previous finite length model developed by other authors, coming to the conclusion that the proposed model gives accurate results at a reduced computational cost.

  • 5.
    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.

  • 6.
    Brabie, Dan
    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.
    Andersson, Evert
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Post-derailment dynamic simulation of rail vehicles: Methodology and applications2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, no Suppl. S, p. 289-300Article in journal (Refereed)
    Abstract [en]

    An earlier developed multi-body system post-derailment module. that predicts the wheelsets' behaviour after impact with concrete sleepers, is upgraded to account for possible wheel-rail fastener impact after train derailments at high speed. The vertical stiffness describing the wheel-fastener impact behaviour is calibrated and validated based on two authentic derailment cases. Geometrical specifications that permit it brake disc and a bogie frame to act as substitute guidance mechanisms after Hart e climbing derailments on Curved track are presented for an X 2000 trailer car. Further, an introductory analysis on the post-derailment vehicle behaviour on tangent track after a 'flange on rail head' derailment condition is also presented its a function of bogie yaw resistance. The risk of carbody overturning after derailments on tangent track is assessed as a function of coupler height and carbody centre of gravity as well as bogie transversal beam position.

  • 7. Bruni, Stefano
    et al.
    Ambrosio, Jorge
    Carnicero, Alberto
    Cho, Yong Hyeon
    Finner, Lars
    Ikeda, Mitsuru
    Kwon, Sam Young
    Massat, Jean-Pierre
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Tur, Manuel
    Zhang, Weihua
    The results of the pantograph-catenary interaction benchmark2015In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, no 3, p. 412-435Article in journal (Refereed)
    Abstract [en]

    This paper describes the results of a voluntary benchmark initiative concerning the simulation of pantograph-catenary interaction, which was proposed and coordinated by Politecnico di Milano and participated by 10 research institutions established in 9 different countries across Europe and Asia. The aims of the benchmark are to assess the dispersion of results on the same simulation study cases, to demonstrate the accuracy of numerical methodologies and simulation models and to identify the best suited modelling approaches to study pantograph-catenary interaction. One static and three dynamic simulation cases were defined for a non-existing but realistic high-speed pantograph-catenary couple. These cases were run using 10 of the major simulation codes presently in use for the study of pantograph-catenary interaction, and the results are presented and critically discussed here. All input data required to run the study cases are also provided, allowing the use of this benchmark as a term of comparison for other simulation codes.

  • 8. Bruni, Stefano
    et al.
    Vinolas, Jordi
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles.
    Polach, Oldrich
    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.
    Modelling of suspension components in a rail vehicle dynamics context2011In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 49, no 7, p. 1021-1072Article in journal (Refereed)
    Abstract [en]

    Suspension components play key roles in the running behaviour of rail vehicles, and therefore, mathematical models of suspension components are essential ingredients of railway vehicle multi-body models. The aims of this paper are to review existing models for railway vehicle suspension components and their use for railway vehicle dynamics multi-body simulations, to describe how model parameters can be defined and to discuss the required level of detail of component models in view of the accuracy expected from the overall simulation model. This paper also addresses track models in use for railway vehicle dynamics simulations, recognising their relevance as an indispensable component of the system simulation model. Finally, this paper reviews methods presently in use for the checking and validation of the simulation model.

  • 9. 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.

  • 10. Burgelman, Nico
    et al.
    Sichani, Matin Sh
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Berg, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Li, Zili
    Dollevoet, Rolf
    Influence of wheel-rail contact modelling on vehicle dynamic simulation2015In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, no 8, p. 1190-1203Article in journal (Refereed)
    Abstract [en]

    This paper presents a comparison of four models of rolling contact used for online contact force evaluation in rail vehicle dynamics. Until now only a few wheel-rail contact models have been used for online simulation in multibody software (MBS). Many more models exist and their behaviour has been studied offline, but a comparative study of the mutual influence between the calculation of the creep forces and the simulated vehicle dynamics seems to be missing. Such a comparison would help researchers with the assessment of accuracy and calculation time. The contact methods investigated in this paper are FASTSIM, Linder, Kik-Piotrowski and Stripes. They are compared through a coupling between an MBS for the vehicle simulation and Matlab for the contact models. This way the influence of the creep force calculation on the vehicle simulation is investigated. More specifically this study focuses on the influence of the contact model on the simulation of the hunting motion and on the curving behaviour.

