| 1. |
- Dirks, Babette, et al.
(författare)
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Prediction model for wheel profile wear and rolling contact fatigue
- 2009
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Ingår i: 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems.
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Konferensbidrag (refereegranskat)abstract
- A lifetime prediction tool for railway wheels and rails should be able to predict both wear and rolling contact fatigue (RCF), which are the two main deterioration phenomena. Several models exist to predict wear or RCF, but not that many models exist which can predict both. In this study, two of these RCF prediction models have been extended. The performance of these models has been studied through a parametric study where multi-body simulations (MBS) provided the input to the models. The influences of several parameters which can have an effect on the wheel/rail life have been studied in order to find the behavior of the different models. These parameters are: curve radius, worn wheel and rail profiles, coefficient of friction, primary stiffness, track irregularities, and cant deficiency. This paper describes the differences between the two models and shows that the adjustments of the models have a significant influence on RCF prediction.
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| 2. |
- Enblom, Roger
(författare)
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Deterioration mechanisms in the wheel-rail interface with focus on wear prediction : a literature review
- 2009
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 47:6, s. 661-700
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Forskningsöversikt (refereegranskat)abstract
- 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.
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| 3. |
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| 4. |
- Enblom, Roger, et al.
(författare)
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Impact of non-elliptic contact modelling in wheel wear simulation
- 2008
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 265:9-10, s. 1532-1541
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Tidskriftsartikel (refereegranskat)abstract
- Advances in simulation of railway wheel wear in the sense of material removal have drawn the attention to the importance of wheel–rail contact modelling. As a further step of enhancing the used simulation procedure in direction of increased generality and reduced need for application-dependent calibration, the focus of this investigation is the influence of non-elliptic contact models on the wheel wear rate and profile shape. To facilitate evaluation the semi-Hertzian contact procedure Stripes, developed by INRETS in France, has been implemented. To investigate the capabilities of Stripes to assess the contact area and pressure, shape comparisons have been made with other numerical methods for a set of wheel–rail contact situations. The referenced results are based on the linear elastic half-space assumption, elastic finite element analysis, and elastic–plastic finite element analysis. For reference also the elliptic contact area according to Hertz is shown as given by the contact data table of the multi-body simulation code. After exploring the properties of the Stripes procedure with respect to contact area estimation and pressure distribution, the focus is moved to the influence on wear rate, being the principal objective of this investigation. First the wear distribution over the contact patch is studied and compared to results using the elliptic model from the MBS code Gensys and the non-elliptic approach with Kalker's code Contact. Finally the evolution of the wheel profile is simulated for a few typical cases. This investigation of wear distributions over non-elliptic patches under different operating conditions indicates significant differences compared to both Contact and the applied Hertzian approach. The expansion from single contact occasions to complete simulations indicates comparable material removal rates but relocation towards the flange side. This tendency is apparent in all of the cases shown, however limited to initial wear in tangent run or reasonably mild curve negotiation.
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| 5. |
- Enblom, Roger, et al.
(författare)
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Industrial implementation of novel railway wheel damage prediction procedures
- 2009
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Ingår i: 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems.
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Konferensbidrag (refereegranskat)abstract
- Adequate performance of the wheel-rail interface is essential for satisfactory operation of a railway system in terms of quality of service and maintenance effort. Pertinent requirements on efficiency tend to push the operation conditions toward higher loads and increased speed while the wheel-rail contact remains as a small and highly stressed area. Dominating modes of deterioration due to high normal and tangential stresses are wear and rolling contact fatigue. Both kinds lead to surface material loss, in the former case as a slow rate profile geometry change with consequences to the dynamic performance and in the latter case different crack patterns and eventually spalling or shelling requiring reprofiling.In this paper the implementation of emerging technologies for wheel damage prediction in an engineering environment is summarised. Methods for prediction of wear and profile geometry evolution as well as for assessment of the risk for onset of rolling contact fatigue are described. Example results from recent applications are given.In general it may be concluded that the implemented methods are becoming useful for prediction of profile alterations, for instance hollow wear linked to conicity increase and flange wear. The fatigue assessment methods are less mature and need further calibration but are still capable to indicate location and significance of risk for damage.
