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  • 1.
    Lundberg, Oskar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    An experimental study on the influence of substrate roughness on the friction of a tread block in rolling and sliding contactManuscript (preprint) (Other academic)
    Abstract [en]

    An experimental study of the friction coefficient is performed for a tyre tread block in rolling and sliding contact with two different asphalt substrates, a smooth aluminium and an anti-slip tape substrate. The sliding friction coefficient is for all substrates seen to increase as the sliding velocity is increasing. However, the slope for the increasing friction as a function of sliding velocity differs significantly between the substrates, presumably due to differences in the respective contribution from adhesive and hysteresis friction mechanisms. Parametric studies of the rolling friction show that the choice of substrate as well as the rolling velocity and the slip ratio has significant influence on the resulting friction coefficient. A linear relation is observed between the longitudinal rolling friction coefficient measured at low values of slip ratio and the sliding friction coefficient measured at low sliding velocities. For the tests of rolling friction at higher values of slip, stick\textendash slip conditions are observed for which the frequency content of the longitudinal force is seen to vary substantially between the different operating conditions and choice of substrate. The outcomes of this study can potentially be used to improve future tyre\textendash road contacts with respect to wear, traction and noise generation.

  • 2.
    Lundberg, Oskar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Friction of a rubber tread block in rolling and sliding contact with asphalt---An experimental studyManuscript (preprint) (Other academic)
    Abstract [en]

    The longitudinal and vertical contact force history of an individual truck tyre tread block in rolling contact with an asphalt surface is experimentally investigated. Different rolling velocities up to approximately 60 km/h and different amount of slip ratios are studied with the use of a novel compact internal drum test rig, leading to results with high signal-to-noise ratio. Interestingly, the longitudinal rolling contact force component and the corresponding friction coefficient exhibit substantial variations not only between the different operating conditions, but also along the contact length of individual impacts. In addition, separate investigatory characterisations for the dynamic elastic deformation of the rubber and for the sliding friction of the rubber\textendash asphalt contact are found to be useful; they provide approximate input values for an initial, promising attempt to separate the contribution from elastic deformation and that from sliding friction. Conclusively, valuable insights are gained which has the potential to further reduce the gap between physically based modelling of friction and empirically based knowledge, which are commonly used in vehicle and tyre industry.

  • 3.
    Lundberg, Oskar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    On the influence of surface roughness on rolling contact forces2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Road vehicle tyres, railway wheels and ball bearings all generate rolling contact forces which are transferred within a finite area of contact between the rolling element and the substrate. Either it is visible or not for the human eye, a certain degree of roughness is always present on the contacting surfaces and it influences the generation of both vertical and lateral contactforces. The purpose of this investigation is to enhance the understanding and modelling of the influence from small-scale surface roughness on the generation of rolling contact forces. To this end, a computationally efficient method to include roughness-induced contact nonlinearities in the dynamic modelling of rolling contacts is proposed. The method is implemented in a time domain model for vertical wheel–track interaction to model rolling-induced rail vibrations, showing good agreement with measurements. Furthermore, a test rig is developed and used for the investigation of tyre–road rolling contact forces. Detailed studies are performed on the influence of substrate roughness on the resulting contact forces for a tyre tread block which is rolling at different operating conditions. The choice of substrate as well as the rolling velocity and the slip ratio is observed to have significant influence on the resulting friction coefficient. For high slip ratios, stick–slip oscillations appear, exhibiting frequency content which is largely dependent on the choice of substrate. The outcomes of this study can potentially be used to improve future tyre–road contacts with respect to wear, traction and noise generation.

  • 4.
    Lundberg, Oskar E.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Nordborg, Anders
    Arteaga, Ines Lopez
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Eindhoven Univ Technol, Netherlands.
    The influence of surface roughness on the contact stiffness and the contact filter effect in nonlinear wheel-track interaction2016In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 366, p. 429-446Article in journal (Refereed)
    Abstract [en]

    A state-dependent contact model including nonlinear contact stiffness and nonlinear contact filtering is used to calculate contact forces and rail vibrations with a time-domain wheel-track interaction model. In the proposed method, the full three-dimensional contact geometry is reduced to a point contact in order to lower the computational cost and to reduce the amount of required input roughness-data. Green's functions including the linear dynamics of the wheel and the track are coupled with a point contact model, leading to a numerically efficient model for the wheel-track interaction. Nonlinear effects due to the shape and roughness of the wheel and the rail surfaces are included in the point contact model by pre-calculation of functions for the contact stiffness and contact filters. Numerical results are compared to field measurements of rail vibrations for passenger trains running at 200 kph on a ballast track. Moreover, the influence of vehicle pre-load and different degrees of roughness excitation on the resulting wheel-track interaction is studied by means of numerical predictions.

