<div><p>Water is inflammable, non-toxic, environmentally friendly--- desirable traits, for a hydraulic fluid. However, its extremely low viscosity diminishes the load-bearing and sealing capacity of lubricating interfaces. Case in point: axial piston machines of swash plate design are compact, highly efficient positive displacement machines at the heart of hydraulic systems in forestry, construction, aerospace, and agricultural equipment, as well as industrial applications (presses, etc.); however, the three main lubricating interfaces decisive to the performance of such units in terms of both component life and efficiency are challenged by the use of water as working fluid. Especially during high-pressure operation, this low-viscosity lubricant can cause the these interfaces to fail in carrying the imposed load, resulting in severe wear, or even pump failure. The piston-cylinder interface is particularly challenging to design for water because it stands under obligation to carry the heavy side load that acts on the pistons of these machines, which increases with operating pressure. Furthermore, the architecture of axial piston machines of swash plate design does not allow this interface to be hydrostatically balanced.</p> <p> </p> <p>Through the development of a methodology that separates the fluid pressure fields of the three main lubricating interfaces of axial piston machines into their hydrostatic and hydrodynamic components, the present work enables a direct comparison of these interfaces in terms of how they support load. A case study of a 75 cc unit running on hydraulic oil conducted via this methodology at three different operating conditions (low pressure/low speed, low pressure/high speed, and high pressure/low speed) demonstrates that in the piston-cylinder interface, the force from hydrostatic pressure reaches such high magnitudes over the high-pressure stroke that less than half of it is needed to counter the load. The excess force from hydrostatic pressure then becomes the load. Consequentially, hydrodynamic pressure must counter a force from hydrostatic pressure that exceeds the original load. In the other two interfaces, by contrast, over half the load is being carried by hydrostatic pressure, thus significantly diminishing the amount of hydrodynamic pressure the interfaces are required to generate in order to achieve full load support. Moreover, nearly all of the moment on the piston is countered by hydrodynamic pressure, while less than half of the moment on the block is countered by hydrodynamic pressure, and the moment on the slipper is negligible by comparison.</p> <p> </p> <p>While this case study only investigates one pump, it shows how critical hydrodynamic pressure can be to load support in the piston-cylinder interface. The use of a low-viscosity fluid, e.g. water, reduces the hydrodynamic pressure that is generated in this interface, which, at challenging operating conditions, can lead to metal-to-metal contact. However, the performance of the interface can be improved via micro surface shaping, i.e. by giving the surface of the piston, or the bore that it moves through, a shape on the order of microns in height. The aim of present work is to pursue design trends leading to surface shapes that will enable this interface to function at higher pressures than currently achievable. </p> <p> </p> <p>This pursuit takes the form of systematic virtual design studies, an optimization procedure, and an algorithm developed specifically for tailoring the bore surfaces through which the pistons travel to piston tilt and deformation. From this emerges not only a set of design trends corresponding to the dimensions of two particularly powerful types of micro surface shaping, but also a profound insight into the behavior of the water-lubricated piston-cylinder interface fluid film, and how that behavior can be manipulated by changing the component surfaces that constitute its borders. Furthermore, in collaboration with Danfoss High Pressure Pumps, a physical prototype of a 444 cc axial piston pump with surface shaping generated via the aforementioned algorithm has been constructed and tested, achieving a total pump efficiency roughly 3% higher than that achievable by the commercial unit that the geometry of the prototype is based on.</p><br></div>

Master of Science

It is desirable to build a single one-cylinder testing engine capable of manipulation so that it can test lubricating oils for wear, corrosion and tendency to oxidation and detergency, and give reproducible results. The purpose of this investigation is three-fold: (1) To install the control accessories required for control of the engine test conditions, and assemble the one cylinder, two-stroke cycle engine as a unit to be used in conducting the tests, (2) To determine the breakdown characteristics of a solvent refined, asphalt base oil at varying conditions of temperature and load in the test engine, and (3) to correlate the breakdown characteristics of the oil with the performance of the test engine so as to rate the engine as a possible test unit for evaluation of lubricating oils. / Master of Science

