Made available in DSpace on 2014-06-11T19:30:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-20Bitstream added on 2014-06-13T19:00:09Z : No. of bitstreams: 1 oliveira_dj_me_bauru.pdf: 2830469 bytes, checksum: 472bcc066d7e9582cfd3189fdd96d740 (MD5) / A aplicação mínima da quantidade de lubrificante (MQL) na usinagem dos metais surgiu como uma alternativa para reduzir a abundância de fluidos de corte e, com isso, atingirn produção mais limpa. Na retificação, apesar de ser considerada uma técnica inovadora no aspecto ambiental, sua aplicação é restrita devido à geração excessiva de calor e ao entupimento dos poros do rebolo causado pelos cavacos, prejudicando a qualidade final do produto e aumentando o desgaste da ferramenta. Esta pesquisa buscou aprimorar o uso do MQL usando, além do jato com a mistura ar e óleo injetado na interface rebolo-peça à alta velocidade, um jato de ar comprimidom para minimizar o empastamento do rebolo gerado durante o processo de usinagem pela mistura formada pelo óleo do MQL mais os cavacos. Foram realizados ensaios na retificação cilíndrica externa de mergulho do aço ABNT 4340, temperado e revenido com dureza média de 54 HRc, usando rebolo de nitreto de boro cúbico (CBN) com ligante vitrificado. Os métodos de lubri-refrigeração propostos foram o convencional com fluido em abundância, MQL (estes dois sem uso do jato de ar para limpeza do rebolo) e MQL com a limpeza, variando o ângulo de incidência do ar comprimido na superfície de corte do rebolo. Consideram-se as variáveis de saída do processo: rugosidade, desgaste diametral do rebolo, circularidade, além de análises metalográficas e medições de microdureza da superfície retificada para verificação de danos térmicos; de forma a analisar a viabilidade da substituição do tradicional método de aplicação dos fluidos em abundância pelo MQL com a limpeza. Os resultados mostraram a possibilidade de implementação da técnica da limpeza do rebolo como um aprimoramento tecnológico da mínima quantidade de lubrificante na retificação, reduzindo o consumo dos fluidos de corte. A técnica MQL com limpeza... / The application of minimum quantity of lubricant (MQL) on machining of metals has emerged as an alternative to reduce the abundance of cutting fluids and then achieve a cleaner production. In grinding, although considered a breakthrough technique in the environmental aspects, its application is restricted due to excessive generation of heat and griding wheel loading caused by the chips, damaging the final product quality and increasing tools wear. The objective of this research was to improve the MQL technique by using an additional jet of compressed air to clean the clogged pores of the wheel. Tests were performed in cylindrical plunge grinding of the ABNT 4340 steel, quanched and tempered (54 HRc) with a vitrified cubic boron nitrite (CBN) grinding wheel. The suggested methods of lubrication were conventional (abundant fluid), MQL (that without the use of air jet to cleaning the wheel) and MQL plus cleaning system, changing the incided angle of the jet of compressed air in the cutting surface of the grinding wheel. The performance of the proposal technique was evaluated based on an analysis of the process output variables: roughness, diametric wear of the grinding, roundness, and metallographic analysis plus microhardness measurements of the grounded surface to verify thermal damage incidence. The results showed the possibility of implementing the technique of cleaning as a technological enhancement to minimum quantity of lubricant in the grinding, reducing the use of cutting fluids. The technique MQL plus cleaning system, in a specific incident angle of the compressed air was extremely efficient, resulting in better surface finish, reduced tool wear and free of thermal damage when compared with conventional methods without cleaning of the wheel