  • 5.
    Lundberg, Oskar Erik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Vibrations induced by surface roughness in nonlinear rolling contacts2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    For efficient transportation in either trains, busses or passenger cars, rolling elements such as wheels, tyres, bearings and transmission elements are fundamental. The energy efficiency and the generation of noise and vibrations in rolling contacts depend on the surface roughness of contacting bodies. In order to optimize the surfaces of rolling elements, prediction of its impact on the dynamic response from rolling excitation is required. A computationally efficient method to include surface roughness in the modelling of rolling contacts is presented. More specifically, nonlinear effects on the contact force due to the threedimensional shape and roughness of the contacting surfaces are introduced in a moving point force formulation. As a consequence of the point force approximation follows the assumption that any dynamic wave motion within the contact area is negligible.The rolling contact force is nonlinear due to a varying relative displacement between contacting bodies and is therefore referred to as state-dependent. A study case for the state-dependent method consisting of a steel ball rolling on a steel beam showed good agreement between numerical predictions and measured beam vibrations. Furthermore, an application to the wheel-rail interaction show that roughness-induced contact nonlinearities have a significant impact on the dynamic response caused by rolling excitation.

  • 6.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Pärssinen, M.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    A nonlinear state-dependent model for vibrations excited by roughness in rolling contacts2015In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 345, no 9, p. 197-213Article in journal (Refereed)
    Abstract [en]

    A state-dependent method to model contact nonlinearities in rolling contacts is proposed. By pre-calculation of contact stiffness and contact filters as functions of vertical relative displacement, a computationally efficient modelling approach based on a moving point force description is developed. Simulations using the state-dependent model have been analysed by comparison with measurements. Results from the investigated case consisting of a steel ball rolling over a steel beam having two different degrees of roughness - show good agreement between nonlinear simulations and measured beam vibrations. The promising results obtained with the proposed method are potentially applicable to wheel rail interaction and rolling element bearings.

  • 7.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Non-linear contact forces for beam/ball-interaction and its influence on the dynamic response of the beam2013In: 42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013: Noise Control for Quality of Life, OAL-Osterreichischer Arbeitsring fur Larmbekampfung , 2013, p. 238-247Conference paper (Refereed)
    Abstract [en]

    A well-defined rolling contact problem is studied with the intention to cover interesting aspects of tyre-road contact modeling and rolling contact in general. More specifically, the dynamic response in a steel beam caused by a steel ball rolling over it is studied by theoretical modeling of the beam- And ball dynamics as well as the contact forces. Validation of the dynamic response simulations is achieved by comparison with measurements. The contact model is shown to be greatly dependent on an accurate estimate of the real contact stiffness. A method to estimate the contact stiffness which leads to good accuracy in dynamic response simulations is presented. Although the contact stiffness is significantly lower for rubber- Asphalt interaction than for steel-steel contact, the results give useful insight for tyre-road contact modeling.

  • 8.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Björklund, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Non-linear contact stiffness and dynamic contact filter for rolling contacts2014In: FISITA 2014 World Automotive Congress - Proceedings, FISITA , 2014Conference paper (Refereed)
    Abstract [en]

    Rolling contacts present in passenger cars such as in bearings and transmission elements are sources of noise and vibration, principally for interior comfort concerns. Moreover, tyre/road noise is the main source of road traffic noise which in turn leads to sleep disturbance and annoyance. In order to simulate friction losses as well as generated noise and vibrations in any rolling contact, it is crucial to have a correct description of the dynamic excitation caused by the roughness of the surfaces in contact. In this paper, a state-dependent modelling approach previously proposed by the authors is applied to a well-defined steel-steel rolling contact. A parametric study investigating the influence of rolling speed on contact conditions is performed, indicating the limits for the use of linear point force expressions for the rolling contact investigated. The state-dependent method is based on pre-calculation of contact stiffness and contact filtering as functions of vertical relative displacement. This leads to a computationally efficient way to include the influence of surface roughness and shape of the contacting bodies in a point force expression. Only vertical contact forces are studied within the scope of this work. Tangential friction forces are likely to affect the resulting vibrations and should therefore be further studied. 

  • 9.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    A compact internal drum test rig for measurements of rolling contact forces between a single tread block and a substrate2017In: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 103, p. 370-378Article in journal (Refereed)
    Abstract [en]

    A novel test rig design is presented which enables detailed studies of the three force components generated in the impact and release phase of rolling contact between a tyre tread block and a substrate. The design of the compact internal drum test rig provides realistic impact and release angles for the tread block-substrate contact and enables force measurements at high rolling speeds with a high signal-to-noise ratio. Measurements of the rolling contact forces are presented for different values of rolling velocity, static pre-load and acceleration. It is demonstrated that this test rig provides results which contribute to the understanding of tyre road interaction and can be used as input to modelling-based development of both tyres and roads aiming for improved handling, safety, energy efficiency and comfort.

  • 10.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design. Eindhoven University of Technology, The Netherlands.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    A compact internal drum test rig for measurements of rolling contact forces between a single treadblock and a substrateManuscript (preprint) (Other academic)
    Abstract [en]

    A novel test rig design is presented which enables detailed studies of the three force components generated in the impact and release phase of rolling contact between a tyre tread block and a substrate. The design of the compact internal drum test rig provides realistic impact and release angles for the tread block-substrate contact and enables force measurements at high rolling speeds with a high signal-to-noise ratio. Measurements of the rolling contact forces are presented for different values of rolling velocity, static pre-load and acceleration. It is demonstrated that this test rig provides results which contribute to the understanding of tyre--road interaction and can be used as input to modelling-based development of both tyres and roads aiming for improved handling, safety, energy efficiency and comfort.