  • 11. Carlbom, P.
    et al.
    Berg, Mats
    KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
    Passengers, seats and carbody in rail vehicle dynamics2002In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 37, p. 290-300Article in journal (Refereed)
    Abstract [en]

    Reliable models of passengers, seats and carbody are essential in order predict ride comfort of rail vehicles. This paper extends previously presented models of passenger-carbody interaction to include vertical seating dynamics. The proposed basic model is based on experimental modal analysis of a rail vehicle with and without passengers. The nations of human-body normalized apparent mass and seat transmissibility are fundamental an the modelling. The possibility of using reduced and approximate gels is also discussed in the paper. The proposed models are easy to use and implemented in commercial rail vehicle software.

  • 12.
    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.

  • 13.
    Chaar, Nizar
    et al.
    KTH, Superseded Departments, Vehicle Engineering.
    Berg, Mats
    KTH, Superseded Departments, Vehicle Engineering.
    Experimental and numerical modal analyses of a loco wheelset2004In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, no Suppl., p. 597-606Article in journal (Refereed)
    Abstract [en]

    Wheelset structural flexibility is believed to have a major influence on the vehicle-track dynamics. Several studies have related the structural flexibility of the wheelset to fluctuations of wheel-rail forces, rail and wheel corrugation, etc. This paper reports part of an ongoing project that studies the effects of wheelset structural flexibility on the vehicle-track dynamics. The paper focuses on experimental and numerical modal analyses of a loco wheelset in the frequency range of 0-500 Hz. Major issues related to modal analyses and modelling of wheelset are presented along with respective results. The results from numerical modal analysis were in good agreement with those obtained from the experiment. In addition, the wheelset had fairly low eigenfrequencies. Reduced versions of the generated wheelset model will be used in coming work in on-track numerical simulations in order to determine the effects of wheelset structural flexibility on the vehicle-track dynamics. Results from these simulations will be validated against existing experimental on-track results.

  • 14.
    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.

  • 15.
    Conde Mellado, Alberto
    et al.
    CEIT and Tecnun, University of Navarra.
    Casanueva, Carlos
    CEIT and Tecnun, University of Navarra.
    Vinolas, Jordi
    CEIT and Tecnun, University of Navarra.
    Giménez, José Germán
    CAF I+D and Tecnun, University of Navarra.
    A lateral active suspension for conventional railway bogies2009In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 47, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    The present paper describes an active centring system for railway vehicles. The proposed solution is based on lateral pneumatic actuators placed between bogie and car body connected to the vertical secondary suspension air springs. The objective of the developed centring system is twofold: the improvement of the curving behaviour of the train and the decrease of the lateral acceleration perceived by the passenger in curve negotiation thanks to the reduction of the ‘souplesse’ coefficient. The system is described in detail in the paper. Results from simulations are included considering a bidimensional model of the vehicle, and a detailed model of the air spring and control valves. The performance in curve negotiation of a vehicle equipped with this system and a conventional one is compared. Specifically, lateral displacements of the secondary suspension, roll angle and lateral accelerations are analysed. The results show noticeable performance improvements in the vehicle curving behaviour. The proposed centring system can be implemented in a conventional bogie without special design requirements; and due to the low air consumption, additional pressurised reservoirs are not required.

  • 16.
    Drugge, Lars
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Juhlin, Magnus
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Aerodynamic loads on buses due to crosswind gusts: extended analysis2010In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 48, p. 287-297Article in journal (Refereed)
    Abstract [en]

    The objective of this work is to use inverse simulations on measured vehicle data in order to estimate the aerodynamic loads on a bus when exposed to crosswind situations. Tyre forces, driver input, wind velocity and vehicle response were measured on a typical coach when subjected to natural crosswind gusts. Based on these measurements and a detailed MBS vehicle model, the aerodynamic loads were estimated through inverse simulations. In order to estimate the lift force, roll and pitch moments in addition to the lateral force and yaw moment, the simulation model was extended by also incorporating the estimation of the vertical road disturbances. The proposed method enables the estimation of aerodynamic loads due to crosswind gusts without using a full scale wind tunnel adapted for crosswind excitation.

