| 1. |
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| 2. |
- Burgelman, Nico, et al.
(författare)
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Influence of wheel-rail contact modelling on vehicle dynamic simulation
- 2015
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 53:8, s. 1190-1203
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Casanueva, Carlos, 1981-, et al.
(författare)
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Comparison of wear prediction models for different contact conditions
- 2016
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Ingår i: Proceedings of the 24th Symposium of the International Association for Vehicle System Dynamics (IAVSD 2015), Graz, Austria, 17-21 August 2015. - : CRC Press. - 9781138028852 - 9781498777025 ; , s. 871-878
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Konferensbidrag (refereegranskat)abstract
- Simulation of wheel and rail wear allows to predict long term profile evolution and thus, study the consequences of wheel damage in the dynamic behaviour of the vehicle, or study future maintenance requirements. Several models have been developed which try to solve the wear issue by relating the energy dissipated in the wheel-rail contact to the worn out material, from which two can be highlighted (Tg/A and Archard) which have significant differences on contact level. Even though, the prediction of long term wheel profile evolution has been validated with these two models, which means that for regular applications they seem to have an equivalent behaviour. In this work similarities and differences between the long term wear prediction methodologies are analysed, discussing their actual limitations. Then, these differences are exploited in specific operational cases to compare their wear prediction performance.
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| 4. |
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| 5. |
- Casanueva, Carlos, 1981-, et al.
(författare)
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On integrated wheel and track damage prediction using vehicle-track dynamic simulations
- 2017
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Ingår i: Proceedings of the Institution of mechanical engineers. Part F, journal of rail and rapid transit. - : Sage Publications. - 0954-4097 .- 2041-3017. ; 231:7, s. 775-785
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Tidskriftsartikel (refereegranskat)abstract
- The renewal costs for wheels and rails are a substantial part of the costs for rolling stock operators and infrastructure managers all over the world. The causes for reprofiling or grinding are, in most cases, related to the following: (1) wheel or rail profiles with unacceptable wear, (2) appearance of rolling contact fatigue cracks in the surface, and (3) wheel flats caused by locking wheels during braking. The first two causes are related to the dynamic behavior of the vehicle-track system, and can be predicted using multibody simulations. However, there are several limitations that restrain the usefulness of these prediction techniques, such as simulation time constraints, necessary simplifications, and lack of experimental data that lead to educated assumptions. In this paper, we take the end-user perspective in order to show whether the latest developments in wheel-rail damage prediction can be integrated in a simplified framework, and subsequently used by the different stakeholders for an improved management of the different assets involved in the operation of rail vehicles.
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| 6. |
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| 7. |
- Dirks, Babette, et al.
(författare)
-
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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| 8. |
- Dirks, Babette, et al.
(författare)
-
Prediction model for wheel profile wear and rolling contact fatigue
- 2011
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 271:1-2, s. 210-217
-
Tidskriftsartikel (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 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 behaviour 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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| 9. |
- Dirks, Babette, et al.
(författare)
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Prediction of wheel profile wear and crack growth : Comparisons with measurements
- 2015
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Ingår i: CM 2015 - 10th International Conference on Contact Mechanics of Wheel / Rail Systems.
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Konferensbidrag (refereegranskat)abstract
- A model which can predict the surface crack length and crack depth in rails was developed in a previous study by the authors1. In the present study, this crack prediction model in combination with a wear prediction model is verified against wheel measurements. For a period of 15 months, the wheels of three units of a Stockholm commuter train were measured with respect to wear and crack development. Vehicle-track dynamics simulations were used to calculate the forces and contact positions for the wear and crack prediction models. It can be concluded that the wear prediction model gives reasonable results, especially considering the large scatter in the wheel profile measurements. Although the crack prediction model had to be adjusted for the current wheel application, the results appear promising.
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| 10. |
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| 11. |
- Dirks, Babette, et al.