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| 6. |
- Enblom, Roger, 1950-
(författare)
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On Simulation of Uniform Wear and Profile Evolution in the Wheel - Rail Contact
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Numerical procedures for reliable wheel and rail wear prediction are rare. Recent development of simulation techniques and computer power together with tribological knowledge do however suggest computer aided wear prediction as possible. The present objective is to devise a numerical procedure able to simulate profile evolution due to uniform wear sufficiently accurate for application to vehicle dynamics simulation. Such a tool should be useful for maintenance planning, optimisation of the railway system and its components as well as trouble-shooting. More specifically, the field of application may include estimation of reprofiling frequency, optimisation of wheel – rail profile match, optimisation of running gear suspension parameters, and recognition of unfavourable profile evolution influencing the dynamic response of the vehicle. The research contribution accounted for in this thesis includes, besides a literature review, modelling of the wheel – rail interface, benchmarking against traditional methods, and validation with respect to full-scale measurements. The first part addresses wheel – rail contact conditions in the context of wear simulation as well as tribological environment and tractive forces. The current approach includes Archard’s wear model with associated wear maps, vehicle dynamics simulation, and railway network definition. One objective is to be able to include variations in operation conditions in the set of simulations instead of using scaling factors. In particular the influence of disc braking and varying lubrication conditions have been investigated. Both environmental factors like moist and contamination and deliberate lubrication need to be considered. As part of the associated contact analysis the influence of tangential elastic deformation of the contacting surfaces has been investigated and found to be essential in case of partial slip contact conditions. The influence on the calculated wear of replacing the Hertzian contact by a non-elliptic semi-Hertzian method has been investigated, showing relocation of material loss towards increased profile curvature. In the second part comparisons have been carried out with traditional methods, where the material loss is assumed to be directly related to the energy dissipated in the contact. Attention has been paid to the understanding of the principle differences between the investigated methods, comparing the distribution of friction energy, sliding velocity, and wear depth. As a prerequisite, contact conditions with dependence on wheelset guidance and curving performance as well as influence of tractive forces have been investigated. In the final part validation of the developments related to wheel wear simulation is addressed. Disc braking has been included and a wear map for moist contact conditions based on recent tests has been drafted. Good agreement with measurements from the reference operation, is achieved. Further a procedure for simulation of rail wear and corresponding profile evolution has been formulated. A simulation set is selected defining the vehicles running on the track to be investigated, their operating conditions, and contact parameters. Trial calculations of a few curves show qualitatively good results in terms of profile shape development and difference in wear mechanisms between gauge corner and rail head. The wear rates related to traffic tonnage are however overestimated. The impact of the model improvements accounted for in the first part of the thesis has been investigated, indicating directions for further development.
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| 7. |
- Enblom, Roger, et al.
(författare)
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Proposed procedure and trial simulation of rail profile evolution due to uniform wear
- 2008
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 222:1, s. 15-25
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Tidskriftsartikel (refereegranskat)abstract
- A procedure for numerical simulation of rail wear and the corresponding profile evolution has been formulated. The wear is assumed to be uniform in the sense that the profiles remain constant along the track portion to be investigated. A simulation set is selected defining the vehicles running on the track, their operating conditions, and contact parameters. Several variations of input data may be included together with the corresponding occurrence probability. Simulation of multi-body dynamics is used to calculate contact forces and positions, and Archard's wear equation is applied for the calculation of wear depth. Wear coefficients as a function of contact pressure and relative sliding velocity are collected from different test results. Trial calculations of four non-lubricated and two lubricated curves with radii from 303 to 802 m show qualitatively reasonable results in terms of profile shape development and difference in wear mechanisms between gauge corner and rail head. The wear rates related to traffic tonnage are, however, overestimated and the lubrication efficiency underestimated. It is expected that model refinements in terms of environmental influence and contact stress calculation are useful to improve the quantitative results.
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| 8. |
- Enblom, Roger, et al.