  • 17.
    Drugge, Lars
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Larsson, Tobias
    Luleå University of Technology.
    Stensson, Annika
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Modelling and simulation of catenary-pantograph interaction2000In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 33, p. 202-213Article in journal (Refereed)
  • 18.
    Edrén, Johannes
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Jonasson, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Volvo Car Corporation, Sweden .
    Jerrelind, Jenny
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Trigell, Annika Stensson
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Utilisation of optimisation solutions to control active suspension for decreased braking distance2015In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, no 2, p. 256-273Article in journal (Refereed)
    Abstract [en]

    This work deals with how to utilise active suspension on individual vehicle wheels in order to improve the vehicle performance during straight-line braking. Through numerical optimisation, solutions have been found as regards how active suspension should be controlled and coordinated with friction brakes to shorten the braking distance. The results show that, for the studied vehicle, the braking distance can be shortened by more than 1 m when braking from 100 km/h. The applicability of these results is studied by investigating the approach for different vehicle speeds and actuator stroke limitations. It is shown that substantial improvements in the braking distance can also be found for lower velocities, and that the actuator strokes are an important parameter. To investigate the potential of implementing these findings in a real vehicle, a validated detailed vehicle model equipped with active struts is analysed. Simplified control laws, appropriate for on-board implementation and based on knowledge of the optimised solution, are proposed and evaluated. The results show that substantial improvements of the braking ability, and thus safety, can be made using this simplified approach. Particle model simulations have been made to explain the underlying physical mechanisms and limitations of the approach. These results provide valuable guidance on how active suspension can be used to achieve significant improvements in vehicle performance with reasonable complexity and energy consumption.

  • 19.
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Rail Vehicles. KTH, School of Engineering Sciences (SCI), Centres, The KTH Railway Group.
    Deterioration mechanisms in the wheel-rail interface with focus on wear prediction: a literature review2009In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 47, no 6, p. 661-700Article, review/survey (Refereed)
    Abstract [en]

    Wheel-rail interface management is imperative to railway operation and its maintenance represents a major share of the total maintenance cost. In general, the course of events usually called wear is a complicated process involving several modes of material deterioration and contact surface alteration. Thus material removal or relocation, plastic flow and phase transformation may take place at, just below, or in-between the contacting surfaces. A higher degree of predictability of deterioration mechanisms and a firm basis for optimisation of the wheel-rail system are anticipated to reveal a great potential for cost savings. Wear in the sense of material loss and related wheel-rail profile evolution represents one of several modes of damage. The purpose of this survey is to explore research on wear simulation, to some degree extended to neighbouring disciplines. It is believed that a cross-disciplinary approach involving, for instance, adhesive and abrasive wear, surface plasticity, and rolling contact fatigue opens new perspectives to improved damage prediction procedures.

  • 20. 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.

  • 21.
    Gebretsadik, Elias Kassa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Johansson, Göran
    Chalmers University of technology.
    Simulation of train-turnout interaction and plastic deformation of rail profiles2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, p. 349-359Article in journal (Refereed)
    Abstract [en]

    Railway turnouts (switches and crossings) require more maintenance than other parts of the railway network. Multiple wheel-rail contacts are common. and impact loads with large magnitudes are generated when the conventional wheel-rail contact conditions are disturbed at various locations along the turnout. The dynamic interaction between train and turnout is simulated in order to predict the forces and creepages in the wheel-rail contacts, and the sizes and locations of the contact patches. Furthermore, the change in rail profile because of plastic deformation is calculated by finite element analysis at a selected position along the switch rail. Contact loads and contact locations, taken from the vehicle dynamics simulation. are then used as input data in the finite element analysis. The objective of the study is to gain knowledge about the influence of different damage mechanisms oil the life of a turnout. This is useful in an optimization of turnout geometry with the purpose to improve vehicle ride dynamics and to decrease maintenance costs.