(författare)
-
Prediction of wheel profile wear and crack growth - comparisons with measurements
- 2016
-
Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 366, s. 84-94
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Tidskriftsartikel (refereegranskat)abstract
- A model which can predict the length of the surface crack and crack depth in rails was developed in a previous study by the authors B. Dirks, R. Enblom, A. Ekberg, M. Berg (2015) []. In the present study, verification of this crack prediction model in combination with a wear prediction model was done against wheel measurements. For a period of 15 months, the wheels of three units of a Stockholm commuter train were measured with respect to wear and crack development for verification of the wheel life prediction tool. Vehicle-track dynamics simulations were used to calculate the forces and contact positions for the wear and crack prediction models. It can be concluded that the wear prediction model gives reasonable results, especially considering the large scatter in the wheel profile measurements. Although the wheel life prediction tool could not be verified, since the crack prediction model had to be recalibrated for the current wheel application, the results appear promising.
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| 12. |
- Dirks, Babette, et al.
(författare)
-
Prediction of wheel profile wear and rolling contact fatigue for the Stockholm commuter train
- 2010
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Ingår i: 16th International Wheelset Congress.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Although several models exist to predict rolling contact fatigue (RCF) or wear, only a few models exist which can predict both. RCF and wear interact with each other, therefore a model has to be developed that can calculate both RCF and wear in order to get a lifetime prediction tool for railway wheels and rails. In this study, vehicle dynamics simulations were performed with the models of two different vehicle types running on the Stockholm commuter network. The performance of these vehicles has been studied with respect to wear and RCF by importing the output from the vehicle dynamics simulations into different wear and RCF models. The performance of these prediction models has also been studied. The influences of several parameters on the behavior of both the vehicles and the prediction models were studied. The results show that not only the vehicles behave differently, but also the wear and RCF prediction models.
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| 13. |
- Dirks, Babette, 1976-
(författare)
-
Simulation and Measurement of Wheel on Rail Fatigue and Wear
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The life of railway wheels and rails has been decreasing in recent years. This is mainly caused by more traffic and running at higher vehicle speed. A higher speed usually generates higher forces, unless compensated by improved track and vehicle designs, in the wheel-rail contact, resulting in more wear and rolling contact fatigue (RCF) damage to the wheels and rails. As recently as 15 years ago, RCF was not recognised as a serious problem. Nowadays it is a serious problem in many countries and ''artificial wear'' is being used to control the growth of cracks by preventive re-profiling and grinding of, respectively, the wheels and rails. This can be used because a competition exists between wear and surface initiated RCF: At a high wear rate, RCF does not have the opportunity to develop further. Initiated cracks are in this case worn off and will not be able to propagate deep beneath the surface of the rail or wheel.When wheel-rail damage in terms of wear and RCF can be predicted, measures can be taken to decrease it. For example, the combination of wheel and rail profiles, or the combination of vehicle and track, can be optimised to control the damage. Not only can this lead to lower maintenance costs, but also to a safer system since high potential risks can be detected in advance.This thesis describes the development of a wheel-rail life prediction tool with regard to both wear and surface-initiated RCF. The main goal of this PhD work was to develop such a tool where vehicle-track dynamics simulations are implemented. This way, many different wheel-rail contact conditions which a wheel or a rail will encounter in reality can be taken into account.The wear prediction part of the tool had already been successfully developed by others to be used in combination with multibody simulations. The crack prediction part, however, was more difficult to be used in combination with multibody simulations since crack propagation models are time-consuming. Therefore, more concessions had to be made in the crack propagation part of the tool, since time-consuming detailed modelling of the crack, for example in Finite Elements models, was not an option. The use of simple and fast, but less accurate, crack propagation models is the first step in the development of a wheel-rail life prediction model.Another goal of this work was to verify the wheel-rail prediction tool against measurements of profile and crack development. For this purpose, the wheel profiles of trains running on the Stockholm commuter network have been measured together with the crack development on these wheels. Three train units were selected and their wheels have been measured over a period of more than a year. The maximum running distance for these wheels was 230,000 km.A chosen fatigue model was calibrated against crack and wear measurements of rails to determine two unknown parameters. The verification of the prediction tool against the wheel measurements, however, showed that one of the calibrated parameters was not valid to predict RCF on wheels. It could be concluded that wheels experience relatively less RCF damage than rails. Once the two parameters were calibrated against the wheel measurements, the prediction tool showed promising results for predicting both wear and RCF and their trade-off. The predicted position of the damage on the tread of the wheel also agreed well with the position found in the measurements.
