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Galas, Radovan. "Friction Modification within Wheel-Rail Contact." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-367508.
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Předložená disertační práce se zabývá experimentálním studiem modifikátorů tření a maziv pro temeno kolejnice, které jsou aplikovány do kontaktu kola a kolejnice za účelem optimalizace adheze a redukce hluku. Hlavním cílem práce bylo objasnit vliv aplikovaného množství a složení těchto látek na adhezi v kontaktu. Hlavní pozornost byla věnována zejména potencionálním hrozbám souvisejících s kriticky nízkou adhezí, která může nastat po aplikaci těchto látek. Experimentální studium probíhalo v laboratorních i reálných podmínkách, konkrétně v tramvajovém provozu. V případě laboratorních experimentů byl využit komerční tribometr a dvoudiskové zařízení umožňující simulovat průjezd vozidla traťovým obloukem. Kromě samotné adheze bylo při experimentech sledováno také opotřebení a míra hluku. Výsledky ukázaly, že maziva pro temeno kolejnice jsou schopna poskytovat požadované třecí vlastnosti, nicméně jejich chování je silně závislé na aplikovaném množství. V případě předávkování kontaktu dochází ke kriticky nízkým hodnotám adheze, které vedou k výraznému prodloužení brzdné dráhy. V případě modifikátorů tření bylo ukázáno, že chování těchto látek je výrazně ovlivněno odpařováním základního média. Výsledky také ukázaly, že nadměrné množství částic pro modifikaci tření může způsobit kriticky nízké hodnoty adheze. U obou výše zmíněných typů produktů byl prokázán pozitivní vliv na míru opotřebení a míru poškození povrchu, zatímco významná redukce hluku byla dosažena pouze v případech, kdy došlo ke značnému poklesu adheze. V závěru této práce jsou uvedena doporučení pro další výzkumné aktivity v této oblasti.
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Lundmark, Jonas. "Rail grinding and its impact on the wear of wheels and rails." Licentiate thesis, Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1757/2007/37/index.html.
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Inglot, Agnieszka, and Oskar Franzén. "PREVENTION OF WHEEL WEAR, A CASE STUDY : Developing a functioning wheel profile for rail-mounted transportation trolley." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-17695.
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This bachelor’s degree project aimed to improve the wheel profile of a rail mounted trolley and determine the cause of wheel failure. The proceedings of this project where modelled after an approach for solving wear problems with an emphasis on designing for sustainability. A case study and root cause analysis (RCA) was performed and the flanged wheels were deemed insufficient for the given heavy-haul system. Possible areas of wheel profile improvement were identified and further researched with multiple literature reviews. Throughout the projects duration several limitations were introduced that reduced the concept testing to exclusively theoretical prediction models. Archard’s model was implemented to predict wear and operating time for the proposed material and wheel tread profile concepts. The wheel flange dimensions were chosen based on recommendations from wheel and rail interference handbooks among other sources. The final wheel and rail profile suggestion improved operating time by approximately 300% and wear resistance by 50% compared to its predecessor. This result was achieved by applying the same theoretical prediction model to both current and suggested profiles. The findings of this project are meant to aid SCA among others in similar cases and additionally highlight the value of product improvement from a technological, sociological, and environmental perspective.
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Zhu, Yi. "Adhesion in the wheel-rail contact under contaminated conditions." Licentiate thesis, KTH, Tribologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48441.
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Railway vehicles require a certain level of adhesion between wheel and rail to operate efficiently, reliably, and economically. Different levels of adhesion are needed depending on the vehicle running conditions. In the wheel tread–railhead contact, the dominant problem is low adhesion, as low adhesion on the railhead negatively affects railway operation: on one hand, the vehicle will lose traction resulting in delay when driving on low-adhesion tracks; on the other hand, low adhesion during deceleration will extend the braking distance, which is a safety issue. This thesis examines the influence of several contaminants, i.e., water, oil, and leaves, on the adhesion in the wheel tread–railhead contact. This study will improve our knowledge of the low-adhesion mechanism and of how various contaminants influence adhesion. The thesis consists of a summary overview of the topic and three appended papers (A–C). Papers A and B focus mainly on water and oil contamination examined using two methods, numerical simulation and lab testing. In paper A, real measured wheel and rail surfaces, low- and high-roughness surfaces, along with generated smooth surfaces are used as input to the numerical model for predicting the adhesion coefficient. Water-lubricated, oil-lubricated, and dry contacts are simulated in the model. In the research reported in paper B, scaled testing using a mini traction machine (MTM) was carried out to simulate the wheel–rail contact under lubricated conditions. Two types of disc surfaces of different roughnesses were run at different contact pressures and temperatures. A stylus machine and atomic force microscopy (AFM) were used to measure the surface topography. A study of leaf contamination on the railhead surface, based on field testing, is presented in paper C. Railhead surface samples were cut and the friction coefficient was measured on five occasions over the course of a year. Electron spectroscopy for chemical analysis (ESCA) and glow discharge optical emission spectrometry (GD-OES) were used to detect the chemical composition of the leaf-contamination layer on the railhead surface. The main conclusion of the thesis is that different contaminants reduce the adhesion coefficient in different ways. Oil reduces the adhesion coefficient by carrying the normal force due to its high viscosity. Water can reduce the adhesion coefficient to different degrees depending on the surface topography and water temperature. The mixture of an oxide layer and water contamination may have an essential impact. A leaf-formed blackish layer causes low adhesion by means of a chemical reaction between the leaves and bulk material. The thickness of the friction-reducing oxide layer predicts the friction coefficient and the extent of leaf contamination.QC 20111123
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Shahzamanian, Sichani Matin. "Wheel-rail contact modelling in vehicle dynamics simulation." Licentiate thesis, KTH, Spårfordon, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-127949.
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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.QC 20130911
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Nepovím, Radovan. "Konstrukce experimentálního zařízení pro studium mazání okolků kolejových vozidel." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230331.
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The diploma thesis deals with construction design and practical realisation of experimental apparatus for investigation of wheel flange track vehicle lubrication. Experimental apparatus in full-scale uses optical interferometry for investigation of lubrication behaviour in wheel flange contact. It is an innovative approach which has not been used for such experiments so far. The aim of the following measurement with this apparatus is to determine the minimal amount of ecological lubrication in wheel flange contact under certain conditions when there is no lubrication film interruption. The apparatus enables to measure real rail wear. This work contains the apparatus description for the study of wheel flange lubrication, wheel flange contact specifications, the description of its influence on wear and acoustic emission, and a detailed description of the experimental apparatus.
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Kvarda, Daniel. "Vliv složení modifikátorů tření na trakci v kontaktu kola a kolejnice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318386.
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Friction modifiers are a new effective way to control adhesion in wheel and rail contact. The aim of this diploma thesis is experimental study of the influence of the constituents of water based friction modifier on adhesion. Measurement of the adhesion behavior for different friction modifier compositions is carried out on a ball–on–disc laboratory device creating point contact. The introductory part of the experiments describes the effect of individual components on adhesion. Subsequently, combinations of different friction modifier compositions are tested. In conclusion, selected compositions are used for wear tests. The results obtained show that the performance of friction modifiers is greatly influenced by evaporation of base medium.
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Rec, Matouš. "Návrh testovacího stavu pro stanovení opotřebení u kontaktu železničního kola a kolejnice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-445166.
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This diploma thesis focuses on the issue of a wear of a railway wheel and a rail. The wear of the components depends on a number of parameters including the contact stress, the contact pressure and the contact surface dimensions. Among the factors determining these parameters belongs primarily the wheel driving gauge, the rail profile and the load of the contact area. Furthermore, the material from which the wheels and rail are made, the roughness and hardness of the functional surfaces and the residual stress in the material have a significant impact on the wear. All the parameters mentioned above are designed for the production of the railway wheels and rails and therefore they meet the standards for the production of these components. However, the existence of the changeable parameters has also a significant impact on the wear. These parameters include the presence of contaminants, or lubricants in contact, the changing driving gauge due to the wear, the slip ratio or the friction coefficient. With the wear being an inevitable process during the application it cannot be eliminated but only controlled. Applying the lubricant into the contact when passing through the arc in order to achieve an ideal coefficient or the maintenance grinding for restoring the driving gauge can serve the purpose. If properly optimized, the importance of the wear research lies in the financial savings. Being the crucial factor for optimization of the intervals between the maintenance grinding, the research is also beneficial. A high-quality wear prediction can be seen as the key field in order to increase the safety of the railway vehicles operation as well. Therefore, the wear research is made using several methods, such as the computational models, the multi-body dynamics software and the technical experiments. This thesis introduces a conceptual design of the test, enabling the wear research via experimental approach. The final device is capable of a simulation of both volume and fatigue wear during the states the railway wheel and railway undergo including riding on the straight track, passing through an arc or a wheel slip during braking.
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Telliskivi, Tanel. "Wheel-rail Interaction Analysis." Doctoral thesis, KTH, Machine Design, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3532.
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A general approach to numerically simulating wear in rollingand sliding contacts is presented in this thesis. A simulationscheme is developed that calculates the wear at a detailedlevel. The removal of material follows Archards wear law,which states that the reduction of volume is linearlyproportional to the sliding distance, the normal load and thewear coefficient. The target application is the wheel-railcontact.
Careful attention is paid to stress properties in the normaldirection of the contact. A Winkler method is used to calculatethe normal pressure. The model is calibrated either withresults from Finite Element simulations (which can include aplastic material model) or a linear-elastic contact model. Thetangential tractions and the sliding distances are calculatedusing a method that incorporates the effect of rigid bodymotion and tangential deformations in the contact zone.Kalkers Fastsim code is used to validate the tangentialcalculation method. Results of three different sorts ofexperiments (full-scale, pin-on-disc and disc-on-disc) wereused to establish the wear and friction coefficients underdifferent operating conditions.
The experimental results show that the sliding velocity andcontact pressure in the contact situation strongly influencethe wear coefficient. For the disc-on-disc simulation, therewas good agreement between experimental results and thesimulation in terms of wear and rolling friction underdifferent operating conditions. Good agreement was alsoobtained in regard to form change of the rollers. In thefull-scale simulations, a two-point contact was analysed wherethe differences between the contacts on rail-head to wheeltread and rail edge to wheel flange can be attributed primarilyto the relative velocity differences in regard to bothmagnitude and direction. Good qualitative agreement was foundbetween the simulated wear rate and the full-scale test resultsat different contact conditions.
Keywords:railway rail, disc-on-disc, pin-on-disc,Archard, wear simulation, Winkler, rolling, sliding
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Jon, Sundh. "On wear transitions in the wheel-rail contact." Doctoral thesis, KTH, Maskinkonstruktion (Avd.), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11563.