  • 22.
    Gebretsadik, Elias Kassa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Nielsen, Jens
    Chalmers University of technology.
    Dynamic interaction between train and railway turnout: full-scale field test and validation of simulation models2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, no 1, p. 521-534Article in journal (Refereed)
    Abstract [en]

    Results from an extensive field test performed in a UIC60-760-1:15 turnout on Svealandsbanan in Sweden are reported. Lateral and vertical wheel-rail contact forces were measured by a wheelset instrumented with strain gauges on the wheel discs. The test train with axle load 25 tonnes passed through the turnout in the main and diverging routes and in the facing and trailingmoves. The influences of train speed and moving direction on the magnitude and the position of the maximum lateral contact force in the diverging route of the switch panel, and the influences of train speed, moving direction and route on the maximum vertical contact force in the crossing panel, are investigated. Measured contact forces are compared with calculated forces for a validation of two previously developed numerical models. The magnitude and position of the calculated maximum lateral contact forces are in good agreement with the corresponding measured values. Both measurements and numerical simulations show an increase in maximum lateral contact force with increasing train speed in both the facing and trailing moves. The facing move of the diverging route leads to the highest lateral contact forces in the switch panel. The maximum vertical contact force is not influenced significantly by whether the train is moving in the facing or trailing moves. However, the train route (main or diverging) has a large influence on the maximum vertical contact force at the crossing.

  • 23.
    Gebretsadik, Elias Kassa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Nielsen, Jens
    Chalmers University of technology.
    Stochastic analysis of dynamic interaction between train and railway turnout2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, no 5, p. 429-449Article in journal (Refereed)
    Abstract [en]

    The performance of a railway turnout (switch and crossing) is influenced by a large number of input parameters of the complex train–turnout system. To reach a robust design that performs well for different traffic situations, random distributions (scatter) of these inputs need to be accounted for in the design process. Stochastic analysis methods are integrated with a simulation model of the dynamic interaction between train and turnout. For a given nominal layout of the turnout, using design of experiments methodology and a two-level fractional factorial screening design, four parameters (axle load, wheel–rail friction coefficient, and wheel and rail profiles) are identified to be the most significant. These parameters are further investigated using a three-level full factorial design and stochastic analysis. The random distributions of transverse wheel profile and set of transverse rail profiles along the switch panel are accounted for by the Karhunen–Loève expansion technique. The influence of the random distributions of the input parameters on the statistical outputs of wheel–rail contact forces, wear and rolling contact fatigue is assessed using Latin hypercube sampling to generate a number of stochastic load realizations.

  • 24.
    Gebretsadik, Elias Kassa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Nielsen, Jens
    Chalmers University of technology.
    Andersson, Clas
    Chalmers University of technology.
    Simulation of dynamic interaction between train and railway turnout2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 44, no 3, p. 247-258Article in journal (Refereed)
    Abstract [en]

    Dynamic train–track interaction is more complex in railway turnouts (switches and crossings) than that in ordinary tangent or curved tracks. Multiple contacts between wheel and rail are common, and severe impact loads with broad frequency contents are induced, when nominal wheel–rail contact conditions are disturbed because of the continuous variation in rail profiles and the discontinuities in the crossing panel. The absence of transition curves at the entry and exit of the turnout, and the cant deficiency, leads to large wheel–rail contact forces and passenger discomfort when the train is switching into the turnout track. Two alternative multibody system (MBS) models of dynamic interaction between train and a standard turnout design are developed. The first model is derived using a commercial MBS software. The second model is based on a multibody dynamics formulation, which may account for the structural flexibility of train and track components (based on finite element models and coordinate reduction methods). The variation in rail profile is accounted for by sampling the cross-section of each rail at several positions along the turnout. Contact between the back of the wheel flange and the check rail, when the wheelset is steered through the crossing, is considered. Good agreement in results from the two models is observed when the track model is taken as rigid.