Tese (doutorado)-Universidade Federal do Rio Grande, Programa de Pós-Graduação em Educação Ambiental, Instituto de Educação, 2011. / Submitted by eloisa silva (eloisa1_silva@yahoo.com.br) on 2012-11-29T17:26:47Z No. of bitstreams: 1 cleivaaguiardelima.pdf: 1112165 bytes, checksum: 25b924c415ad9c5f6b1305c043274e27 (MD5) / Made available in DSpace on 2012-11-29T17:26:47Z (GMT). No. of bitstreams: 1 cleivaaguiardelima.pdf: 1112165 bytes, checksum: 25b924c415ad9c5f6b1305c043274e27 (MD5) Previous issue date: 2011 / Este trabalho apresenta uma pesquisa sobre formação de formadores no âmbito do Programa Nacional de Integração da Educação Profissional com a Educação Básica, na Modalidade de Educação de Jovens e Adultos (PROEJA). A pesquisa foi desenvolvida com oito professores formadores em formação que se reuniam semanalmente no Campus Rio Grande do Instituto Federal do Rio Grande do Sul (IFRS) para planejar e executar um curso de formação continuada – Encontros Dialógicos com o PROEJA. Alguns pressupostos orientaram a pesquisa: a concepção freireana do homem e da mulher como seres inconclusos, portanto, em processo de construção e do registro como subsídio para a reflexão sobre a prática; a possibilidade de propostas de formação em Roda, a partir da qual, é possível exercitar o diálogo, a partilha, a escuta; a necessidade do professor assumir a escrita como um exercício para pensar na perspectiva de Galiazzi (2003) e Marques (2008). A Pesquisa Ação Participante foi construída no movimento da Roda dos Formadores com os professores, incluindo esta pesquisadora e envolveu uma ação e a participação dos sujeitos investigados, na perspectiva política de transformação como propõe Brandão (2003). O Diário em Roda foi, ao mesmo tempo, dispositivo de formação e de investigação. Dispositivo em movimento em que a mediação pedagógica, processo construído na Roda, orientou os rumos da escrita e dos registros. Com isso, o Diário configurou-se em três momentos: descrição da Roda, registro de como nos tornamos professores nessa Roda e elaboração de episódios com base nos encontros da Roda dos Formadores. A análise do Diário em Roda, realizada mediante a Análise Textual Discursiva proposta por Moraes e Galiazzi (2007), possibilitou a produção de significados a partir da organização das unidades de significado e da emergência de categorias. Assim, a compreensão do processo investigado ocorreu num movimento recursivo de interpretação que permitiu perceber a necessidade do Diário em Roda ser pesquisado durante a sua elaboração. Ao mesmo tempo, a pesquisa aponta para a necessidade desse dispositivo formativo ser lido e problematizado em Roda, por meio da mediação pedagógica, para ampliar a compreensão da formação docente e da constituição de educadores ambientais. A Roda dos Formadores, entendida como um espaço coletivo e colaborativo constituiu-se num espaço de formação, potencializado pela leitura, pelo diálogo e pela escrita. Esse modo de formar-se ao formar, concebido como uma re(invenção) dos Círculos de Cultura (FREIRE, 2006b), propôs um modo de formação que rompe com estruturas tradicionais de formação permanente. Ao superar modelos individualistas e solitários, pressuposto da Educação Ambiental, a Roda vivenciou uma proposta formativa que valorizou o grupo, a parceria, a partilha, com o objetivo de construir coletivamente aprendizagens, sobre ser professor e formador, registradas em um Diário. A tese defendida é que escrever num Diário em Roda potencializa processos de formação docente porque possibilita a aprender a ser Roda ao aprender a elaborar o Diário, ao aprender o que registrar, ao aprender a formar-se em Roda e assim formar a Roda. Com tudo isso se aprende sobre o significado do Diário e, repito, a ser Roda. / This text reports a study on teacher education in a Brazilian program which aims at integrating professional education and elementary education for young adults and adults (PROEJA). It was carried out with eight teachers who had weekly meetings on the campus of the Instituto Federal do Rio Grande do Sul (IFRS) in Rio Grande, RS, to plan and implement a course in continuing education called Dialogic Meetings with PROEJA. The following presuppositions have guided this study: the Freirian concept of man and woman as incomplete beings, thus, in an ongoing construction process and of records as tools for reflection on practices; the possibility of proposals for teacher education in a Wheel, which leads to dialogue, sharing and listening; and the need the teacher has to take on writing as an exercise to think according to Galiazzi’s (2003) and Marques’ (2008) perspectives. This research was characterized as a participatory action-research and constructed in the Education Wheels with the teachers and myself. It meant the participation of the subjects under investigation in the political perspective of transformation proposed by Brandão (2003). The Diary in a Wheel was a device for education and investigation, as well. Pedagogical mediation, a process that was constructed in the Wheel, guided writing. The Diary was made in three phases: the description of the Wheel, records regarding how we become teachers in this Wheel and episodes based on the meetings of the Education Wheel. The analysis of the Diary in the Wheel was carried out by applying Moraes and Galiazzi’s Textual Discursive Analysis (2007). It enabled me to produce meanings based on the organization of units of meaning and the emergence of categories. Therefore, the comprehension of the process under investigation occurred in a recursive interpretation moment which enabled me to perceive that the Diary in the Wheel needed to be investigated during its elaboration. Likewise, the research shows that this device must be read and problematized in the Wheel through pedagogical mediation in order to broaden the comprehension of teacher education and the constitution of environmental educators. The Education Wheel is a collective and collaborative space which becomes an educational space triggered by readings, dialogues and writings. This way of educating yourself while educating others, which was proposed as a (re)invention of Cultural Circles (FREIRE, 2006b), suggested a new way for teacher education that eliminates traditional structures in continuing education. By discharging individual and solitary models, a pressuposition of Environmental Education, the Wheel experienced a proposal that enhanced the group, partnership and sharing with the objective of constructing collective learning – recorded in a Diary - about being a teacher. I have defended that writing a Diary triggers teacher education processes since it enables us to learn how to be a Wheel while we learn to write a Diary, learn what to record and learn to develop in the Wheel; thus, constructing the Wheel. Therefore, we learn about the meaning of the Diary and how to become a Wheel.