  • 11.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Experimental study of the rolling contact forces between a tyre tread-block and a road2016In: Proceedings of the INTER-NOISE 2016 - 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future, German Acoustical Society (DEGA) , 2016, p. 2179-2184Conference paper (Refereed)
    Abstract [en]

    For a rolling tyre, forces arise within the tyre-road contact patch, leading to the excitation of tyre vibrations and in turn to noise radiation. This is the main cause of highway noise and consequently much effort has been made to understand and model the tyre vibrational character as well as the sound radiation. However, when it comes to the generation of contact forces in the tyre-road interface, there is still a demand for future research. Specifically, the understanding and modelling of the influence from tangential force excitation on the resulting tyre-road noise is a complicated topic which involves many parameters such as tread rubber characteristics, road surface character, rolling velocity, rolling resistance and normal load. In this paper, an experimental study of the tangential friction contact forces which arise for a single truck tyre tread block in rolling contact with a road surface is presented. Both the dynamic tangential dynamic stiffness as well as the sliding frictional behavior of the same tread block is experimentally investigated. Moreover, an example measurement with the novel compact internal drum (CID) test rig is presented. The test rig can be used to study the influence on the resulting contact forces from parameters such as rolling velocity, road surface topography and normal load.

  • 12.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Nordborg, A.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Estimation of nonlinearities in the wheel-rail rolling noise generation process2014In: Proceedings of ISMA 2014 - International Conference on Noise and Vibration Engineering and USD 2014 - International Conference on Uncertainty in Structural Dynamics, 2014, p. 3485-3496Conference paper (Other academic)
    Abstract [en]

    The dynamics of wheel-rail interaction is predicted using a time-domain rolling contact model and a state-dependent method to model nonlinear contact forces in the wheel-rail interaction. Contact stiffness and contact filters are pre-calculated as functions of the vertical wheel-rail relative displacement (state-dependency) using three-dimensional surface data in quasi-static contact computations. By including the state-dependent functions in time-domain prediction of wheel-rail interaction, a computationally efficient method to include nonlinear effects is obtained. Results from predictions of contact forces as well as rail vibrations are presented for two conditions; first, both wheel and rail have surface roughness of broadband character and secondly, a rail corrugation is simulated by superimposing a sinusoidal component on the broadband rail roughness. For a train speed of 200 kph, the contact forces and the dynamic response of the rail exhibit nonlinear contact conditions for both the broadband roughness case as well as for the case where a rail corrugation is simulated.

  • 13.
    Lundberg, Oskar
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Nordborg, A
    Lopez-Arteagac, I
    La generación de ruido en el contacto entre la rueda y el carril – efectos no lineales2014Conference paper (Other academic)
    Abstract [es]

    La fuente más importante de ruido y vibraciones en sistemas ferroviarios proviene del contacto entre la rueda y el carril. Junto con el perfil geométrico de la rueda y del carril, la rugosidad de las superficies definen la magnitud de la rigidez de contacto así como también la magnitud del filtro espacial de contacto que efectivamente reduce la excitación de ruido y vibraciones de altas frecuencias(rugosidades con corta longitud de onda). Normalmente, los modelos de interacción dinámica entre la rueda y el carril son lineales y la solución se deriva en el dominio frecuencial, lo cual conduce a aproximar la magnitud de la rigidez y del filtro espacial a valores constantes. El presente trabajo expone resultados del modelado de dicha interacción dinámica entre la rueda y el carril efectuado en el dominio temporal. El método utilizado incluye los efectos no lineales en la rigidez de contacto y en el filtro espacial generados por el perfil geométrico de la rueda/el carril y la rugosidad de las superficies. Los resultados de una investigación paramétrica revelan la influencia de los efectos no lineales sobre la generación de las fuerzas producidas en el contacto rodante.

  • 14. Nordborg, A.
    et al.
    Lundberg, Oskar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Contributions of contact nonlinearities to wheel/rail noise generation2014In: Proceedings of Forum Acusticum, European Acoustics Association (EAA), 2014Conference paper (Refereed)
    Abstract [en]

    A model for calculation of generation and radiation of railway noise is presented. Thanks to a Green's function formulation, in the time as well as in the frequency domain, not only roughness excitation, but also parametric excitation (due to varying rail receptance along the track) and excitation due to nonlinear effects in the rail/wheel contact region are included in the description. Another advantage of the model is that vibration propagation and decay along the track is an inherent property of the Green's function of the periodically supported rail. The advantages of the model is demonstrated with a calculation example of rail/wheel contact force and noise radiation from the rail for a typical sleeper-supported ballast track. Noise radiation peaks around 1000 Hz. For higher frequencies, parametric excitation and nonlinear effects may contribute significantly to total railway noise radiation.

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