  • 25.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Alexander, Lönnergård
    SEGULA Technologies.
    Mohit, Asher
    Volvo Cars.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Bakker, Egbert
    Volvo Cars.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Analysis and optimisation of objective vehicle dynamics testing in winter conditions2017In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 55, no 7, p. 945-969Article in journal (Refereed)
    Abstract [en]

    Objective testing of vehicle handling in winter conditions has not been implemented yet because of its low repeatability and its low signal-to-noise ratio. Enabling this testing, by identifying robust manoeuvres and metrics, was the aim of this study. This has been achieved by using both experimental data, gathered with steering-robot tests on ice, and simulation models of different complexities. Simple bicycle models with brush and MF-tyre models were built, both optimally parameterised against the experimental data. The brush model presented a better balance in complexity performance. This model was also implemented in a Kalman filter to reduce measurement noise; however, a simpler low-pass filter showed almost similar results at lower cost. A more advanced full vehicle model was built in VI-CarRealTime, based on kinematics and compliance data, damper measurements, and real tyre measurements in winter conditions. This model offered better results and was therefore chosen to optimise the initial manoeuvres through test design and simulations. A sensitivity analysis (ANOVA) of the experimental data allowed one to classify the robustness of the metrics. Finally, to validate the results, the proposed and the initial manoeuvres were tested back to back in a new winter campaign.

  • 26.
    Gil Gómez, Gaspar
    et al.
    Volvo Cars.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Bakker, Egbert
    Volvo Cars.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Findings from subjective evaluations and driver ratings of vehicle dynamics: steering and handling2015In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, no 10, p. 1416-1438Article in journal (Refereed)
    Abstract [en]

    This paper investigates subjective assessments (SA) of vehicle handling and steering feel tests, both numerical and verbal, to understand drivers’ use of judgement scales, rating tendencies and spread. Two different test methods are compared: a short multi-vehicle first-impression test with predefined-driving vs the standard extensive single-vehicle free-driving tests, both offering very similar results but with the former saving substantial testing time. Rating repeatability is evaluated by means of a blind test. Key SA questions are identified by numerical subjective assessment autocorrelations and by generating word clouds from the most used terms in verbal assessments, with both methods leading to similar key parameters. The results exposed in this paper enable better understanding of SA, allowing improving the overall subjective testing and evaluation process, and improving the data collection and analysis process needed before identifying correlations between SA and objective metrics.

  • 27.
    Gil Gómez, Gaspar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. Volvo Cars.
    Nybacka, Mikael
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Bakker, Egbert
    Volvo Cars.
    Machine learning to classify and predict objective and subjective assessments of vehicle dynamics: the case of steering feel.2018In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, no 1, p. 150-171Article in journal (Refereed)
    Abstract [en]

    Objective measurements and computer-aided engineering simu- lations cannot be exploited to their full potential because of the high importance of driver feel in vehicle development. Further- more, despite many studies, it is not easy to identify the relation- ship between objective metrics (OM) and subjective assessments (SA), a task further complicated by the fact that SA change between drivers and geographical locations or with time. This paper presents a method which uses two artificial neural networks built on top of each other that helps to close this gap. The first network, based solely on OM, generates a map that groups together similar vehicles, thus allowing a classification of measured vehicles to be visualised. This map objectively demonstrates that there exist brand and vehi- cle class identities. It also foresees the subjective characteristics of a new vehicle, based on its requirements, simulations and measure- ments. These characteristics are described by the neighbourhood of the new vehicle in the map, which is made up of known vehicles that are accompanied by word-clouds that enhance this description. This forecast is also extended to perform a sensitivity analysis of the tolerances in the requirements, as well as to validate previously pub- lished preferred range of steering feel metrics. The results suggest a few new modifications. Finally, the qualitative information given by this measurement-based classification is complemented with a second superimposed network. This network describes a regression surface that enables quantitative predictions, for example the SA of the steering feel of a new vehicle from its OM. 

  • 28.
    Harell, Pia
    et al.
    KTH, Superseded Departments, Vehicle Engineering.
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Reijm, Marten
    Multiple pantograph operation: effects of section overlaps2004In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, p. 687-696Article in journal (Refereed)
    Abstract [en]

    The traffic situation of the future goes towards flexibility of train configurations and increasing speed. There is a need for the ability to adjust the number of passenger cars as well as the energy consumption for trains to run efficiently, leading to multiple pantographs and short pantograph distances. Limitations due to this were studied on an existing catenary system. A model of the pantograph catenary system was developed in a finite element program. To verify the correctness of the model, comparison with full scale experiments was done. Results from the simulations indicates that trailing pantographs suffers from high dynamic effects within the section overlap. Effects of changes in design of the section overlap was studied. The results show that it is possible to get lower dynamic effects in the section overlap, even lower than within an ordinary span.