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Wear transitions in the wheel–rail contact are of increasing interest since the general trend in railway traffic is toward increased velocities and axle loads. Curving increases the risk of flanging, causing the contact to change from an almost pure rolling wheel tread–rail head contact to more of a sliding wheel flange–rail gauge contact on the high rail in curves. Under wheel flange–rail gauge contact conditions, wear transitions to severe or catastrophic wear will occur if the contact is improperly lubricated. Such a transition is the most undesirable transition in the wheel–rail contact, as it represents a very expensive operating condition for railway companies. The contact conditions responsible for this transition are very severe as regards sliding velocity and contact pressure, and thus place high demands on both the lubricant and the wheel and rail materials. The focus of this thesis is on the transitions between different wear regimes in a wheel–rail contact. Wear is discussed both in traditional tribological terms and in terms of the categories used in the railway business, namely mild, severe and catastrophic wear. Most of the work was experimental and was performed at the Royal Institute of Technology (KTH), Department of Machine Design. The effects of contact pressure, sliding velocity, and type of lubricant have been investigated, producing results that resemble those of other studies presented in the literature. The absence of research relating to the wheel flange–rail gauge contact is addressed, and it is concluded that a lubricant film must be present on rails in curves to prevent severe or catastrophic wear. The formulation of this lubricant can further increase its wear- and seizure-preventing properties. To obtain a deeper understanding of wear transitions, methods such as airborne particle measurement and electron microscopy have been used. Paper A presents the test methodology used to detect seizure and discusses the wear-reducing influence of free carbon in highly loaded contacts. Paper B presents the testing of seizure-initiating conditions for a range of environmentally adapted lubricants applied to wheel and rail materials; a transient pin-on-disc test methodology was used for the testing. Paper C presents the use of pin-on-disc methodology to study the wear-reducing effects of a wide range of lubricants. The best performing lubricant was a mineral oil containing EP and AW additives. Paper D relates wear rates and transitions to airborne particles generated by an experimentally simulated wheel–rail contact. The airborne particles generated varied in size distribution and amount with wear rate and mechanism. Paper E relates additional analysis techniques, such as FIB sectioning, ESCA analysis, airborne particle measurements, and SEM imaging of airborne wear particles, to the contact temperature.QC 20100721
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Sánchez, Arandojo Adrián. "On validation of a wheel-rail wear prediction code." Thesis, KTH, Spårfordon, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134706.
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During the past years, several tools have been developed to try predicting wheel and rail wear of railway vehicles in an e-cient way. In this MSc thesis a new wear prediction tool developed by I.Persson is studied and compared with another wear prediction tool, developed by T.Jendel, which has been already validated and is in use since several years ago. The advantages that the new model gives are simpler structure, the consideration of wear as a continuous variable and that all the code is integrated in the same software. The two models have the same methodology until the part of the wear calculations and the post-processing. Wheel-rail geometry functions and time domain simulations are performed with the software GENSYS. In the simulation model the track and the vehicle are dened as well as other important properties such as vehicle speed and coe-cient of friction. Three simple tracks are used: tangent track, R=500 m curve with a cant of ht=0.15 m on the outer rail and R=1000 m curve with a cant of ht=0.1 m on the outer rail. The model is assumed to be symmetric so just outer (first and fourth axle) and inner (second and third axles) wheels are considered. During the vehicle-track interaction, the normal and tangential problems are solved. The wheel-rail contact is modelled according to Hertz's theory and Kalker's simplied theory with the help of the algorithm FASTSIM. Then wear calculations are performed according to Archard's wear law. It is applied in dierent ways, obtaining wear depth directly in Jendel's and wear volume rate in Persson's model. Jendel's model is rstly analyzed. Its specifc methodology is briefly explained and modications are performed on the code to make it work as similar as possible to Persson's model. Also parameters regarding the distance in which wear calculations are taken, the discretization of the width of the wheel and the discretization of the contact patch are analyzed. The methodology of Persson's model is also studied, most of all the performance of the post-processing which is one of the keys to the code. The parameters analyzed in this code are the ones regarding a statistical analysis performed during the post-processing and the discretization of the contact patch. Finally the comparisons between the wear depth obtained for both models are carried out. The discrepancies between the models are explained with the parameters analyzed and the dynamic behaviour of both models. Also a theoretical case is used as reference for comparison.
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Robla, Sánchez Ignacio. "Wheel Wear Simulation of the Light Rail Vehicle A32." Thesis, KTH, Spårfordon, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261228.
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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.
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Pálinkó, Márton. "Estimation of wheel-rail friction at vehicle certication measurements." Thesis, KTH, Spårfordon, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203818.
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In certification of new rail vehicles with respect to running characteristics, a wide variety of operating conditions needs to be considered. Behaviour on straight and curved tracks, including twisted tracks at various speeds, is of great importance. However, the wheel-rail friction should always be high corresponding to dry conditions. It means that the certification tests have to be carried out during dry weather conditions and unlubricated rails. But measuring the friction at test conditions is a great challenge.Therefore, in a recent work (Petrov et al.), an algorithm was proposed for the continu-ous estimation of wheel-rail friction along both rails. The algorithm is based on wheel-rail forces in all three directions (Y, Q, X ) for both wheels in a wheelset, lateral contact po-sition on its wheels and wheelset angle of attack. The algorithm was evaluated with a fictional vehicle with vehicle-track dynamics simulations on various tracks (straight and curves) and track irregularities.In cooperation with SNC Lavalin (formerly Interfleet Technology), an opportunity arose to get the required data from on-track tests. In this way, all nine quantities above were measured during test runs of a new vehicle, so the algorithm could be evaluated under realistic conditions. The tests in tight curves of radius 150 m are used in the present work for this purpose. The measured data and the algorithm were processed in a Matlab program to get the friction estimate. Apart from the friction, the creepages and spin are also estimated with the aim to serve as quality indicators of the estimated friction.As the vehicle measurements include noise, errors and uncertainties, a statistical tool was introduced. Moreover, a sensitivity analysis was performed. It was observed that in these tight curves, the friction estimation on the outer wheel is poor, but a phenomenon arose that with increasing spin corresponding to even higher contact angle the friction might be estimated again. However, small spin gives a good friction estimation provided the total creep is high enough. Therefore, sharp curves, traction/braking or large track irregularities are necessary to estimate the friction well.In order to continue the work deeper into the area, other tests with the above scenarios would be usefulVid certifiering av nya spårfordon med avseende pa gångegenskaper, behöver hänsyn tas till ett stort antal driftsförhållanden. Fordonets beteende på rakt, krökt och skevt spår vid olika hastigheter har stor betydelse. Dock måste hjul-räl friktionen alltid vara hög motsvarande torra förhållanden. Detta betyder att proverna för certifieringen alltid måste ske under torra väderförhållanden med osmorda räler. Att mäta friktionen vid dessa förhållanden ar en stor utmaning. På grund av detta har, i ett tidigare arbete (Petrov m..), en algoritm föreslagits för kontinuerlig uppskattning av hjul-räl friktion längs båda rälerna. Algoritmen baseras på hjul-räl friktioner i tre riktningar (Y, Q, X) för båda hjulen i ett hjulpar, deras laterala kontaktpunkter, samt hjulparets attackvinkel. Algoritmen utvärderades med ett fiktivt fordon med fordon-/ spårdynamiska simuleringar på både rakspår och kurdspår samt med spårlägesfel. I samarbete med SNC Lavalin (tidigare Intereet Technology), uppstod en möjlighet att få data från verkliga test. På detta sätt kunde alla nio ovan nämnda kvantiteter mätas under provkörningar av ett nytt fordon, och på så sätt utvärdera algoritmen under verkliga förhållanden. I denna uppsats har test i snäva kurvor med en radie på 150 m använts i detta syfte. Uppmätta data och algoritmen behandlades i ett MATLAB-program för att få fram en uppskattning av friktionen. Förutom friktionen, har även kryp och spinn uppskattats, med målet att kunna använda dessa som kvalitetsindikatorer för den uppskattade friktionen. Eftersom att mätdata innehöll brus, fel och osäkerheter, har ett statistiskt verktyg använts. Utöver detta har även en känslighetsanalys utförts. Det observerades att den uppskattade friktionen på det yttre hjulet i så pass snäva kurvor var låg, men att ett fenomen uppstod där ökat spinn motsvarande en ännu högre kontaktvinkel gjorde att friktionen kunde uppskattas igen. Litet spinn ger god friktionsuppskattning förutsatt att det totala krypet är högt nog. Därför är snäva kurvor, drivning/bromsning eller stora spårlägesfel nödvändiga för att på ett tillfredsställande sätt kunna uppskatta friktionen. För fortsatt fördjupning inom området skulle er prov inom ovannämnda scenarier vara användbara.
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Spangenberg, Ulrich. "Reduction of rolling contact fatigue through the control of the wheel wear shape." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/62796.
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Heavy haul railway operations permit the transport of huge volumes at lower cost than other modes of transport. The low cost can only be sustained if the maintenance costs associated with such railway operations are minimised. The maintenance costs are mainly driven by wheel and rail damage in the form of wear and rolling contact fatigue (RCF). Low wear rates in the wheel-rail interface have resulted in an increase in the prevalence of rail RCF, thereby increasing rail maintenance costs. The aim of this study is to develop an approach to reduce rail RCF on South Africa’s iron ore export line by managing the worn wheel shape. This approach is developed by evaluating wheel and rail profile shapes that contribute the most to RCF initiation, studying the influence of suspension stiffness and rail profile changes as well as a redesign of the wheel profile. The influence of wheel and rail profile shape features on the initiation of rolling contact fatigue (RCF) cracks was evaluated based on the results of multibody vehicle dynamics simulations. The damage index and surface fatigue index were used as two damage parameters to assess the influence of the different features. The damage parameters showed good agreement to one another and to in-field observations. The wheel and rail profile shape features showed a correlation to the predicted RCF damage. The RCF damage proved to be most sensitive to the position of hollow wear and thus bogie tracking. RCF initiation and crack growth can be reduced by eliminating unwanted shape features through maintenance and design and by improving bogie tracking. Two potential mitigation measures had been adapted from those published in literature to reduce RCF. The mitigation measures involved changes in suspension stiffness to spread wheel wear across the tread and the use of gauge corner relief rail profiles. These mitigation measures were evaluated by means of multibody dynamics and wear maintenance costs. These mitigation measures, however, did not prove to be successful in reducing RCF initiation while maintaining a low wheel wear rate. The current operating conditions on South Africa’s iron ore line, although still not optimal overall, were found to be better in terms of their wear and RCF performance than the two proposed RCF mitigation measures. Based on the finding of the study on two RCF mitigation measures it was recommended that a conformal wheel profile be developed to spread the wheel wear across the tread to reduce the occurrence and propagation of RCF cracks, while still maintaining low wheel wear rates. A comparative study of this new wheel profile design and the current wheel profile design was therefore performed using multibody dynamics simulation together with numerical wheel wear and RCF predictions. The advantages of the conformal wheel profile design were illustrated by evaluating the worn shape and resulting kinematic behaviour of the conformal design. The conformal design had a steadier equivalent conicity progression and a smaller conicity range compared with the current wheel profile design over the wheel’s wear life. The combination of a conformal wheel profile design with 2 mm hollow wear and inadequate adherence to grinding tolerances often result in two-point contact, thereby increasing the probability of RCF initiation. The conformal wheel profile design was shown to have many wear and RCF benefits compared with the current wheel profile design. However, implementation of such a conformal wheel profile must be accompanied by improved rail grinding practices to ensure rail profile compliance. Based on these findings an approach is proposed where the conformal wheel profile design together with improved compliance of the in-service rail profiles to the target rail profile are implemented. This has the potential to reduce RCF initiation on South Africa’s iron ore export line.Thesis (PhD)--University of Pretoria, 2017.
Mechanical and Aeronautical Engineering
PhD
Unrestricted
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Dirks, Babette. "Simulation and Measurement of Wheel on Rail Fatigue and Wear." Doctoral thesis, KTH, Spårfordon, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168023.