The main aim of this research project is to extend theories of four-wheel-steering as developed by J. Ackermann to include an individually steered four-wheel steering system for passenger vehicles. Ackermann’s theories, including theories available in this subject area, dwell much on vehicle system dynamics developed from what is called single track model and some call it a bicycle model. In the bicycle model, the front two wheels are bundled together. Similarly, the rear wheels are bundled together. The problem with this is that it assumes two front wheels or two rear wheels to be under the same road, vehicle and operating conditions. The reality on the ground and experiments that are conducted are to the contrary. Therefore this study discusses vehicle disturbance rejection through robust decoupling of yaw and lateral motions of the passenger vehicle. A mathematical model was developed and simulated using Matlab R2008b. The model was developed in such a way that conditions can be easily changed and simulated. The model responded well to variations in road and vehicle conditions. Focus was in the ability of the vehicle to reject external disturbances. To generate yaw moment during braking, the brake on the left front wheel was disconnected. This was done because lateral wind generators, as used by Ackermann, were not available. The results from both simulations and experiments show disturbance rejection in the steady state. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Mechanical and Aeronautical Engineering / unrestricted

Diploma work describes in its theoretical part particular types of pairs of wheels used on railway vehicles in Czech Republic as well as their components and assembly instructions. Practical part describes workplace for wheels in reparation DPOV, a.s. at repairing centre Nymburk, its facilities and repairing possibilities by total repair of pairs of wheels. Practical part brings at the end particular report with results of pairs of wheels measuring.

This diploma thesis deals with construction concept of rear upright for a car of the Formula Student category. Further it looks into the details of overall order of the entire rear-wheel carrier. The concept is designed in the CAD Pro-engineer system. The calculation model is created and the tension analysis is performed by MKP method in the Ansys Workbench system.

The thesis consists of rear wheel suspension design for light Formula Student racing car, especially design of upright, wheel hub and other parts of the assembly. Design was done in CAD software PTC Creo 2.0. Thesis also mentions calculation of critical wheel loads, wheel bearing life calculation and wheel loads during the race as well as stress analysis in Ansys Workbench and fatigue life analysis.

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.

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

No description available.

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 / Rail vehicles are supported, steered, accelerated, and decelerated by contact forces acting in extremely small wheel-rail contact areas. The behavior of these forces is quite complex and a broad interdisciplinary research is needed to understand and optimize the contact mechanics and dynamics problem. Key industry issues, such as control of Rolling Contact Fatigue (RCF), maximizing wheelset mileages, and minimizing the impact of rolling stock on the infrastructure, are directly related to the interaction at the wheel-rail contact. 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. 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). Experimental studies are conducted on the VT – FRA Roller Rig that involved varying the angle of attack, the wheel and rail surface lubricity condition (i.e., wet vs. dry rail), and the wheel wear to study their effects 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.