  • 29.
    Holen, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Experimental evaluation of modally distributed damping in heavy vehicles2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, no 6, p. 523-541Article in journal (Refereed)
    Abstract [en]

    This work presents theory as well as implementation of a modally distributed damping system with electronically controlled variable dampers. The presented approach follows from estimation of vehicle modal motions, through calculation of desirable modal damping forces to distribution of forces on the Utilised dampers. The response time of the damping system is first evaluated in a damper test rig. The damping system is then implemented on a 4 x 2 tractor that is connected to a semi-trailer. Several road tests are performed to investigate how the system work under real driving conditions on a real vehicle, that includes nonlinearities and chassis frame flexibility that are theoretically unaccounted for, together with the limitations that comes with the control algorithm implementation. It is shown that the approach works and that it results in a considerable improvement for both the bounce and pitch modes, i.e. the system enables selecting damping for the sprung mass modes separately.

  • 30.
    Holen, Peter
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Strandemar, Katrin
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Estimating modal coordinates from damper displacements – A system identification approach2006In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Supplement to Vehicle system dynamics, Vol. 44, p. 805-813Article in journal (Refereed)
    Abstract [en]

    For modal damping systems, estimations of the modal coordinates are crucial. This article shows how the identification of time-domain system can be used to obtain better estimations of the modal coordinates in bounce, pitch and roll for a heavy vehicle. Low-order multiple-input-single-output models used for modal coordinate estimation are identified on data both from multi-body systems' simulations and from vehicle measurements. The identified models show considerable improvements in accuracy when compared with the previously used geometric calculations. Although good models are obtainable for all tested load cases, their validity is somewhat limited to load cases of similar excitation type because driver-induced manoeuvres such as braking and steering wheel action provide different vehicle excitation in comparison to road bumps. A compromise would be to identify an estimation data containing all relevant load cases.

  • 31.
    Holen, Peter
    et al.
    KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
    Thorvald, Boris
    KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
    Possibilities and limitations with distributed damping in heavy vehicles2004In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Supplement to Vehicle System Dynamics, Vol. 41, p. 172-181Article in journal (Refereed)
    Abstract [en]

    This paper investigates passive damping performance in heavy vehicles. The objective is comparison of conventional individual dampers and system with modally distributed damping. An analytical model with 7 DOF is first used to derive theoretical damping expressions. Considered degrees of freedom are for sprung mass; bounce, pitch, roll and for unsprung mass; bounce and roll. Vehicle simulations are then performed with a 4x2-tractor semitrailer combination. Load cases of both ride and handling character are used for damping system evaluation and comparison. The vehicle model with conventional individual dampers is validated against measurement data.

  • 32.
    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.

  • 33. Iwnicki, S. D.
    et al.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Orlova, A.
    Hecht, M.
    Dynamics of railway freight vehicles2015In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 53, no 7, p. 995-1033Article in journal (Refereed)
    Abstract [en]

    This paper summarises the historical development of railway freight vehicles and how vehicle designers have tackled the difficult challenges of producing running gear which can accommodate the very high tare to laden mass of typical freight wagons whilst maintaining stable running at the maximum required speed and good curving performance. The most common current freight bogies are described in detail and recent improvements in techniques used to simulate the dynamic behaviour of railway vehicles are summarised and examples of how these have been used to improve freight vehicle dynamic behaviour are included. A number of recent developments and innovative components and sub systems are outlined and finally two new developments are presented in more detail: the LEILA bogie and the SUSTRAIL bogie.

  • 34.
    Jarlmark, Jonas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Modelling and validation of steering system response to road and driver induced forces2004In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, no SUPPL., p. 371-380Article in journal (Refereed)
    Abstract [en]

    The driver serves both as a controller for the vehicle direction as well as a sensor for the road induced forces. A vehicle model is developed with both computer simulations as well as driving simulator use in mind. Therefore, the included steering system model was divided into one part below and one part above the steering gear. The presented steering system model focuses on force transmission from the wheels to the steering rack and the rack movements including a friction model. Above the steering gear, the model focuses on servo control through the twist of a torsion bar and includes steering wheel inertia and steering column stiffness and friction. The vehicle model has ten degrees of freedom, includes a Magic Formula 5.1 tyre model and is validated together with the steering system model as well as a geometric road model as a complete vehicle-environment model. The validation is made using data from the KTH experimental vehicle in a number of isolated driving cases performed at the Volvo Hällered test track. The simulations performed with the model are mainly focused on the steering wheel moment, sensed by the driver.