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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.QC 20150526
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Shebani, Amer. "Prediction of wheel and rail wear using artificial neural networks." Thesis, University of Huddersfield, 2016. http://eprints.hud.ac.uk/id/eprint/32047/.
Full textAbstract:
The prediction of wheel wear is a significant issue in railway vehicles. It is correlated with safety against derailment, economy, ride comfort, and planning of maintenance interventions, and it can result in delay, and costs if it is not predicted and controlled in an effective way. However, the prediction of wheel and rail wear is still a great challenge for railway systems. Therefore, the main aim of this thesis is to develop a method for predicting wheel wear using artificial neural networks. Initial tests were carried out using a pin-on-disc machine and this data was used to establish how wear can be measured using an Alicona profilometer. A new method has been developed for detailed wheel wear and rail wear measurements using ‘Replica’ material which was applied to the wheel and rail surfaces of the test rig to make a copy of both surfaces. The replica samples were scanned using an optical profilometer and the results were processed to establish wheel wear and rail wear. The effect of load, and yaw angle on wheel wear and rail wear were examined. The effect of dry, wet, lubricated, and sanded conditions on wheel wear and rail wear were also investigated. A Nonlinear Autoregressive model with eXogenous input neural network (NARXNN) was developed to predict the wheel and rail wear for the twin disc rig experiments. The NARXNN was used to predict wheel wear and rail wear under deferent surface conditions such as dry, wet, lubricated, and sanded conditions. The neural network model was developed to predict wheel wear in case of changing parameters such as speed and suspension parameters. VAMPIRE vehicle dynamic software was used to produce the vehicle performance data to train, validate, and test the neural network. Three types of neural network were developed to predict the wheel wear: NARXNN, backpropagation neural network (BPNN), and radial basis function neural network (RBFNN). The wheel wear was calculated using an energy dissipation approach and contact position on straight track. The work is focused on wheel wear and the neural network prediction of rail wear was only carried out in connection with the twin disk wear tests. This thesis examines the effect of neural network parameters such as spread, goal, maximum number of neurons, and number of neurons to add between displays on wheel wear prediction. The neural network simulation results were implemented using the Matlab program. The percentage error for wheel and rail wear prediction was calculated. Also, the accuracy of wheel and rail wear prediction using the neural network was investigated and assessed in terms of mean absolute percentage error (MAPE). The results reveal that the neural network can be used efficiently to predict wheel and rail wear. Further work could include rail wear and prediction on a curved track.
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Enblom, Roger. "Simulation of Wheel and Rail Profile Evolution : Wear Modelling and Validation." Licentiate thesis, KTH, Aeronautical and Vehicle Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1754.
Full textAbstract:
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 Archards 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
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Sundh, Jon. "An experimental study on wear transitions in the wheel-rail contact /." Stockholm : Institutionen för maskinkonstruktion, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4389.
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Evans, Martin David. "Performance assessment of friction management products in the wheel-rail interface." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22972/.
Full textAbstract:
The wheel-rail contact is a crucial aspect of all railway systems. Within the wheel-rail contact, an important factor is the frictional behaviour between the wheel and rail materials. Frictional behaviour can dictate how effectively a railway vehicle accelerates/ decelerates, its steering behaviour, as well as influencing how much damage occurs to wheel and rail materials as the vehicles negotiates a railway system. An inherent property of the wheel-rail contact is that it is an open system, vulnerable to outside influences such as the weather conditions and third body materials entering the contact; this results in variable and difficult to predict frictional behaviours affecting the operation of the railway system as a whole. Improving understanding of friction in the wheel-rail interface and how it affects damage mechanisms allows for better predictive models to estimate the prevalence of damage, and allow us to predict the effect of altering friction. This is turn allows us to estimate the cost benefit of altering frictional behaviour in the wheel-rail interface. This aim of this project has been to develop laboratory testing of friction behaviour in the wheel-rail interface (WRI), considering how the results of laboratory tests can be related to behaviour in the full scale interface. There was a particular focus on the behaviour of Friction Management products in the interface. Twin-disc testing was performed to investigate the suitability of twin-disc testing for assessing the performance of friction management products and other third bodies materials. This concluded that twin-discs are suitable for the testing of some third body materials, however, limitations were found when investigating third body layers that might be consumed as a test progresses. High Pressure Torsion (HPT) testing, in conjunction with the Extended Creep Force (ECF) model, was suggested as an alternative addressing the limitations of twin-disc experimentation. The most significant section of this project details the development of the HPT methodology on a servo-hydraulic test machine at the University of Sheffield; from the design of specimens and initial trials, to the final procedure and trials. The results of the HPT trials were used as inputs to the ECF model, allowing comparison against both a full-scale test and scaled twin-disc test results. The ECF model successfully predicted the results of both full-scale and scaled-down experiments. Issues with the input parameters which determine the influence of temperature were found; the issue can be solved and recommendations for further work to improve and validate the HPT/ECF methodology have been made.
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Enblom, Roger. "On Simulation of Uniform Wear and Profile Evolution in the Wheel - Rail Contact." Doctoral thesis, Stockholm : Dept. of aeronautics and vehicle engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4184.
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Hibbert, Morgan John Edwin. "Understanding the wheel/rail transfer mechanism in liquid friction modifier carry-down." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61359.
Full textAbstract:
In the rail road industry liquid friction modifiers (LFM’s) are used on the
top of rail (TOR) between the wheel/rail interface to reduce curve noise,
lateral forces, rail wear and fuel consumption. The friction modifier may be
applied to the rail via a track side applicator and is carried down by the
train into curved sections of the track where the greatest benefit is seen.
A custom laboratory scale machine was designed and built for the purpose of conducting experiments to study the behaviour of LFM carry-down
over a large number of wheel/rail interactions. The machine was also designed so that the film transfer at the wheel/rail interaction location could
be studied.
The use of a fluorescent agent to enhance the ability to visualize LFM
carry-down showed promising results, enabling small amounts of carry-down
that couldn’t otherwise be seen under ambient light conditions to now be
seen under fluorescence.
Qualitative experiments using the machine were performed showing that
an increase in the wheel speed results in an increase in the amount of friction
modifier transferred from the rail to the wheel at the initial pickup location,
thus increasing the carry-down. Increasing the applied load had the opposite
effect and reduced the amount of friction modifier initially transferred from
the rail to the wheel, and thus reducing the carry-down. The profile of the
wheel was observed to effect the initial transfer amount and the ensuing
carry-down due to high/low pressure zones along the wheel/rail interface.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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Buckley-Johnstone, Luke. "Wheel/rail contact tribology : characterising low adhesion mechanisms and friction management products." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/17291/.
Full textAbstract:
Friction management and control of adhesion at the wheel/rail interface is vital for an efficient and cost effective railway network. The understanding of how the friction management products (grease and friction modifiers) work and effectively test these products is necessary to improve the performance of a railway network. The papers presented concern the effective benchmarking of wayside curve lubricants (grease) in a twin disc test rig. They compare the effectiveness of several greases in respect to adhesion, wear protection and retentivity (number of cycles of adequate lubrication). A new method for assessment of grease carry down has been trialled in the field. The modified pendulum was able to detect the difference between a dry and lubricated rail gauge face. Top of rail friction modifiers (TOR-FMs) have been tested at two different laboratory test scales. The results showed the difference in operational behaviour of the chosen TOR-FM when used in a laboratory versus the field. The ‘wet-rail’ phenomena, where low adhesion as a result of water on the rail head, has been investigated at two scales of laboratory test and results have been used to generate a model to predict adhesion coefficients for a range of water and iron oxide mixtures. The results presented show how the addition of small amounts of water to a wheel/rail contact can cause reduced adhesion to ‘low/ultra-low’ levels when combined with third body materials (iron oxides, wear debris etc.). A novel treatment method to protect the rail head using hydrophobic solutions was investigated using twin disc and pendulum testing. Tests showed that these products, when sufficiently diluted, do not reduce friction to dangerous levels or isolate the vehicle from the track circuit. However, the benefits of use in the field are questioned.
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Lee, Hyunwook. "A Polynomial Chaos Approach for Stochastic Modeling of Dynamic Wheel-Rail Friction." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77195.
Full textAbstract:
Accurate estimation of the coefficient of friction (CoF) is essential to accurately modeling railroad dynamics, reducing maintenance costs, and increasing safety factors in rail operations. The assumption of a constant CoF is popularly used in simulation studies for ease of implementation, however many evidences demonstrated that CoF depends on various dynamic parameters and instantaneous conditions. In the real world, accurately estimating the CoF is difficult due to effects of various uncertain parameters, such as wheel and rail materials, rail roughness, contact patch, and so on. In this study, the newly developed 3-D nonlinear CoF model for the dry rail condition is introduced and the CoF variation is tested using this model with dynamic parameters estimated from the wheel-rail simulation model. In order to account for uncertain parameters, a stochastic analysis using the polynomial chaos (poly-chaos) theory is performed using the CoF and wheel-rail dynamics models.
The wheel-rail system at a right traction wheel is modeled as a mass-spring-damper system to simulate the basic wheel-rail dynamics and the CoF variation. The wheel-rail model accounts for wheel-rail contact, creepage effect, and creep force, among others. Simulations are performed at train speed of 20 m/s for 4 sec using rail roughness as a unique excitation source. The dynamic simulation has been performed for the deterministic model and for the stochastic model. The dynamics results of the deterministic model provide the starting point for the uncertainty analysis. Six uncertain parameters have been studied with an assumption of 50% uncertainty, intentionally imposed for testing extreme conditions. These parameters are: the maximum amplitude of rail roughness (MARR), the wheel lateral displacement, the track stiffness and damping coefficient, the sleeper distance, and semi-elliptical contact lengths. A symmetric beta distribution is assumed for these six uncertain parameters. The PDF of the CoF has been obtained for each uncertain parameter study, for combinations of two different uncertain parameters, and also for combinations of three different uncertain parameters.
The results from the deterministic model show acceptable vibration results for the body, the wheel, and the rail. The introduced CoF model demonstrates the nonlinear variation of the total CoF, the stick component, and the slip component. In addition, it captures the maximum CoF value (initial peak) successfully. The stochastic analysis results show that the total CoF PDF before 1 sec is dominantly affected by the stick phenomenon, while the slip dominantly influences the total CoF PDF after 1 sec. Although a symmetric distribution has been used for the uncertain parameters considered, the uncertainty in the response obtained displayed a skewed distribution for some of the situations investigated. The CoF PDFs obtained from simulations with combinations of two and three uncertain parameters have wider PDF ranges than those obtained for only one uncertain parameter.
FFT analysis using the rail displacement has been performed for the qualitative validation of the stochastic simulation result due to the absence of the experimental data. The FFT analysis of the deterministic rail displacement and of the stochastic rail displacement with uncertainties demonstrates consistent trends commensurate with loss of tractive efficiency, such as the bandwidth broadening, peak frequency shifts, and side band occurrence. Thus, the FFT analysis validates qualitatively that the stochastic modeling with various uncertainties is well executed and is reflecting observable, real-world results.
In conclusions, the development of an effective model which helps to understand the nonlinear nature of wheel-rail friction is critical to the progress of railroad component technology and rail safety. In the real world, accurate estimation of the CoF at the wheel-rail interface is very difficult since it is influenced by several uncertain parameters as illustrated in this study. Using the deterministic CoF value can cause underestimation or overestimation of CoF values leading to inaccurate decisions in the design of the wheel-rail system. Thus, the possible PDF ranges of the CoF according to key uncertain parameters must be considered in the design of the wheel-rail system.Ph. D.