(författare)
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Simulation of railway wheel profile development due to wear : influence of disc braking and contact environment
- 2005
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Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 258:7-8, s. 1055-1063
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Tidskriftsartikel (refereegranskat)abstract
- This paper addresses issues related to braking and wheel-rail contact conditions in the context of wheel wear simulation. The KTH approach to the topic includes Archard's wear model with associated wear maps, vehicle dynamics simulation and railway network definition. In previous work at KTH certain variations in operating conditions have been accounted for through empirically estimated average scaling factors. The objective of the current research is to be able to include such variations in the set of simulations. In particular the influence of disc braking as well as varying friction and lubrication conditions are investigated. Both environmental factors like moist and contamination and deliberate lubrication need to be considered. As part of the associated contact analysis the influence of local elastic deformation on the sliding velocity has been separately investigated.
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| 9. |
- Enblom, Roger
(författare)
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Two-level numerical optimization of ride comfort in railway vehicles
- 2006
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - 0954-4097 .- 2041-3017. ; 220:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- This article addresses the interaction between and tuning of different mechanical subsystems in railway vehicle design. Application of numerical methods in a two-ievel optimization process, involving multi-body vehicle dynamics simulation and finite-element structural analysis, is proposed. The focus is on vibration ride comfort and tuning of dynamic properties of the vehicle, running gear, and carbody structure. As a background, a brief overview of multi-disciplinary and structural optimization methods is given. The selected solution based on the loosely coupled collaborative optimization approach, here implemented as a two-level structure, is presented. Numerical examples are provided to illustrate the choice of optimization algorithms suitable for this type of resonant systems and to demonstrate the performance of the numerical procedures on a realistic engineering problem. The leading coach of a three-car train-set is successfully optimized in terms of mass reduction and reduced natural frequency requirements, despite an infeasible initial design.
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| 10. |
- Iwnicki, Simon, et al.
(författare)
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Wheel-rail contact mechanics
- 2009
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Ingår i: Wheel-rail interface handbook. - Cambridge, UK : Woodhead Publishing Ltd. - 9781845694128 - 9781845696788 - 9781439801468 ; , s. 58-92
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Bokkapitel (refereegranskat)
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| 11. |
- Kabo, Elena, 1972, et al.
(författare)
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Assessing risks of subsurface initiated rolling contact fatigue from field measurements
- 2009
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Ingår i: Proceedings of the 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems. ; 1, s. 355-361
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Konferensbidrag (refereegranskat)abstract
- A previous simplification of the Dang Van equivalent stress measure for cases of wheel–rail contact is modified. The new criterion is suited for real-time rolling contact fatigue assessment of measured wheel–rail contact forces. The only parameters in the new expression for the equivalent stress are the vertical force and the wheel and rail radii.Comparisons between the new and the original criterion are carried out and show good agreement for the studied cases of tangent track operation. By employing principles of vehicle dynamics the criterion is further extended to the case of operations in curves. Finally the influence of transient loads on the growth of RCF cracks in wheels was investigated. It was demonstrated that transients need to be spaced closer than roughly 10 meters to give any substantial increase in crack growth rates.
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| 12. |
- Stichel, Sebastian, et al.
(författare)
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Investigation of the risk for Rolling Contact Fatigue on wheels of different passenger trains
- 2008
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 46:suppl. 1, s. 317-327
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Tidskriftsartikel (refereegranskat)abstract
- Of late, rolling contact fatigue (RCF) has become more common oil wheels of passenger trains. Cracks initiated at the wheel surface have been found on certain trains, which has led to wheel damage and more frequent re-profiling, reducing the lifetime of the wheels. Two possible theories to predict circumferential RCF have been identified, i.e. the shakedown theory and damage function. Investigations have been performed with the MBS simulation tool SIMPACK. The wheel profiles in the investigations are mainly P8 and S1002. In principle, the correlation between field observations and predicted damage is fairly good. It is concluded that both the shakedown theory and damage function can be used for indicative predictions using quasi-static simulations. With the limitations of the study, some guidelines are given for the assessment of results from quasi-static simulations in Curves.
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