  • 35. Jendel, T.
    et al.
    Berg, Mats
    KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
    Prediction of wheel profile wear - Methodology and verification2002In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 37, p. 502-513Article in journal (Refereed)
    Abstract [en]

    A wheel profile wear prediction toot is presented and verified by using a case study. A methodology is introduced that is based an a load collective concept, where representative vehicle-track simulations are chosen to take into account parameters that affect wheel wear. Key parts of the toot are load collective design, vehicle-track simulations, wheel-rail contact response calculations, wear calculations and wheel profile updating. Simulated and measured wheel profiles and corresponding scalar wear measures agree well.

  • 36.
    Jonasson, M.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Volvo Cars, Act Safety & Vehicle Dynam Funct, Gothenburg, Sweden.
    Thor, M.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Steering redundancy for self-driving vehicles using differential braking2018In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 56, no 5, p. 791-809Article in journal (Refereed)
    Abstract [en]

    This paper describes how differential braking can be used to turn a vehicle in the context of providing fail-operational control for self-driving vehicles. Two vehicle models are developed with differential input. The models are used to explain the bounds of curvature that differential braking provides and they are then validated with measurements in a test vehicle. Particular focus is paid on wheel suspension effects that significantly influence the obtained curvature. The vehicle behaviour and its limitations due to wheel suspension effects are, owing to the vehicle models, defined and explained. Finally, a model-based controller is developed to control the vehicle curvature during a fault by differential braking. The controller is designed to compensate for wheel angle disturbance that is likely to occur during the control event.

  • 37.
    Jonasson, Mats
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Andreasson, Johan
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Exploiting autonomous corner modules to resolve force constraints in the tyre contact patch2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, no 7, p. 553-573Article in journal (Refereed)
    Abstract [en]

    This paper presents a general force allocation strategy for over-actuated vehicles, utilising technologies where tyre forces can be more freely controlled than in conventional vehicles. For the purpose of illustration, this strategy has been applied and evaluated using a design proposal of an autonomous corner module (ACM) chassis during a transient open-loop response test. In this work, the vehicle has been forced to follow a trajectory, identical to the performance of a conventional front-steered vehicle during the manoeuvre studied. An optimisation process of tyre force allocation has been adopted along with tyre force constraints and cost functions to favour a desired solution. The vehicle response has been evaluated as open-loop, where tyre forces are shown to be allocated in a different manner than in conventional front-steered vehicles. A suggested approach for a control scheme of steering actuators is presented, where the actuator limitation is related to the lateral force possible. Finally, the force allocation strategy involves the ability to control vehicle slip independently from vehicle yaw rate. This opportunity has been adapted in the ACM vehicle in order to relax vehicle slip from the original trajectory description. In such circumstances, the ACMs demonstrate better utilisation of the adhesion potential.

  • 38.
    Juhlin, Magnus
    KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
    Directional stability of buses under influence of crosswind gusts2004In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, p. 93-102Article in journal (Refereed)
    Abstract [en]

    Incidents with heavy vehicles have put the issue of directional stability of buses under influence of crosswind gusts into focus. In this work the directional stability of buses when exposed to crosswind gusts has been investigated by using a MBS vehicle model combined with a generalised crosswind gust model and results from static wind tunnel measurements. The simulations carried out show the importance of the aerodynamic properties of buses as well as the importance of a proper weight distribution. It is also shown how important the driver model is in order to get realistic directional deviation in simulations and thereby also how important the driver is in order to keep the directional deviation to a minimum in real life situations.