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Waara, Patric. "Wear reduction performance of rail flange lubrication." Licentiate thesis, Luleå, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26422.
Full textAbstract:
Rail and rail wheel flange wear on the rail track has been a problem of attention for the last 30 years. The problems arise in curves and depend on increased traffic volume, heavier axle load and also higher speed. Axle loads of 22,5-25 ton is common nowadays and the trend is towards heavier axle loads where the next step is 30-35 ton. Flange wear includes both wheel and rail flanges and is therefore a problem for the operating company as well as the infrastructure owner. The flange wear depend mainly on the number of passed axles, type of traffic, speed and curve radius but also the axle load contributes. Flange lubrication on high rail is a well known way to reduce wear since the middle of 70th and a number of techniques to lubricate the rail flange are developed as grease, aerosol of oil and dry stick with solid lubricants. The trackside lubricator can not apply the grease on the rail flange when the climate is during the winter. The infrastructure owner in Sweden was interested to evaluate the effectiveness of the track side lubricator. The investment in trackside lubricators over 20 years was about 75 Mkr (7,6 USD) and also an additional yearly costs to operate 3000 apparatuses. The work to evaluate effectiveness of the lubrication started 1997 there one of the important matter concern the possibility to use environmentally adapted lubricants without hazard the rail. This licentiate thesis concern effectiveness of trackside lubricators to reduce wear in sharp railroad curves. Also the environmentally aspects have been considered and therefore natural esters synthetic esters and additives suited for those kind of lubricants have been evaluated. The research proved that environmentally adapted lubricants could lubricate as good as earlier used greases. Some amount of metal removal is probably healthy for this kind of application. Lubricants as synthetic esters can be designed get those qualities. It was also found significant difference between the seasons concerning flange wear. This difference depends on the problem to apply grease on the rail flange during the winter.
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Lewis, Stephen Robert. "Measurement, control and enhancement of friction/traction in a simulated wheel/rail contact." Thesis, University of Sheffield, 2011. http://etheses.whiterose.ac.uk/12868/.
Full textAbstract:
The focus on rail transportation has shifted in recent years to be a viable alternative to road based means of travel and freight distribution. With a finite stockpile of the world's natural hydrocarbon based fuels and ever increasing road congestion, rail research has become a prime topic of late. In this thesis the focus has been on the wheel/rail contact and the measurement of rail head friction. The initial project was the development of an alternative technique to measure railhead friction. Adhesion loss is a major problem on railways around the world and is common during the autumn, at times for no obvious reason. Currently there are hand-pushed Tribometers which are used by rail networks to periodically measure and record friction on their rails. These devices however, are large bulky items and due to their design can only measure friction over a relatively large distance. However, most adhesion loss problems are caused by localised phenomena. A pendulum tester was chosen as a potentially viable alternative to the Tribometer as it could measure over shorter lengths of track (i. e. 13 cm compared to 3 in as in the case of the Salient Systems Tribometer). The pendulum is also relatively small and hence is convenient to transport. After a series of laboratory and field based tests the pendulum has been shown to match very well with Tribometer and twin-disc data. Friction modifiers are commonly used on railways around the world and are promoted to have many benefits such as reduced fuel consumption, reduced wear and damage to wheels and rails and reductions in operating noise. These products have been adopted in many different countries. It was noticed in the literature that very little study had been done on how the performance of these products is affected by varying atmospheric conditions or levels of railhead contamination. Another aspect of this thesis has been the measurement of one of the leading brands of top of rail friction modifier using a pin-on-disc tester with attached atmospheric chamber. It was found that humidity and the presence of iron oxide have a far greater effect on the friction modifier than temperature. In the final two chapters a study was carried out to measure the performance of traction enhancing products. These are intended to restore traction in cases of adhesion loss from, for example, leaves on the line. It is critical that correct levels of adhesion/traction are maintained for braking and acceleration purposes. A twin-disc tester was used in this study and a technique for forming a crushed leaf layer on the discs was developed. The traction enhancers consist of sand particles of uniform size suspended in a water based gel. There were four products tested each using a different sand grain size. The first series of tests measured the performance of each product in terms of traction compared to that of a leaf layer alone. It was found that the smaller particles showed the best performance by restoring the traction to uncontaminated levels in the shortest time. The second series of tests focused on the impact these products had on wheel and rail wear and track signalling. Wear was also measured in terms of mass lost from the discs. An A. C. circuit operating at 2 kHz was used to simulate a T121 track circuit which is used in the UK as part of the signalling system. Impedance caused by each product was measured and compared to impedance levels for uncontaminated discs. It was found that the impedance of a leaf layer plus the product was lower than the impedance of the leaf layer alone. There also seemed to be no correlation between particle size and impedance. The impedance levels seen with the products were not deemed to be enough to cause a significant issue to the signalling system.
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Hasan, Abdullah Mohammed. "Quantitative Laser-based Assessment of Top of Rail Friction Modifiers for Railroad Application." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/70916.
Full textAbstract:
The primary purpose of this study is to assess the effectiveness and utility of laser-based sensors for measuring, quantitatively, the presence and extent of top-of-rail (TOR) friction modifiers that are commonly used in the railroad industry for reducing friction between railcar wheels and rail. Modifying the friction between the wheel and rail is not only important for significantly reducing rolling resistance, but it also contributes to reducing wheel and rail wear, lowering rolling contact fatigue, and potentially curving resistance. It is common to monitor rail lubrication empirically by manually observing the sheen of the rail and tactically sensing any residues that may be present on the rail. Often performed by experienced railroad engineers, such methods are highly subjective and do not provide a quantitative assessment of how lubricated or unlubricated the track may be.
A new, quantitative measurement method for accurately assessing the state of lubrication of rail is developed and studied in depth. The method takes advantage of the light reflection and dispersion properties of laser-based optical sensors to provide a repeatable, verifiable, and accurate measure of the presence of TOR friction modifiers on the rail. The measurement system is assembled in a self-contained, portable rail cart that can be pushed on the rail at walking speeds.
Various TOR states are assimilated in the lab for assessing the effectiveness of the laser system. Additionally, the laboratory results are repeated in the field on various tracks, including revenue service track. The results of the tests indicate that the developed system is able to accurately measure the presence of TOR friction modifiers from none to fully-saturated, but is not affected by environmental factors such as rain, sunlight, type of rail, and top-of-rail condition. The measurements provide the means for classifying the state of rail friction in an indexed manner. The results of the study will not only have a significant effect on more efficient use of TOR friction modifiers for promoting better fuel efficiency, but they can also have a major impact on braking practices in applications such as Positive Train Control (PTC).Ph. D.
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Kothari, Karan. "Accurate Wheel-rail Dynamic Measurement using a Scaled Roller Rig." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/96633.
Full textAbstract:
The primary purpose of this study is to perform accurate dynamic measurements on a scaled roller rig designed and constructed by Virginia Tech and the Federal Railroad Administration (VT-FRA Roller Rig). The study also aims at determining the effect of naturally generated third-body layer deposits (because of the wear of the wheel and/or roller) on creep or traction forces. The wheel-rail contact forces, also referred to as traction forces, are critical for all aspects of rail dynamics. These forces are quite complex and they have been the subject of several decades of research, both in experiments and modeling. The primary intent of the VT-FRA Roller Rig is to provide an experimental environment for more accurate testing and evaluation of some of the models currently in existence, as well as evaluate new hypothesis and theories that cannot be verified on other roller rigs available worldwide.
The Rig consists of a wheel and roller in a vertical configuration that allows for closely replicating the boundary conditions of railroad wheel-rail contact via actively controlling all the wheel-rail interface degrees of freedom: angle of attack, cant angle, normal load and lateral displacement, including flanging. The Rig has two sophisticated independent drivelines to precisely control the rotational speed of the wheels, and therefore their relative slip or creepage. The Rig benefits from a novel force measurement system, suitable for steel on steel contact, to precisely measure the contact forces and moments at the wheel-rail contact.
Experimental studies are conducted on the VT ��" FRA Roller Rig that involved varying the angle of attack, wheel and rail surface lubricity condition (i.e., wet vs. dry rail), and wheel wear, to study their effect on wheel-rail contact mechanics and dynamics. The wheel-rail contact is in between a one-fourth scale AAR-1B locomotive wheel and a roller machined to US-136 rail profile. A quantitative assessment of the creep-creepage measurements, which is an important metric to evaluate the wheel-rail contact mechanics and dynamics, is presented. A MATLAB routine is developed to generate the creep-creepage curves from measurements conducted as part of a broad experimental study. The shape of the contact patch and its pressure distribution have been discussed. An attempt is made to apply the results to full-scale wheels and flat rails. The research results will help in the development of better simulation models for non-Hertzian contact and non-linear creep theories for wheel-rail contact problems that require further research to more accurately represent the wheel-rail interaction.MS
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Harmon, M. "Understanding application and tribological mechanisms of lubricants and friction modifiers in the wheel-rail interface." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22377/.
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Doulgerakis, Emmanouil. "Influence of Switches and Crossings on Wheel Wear of a Freight Vehicle." Thesis, KTH, Spårfordon, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134704.
Full textAbstract:
Turnouts (Switches & Crossings) are important components in railway networks, as they provide the necessary flexibility for train operations by allowing trains to change among the tracks. But the turnout’s geometry with discontinuity in rail profiles and lack of transition curve causes additional wear both on track and on vehicle. The main goal of this MSc thesis is to investigate the influence of turnouts on wheel wear of a freight vehicle. This will be obtained by simulations in the commercial MBS software GENSYS. The wheel-rail contact is modelled according to Hertz’s theory and Kalker’s simplified theory, with the FASTSIM algorithm, and the wear calculations are performed according to Archard’s law. Wheel wear is estimated by considering variations in parameters which have effect on wheel-rail contact. All these variations are common in daily rail operation, and they are caused by it, i.e. worn wheel profiles, worn crossing nose and different stiffness of the stock and the switch rails at the beginning of the turnout. Moreover, the wheel wear is calculated for both possible directions which a vehicle can run, the diverging and the straight direction of the turnout. Especially for the straight direction, various running speeds have been tested as the speed limit when the vehicle follows the straight direction is higher than for the diverging part. Running with worn wheel profiles has the greatest impact in terms of increasing the wheel wear, especially on the outer part of wheel tread. In addition, the worn crossing nose results in increased wheel wear in this area. The results of the simulations concerning the different stiffness showed that the wheel wear caused by the contact of wheel and stock rail increases whereas the wear caused by the contact with the switch rail is kept at about the same level or decreases. It is concluded that turnouts have a significant impact on wheel wear, mainly because of the discontinuity in rail geometry and all the investigated parameters increase this impact. Moreover, great differences in wear values for areas close to each other are observed, mainly because of the wear coefficient values chosen in Archard’s wear map.
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Abbasi, Saeed. "Towards elimination of airborne particles from rail traffic." Doctoral thesis, KTH, Maskinelement, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-131372.
