<p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p>

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. / QC 20110124

En väl fungerande järnväg är en viktig del av Sveriges och stora delar av världens infrastruktur. Hundratusentals människor transporterar sig dagligen till och från arbete efter den svenska järnvägen samtidigt som det efter samma spår sker en storskalig godstransport genom tungt lastade godståg.   Att kunna planera underhållet av ett järnvägssystem är en viktig del för att erhålla en hög funktionssäkerhet hos systemet. Plötsliga fel och haverier av järnvägshjul är i dagsläget en stor anledning till driftstörningar och driftstopp. Med en utökad kunskap kring spridningen av nötningen i järnvägshjulet kan man prediktera slitage och prognostisera hjulets livslängd och då även planera framtida underhåll. På så sätt kan funktionssäkerheten öka, detta genom att minska risken för driftstörningar.   Arbetets resultat kommer att redovisas genom en statistisk analys av hjulparametrar i en teknisk rapport innehållande nödvändig teori samt överskådliga figurer i form av tabeller, diagram och plottar. Figurerna är baserade på analys av insamlade mätdata från LKAB:s lokverkstad i Kiruna, Sverige.   Studien visar att nötning och skador uppträder runt om hela hjulets omkrets där flänsbredden är den parameter där det sker störst förändring. / A well-functioning railway is an important part of Sweden's amongst many other countries infrastructure. On daily basis hundreds of thousands of people use the railway as their primary mode of transportation. Meanwhile on the same track there’s a large-scale transportation of goods by heavy loaded cargo trains.   Planning the maintenance of the railway and its components is important in order to achieve a high-level functionality of the system. Sudden failure of railway wheels is one of the biggest causes of downtime of the railway system. Increased knowledge about the spread of wear around the wheel could result in a higher level of functionality of the system, this by being able to predict the wear and prognosis the need of maintenance.   This project will be presented as a statistical analysis in the form of a technical report which contains the necessary theory as well as figures in the form of diagrams and plots. The figures are based on analysis of collected measurement data from LKAB’s locomotive workshop in Kiruna, Sweden.   This study shows that abrasion and other types of wheel damage occur all around the circumference of the wheel and the flange width is the parameter where most abrasion occurs.

<p>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.</p><p>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.</p><p>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.</p><p>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.</p><p>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.</p> / QC 20100531

Hållbara transporter är en viktig faktor för att minska koldioxidutsläppen och bidra till en mer hållbar framtid. Den svenska järnvägen är en viktig del av infrastrukturen och transporterar dagligen hundratusentals människor och stora mängder varor. Transportsektorn förbrukar nu cirka en tredjedel av den totala energin i världen. Därför är det allt viktigare för alla transportslag, inklusive järnvägstransporter, att förbättra sin energieffektivitet och minska sina CO2-utsläpp. För att bidra till en hållbar utveckling av järnvägstransporter krävs smartare och mer innovativa lösningar än vad som finns tillgängligt idag. Denna rapport är kopplad till ett studentprojekt på KTH som syftar till att i framtiden ställa upp i tävlingen Delsbo Electric. Tävlingen går ut på att konstruera ett spårgående batteridrivet fordon med så låg energiförbrukning som möjligt. Syftet med tävlingen är bland annat att stimulera innovation inom området transportlösningar. Hjulprofilen hos ett spårfordon har stor inverkan på dess körbeteende och påverkar hjulslitage, stabilitet och kontaktspänningar. I detta arbete studeras hjulprofilen hos tåg genom en förstudie av nuvarande forskning följt av ett antal datasimuleringar i programmet Simpack. Data från simuleringarna jämförs mellan de olika hjulprofilerna och med standarder för tågindustrin. Fordonets säkerhet och komfort påverkas av hjulprofilen och dess konicitet. I rapporten jämförs olika grad konicitets inverkan på dessa genom industristandarder. Resultatet presenteras i grafer och tabeller med data från simuleringarna. Sju grader konicitet gav bäst resultat i simuleringarna för både säkerhet och komfort. / Sustainable transportation is an important factor in reducing carbon dioxide emissions and contributing to a more sustainable future. The Swedish railway is an important part of the infrastructure and transports hundreds of thousands of people and large quantities of goods every day. The transport sector today consumes about a third of the total energy in the world. Therefore, it is increasingly important for all modes of transport, including rail transport, to improve their energy efficiency and reduce their CO2 emissions. To contribute to the sustainable development of rail transport, smarter and more innovative solutions are required than what is available today. This report is connected to a student project at KTH which aims to enter the Delsbo Electric competition in the future. The purpose of the competition is to construct a track-going battery-powered vehicle with as low energy consumption as possible. The purpose of the competition is, among other things, to stimulate innovation in the field of transport solutions. The wheel profile of a tracked vehicle has a major impact on its driving behavior and affects wheel wear, stability and contact stresses. In this work, the wheel profile of trains is studied through a preliminary study of current research followed by several computer simulations in the program Simpack. The data from the simulations are compared between the different wheel profiles and with standards for the train industry. The safety and comfort of the vehicle is affected by the wheel profile and its conicity. The report compares the impact of different degrees of conicity on these through industry standards. The result is presented through graphs and tables with the data from the simulations. Seven degrees of conicity gave the best results in the simulations for both safety and comfort.

During the last decade, a novel methodology for wheel wear simulation has been developed in Sweden. The practical objective of this simulation procedure is to provide an integratedengineering tool to support rail vehicle design with respect to wheel wear performance and detailed understanding of wheel-rail interaction. The tool is integrated in a vehicle dynamicssimulation environment.The wear calculation is based on a set of dynamic simulations, representing the vehicle, the network, and the operating conditions. The wheel profile evolution is simulated in an iterativeprocess by adding the contribution from each simulation case and updating the profile geometry.The method is being validated against measurements by selected pilot applications. To strengthen the confidence in simulation results the scope of application should be as wide aspossible in terms of vehicle classes. The purpose of this thesis work has been to try to extend the scope of validation of this method into the light rail area, simulating the light rail vehicleA32 operating in Stockholm commuter service on the line Tvärbanan.An exhaustive study of the wear theory and previous work on wear prediction has been necessary to understand the wear prediction method proposed by KTH. The dynamicbehaviour of rail vehicles has also been deeply studied in order to understand the factors affecting wear in the wheel-rail contact.The vehicle model has been validated against previous studies of this vehicle. Furthermore new elements have been included in the model in order to better simulate the real conditionsof the vehicle.Numerous tests have been carried out in order to calibrate the wear tool and find the settings which better match the real conditions of the vehicle.Wheel and rail wear as well as profile evolution measurements were available before this work and they are compared with those results obtained from the simulations carried out.The simulated wear at the tread and flange parts of the wheel match quite well the measurements. However, the results are not so good for the middle part, since themeasurements show quite evenly distributed wear along the profile while the results from simulations show higher difference between extremes and middle part. More tests would benecessary to obtain an optimal solution.

The diploma thesis deals with the perpendicular crossing of tram track with railway siding. The structure of crossing is described both in the Czech Republic and in the world. The aim of the thesis is to find the recommended design solution for the crossing of tram and railway tracks with regard to legislation and feasibility. After a comparison of the existing structures is chosen which satisfies the conditions of feasibility.

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. / QC 20100531