  • 39. Juhlin, Magnus
    Directional stability of buses under influence of crosswinds gusts2004In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 41, p. 93-102Article in journal (Refereed)
    Abstract [en]

    Incidents with heavy vehicles have put the issue of directional stability of buses under influence of crosswind gusts into focus. In this work the directional stability of buses when exposed to crosswind gusts has been investigated by using a MBS vehicle model combined with a generalised crosswind gust model and results from static wind tunnel measurements. The simulations carried out show the importance of the aerodynamic properties of buses as well as the importance of a proper weight distribution. It is also shown how important the driver model is in order to get realistic directional deviation in simulations and thereby also how important the driver is in order to keep the directional deviation to a minimum in real life situations.

  • 40.
    Juhlin, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Stensson Trigell, Annika
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Eriksson, Peter
    Aerodynamic loads on buses due to crosswind gusts – On-road measurements2008In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 46, p. 827-835Article in journal (Refereed)
    Abstract [en]

    Bus and coach traffic is considered to be one of the safest means of travelling. Still, there is a problem with accidents due to crosswind gusts. Therefore it is a need of improving the crosswind performance of buses. As a part of the work with improving the crosswind performance a method for estimating the aerodynamic loads on a bus when exposed to natural crosswind is proposed. The method is based on measurements of the vehicle response and the tire forces from which the aerodynamic loads are estimated using inverse simulations. The results are also shown to agree well with the results of other studies based on wind tunnel measurements. The estimated aerodynamic loads are intended to be used in a future study on crosswind sensitivity using a moving base simulator.

  • 41.
    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.

  • 42.
    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

  • 43.
    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.

  • 44.
    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.

  • 45. Knothe, Klaus
    et al.
    Stichel, Sebastian
    Technical University of Berlin, Aerospace Institute.
    Direct Covariance Analysis for the Calculation of Creepages and Creep-Forces for Various Bogies on Straight Track with Random Irregularities1994In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 23, no 1, p. 237-251Article in journal (Refereed)
    Abstract [en]

    In this paper creep-forces and creepages for an ICE express train coach and an electric locomotive BR 120 of the DB on straight track with random irregularities are investigated. The calculations are made with the multibody program MEDYNA using direct covariance analysis. One of the aims of this article is to emphasize the advantages of the direct covariance method (time domain) compared with the power spectral density method (frequency domain).

  • 46.
    Lesser, Martin
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Karlsson, Lennart
    Luleå Tekniska Universitet .
    Drugge, Lars
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    An interactive model of a pantograph-catenary system1996In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159, Vol. 25, p. 397-412Article in journal (Refereed)
  • 47. 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.

  • 48. 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.

  • 49.
    Li, Yuyi
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering. Beijing Jiaotong Univ, Sch Mech Elect & Control Engn, Beijing, Peoples R China.
    Ren, Zunsong
    Beijing Jiaotong Univ, Sch Mech Elect & Control Engn, Beijing, Peoples R China..
    Enblom, Roger
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Stichel, Sebastian
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Li, Guodong
    CRRC Changchun Railway Vehicles Co Ltd, Dept Bogie Res & Dev, Changchun, Jilin, Peoples R China..
    Wheel wear prediction on a high-speed train in China2019In: Vehicle System Dynamics, ISSN 0042-3114, E-ISSN 1744-5159Article in journal (Refereed)
    Abstract [en]

    The number of operating high-speed trains in China is around 2800 today and 179,200 wheels are under maintenance in one reprofiling period. To help researchers to understand the evolution of the wheel profile and improve the reprofiling strategy of the wheels, this study predicts the development of wheel profiles on a high-speed train as function of mileage and compare simulated worn wheel profiles with measured ones. The methodology includes transient multi-body dynamic simulation, wheel-rail contact calculation and wear calculation with Archard's model. Calibrated by analysing measurements of worn S1002CN profiles and performing parameters sensitivity study in the wear model, the model is then used to predict the development of a recently designed wheel profile, called S1002CN-RF. The simulation results for S1002CN and S1002CN-RF show that the predicted wheel profiles coincide with the measured ones. Wear prediction of another high-speed wheel profile (LMA) validates that the vehicle performance with respect to wear could be further improved compared to using S1002CN or S1002CN-RF. Finally, the influence of track alignment and operating speed is investigated. The wear increases with the speed increasing up to 300 km/h, but stays almost constant with a further speed increase from 300 to 400 km/h.

  • 50.
    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.

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