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Since the investigation of wear particles from rail transport started in the late 1910s, the high mass concentrations of these particles have prompted concern among researchers interested in air quality. However, effective action has yet to be taken because relevant knowledge is still missing. This thesis provides knowledge of airborne wear particles originating from rail transport. Some aspects of their characteristic parameters, such as size, mass concentration, number concentration, and morphology, were investigated in the field and in laboratory tests. We also discuss means to mitigate non-exhaust emissions, as well as the advantages and disadvantages of various test set-ups in the seven appended journal papers:Paper A reviews recent studies of exhaust and non-exhaust emissions from rail vehicles. The results, measurements, adverse health effects, and proposed or applied solutions presented in this literature are summarized in this paper.Paper B summarizes the results of field tests we conducted. The effects of curve negotiation and braking under different real conditions were investigated in a field test in which on-board measurements were made. The elemental composition and morphology of the particles emitted and their potential sources were also investigated.Paper C describes how a pin-on-disc machine can be used to reproduce real operating conditions during mechanical train braking in a controlled laboratory setting. The results were validated by comparing the field test results with the results of laboratory studies.Paper D presents comprehensive results of laboratory studies of airborne particles from different braking materials. A new index is introduced in this paper, which can be used as a quantitative metric for assessing airborne wear particle emission rates.Paper E describes the effects of using various friction modifiers and lubricants on the characteristics of airborne particles from wheel–rail contact under lubricated and unlubricated conditions.Paper F reports work to simulate thermoelastic instability in the cast-iron braking material. We simulated the fluctuation of the flash temperature by considering the temperature dependency of the material properties and the transformation of the contact state due to thermomechanical phenomena and wear.Paper G reviews new full- and sub-scale measurements of non-exhaust emissions from ground transport. The advantages and disadvantages of on-board measurements, pin-on-disc tests, dynamometer tests, and test rig studies are discussed in this paper.QC 20131025
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Shahrezaei, Khashayar, and Edvin Öberg. "Evaluation Methods for Friction Materials in a Four-Wheel Drive Drivetrain." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70776.
Full textAbstract:
BorgWarner located in Landskrona are developing components for the four-wheeldrive drivetrain that are being massed produced in the automotive industry. Thanks to Borg- Warner’s unique product’s properties they have achieved a worldwide leading position as a provider of systems for advanced four-wheeldrive drivetrain (all-wheel drivetrain). The assignment from the BorgWarner is to create a better understanding about when vibrations occur and what properties of a friction disc affect vibrations in the wet clutch. The goals of this thesis are to: Map system parameters like Surface topografy. Measure pressure distribution between the friction discs. Measure the Youngs modulus, also known as stiffness. It is not sure that a bad pressure distribution could cause vibrations in the wet clutch. The results from the topography explain the appearance of the pressure distribution. Varying stiffness means that the density of the material is also varying because the stiffness depends on the material composition. When forces are applied on the friction disc, it leads to varying deformation on samples. When the samples all deforms different, the result of the different deformation could be slanting surface. When a disc with non- parallel friction surface rotates it could generate vibration in the wet clutch.
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Jbily, Dalia. "Prise en compte de l’usure dans la modélisation du comportement sous charge des engrenages roues et vis tangentes." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI037/document.
Full textAbstract:
Les engrenages roues et vis sans fin sont une solution avantageuse pour transmettre le couple entre des axes perpendiculaires non concourants. Ces engrenages offrent une solution simple et efficace en terme de coût dans les applications de transmission de puissance, où un grand rapport de réduction est nécessaire, en comparaison avec les engrenages classiques à axes parallèles qui nécessitent normalement deux ou trois étapes pour obtenir les mêmes réductions avec une augmentation conséquente de complexité et du nombre de pièces. L’usure de surface est un des modes de défaillance observés dans la vie des engrenages roues et vis sans fin qui influe sur la portée de contact, les caractéristiques de transmission et le bruit résultant. La première étape de ces travaux est la mise au point d’un modèle numérique pour étudier le comportement quasi statique des engrenages roues et vis sans fin avec une roue en bronze et une vis en acier. Le modèle est basé sur la résolution des équations de compatibilité des déplacements ainsi que sur la méthode des coefficients d’influence. Les effets globaux de flexion et les effets locaux de contact ont été séparés. Les effets de contact ont été obtenus par la théorie de Boussinesq. Les coefficients de flexion sont estimés par la combinaison d’un calcul Éléments Finis et des fonctions d’interpolation, permettant d’une part de prendre en compte l’environnement de l'engrenage (la géométrie des arbres, des jantes et des voiles, l’emplacement des roulements,...) et d’autre part de réduire significativement les temps de calculs. Dans une seconde étape, une méthodologie est proposée pour modéliser l’usure de la surface de dent de la roue. Le modèle de contact quasi-statique de la répartition des charges est combiné avec un modèle d’usure d’Archard. Ce modèle suppose que la profondeur d’usure est directement proportionnelle à la pression de contact et à la distance de glissement et inversement proportionnelle à la dureté du matériau. Cette loi d’usure est modifiée pour prendre en compte l’influence des conditions de lubrification en utilisant un coefficient d’usure local, dépendant de l’épaisseur du film lubrifiant, rapportée à l’amplitude des rugosités des surfaces. L’enlèvement de matière par l’usure du flanc de la roue influe sur la répartition des pressions et donc les modifications de la géométrie des dents doivent être incluses dans la prédiction de l’usure. Le calcul des pressions de contact est ainsi mis à jour pour tenir compte des changements de géométrie. Enfin, pour valider le modèle développé des comparaisons du modèle avec des résultats expérimentaux issus de la bibliographie ont été effectuéesWorm gears are one of the technical devices for transmitting torque between spatial crossed axes. They provide a simple and cost effective solution in power transmission applications, where a high reduction ratio is required. Comparable conventional parallel axis gearing would normally require two or three stages to achieve the same reduction, with a consequent increase in complexity and number of parts. Surface wear is one of the failure modes observed in life worm gear sets which affects the contact patterns, the other transmission characteristics and the resultant noise. The first step of this work is the development of a numerical model to study provide the quasi-static behavior of worm gears with bronze wheel and steel worm. The model is based on solving of the equation of displacement compatibility and the influence coefficient method. The global effects of bending and local effects of contact are separated. The contact effects are obtained with the theory of Boussinesq. Bending effects are estimated by the combination of one standard FEM computation and interpolation functions. These methods allow, on the one hand, to take into account the environment of the gear (shaft shape, rim, web, bearing location ...) and on the other to reduce significantly the computation time. In a second step, a methodology is proposed for predicting the wear of the wheel tooth surface. In this process, a quasi-static contact model of the load distribution is combined with Archard's wear model. This model assumes that the wear depth is directly proportional to the contact pressure and sliding distance and inversely proportional to the hardness of the material. The wear law is modified to take into account the influence of the lubrication conditions using a local wear coefficient, depending on the lubricant film thickness, relative to the amplitude of surface roughness. Removal of material by wear on the wheel flank affects the pressure distribution, therefore the changes in teeth must be included in the prediction of wear. The calculation of contact pressures must also be updated to take into account the modification of the gear flank geometry. The last step concerns the validation of the numerical. Comparisons have been carried out between the model results and experimental ones issued from the bibliography
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Keylin, Alexander. "Analytical Evaluation of the Accuracy of Roller Rig Data for Studying Creepage in Rail Vehicles." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/49607.
Full textAbstract:
The primary purpose of this research is to investigate the effectiveness of a scaled roller rig for accurately assessing the contact mechanics and dynamics between a profiled steel wheel and rail, as is commonly used in rail vehicles. The established creep models of Kalker and Johnson and Vermeulen are used to establish correction factors, scaling factors, and transformation factors that allow us to relate the results from a scaled rig to those of a tangent track. �Correction factors, which are defined as the ratios of a given quantity (such as creep coefficient) between a roller rig and a track, are derived and used to relate the results between a full-size rig and a full-size track. Scaling factors are derived to relate the same quantities between roller rigs of different scales. Finally, transformation factors are derived by combining scaling factors with correction factors in order to relate the results from a scaled roller rig to a full-size tangent track. Close-end formulae for creep force correction, scaling, and transformation factors are provided in the thesis, along with their full derivation and an explanation of their limitations; these formulae can be used to calculate the correction factors for any wheel-rail geometry and scaling.For Kalker\'s theory, it is shown that the correction factor for creep coefficients is strictly a function of wheel and rail geometry, primarily the wheel and roller diameter ratio. For Johnson and Vermeulen\'s theory, the effects of creepage, scale, and load on the creep force correction factor are demonstrated. �It is shown that INRETS\' scaling strategy causes the normalized creep curve to be identical for both a full-size and a scaled roller rig. �It is also shown that the creep force correction factors for Johnson and Vermeulen\'s model increase linearly with creepage, starting with the values predicted by Kalker\'s theory. �Therefore, Kalker\'s theory provides a conservative estimate for creep force correction factors. �A case study is presented to demonstrate the creep curves, as well as the correction and transformation factors, for a typical wheel-rail configuration. �Additionally, two studies by other authors that calculate the correction factor for Kalker\'s creep coefficients for specific wheel-rail geometries are reviewed and show full agreement with the results that are predicted by the formulae derived in this study. �Based on a review of existing and past roller rigs, as well as the findings of this thesis, a number of recommendations are given for the design of a roller rig for the purpose of assessing the wheel-rail contact mechanics. �A scaling strategy (INRETS\') is suggested, and equations for power consumption of a roller rig are derived. Recommendations for sensors and actuators necessary for such a rig are also given. Special attention is given to the resolution and accuracy of velocity sensors, which are required to properly measure and plot the creep curves.
Master of Science
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Knápek, Jiří. "Experimentální studium modifikátorů tření v kolejové dopravě." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318387.
Full textAbstract:
The adhesion in the wheel-rail contact can be effectively controlled by using the friction modifier. Adhesion control can reduce excessive wear of the contact bodies or noise. The essence of this diploma thesis is to determine the optimal amount of friction modifier in wheel-rail contact depending on the climatic and operating conditions. For experimental study of the behavior of the friction modifier, the twin-disc device is used. Twin-disc simulates and controls the most important operating parameters such as speed, slip, attack angle or contact pressure. On the basis of these findings, the off-board top-of-rail lubricator system was designed. This system controls the amount of friction modifier according to current climatic and operating conditions.
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Skurka, Šimon. "Vývoj maziva pro temeno kolejnice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443457.
Full textAbstract:
Friction modification within the wheel-rail interface is an important way of achieving ecologically friendly transportation of both persons and goods. This thesis aims to develop a new TOR lubricant, which will be able to maintain suitable frictional conditions while securing minimal adhesion required for traction. All measurements were carried out on tribometer MTM in the ball-on-disc configuration. In the first step, individual components were examined. More complex compositions were measured after that and the three best of them were compared with commercial TOR lubricants. The results show a good ability of developed compositions to maintain required adhesion, reduce wear, and all of them had resistivity against over-lubrication. Lastly, the process of lubricant verification before its application in real traffic was discussed.
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Frýza, Josef. "Experimentální studium mazání okolku kolejových vozidel." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230983.
Full textAbstract:
This diploma thesis deals with the experimental study of the influence of operating conditions on the tribological aspects of the wheel flange and rail gauge contact. The wheel flange contact occurs when the vehicle moves on a curve track and it leads to severe up to catastrophic wear regime. For effective reduction of wear is important to apply a suitable amount of lubricant at appropriate intervals into the contact. The issue in this work comprehensively studies using of three laboratory apparatus and six methods that are theoretically and experimentally compared. Assessed are friction, wear, distribution and film thickness of lubricants for different contact conditions. The resulted amount of lubricant and interval of its application eliminates development of seizure at low consumption of lubricant. The understanding of mechanisms that occur in the wheel-rail contact not only helps to reduce operating costs and improved to energy efficiency of movement of vehicle on a track, but it is the basis for safe, reliable and ecological operation of rail transport.