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| 14. |
- Dirks, Babette, et al.
(författare)
-
The development of a crack propagation model for railway wheels and rails
- 2015
-
Ingår i: Fatigue and Fracture of Engineering Materials and Structures. - : Wiley. - 8756-758X .- 1460-2695. ; 38:12, s. 1478-1491
-
Tidskriftsartikel (refereegranskat)abstract
- Rolling contact fatigue (RCF) and wear of railway wheels and rails are the main phenom-ena that affect their m aintenance costs. When crack propagation and wear rates can bepredicted, maintenance planning can be optimised, and cost-effective measures can bedeveloped. Several RCF models exist, but none which can be used in combination withvehicle dynamics simulations and can predict the actual crack depth. This study showsthe development of a crack propagation model that can be applied for both railwaywheels and rails. Two unknow n material parameters in the model were calibrated againstcrack measurements in a curve on the Dutch railways over a period of 5 years. Two dif-ferent RCF models were used to calculate the stress magnitudes for the propagationmodel. The propagation model can be used in combination with vehicle-track dynamicssimulations and shows promise in predicting the actual crack depth and/or surface length.Further research is needed to determine the model’s validity for other operationalconditions.
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| 15. |
- Enblom, Roger
(författare)
-
Deterioration mechanisms in the wheel-rail interface with focus on wear prediction : a literature review
- 2009
-
Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 47:6, s. 661-700
-
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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| 16. |
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| 17. |
- Enblom, Roger
(författare)
-
Getting to the root of wheel wear
- 2010
-
Ingår i: Railway Gazette International. - Sutton, UK : DVV Media UK Ltd. - 0373-5346. ; 166:3, s. 35-38
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 18. |
- Enblom, Roger, et al.
(författare)
-
Impact of non-elliptic contact modelling in wheel wear simulation
- 2008
-
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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| 19. |
- Enblom, Roger, et al.
(författare)
-
Industrial implementation of novel procedures for the prediction of railway wheel surface deterioration
- 2011
-
Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 271:1-2, s. 203-209
-
Tidskriftsartikel (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 towards higher loads and increased speed while the wheel-rail contact remains 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 the prediction of wheel surface deterioration in an engineering environment is summarised. Methods for the prediction of wear and profile geometry evolution as well as for the assessment of the risk for the 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 the 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 of indicating location and significance of risk for damage.
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| 20. |
- Enblom, Roger, et al.
(författare)
-
Industrial implementation of novel railway wheel damage prediction procedures
- 2009
-
Ingår i: 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems.
-
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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| 21. |
- Enblom, Roger, 1950-
(författare)
-
On Simulation of Uniform Wear and Profile Evolution in the Wheel - Rail Contact
- 2006
-
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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| 22. |
- Enblom, Roger, et al.
(författare)
-
Proposed procedure and trial simulation of rail profile evolution due to uniform wear
- 2008
-
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
-
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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| 23. |
- Enblom, Roger, et al.
(författare)
-
Simulation of railway wheel profile development due to wear : influence of disc braking and contact environment
- 2005
-
Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 258:7-8, s. 1055-1063
-
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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| 24. |
- Enblom, Roger
(författare)
-
Simulation of Wheel and Rail Profile Evolution : Wear Modelling and Validation
- 2004
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Numerical procedures for reliable wheel and rail wearprediction are rare. Recent development of simulationtechniques and computer power together with tribologicalknowledge do however suggest computer aided wear prediction.The objective of the related research field at the RoyalInstitute of Technology (KTH) is to arrive at a numericalprocedure able to simulate profile evolution due to uniformwear to a degree of accuracy sufficient for application tovehicle dynamics simulation. Such a tool would be useful formaintenance planning as well as optimisation of the transportsystem and its components. The research contribution accounted for in this thesisincludes, in addition to a literature review, refinement ofmethods applied to uniform wheel wear simulation by inclusionof braking and improvement of the contact model. Further atentative application to uniform rail wheel simulation has beenproposed and tested. The first part addresses issues related to braking andwheel-rail contact conditions in the context of wheel wearsimulation. The KTH approach includes Archard’s wear modelwith associated wear maps, vehicle dynamics simulation andrailway network definition. In previous work at KTH certainvariations in operating conditions have been accounted forthrough empirically estimated average scaling factors. Theobjective of the current research is to be able to include suchvariations in the set of simulations. In particular theinfluence of disc braking and varying friction and lubricationconditions are investigated. Both environmental factors likemoist and contamination and deliberate lubrication need to beconsidered. As part of the associated contact analysis theinfluence of tangential elastic deformation of the contactingsurfaces on the sliding velocity has been separatelyinvestigated and found to be essential in case of partial slipcontact conditions. In the second part validation of the improvements related towheel wear simulation is addressed. Disc braking has beenincluded in the simulation set and a wear map for moist contactconditions based on recent tribometer tests has been draftedand tested. It has been shown that the previously used brakingfactor accounts for the combination of the contributions fromsurface elasticity and braking. Good agreement withmeasurements from the Stockholm commuter service is achieved.It is concluded that the model improvements accounted for aresufficient for adequate simulation of tread wear but thatfurther development of the flange / gauge corner contactmodelling may be needed. In the final part a procedure for simulation of rail wearand corresponding profile evolution has been formulated. Asimulation set is selected defining the vehicles running on thetrack to be investigated, their operating conditions, andcontact parameters. Several variations of input data may beincluded together with the corresponding occurrenceprobability. Trial calculations of four non-lubricated curveswith radii from 303 m to 802 m show qualitatively reasonableresults in terms of profile shape development and difference inwear mechanisms between gauge corner and rail head. The wearrates related to traffic tonnage are however overestimated. Itis believed that model refinements in terms of environmentalinfluence and contact stress calculation are useful to improvethe quantitative results.
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| 25. |
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| 26. |
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| 27. |
- Enblom, Roger
(författare)
-
Two-level numerical optimization of ride comfort in railway vehicles
- 2006
-
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
-
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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| 28. |
- Enblom, Roger, et al.
(författare)
-
Wheel Wear Modelling Including Disc Braking and Contact Environment : Simulation of 18 Months of Commuter Service in Stockholm
- 2004
-
Ingår i: Proceedings of the 14th International Wheelset Congress.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper addresses some aspects of modelling and validation of wheel wear simulation. In previous work at KTH the influences of braking and lubrication have been accounted for through empirically estimated average scaling factors. The current research shows how to include those effects in the set of simulations instead. Disc braking has been included in the simulation set and a wear map for moist contact conditions based on recent tribometer tests has been drafted and tested. Good agreement with measurements from theStockholmcommuter service is achieved. It is concluded that the model improvements accounted for are sufficient for adequate simulation of tread wear but that further development of the flange / gauge corner contact modelling is needed.
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| 29. |
- Iwnicki, Simon, et al.
(författare)
-
Wheel-rail contact mechanics
- 2009
-
Ingår i: Wheel-rail interface handbook. - Cambridge, UK : Woodhead Publishing Ltd. - 9781845694128 - 9781845696788 - 9781439801468 ; , s. 58-92
-
Bokkapitel (refereegranskat)
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| 30. |
- Kabo, Elena, 1972, et al.
(författare)
-
A simplified index for evaluating subsurface initiated rolling contact fatigue from field measurements
- 2011
-
Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 271:1-2, s. 120-124
-
Tidskriftsartikel (refereegranskat)abstract
- A previous simplification of the Dang Van equivalent stress measure for assessment of subsurface initiated rolling contact fatigue (RCF) related to wheel-rail contact is modified. The new criterion is intended for real-time assessment of subsurface RCF from measured wheel-rail contact forces. The only needed 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 operations. By employing principles of vehicle dynamics the criterion is further extended to the case of operations in curves. Reasonable consistency was found for curve radii down to approximately 2000 m.
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| 31. |
- Kabo, Elena, 1972, et al.
(författare)
-
Assessing risks of subsurface initiated rolling contact fatigue from field measurements
- 2009
-
Ingår i: Proceedings of the 8th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems. ; 1, s. 355-361
-
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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| 32. |
- Li, Yuyi, et al.