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Jandora, Radek. "Výpočtové modelování dynamických projevů v kontaktu kola a kolejnice s obecnou geometrií kontaktních povrchů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234020.
Full textAbstract:
During life of railway vehicles, shape irregularities develop on wheels and rails because of wear. The shape irregularities then affect forces in wheel-rail contact and cause further damage of contact surfaces, vibrations and noise and increase risk of derailment. A numerical simulation of railway vehicle motion with more details on contact surfaces geometry was created to investigate dynamic contact loads in wheel-rail contact. A variety of methods can be used to evaluate forces in rolling contact, the method chosen for this study was algorithm CONTACT based on boundary element method. Four studies are presented in this papers: contact loads from a wheel with a flat and with a wavy tread pattern, loads on wavy rail and load in a curve. The first three studies investigated effects of existing wear patterns, the last one looked for cause of common wear pattern developing on rails. Results of the studies with worn components used showed that the worst kind of shape irregularities is a flat present on wheel. This type of shape cause loss of contact and following impacts. The study of ride in curve showed that cause of high wear in curves, especially those with small radii, is caused by vibration of wheelset. This vibration is then caused by different length of inner and outer rail and wheels travelling along a different path.
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Tomčová, Renata. "Testování výkonnosti maziv pro kolejovou dopravu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443211.
Full textAbstract:
Top-of- rail lubricants are an effective way to control adhesion, reduce contact wear and noise in rail transport. However, despite the widespread use of these lubricants, there is currently no standard defining how to test and evaluate their performance. This work aims to develop a methodology for testing top-of-rail lubricants in a laboratory environment using a tribometer in a ball-on-disk configuration. At first, important operational parameters of experiments are analyzed and experimentally tested. These are mainly wear-in and run-in, method of application, roughness and geometric parameters of contact bodies. The result of this work is a testing methodology that guarantees good repeatability and reliability of results. In the last part of this work, the methodology is verified using commercial top-of-rail lubricants.
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Burian, Josef. "Výpočtové modelováni komplexních vlastních frekvencí tramvajového kola při průjezdu zatáčkou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254382.
Full textAbstract:
This Master’s thesis deals with the computational modeling of complex natural frequencies of the tram wheels during cornering. The aim of this work is to determine eigenvalues, perform analysis of the influence of different parameters on eigenvalues and perform harmonic response analysis in order to find surface velocities that can be used in future noise emission analysis.
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Lundberg, Oskar. "On the influence of surface roughness on rolling contact forces." Doctoral thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193935.
Full textAbstract:
Road vehicle tyres, railway wheels and ball bearings all generate rolling contact forces which are transferred within a finite area of contact between the rolling element and the substrate. Either it is visible or not for the human eye, a certain degree of roughness is always present on the contacting surfaces and it influences the generation of both vertical and lateral contactforces. The purpose of this investigation is to enhance the understanding and modelling of the influence from small-scale surface roughness on the generation of rolling contact forces. To this end, a computationally efficient method to include roughness-induced contact nonlinearities in the dynamic modelling of rolling contacts is proposed. The method is implemented in a time domain model for vertical wheel–track interaction to model rolling-induced rail vibrations, showing good agreement with measurements. Furthermore, a test rig is developed and used for the investigation of tyre–road rolling contact forces. Detailed studies are performed on the influence of substrate roughness on the resulting contact forces for a tyre tread block which is rolling at different operating conditions. The choice of substrate as well as the rolling velocity and the slip ratio is observed to have significant influence on the resulting friction coefficient. For high slip ratios, stick–slip oscillations appear, exhibiting frequency content which is largely dependent on the choice of substrate. The outcomes of this study can potentially be used to improve future tyre–road contacts with respect to wear, traction and noise generation.QC 20161013
Centre for Eco2 Vehicle Design
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Öhnander, Fred. "An Attempt Towards FE-Modelling of Fracture Propagation in Railway Wheels." Thesis, KTH, Spårfordon, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-234468.
Full textAbstract:
The demand for higher velocities and heavier axle loads for freight trains leads to higher forces on the railway wheels which in turn lead to an increase in stresses on and below the surface of the wheel-rail contact. By time, this induces wear on the wheels which consequently lead to higher maintenance costs and in some cases accidents. The ability to predict the evolution of wheel profiles due to uniform wear has been demonstrated with a rather accurate precision in most operational conditions. These wear models are based on wear coefficients and since they are not usually valid for real operational conditions, the models are generally calibrated against real-life scenarios in order to adjust the coefficients from test conditions to real-life lubrication conditions. This engineering approach can be useful in prediction of wear in systems where the materials and contact conditions do not vary. However, when addressing material development focused on reducing specific damage modes, the approach is of limited use because the obtained wear coefficients are not directly related to material properties. Therefore, attempts towards developing physical fracture propagation models that relates to the contact conditions and material properties have been made. The purpose has been to retrieve vital information about where a fracture initiates and how it propagates. In the long run, it is of great interest to be able to attain information about how a material particle is removed from the contact surface. Studies for this type of model was done in the 70’s and 80’s mainly with pin-disk experiments but has not been utilized in the specific field of wheel-rail contact. The thesis is part of the FR8RAIL project arranged by the European rail initiative Shift2Rail. Literature studies have been the basis for the thesis in order to gain vital insights into fracture mechanics and other related fields. The physical fracture propagation models have been constructed in the FE software Abaqus with the implementation of the XFEM. For the 2D model, the fracture initiates at the top of the implanted inclusion when the friction coefficient is and propagates upwards a few elements. For , the fracture initiates at the right surface boundary where the pressure distribution and traction is applied. The fracture propagation angle increases relative to the surface as the friction coefficient value is increased. The fracture for the 3D model extends broader compared to the 2D model at the top of the inclusion in the case of . The fracture initiates at the same surface location as for the 2D model for . The fracture propagation is however non-existent due to convergence problems. The FE-models constructed are initial steps towards analysing the fracture propagation and closely related phenomena for a railway freight wheel in detail. At the end of the thesis, the simplified models give mainly information about the fracture initiation, propagation and its patterns. From this first phase, further adjustments and improvements can take place in order to eliminate the margins of error. In the long run, fully integrated models with further implementations such as detailed microstructure for the contact conditions, plastic behaviour for the material, and complete three-dimensional models can finally be employed.Efterfrågan på högre hastigheter och tyngre axelbelastningar för godståg leder till högre krafter på järnvägshjulen som i sin tur leder till ökade spänningar på och under ytan vid hjul-räl-kontakten. Med tiden induceras slitage på hjulen som följaktligen leder till höga underhållskostnader och i vissa fall olyckor. Förmågan att förutse utvecklingen av hjulprofiler på grund av enhetligt slitage har visats kunna ske med en noggrann precision under de flesta driftsförhållanden. Dessa slitagemodeller bygger på slitagekoefficienter, och eftersom de vanligtvis inte är giltiga under realistiska driftsförhållanden är modellerna i allmänhet kalibrerade mot verkliga händelseförlopp för att justera koefficienterna från testförhållandena till realistiska smörjförhållanden. Detta tekniska tillvägagångssätt kan vara användbart vid prognos av slitage i system där material och kontaktförhållanden inte varierar. När man addresserar materialutveckling inriktad på att reducera specifika skadelägen är emellertid tillvägagångssättet av begränsad användning eftersom de erhållna slitagekoefficienterna inte är direkt relaterade till materialegenskaper. Därför har försök gjorts till att utveckla fysikaliska sprickbildningsmodeller som relateras till kontaktförhållanden och materialegenskaper. Syftet har varit att erhålla viktig information om var en spricka initieras och hur den fortskrider. I det långa loppet är det även av stor vikt att kunna erhålla information om hur en materialpartikel avlägsnas från kontaktytan. Studier för denna typ av modeller har gjorts på 70- och 80-talet i huvudsak med stift- och skivexperiment men har inte använts inom det specifika området för hjul-räl-kontakt. Avhandligen ingår i FR8RAIL-projektet som arrangeras av det europeiska järnvägsinitiativet Shift2Rail. Literaturstudier har varit grunden för avhandlingen för att få väsentlig insikt i frakturmekanik och andra relaterade områden. De fysiska sprickbildningsmodellerna har konstrueras i FE-mjukvaran Abaqus med XFEM som implementering. För 2D-modellen initieras sprickan överst vid den implanterade imperfektionen när friktionskoefficienten är och propagerar uppåt några få element. För initieras sprickan på högra ytgränsen där tryckfördelning och friktionskraft appliceras. Utbredningsvinkeln för sprickan ökar relativt till ytan då friktionskoefficienten ökar. Sprickan för 3D-modellen breder ut sig mer jämfört med 2D-modellen överst vid imperfektionen då . Sprickan initieras på samma ytplats som för 2D-modellen vid . Sprickbildningen är dock obefintlig på grund av konvergensproblem. De konstruerade FE-modellerna är initiala steg mot att analysera sprickutbredningen och närbesläktade fenomen för ett godstågs järnvägshjul i detalj. I slutet av avhandlingen ger de förenklade modellerna huvudsakligen information om sprickinitiering, utbredning och dess mönster. Ytterligare justeringar och förbättringar kan ske efter denna första fas i syfte att eliminera felmarginalerna. På lång sikt kan slutligen helt integrerande modeller med ytterligare implementeringar såsom detaljerad mikrostruktur för kontaktförhållandena, oelastiskt materialbeteende och kompletta tredimensionella modeller användas.
FR8RAIL
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Mai, Si Hai. "Etude de dégradation des voies ferrées urbaines." Phd thesis, Université Paris-Est, 2011. http://pastel.archives-ouvertes.fr/pastel-00659068.
Full textAbstract:
Ce travail réalisé dans le cadre d'une collaboration industrielle avec la société ALSTOM Transport porte sur l'étude de la dégradation des voies ferrées urbaines. Les composantes de voie retenus pour cette étude sont le rail et la dalle de voie en béton. Concernant le rail, différents problèmes sont abordés : contact roue - rail, usure du rail, usure ondulatoire du rail, et fatigue de contact de roulement (RCF) du rail. Un outil numérique avec des interfaces graphiques, nommé CONUS, est développé pour le problème de contact roue - rail et le problème d'usure du rail. Des théories classiques (Hertz, Kalker, Archard, etc.) sont implantées dans cet outil. La méthode stationnaire est implantée dans un code de calcul par éléments finis pour étudier l'état asymptotique de l'acier du rail sous le chargement répété des trains. Ceci nous permet de prédire les régimes de RCF du rail. La mécanique de l'endommagement est utilisée pour prédire la fatigue du matériau béton. Le formalisme de Marigo couplé avec le modèle d'endommagement de Mazars permet de modéliser la dégradation progressive de la rigidité du matériau sous chargement cyclique. Une campagne d'essais de fatigue du béton en flexion a été réalisée. Elle a pour but de valider le modèle théorique et d'identifier les paramètres du matériau. Le dimensionnement d'une dalle de voie en béton a fait l'objet d'une application de cette méthode. Le modèle de réseau de poutres (lattice model) a été utilisé pour étudier la propagation des fissures dans les structures en béton. Ce modèle a été implanté dans le logiciel de calcul par éléments finis, CESAR-LCPC. Les résultats numériques (propagation de fissures) obtenus pour les structures simples sous chargement statique sont en tout point comparables avec les résultats d'essais expérimentaux. Ce modèle a ensuite été utilisé pour étudier la fissuration sous chargement de fatigue. Pour cela un modèle d'endommagement simple modélisant la dégradation des éléments "poutres" s'est avéré suffisant pour décrire la cinématique de propagation des fissures
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Giner, Navarro Juan. "Advances Techniques for Time-Domain Modelling of High-Frequency Train/Track Interaction." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/90637.
Full textAbstract:
[EN] The aim of the present Thesis is to develop models for the study of very high-frequency phenomena associated with the coupling dynamics of a railway vehicle with the track. Through these models, this Thesis intends to address squeal noise as a particular case of rolling noise when the train negotiates a small radius curve.
Wheel/rail interaction is the predominant source of noise emission in railway operations. Rolling contact couples the wheel and the rail through a very small area, characterised by strongly non-linear and non-steady state dynamics that differentiates rolling noise from any other noise problem. Wheel/rail contact problem is studied based on Kalker's variational theory and the local falling behaviour of the coefficient of friction is introduced by means of a regularisation of Coulomb's law. Its implementation shows that the influence of the falling friction on the creep curves can be assumed negligible, thus rolling contact is finally modelled using a constant coefficient of friction.
Flexibility is introduced in railway substructures through the Finite Element (FE) method in order to cover the high-frequency range. This work adopts a rotatory wheelset model that takes computational advantage of its rotational symmetry. It also develops a cyclic flexible rail model that fixes the translational contact force in a spatial point of the mesh through a technique called Moving Element (ME) method. A modal approach is used to reduce significantly the number of degrees of freedom of the global problem and a diagonalisation technique permits to decouple the resulting modal equations of motion in order to increase the computational velocity of the time integrator.
Simulations in curving conditions in the time domain are carried out for constant friction conditions in order to study if the proposed interaction model can reproduce squeal characteristics for different curve radii and coefficients of friction.[ES] El objetivo de la presente Tesis es desarrollar modelos para el estudio de fenómenos de muy alta frecuencia asociados a la dinámica acoplada de un vehículo ferroviario con la vía. A través de estos modelos, esta Tesis pretende abordar el fenómeno de los chirridos como un caso particular de ruido de rodadura en condiciones de curva cerrada. La interacción rueda/carril es la fuente predominante de ruido en las operaciones ferroviarias. El contacto es el responsable del acoplamiento entre la rueda y el carril a través de un área muy pequeña caracterizada por una dinámica fuertemente no lineal y no estacionaria. El problema de contacto rueda/carril se estudia mediante la teoría variacional de Kalker y la caída local del coeficiente de fricción se introduce por medio de una regularización de la ley de Coulomb, que muestra que su influencia sobre las curvas de fluencia se puede despreciar. Como consecuencia, el coeficiente de fricción se considera constante. La flexibilidad se introduce en las subestructuras ferroviarias a través del método de los Elementos Finitos (EF) para cubrir el rango de las altas frecuencias. La Tesis adopta un modelo de eje montado rotatorio que toma ventaja computacional de su simetría rotacional. También desarrolla un modelo de carril flexible y cíclico que fija la fuerza de contacto en un punto espacial de la malla mediante el método de los Elementos Móviles (EM). Se utiliza un enfoque modal para reducir significativamente el número de grados de libertad del problema global; las ecuaciones de movimiento resultantes en coordenadas modales se desacoplan mendiante una técnica de diagonalización para aumentar la velocidad computacional del integrador temporal. Las simulaciones en condiciones de curva en el dominio del tiempo se llevan a cabo en condiciones de fricción constante con el objetivo de estudiar si el modelo de interacción propuesto puede reproducir las características del chirrido en curva para diferentes radios de curva y coeficientes de fricción.
[CAT] L'objectiu de la present Tesi és desenvolupar models per a l'estudi de fenòmens de molt alta freqüència associats amb la dinàmica acoblada d'un vehicle ferroviari amb la via. Aquests models permeten simular el soroll de rodament encara que, en particular, aquest treball es proposa abordar el fenomen del soroll grinyolant produït quan el tren negocia un radi de curvatura estret. La interacció roda/carril és la font predominant de l'emissió de soroll en les operacions ferroviàries. El contacte acobla la roda i el carril a través d'una àrea molt reduïda que es caracteritza per una dinàmica fortament no lineal i no estacionària. El problema de contacte roda/carril s'estudia mitjançant la teoria variacional de Kalker i el descens local del coeficient de fricció s'introdueix per mitjà d'una regularització de la llei de Coulomb, què demostra que la seua influència en les corbes de fluència es pot suposar insignificant. Per tant, s'utilitza un coeficient de fricció constant per a modelar el contacte. La flexibilitat s'introdueix en les subestructures de ferrocarril a través del mètode d'Elements Finits (EF) per tal de cobrir el rang d'alta freqüència. La present tesi adopta un model d'eix muntat rotatori que s'aprofita de la seua la simetria rotacional per a augmentar la eficiència computacional. També desenvolupa un model de carril flexible i cíclic que fixa la força de contacte en un punt espacial de la malla a través del mètode dels Elements Mòbils (EM). S'empra un enfocament modal per reduir significativament el nombre de graus de llibertat del problema global, al temps que s'implementa una tècnica diagonalització que permet desacoblar les equacions modals de moviment per a augmentar la velocitat computacional de l'integrador temporal. Les simulacions en les condicions de corba en el domini del temps es duen a terme per a condicions de fricció constant per tal d'estudiar si el model d'interacció proposat pot reproduir les característiques del soroll grinyolant per a diferents radis de corba i coeficients de fricció.
Giner Navarro, J. (2017). Advances Techniques for Time-Domain Modelling of High-Frequency Train/Track Interaction [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90637
TESIS
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Под’єльніков, Ігор Валерійович, Игорь Валериевич Подъельников, and Igor V. Podjelnikov. "Поліпшення взаємодії вантажних вагонів та колії за рахунок вдосконалення візків і профілів пари “колесо-рейка”." Thesis, Видавництво Дніпропетровського національного університету залізничного транспорту імені академіка В. Лазаряна, 2012. http://eadnurt.diit.edu.ua:82/jspui/handle/123456789/1320.
Full textAbstract:
Под'єльніков, І. В. Поліпшення взаємодії вантажних вагонів та колії за рахунок вдосконалення візків і профілів пари "колесо-рейка" : авт. дис. к. т. н.: 05.22.07 / І. В. Под'єльніков ; Дніпропетр. нац. ун-т залізн. трансп. ім. акад. В. Лазаряна. - Д. : Вид-во Днiпропетр. нац. ун-ту залізн. трансп. iм. акад. В. Лазаряна, 2012. УДК 625.1.03:629.463.027.1 ГРНТИ 73.29.11UK: АНОТАЦІЯ Дисертацію присвячено поліпшенню умов взаємодії системи “вагон-колія” за рахунок вдосконалення профілів контактних поверхонь коліс та рейок, а також застосування у комплексно модернізованих візках вантажних вагонів діагональних зв’язків між боковими рамами. У дисертації визначено усереднені форми головок рейок з різною мірою зносу в зовнішніх нитках кривих малого і середнього радіусів. Встановлено, що форми зносу головок рейок в кривих малого і середнього радіусів у своїй робочій зоні практично не відрізняються одна від одної. Отримано також усереднені форми зношених в різному ступені ободів коліс з різними первинними профілями. Виявлено, що форми ободів коліс, первинний профіль яких до початку експлуатації був різним, по мірі зносу наближаються до однієї і тієї ж форми (але після суттєво різних пробігів). Розроблено вдосконалений профіль ободів коліс для вантажних вагонів, обладнаних візками з боковими ковзунами постійного контакту, що дозволяє істотно зменшити знос коліс та поліпшити напружено-деформований стан у парі “колесо-рейка”, тим самим поліпшити взаємодію вагонів і колії. Розроблено нові профілі головок рейок для зовнішніх ниток кривих малого і середнього радіусів, що дозволяють понизити боковий знос рейок та поліпшити умови вписування вагонів у криві. Встановлено, що застосування у комплексно модернізованих візках діагональних зв’язків між боковими рамами приводить до деякого поліпшення динамічних показників коливань вагона у горизонтальному напрямку і до значного зниження зносу коліс в кривих, тим самим сприяє поліпшенню умов взаємодії вантажних вагонів і колії. RU: АННОТАЦИЯ Диссертация посвящена улучшению условий взаимодействия системы “вагон-путь” за счет усовершенствования профилей контактных поверхностей колес и рельсов, а также применения в комплексно модернизированных тележках грузовых вагонов диагональных связей между боковыми рамами. На железных дорогах Украины и других стран СНГ актуальной является проблема улучшения взаимодействия грузовых вагонов и пути, в том числе за счет уменьшения износа гребней колес грузовых вагонов и боковых поверхностей головок рельсов в наружных нитях кривых малого и среднего радиуса. Одним из эффективных путей уменьшения износа колес и рельсов является усовершенствование профилей их контактных поверхностей. Наиболее перспективными являются профили колес и рельсов, обеспечивающие конформный контакт, при котором имеют место наибольшая площадка контакта и наименьшие контактные напряжения по сравнению с неконформными профилями. Взаимодействие вагонов и пути зависит от ходовых частей вагонов. Применение комплексной модернизации тележек позволяет существенно снизить износ гребней колес и улучшить динамические качества грузовых вагонов. Одним из перспективных путей дальнейшего улучшения динамических качеств грузовых вагонов является установка диагональных связей между боковыми рамами тележки, благодаря чему уменьшается забегание боковин. В диссертации определены усредненные формы головок рельсов с различной степенью износа в наружных нитях кривых различных радиусов. Установлено, что формы износа головок рельсов в кривых малого и среднего радиусов в своей рабочей зоне практически не отличаются друг от друга. Получены также усредненные формы изношенных в различной степени ободьев колес с разными первоначальными профилями. Обнаружено, что, формы ободьев колес, исходный профиль которых до начала эксплуатации был различным, по мере износа стремятся принять одно и то же очертание (но после существенно разных пробегов). Разработан усовершенствованный профиль ободьев колес для грузовых вагонов, оборудованных тележками с боковыми скользунами постоянного контакта, позволяющий существенно уменьшить износ колес и улучшить напряженно-деформированное состояние в паре “колесо-рельс”, тем самым улучшить взаимодействие вагонов и пути. Разработаны новые профили головок рельсов для наружных нитей кривых малого и среднего радиусов, позволяющие снизить боковой износ рельсов и улучшить условия вписывания вагонов в кривые. Проведена оценка эффективности применения диагональных связей в комплексно модернизированных тележках и уменьшения толщины гребней колес. Установлено, что уменьшение первоначальной толщины гребней неизношенных колес улучшает горизонтальные динамические показатели вагона, а также снижает износ колес при движении вагона в кривых. При уменьшении толщины гребня колес вследствие износа горизонтальные динамические показатели вагона ухудшаются. Введение в комплексно модернизированную тележку диагональных связей между боковыми рамами приводит к некоторому улучшению динамических показателей колебаний вагона в горизонтальном направлении и к значительному снижению износа колес в кривых, тем самым способствует улучшению условий взаимодействия грузовых вагонов и пути. Использование полученных в диссертации результатов и закономерностей позволит улучшить взаимодействие грузовых вагонов и пути на железных дорогах колеи 1520 мм. EN: ABSTRACT The thesis is devoted to improvement of interaction terms of the system “car-track” by the perfection of profiles of wheels and rails contact surfaces and by application of diagonal braces between side frames in the complex modernized freight car trucks. The averaged forms of rail heads with various wear rates of the outer rails in sharp and middle curves are determined in the thesis. It is searched out that the modes of rail head wear in the working zone practically do not differ from each other in sharp and middle curves. The averaged forms of wheel treads with various wear rates and different original profiles are also determined. It is educed that the forms of wheels treads, which had different original profiles before the operation, approach to the same shape as they wear (but after substantially different runs). The improved profile of wheels treads for the freight cars, equipped by trucks with lateral bearings of permanent contact, which make its possible to substantially decrease the wear of wheels, improvement of tensely-deformed state in a pair “wheel-rail”, to improve interaction of car and track is developed. The new profiles of rail head for the outer rails of sharp and middle curves are developed for the purpose of reducing the lateral wear of rails and improve the terms of inscribing of cars in curves. It is determinate that the use of diagonal braces between side frames in the complex modernized trucks results in some improvement of dynamic indexes of vibrations of car in horizontal direction and to the considerable decreasing of wear of wheels in curves, assists the same to the improvement of terms of interaction of freight cars and track.