(författare)
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Influence of an alternative non-elliptic contact model on wheel wear calculation
- 2018
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Ingår i: The Dynamics of Vehicles on Roads and Tracks. - : CRC Press. - 9781138035713 ; , s. 937-943
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Konferensbidrag (refereegranskat)abstract
- The contact model between wheel and rail is significant for predicting wear of the wheel profile with help of multi-body dynamics simulation. Among the contact models, Hertz’s theory and Fastsim algorithm are widely used in MBS software due to high computational efficiency and acceptable precision. But with respect to wear, the accuracy of such a contact model is insufficient, especially for predicting the wear distribution. A new non-elliptic contact model called ANALYN/FaStrip with fast calculation speed has been proposed to improve the precision for both normal and tangential solutions. This paper investigates the influence of this new contact model on the wear calculation by comparing with Hertz/Fastsim in terms of contact pressure and creep forces, and finally indicates the difference of wear depth calculated by the two contact models. The results illustrate that significant improvements can be gained by implementing ANALYN/FaStrip into the wheel wear prediction.
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| 33. |
- Li, Yuyi, et al.
(författare)
-
Wheel wear prediction on a high-speed train in China
- 2020
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Ingår i: Vehicle System Dynamics. - : Taylor & Francis. - 0042-3114 .- 1744-5159. ; 58:12, s. 1839-1858
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 34. |
- S. Sichani, Matin, et al.
(författare)
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Comparison of Non-elliptic Contact Models : Towards Fast and Accurate Modelling of Wheel-Rail Contact
- 2012
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Ingår i: Proceeding of 9th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems. ; , s. 120-128
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Konferensbidrag (refereegranskat)abstract
- The demand to investigate and predict the surface deterioration phenomenain the wheel-rail interface necessitates fast and accurate contact modelling.During the past twenty years, there have been attempts to determine more realisticcontact patch and stress distributions using fast non-iterative methods.The main aim of the present work is to compare some of these state-of-theart,non-elliptic contact models available in the literature. This is consideredas the first step in introducing a fast and accurate non-elliptic contact modelthat can be used on-line with vehicle dynamics analysis. Three contact models,namely STRIPES, Kik-Piotrowski and Linder methods are implementedand compared in terms of contact patch prediction, as well as contact pressureand traction distributions. The paper also discusses the gaps to be filledin terms of contact model evaluation and the results indicate the need forbetter contact pressure and patch estimation in certain contact cases.
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| 35. |
- Sh. Sichani, Matin, et al.
(författare)
-
An approximate analytical method to solve frictionless contact between elastic bodies of revolution
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- An analytical method is proposed for calculating the contact patch and pressure distribution between two elastic bodies generated by rotating arbitrary profiles about parallel axes. The elastic deformation is approximated based on the separation between the bodies in contact. This makes it possible to estimate the contact patch analytically. The contact pressure distribution, in the direction perpendicular to the axes of rotation, is assumed to be elliptic with its maximum calculated by applying Hertz solution locally. The results are exact for contact between two ellipsoids when compared against Hertz's. In non-elliptic contact cases (e.g. in wheel-rail contact) good agreement is achieved in comparison to more accurate but computationally expensive methods such as Kalker's variational method (CONTACT algorithm). Compared to simplified non-elliptic contact methods based on virtual penetration, the calculated contact patch and pressure distribution are markedly improved. The computational cost of the proposed method is significantly lower than the more detailed methods, making it worthwhile to be applied to rolling contact in rail vehicle dynamic simulation.
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| 36. |
- Sh. Sichani, Matin, et al.
(författare)
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Comparison of non-elliptic contact models : Towards fast and accurate modelling of wheel-rail contact
- 2014
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 314:1-2, s. 111-117
-
Tidskriftsartikel (refereegranskat)abstract
- The demand to investigate and predict the surface deterioration phenomena in the wheel-rail interface necessitates fast and accurate contact modelling. During the past 20 years, there have been attempts to determine more realistic contact patch and stress distributions using fast simplified methods. The main aim of the present work is to compare some of these state-of-the-art, non-elliptic contact models available in the literature. This is considered as the first step to develop a fast and accurate non-elliptic contact model that can be used on-line with vehicle dynamics analysis. Three contact models, namely STRIPES, Kik-Piotrowski and Linder are implemented and compared in terms of contact patch prediction, as well as contact pressure and traction distributions. The evaluation of these models using CONTACT software indicate the need for improvement of contact patch and pressure estimation in certain contact cases.
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| 37. |
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| 38. |
- Shahzamanian Sichani, Matin, et al.
(författare)
-
A novel method to model wheel-rail normal contact in vehicle dynamics simulation
- 2014
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Ingår i: Vehicle System Dynamics. - : Informa UK Limited. - 0042-3114 .- 1744-5159. ; 52:12, s. 1752-1764
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Tidskriftsartikel (refereegranskat)abstract
- An approximate analytical method is proposed for calculating the contact patch and pressure distribution in the wheel-rail interface. The deformation of the surfaces in contact is approximated using the separation between them. This makes it possible to estimate the contact patch analytically. The contact pressure distribution in the rolling direction is assumed to be elliptic with its maximum calculated by applying Hertz' solution locally. The results are identical to Hertz's for elliptic cases. In non-elliptic cases good agreement is achieved in comparison to the more accurate but computationally expensive Kalker's variational method (CONTACT code). Compared to simplified non-elliptic contact methods based on virtual penetration, the calculated contact patch and pressure distribution are markedly improved. The computational cost of the proposed method is significantly lower than the more detailed methods, making it worthwhile to be applied to rolling contact in rail vehicle dynamics simulation. Such fast and accurate estimation of contact patch and pressure paves the way for on-line modelling of damage phenomena in dynamics simulation packages.
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| 39. |
- Shahzamanian Sichani, Matin, et al.
(författare)
-
An alternative to FASTSIM for tangential solution of the wheel-rail contact
- 2016
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Ingår i: The Dynamics of Vehicles on Roads and Tracks - Proceedings of the 24th Symposium of the International Association for Vehicle System. - : CRC Press. - 9781498777025 - 9781138028852 ; , s. 1377-1385
-
Konferensbidrag (refereegranskat)abstract
- In most rail vehicle dynamics simulation packages, creep forces are estimated by means of Kalker's FASTSIM algorithm. While 5%-25% error is expected for force estimation the errors of shear stress distribution, needed for wheel/rail damage analysis, may rise above 30%. This is mainly due to the use of parabolic traction bound in FASTSIM. Thus, a novel algorithm called FaStrip is proposed as an alternative to FASTSIM. It is based on the strip theory in which elliptic traction bound is used. The comparison between the two algorithms, evaluated by CONTACT, shows that using FaStrip improves the accuracy of the estimated shear stress distribution while the creep force estimation in all studied cases is significantly improved as well. In one case, for instance, the error in force estimation reduces from 18% to less than 2%. Since FaStrip is as fast as FASTSIM, it can be an alternative for tangential solution of the wheel-rail contact in simulation packages.
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| 40. |
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| 41. |
- Shahzamanian Sichani, Matin, et al.
(författare)
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An alternative to FASTSIM for tangential solution of the wheel–rail contact
- 2016
-
Ingår i: Vehicle System Dynamics. - : Taylor & Francis. - 0042-3114 .- 1744-5159. ; 54:6, s. 748-764
-
Tidskriftsartikel (refereegranskat)abstract
- In most rail vehicle dynamics simulation packages, tangential solution of the wheel–rail contact is gained by means of Kalker's FASTSIM algorithm. While 5–25% error is expected for creep force estimation, the errors of shear stress distribution, needed for wheel–rail damage analysis, may rise above 30% due to the parabolic traction bound. Therefore, a novel algorithm named FaStrip is proposed as an alternative to FASTSIM. It is based on the strip theory which extends the two-dimensional rolling contact solution to three-dimensional contacts. To form FaStrip, the original strip theory is amended to obtain accurate estimations for any contact ellipse size and it is combined by a numerical algorithm to handle spin. The comparison between the two algorithms shows that using FaStrip improves the accuracy of the estimated shear stress distribution and the creep force estimation in all studied cases. In combined lateral creepage and spin cases, for instance, the error in force estimation reduces from 18% to less than 2%. The estimation of the slip velocities in the slip zone, needed for wear analysis, is also studied. Since FaStrip is as fast as FASTSIM, it can be an alternative for tangential solution of the wheel–rail contact in simulation packages.