Інститут технічної механіки Національної академії наук України і Національне космічне агентство України
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(9825794), Michelle Pearce. "Railway operational benefits from bogie rotation friction management: Numerical simulations of bogie dynamics." Thesis, 2006. https://figshare.com/articles/thesis/Railway_operational_benefits_from_bogie_rotation_friction_management_Numerical_simulations_of_bogie_dynamics/20341539.
Full textAbstract:
The purpose of this project was to prove or disprove the hypothesis that wheel and rail wear, and incidents of wheel squeal increase with increasing bogie rotation friction, while decreasing bogie rotation friction leads to increased incidents of hunting and increased wheel and rail wear. Therefore for any given combination of factors (vehicle type, curve radius, wheel profile, etc) an optimal bogie rotation friction level should exist at which incidents of hunting and wheel squeal are eliminated and wheel and rail wear is minimised.
In order to test the hypothesis a literature review was first undertaken. The purpose of the review was to examine the results from previous similar projects and identify any areas that may be improved upon in order to achieve the most accurate results. As a result of the literature review the simulation vehicle model was designed. Past studies featured a three-dimensional wagon body with the centre bowl connection modelled as a single spring, or the centre bowl was modelled in isolation. However for this project the vehicle included a centre bowl connection modelled using centre plate springs evenly distributed across the top centre, and plate and rim friction on the centre bowl, radial bumpstops around the rim and a vertical restraint from the cotter pin. Additional features of the simulation vehicle model were friction wedges, in order to properly represent the damping present at the spring nest connection, and a non -circular top centre, to reflect the design currently used by QR (Queensland Rail).
The remainder of the project focussed on computer simulations of the vehicle model using different combinations of parameters (vehicle type, curve radius, wheel profile, centre bowl friction and loading condition) to examine the way that the vehicle behaviour responded. The vehicle response was determined by measuring the wheelset lateral position, wheelset angle of attack and wear index (calculated using creep force and creepage).
The first series of simulations were used to prove that the centre bowl friction levels could be determined using wayside monitoring equipment provided that particular conditions were met. Provided that the vehicle was travelling through an area of constant curvature (not in transition or tangent), in 75% of cases the centre bowl friction level to lateral position relationship was relatively linear. Therefore after initial studies to calibrate the system according to the curve radius and type of vehicle it would be possible to calculate the centre bowl friction using wayside monitoring equipment. However if the system was limited to curves with a radius larger than 800m, the accuracy of the system increased to 83% of cases following a linear relationship.
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Soares, André Roberto. "Desenvolvimento de modelos para previsão de desgaste em contactos roda/caril de veículos ferroviários." Master's thesis, 2014. http://hdl.handle.net/10316/38948.
Full textAbstract:
Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraAtualmente, a manutenção assume um carácter de extrema importância, não só a nível económico mas também a nível da segurança. Este tema associado ao setor ferroviário elucida o objetivo da presente dissertação, inserida num projeto que em vista este tema. Assim, o desenvolvimento de uma ferramenta de previsão de desgaste no contacto roda/carril surge como o objetivo principal do estudo realizado. De salientar que o presente estudo dá seguimento a estudos já realizados no âmbito do projeto “WearWheel”. Primeiramente foi realizada uma cadeia de ensaios de atrito e desgaste com contacto rolamento/escorregamento de provetes obtidos de uma roda de um veículo ferroviário e de um carril da ferrovia. Os ensaios foram executados numa máquina de discos a fim de simular o contacto roda/carril presente num troço reto da ferrovia. Com base na análise numérica dos resultados alcançados nos ensaios rolamento/escorregamento, foi desenvolvido um modelo apto a realizar a previsão da taxa específica de desgaste, consoante as condições de funcionamento impostas. Para este modelo foram considerados três parâmetros determinantes para o desgaste – velocidade linear, pressão de contacto e percentagem de escorregamento – sobre os quais se determinaram funções de peso que pudessem traduzir a sensibilidade da variação de cada um deles na taxa específica de desgaste. Estas funções de peso corrigem o valor da taxa específica de desgaste standard, adaptando-o às condições de contacto pretendidas. Comparados os valores obtidos experimentalmente com os valores obtidos pelo modelo de previsão considerando a influência de cada função de peso referente aos três parâmetros já identificados, foi possível verificar uma boa aproximação dos resultados experimentais e teóricos, que atestam a fiabilidade do método desenvolvido.
Currently, maintenance assumes an extremely important character, not only on an economic matter, but also for safety issues. This theme, associated to the railroad sector, clears a present objective for this thesis, inserted in a project to be discussed forwardly. Having this in mind, the development of a prevision tool of wear in the contact between wheel/rail, appears as the main objective of study. It is important to remind that this project is a continuation of a past study named “WearWheel”. At a first approach, a series of trials of wear and friction were performed with the rolling-sliding contact of specimens obtained on a wheel of a train wheel and of a rail track. The tests were executed of a disk machine with the purpose of simulating the contact between wheel and rail, present on a segment of a rail track. Based on the numeric analyses of the achieved results of the specimens rollingsliding, a model was developed to create the prevision of the specific wear rate, having in consideration the function conditions imposed. For the model imposed, three parameters were considered to me determinant for the wear – linear velocity, contact pressure and slide percentage – followed by the function determination of the weight that could be traduced in variation sensibility of each one of them on the specific wear. The weight functions correct the standard wear rate, adapting them to the contact conditions pretended. After comparing the obtained values with the ones obtained by the prevision model, considering the influence of the weight function referred by the three parameters already identified, it was possible to verify a good approximation of the experimental and theoretical values that give the liability of the method developed.
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(9841550), Md Uddin. "Development of wayside rail curve lubrication model for Australian heavy haul lines." Thesis, 2016. https://figshare.com/articles/thesis/Development_of_wayside_rail_curve_lubrication_model_for_Australian_heavy_haul_lines/13387283.
Full textAbstract:
Wheel and rail wear and ineffective lubrication are serious concerns for rail operators around the globe. These assets have to be maintained and operated effectively to maximise the benefits to the stakeholders and minimise the cost to rail operators. Proper management of the wheel/rail interface helps the rail industry to grow business, improve reliability of service and commitment to their clients. Rail wear and effectiv lubrication are significant issues that have direct impact on operating costs of the rail operation. Wear causes detrimental effects on rail/wheel life and maintenance costs. Thus a better understanding of causes, mechanisms and effects of wear at the wheel/rail interface is necessary. Lubrication is considered as one of the most effective maintenance programs to reduce wear, energy consumption and noise.
Therefore, implementation of an effective lubrication program is necessary to achieve cost effective rail operation.
The wayside lubrication method is widely used in the rail industry. In the past, lubricators were installed either too close together or too far apart. The literature indicates that quite a few approaches have been attempted for developing an effective placement model for wayside lubricators. There are different types of lubricators, lubricants and a variety of
lubrication strategies across different networks, and also within the same network. A critical literature review revealed that there is a need for a more scientific approach to develop a reliable rail curve lubrication model. Keeping this fact in view, field investigations were carried out on the live track in the current study with the assistance of maintenance team of
the Australian heavy haul network operators. The first observation revealed that the grease carried by the wheels lasts only a few meters from the wayside lubricator sites in many curves. The performance of lubricants in the track can vary significantly depending on the weather conditions, track characteristics, dispensing equipment, type of lubricant being used and maintenance activities. In this field study it is clearly identified that there is a need for an improved understanding of the effect of lubricator performance, applicator bars (short and long bars) and locations of the bars based on track geometry, direction of traffic etc. Proper application of wayside lubricators also includes selection of appropriate equipment and a suitable lubricant for the known operating conditions, measurement and management of the lubrication effectiveness, positioning of lubricators and their appropriate maintenance.
Wayside lubricator spacing for maximum benefits is directly related to the lubricant carry distance. Whereas, carry distance is affected by track type, traffic, lubricant and the lubricator itself. Hence, there is a clear need to develop an improved lubricator placement model based on the combined effects of lubricants, applicator bars, lubricator, locations and track/traffic
characteristics. The scope of this study also includes the survey of the current practices of curve lubrication and assesses their effectiveness; develop a hierarchical wayside lubricator placement model based on the evaluation of effectiveness and cost/benefit analysis and set up a standard practice for lubrication of heavy haul lines. A detailed review on currently available technologies applicable for heavy haul lines was performed. This was followed by the field investigations for real data collection to confirm the performance evaluation, development of lubricator placement model, cost/benefit analysis, model development of the grease transport mechanism, and optimisation of modelled parameters. The study concluded that electric lubricators are highly reliable and effective compared to older technologies, long applicator bars in the tangent track with high quality grease generate the longest carry distances and short applicator bars in the transition curve, even with high quality grease, didn't achieve long carry distances.
The rate of grease application is very crucial from the perspective of both effectiveness and economic returns. It is also known that equipment, their limitations, performance, appropriate location, quality of installation and their maintenance, various properties of greases and column strength of the grease bead contribute significantly to the grease transport mechanism. This study suggests that to ensure the effectiveness of way side curve lubrication, remote condition monitoring could be an effective tool which can significantly improve the reliability, maintainability and operating cost of electric lubricators.
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Fergusson, Shelley Nadine. "Minimising wheel wear by optimising the primary suspension stiffness and centre plate friction of self-steering bogies." Thesis, 2010. http://hdl.handle.net/10210/3045.
Full textAbstract:
M.Ing.This report documents the steps taken to gain insight into the dynamics of a HS MkVII self-steering three piece bogie. This was done by firstly studying the dynamics and stability of linear simplifications of the bogie and wagon and then by investigating the dynamics of the bogie by means of a non-linear model.With the necessary insight into the dynamics of the bogie, an optimised relationship between the primary suspension stiffness and the centre plate friction of a self-steering three-piece bogie was achieved. The optimised model’s wear is less than half that of the reference model and has a safe operating speed of 80km/h for an empty wagon and 140 km/h for a loaded wagon. It is recommended that the following be done before issuing a final technical recommendation; • A final optimisation of the lateral and longitudinal primary suspension stiffness arrangement; taking into consideration the physical vertical load bearing capacity of the rubber suspension elements. • A study in order to quantify the effects, on wear, of the increased misaligned position of the bogie on straight track following a curve. A verification of the ADAMS/Rail simulation results by conducting specific on-track tests. • A comprehensive cost-benefit analysis.