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| 42. |
- Shahzamanian Sichani, Matin, et al.
(författare)
-
Non-Elliptic Wheel-Rail Contact Modelling in Vehicle Dynamics Simulation
- 2014
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Ingår i: The international Journal of railway technology. - 2049-5358 .- 2053-602X. ; 3:3, s. 77-94
-
Tidskriftsartikel (refereegranskat)abstract
- An approximate rolling contact model is introduced for fast evaluation of the contactpatch and stress distribution in the wheel-rail interface, capable of being usedon-line with dynamics simulations. The normal part of the model is based on a novelapproach in which the surface deformations are approximated, resulting in accuratepatch and pressure estimation. The tangential part is based on an adaptation of FASTSIMalgorithm to non-elliptic patches. The new model is compared to the approximatemodel of Kik and Piotrowski and the results are evaluated using Kalker’s CONTACTcode. The comparison clearly shows that the new model is more accurate than Kikand Piotrowski’s in terms of contact patch and stress distribution as well as creepforce estimation.
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| 43. |
- Shahzamanian Sichani, Matin, 1986-
(författare)
-
On Efficient Modelling of Wheel-Rail Contact in Vehicle Dynamics Simulation
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The wheel-rail contact is at the core of all research related to vehicletrackinteraction. This tiny interface governs the dynamic performanceof rail vehicles through the forces it transmits and, like any high stressconcentration zone, it is subjected to serious damage phenomena. Thus,a clear understanding of the rolling contact between wheel and rail is keyto realistic vehicle dynamics simulation and damage analysis.In a multi-body dynamics simulation, the demanding contact problemshould be evaluated at about every millisecond for several wheel-rail pairs.Hence, a rigorous treatment of the contact is highly time-consuming.Simplifying assumptions are therefore made to accelerate the simulationprocess. This gives rise to a trade-o between the accuracy and computationaleciency of the contact model in use.Conventionally, Hertz+FASTSIM is used for calculation of the contactforces thanks to its low computational cost. However, the elliptic patchand pressure distribution obtained by Hertz' theory is often not realisticin wheel-rail contact. Moreover, the use of parabolic traction bound inFASTSIM causes considerable error in the tangential stress estimation.This combination leads to inaccurate damage predictions.Fast non-elliptic contact models are proposed by others to tacklethis issue while avoiding the tedious numerical procedures. The studiesconducted in the present work show that the accuracy of these models iscase-dependent.To improve the accuracy of non-elliptic patch and pressure estimation,a new method is proposed. The method is implemented in an algorithmnamed ANALYN. Comparisons show improvements in patch and, particularly,pressure estimations using ANALYN.In addition, an alternative to the widely-used FASTSIM is developed, named FaStrip. Unlike FASTSIM, it employs an elliptic traction boundand is able to estimate the non-linear characteristic of tangential stressdistribution. Comparisons show more accurate estimation of tangentialstress and slip velocity distribution as well as creep forces with FaStrip.Ultimately, an ecient non-elliptic wheel-rail contact model consistingof ANALYN and FaStrip is proposed. The reasonable computationalcost of the model enables it to be used on-line in dynamics simulationand its accuracy can improve the damage predictions.
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| 44. |
- Shahzamanian Sichani, Matin
(författare)
-
Wheel-rail contact modelling in vehicle dynamics simulation
- 2013
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The wheel-rail contact is at the core of all research related to vehicle-track interaction. This tiny interface governs the dynamic performance of rail vehicles through the loads it transmits and, like any high stress concentration zone, it is subjected to serious damage phenomena. Thus, a clear understanding of the rolling contact between wheel and rail is key to realistic vehicle dynamic simulation and damage analyses.In a multi-body-system simulation package, the essentially demanding contact problem should be evaluated in about every millisecond. Hence, a rigorous treatment of the contact is highly time consuming. Simplifying assumptions are, therefore, made to accelerate the simulation process. This gives rise to a trade-off between accuracy and computational efficiency of the contact models in use.Historically, Hertz contact solution is used since it is of closed-form. However, some of its underlying assumptions may be violated quite often in wheel-rail contact. The assumption of constant relative curvature which leads to an elliptic contact patch is of this kind. Fast non-elliptic contact models are proposed by others to lift this assumption while avoiding the tedious numerical procedures. These models are accompanied by a simplified approach to treat tangential tractions arising from creepages and spin.In this thesis, in addition to a literature survey presented, three of these fast non-elliptic contact models are evaluated and compared to each other in terms of contact patch, pressure and traction distributions as well as the creep forces. Based on the conclusions drawn from this evaluation, a new method is proposed which results in more accurate contact patch and pressure distribution estimation while maintaining the same computational efficiency. The experience gained through this Licentiate work illuminates future research directions among which, improving tangential contact results and treating conformal contacts are given higher priority.
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| 45. |
- Sichani, Martin Sh., et al.
(författare)
-
A fast non-elliptic contact model for application to rail vehicle dynamics simulation
- 2014
-
Konferensbidrag (refereegranskat)abstract
- An approximate rolling contact model is introduced for fast evaluation of the contact patch and stress distribution in the wheel-rail interface, capable of being used on-line with dynamics simulations. The normal part of the model is based on a novel approach in which the surface deformations are approximated, resulting in accurate patch and pressure estimation. The tangential part is based on an adaptation of the FASTSIM algorithm to non-elliptic patches. The new model is compared to the approximate model of Kik and Piotrowski and the results are evaluated using the rigorous solution of Kalker's CONTACT code. The comparison clearly shows the new model to be more accurate than Kik-Piotrowski's in terms of contact patch and stress distribution as well as creep force estimation.
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| 46. |
- Sichani, Matin Sh., et al.
(författare)
-
A fast wheel-rail contact model for application to damage analysis in vehicle dynamics simulation
- 2016
-
Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 366, s. 123-130
-
Tidskriftsartikel (refereegranskat)abstract
- A novel wheel-rail contact model is proposed to be implemented for multi-body dynamics simulation, in order to facilitate accurate online calculation of damage phenomena such as wear and rolling contact fatigue. The normal contact, i.e. contact patch and pressure distribution, is calculated using a fast non elliptic algorithm called ANALYN. The tangential contact, i.e. tangential stress distribution, stick-slip division and creep force calculation, is treated using an alternative to the FASTSIM algorithm that is based on a strip theory which extends the two-dimensional solution of rolling contact to three-dimensional contacts. The proposed contact model is compared to the Hertz+FASTSIM model and evaluated using the CONTACT code in terms of contact patch and stress distribution as well as creep force curves. The results show that the proposed model can significantly improve the estimation of the contact solution both in terms of creep force estimation and contact details, such as stress distribution, needed for damage predictions.
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| 47. |
- Sichani, Matin Shahzamanian, et al.
(författare)
-
Wheel-rail contact modeling for damage predictions in dynamics simulation software
- 2015
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Ingår i: CM 2015 - 10th International Conference on Contact Mechanics of Wheel / Rail Systems. - : International Conference on Contact Mechanics of Wheel.
-
Konferensbidrag (refereegranskat)abstract
- A novel wheel-rail contact model is proposed to be implemented for multi-body dynamics simulation, in order to facilitate accurate online calculation of damage phenomena such as wear and rolling contact fatigue. The normal contact, i.e. contact patch and pressure distribution, is calculated using a fast non-elliptic algorithm called ANALYN. The tangential contact, i.e. tangential stress distribution, stick-slip division and creep force calculation, is treated using an alternative to the FASTSIM algorithm that is based on a strip theory which extends the exact two-dimensional solution of rolling contact to three-dimensional contacts. The proposed contact model is compared to the Kik-Piotrowski model and evaluated using the CONTACT code in terms of contact patch and stress distribution as well as creep force curves. The results show that the proposed model can significantly improve the estimation of the contact solution both in terms of creep force estimation and contact details, such as stress distribution, needed for damage predictions.
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| 48. |
- 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
-
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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