Pumping is the most efficient transportation and placing method for concrete. Despite the immense progress in the field of concrete technology in the last years, so far there are still neither official regulations nor verified theoretical foundations to be used for the assessment and accurate prediction pumping behaviour of ordinary and high performance concretes. This thesis aims at purposefully investigating pumping of modern concretes and bridging the existing knowledge gap. The main achievement of the present research is the development and verification of a sitecompliant and scientifically based methodology for characterisation and prediction of fresh concrete pumping behaviour. The research focus is set on the importance of the forming lubricating layer (LL) during pumping. Within an extended experimental program, the properties of the LL are captured and quantified. They determine the reduction of friction at the pipe wallconcrete interface and thereby govern the concrete flow. It is proven that the composition and the rheological properties of the forming LL exert an enormous impact on pumping since most of the induced shear stress by pumping pressure is concentrated in this layer. In a further step, the flow pattern of concrete is analytically and numerically determined. The concrete exhibits various principal flow types which are already defined at low flow rates: plug flow in case of strainhardening cementbased composite (SHCC), partial concrete bulk shear in ordinary concretes and pronounced bulk shear for selfcompacting concrete (SCC). The results from the fullscale pumping campaign are confronted with the existing pressure performance nomogram on the determination of pumping parameters. The nomogram’s prediction capacity is extended and verified for highly flowable concretes by replacing the slump and flow table results with the viscosity parameter of the LL. Furthermore, the challenges during pumping of concrete, inter alia, priming of the pipeline, blockage formation and final cleaning, are exemplified, and recommendations for the practitioners are provided. Finally, the transfer of the developed scientifically based and ready to use methodology on site is strongly advocated as a part of the future in situ rheology monitoring concept towards envisaged full automation of concrete production and casting processes.:ZUSAMMENFASSUNG V ABSTRACT VII VORWORT DES HERAUSGEBERS IX DANKSAGUNG XI SYMBOLS XVII INTRODUCTION 1 1.1 FLASHLIGHTS ON HISTORY 1 1.2 MOTIVATION 1 1.3 RESEARCH FIELD 3 1.4 RESEARCH CONCEPT 6 1.5 ECONOMIC RELEVANCE 8 1.6 STRUCTURE AND BOUNDARIES OF THE THESIS 10 STATE OF THE ART 13 2.1 GENERAL 13 2.2 CONCRETE FLOW IN PIPELINE 13 2.3 INFLUENCE OF CONCRETE RHEOLOGY ON PUMPING BEHAVIOUR 16 2.3.1 CEMENT HYDRATION 16 2.3.2 MIXTURE COMPOSITION 17 2.3.2.1 WATER-TO-BINDER RATIO AND PASTE VOLUME 18 2.3.2.2 AGGREGATES 20 2.3.2.3 ADMIXTURES AS PUMPING AIDS 22 2.3.3 HYDRODYNAMIC INTERACTIONS 25 2.3.4 SHEAR HISTORY 27 2.3.5 TEMPERATURE 28 2.4 FORMATION OF LUBRICATING LAYER 30 2.4.1 FLOW-INDUCED PARTICLE MIGRATION 30 2.4.2 PROPERTIES 31 2.4.3 EXPERIMENTAL CHARACTERISATION 32 2.5 BOUNDARY CONDITIONS 32 2.6 PUMPING EQUIPMENT 34 2.7 PRIMING 35 3 APPLIED METHODS 37 3.1 GENERAL 37 3.2 RHEOMETRY 37 3.3 DIRECT DETERMINATION OF PUMPING PRESSURE 40 3.4 SAMPLING AND PRODUCTION OF LUBRICATING MATERIAL 42 3.5 MEASUREMENT OF FILTRATE AMOUNT 45 3.6 ANALYTICAL DETERMINATION OF LUBRICATING LAYER THICKNESS 47 3.7 SMALL-SCALE PUMPING 49 3.8 FULL-SCALE PUMPING 50 3.9 NUMERICAL METHOD 56 3.9.1 MATERIAL MODEL 56 3.9.2 NUMERICAL IMPLEMENTATION 58 4 CHARACTERISATION OF CONCRETE PUMPABILITY 63 4.1 GENERAL 63 4.2 MIXTURE DESIGN PARAMETERS 63 4.3 COMPARISON BETWEEN REFERENCE AND DESIGN MORTARS 65 4.4 RESULTS AND DISCUSSION 65 4.4.1 RHEOLOGICAL BEHAVIOUR OF CONCRETES AND DESIGN MORTARS 65 4.4.2 INFLUENCE OF WALL ROUGHNESS ON RHEOLOGICAL PARAMETERS 67 4.4.3 PREDICTION OF PUMPING PRESSURE 72 4.5 SUMMARY 74 5 LUBRICATING LAYER THICKNESS AND CONCRETE FLOW 75 5.1 GENERAL 75 5.2 MIXTURE DESIGN PARAMETERS 75 5.3 RESULTS AND DISCUSSION 76 5.3.1 CONCRETE FLOW TYPE 76 5.3.2 PREDICTION AND VERIFICATION OF PUMPING PRESSURE 77 5.3.3 QUANTIFICATION OF LUBRICATING LAYER THICKNESS 79 5.4 SUMMARY 82 6 FULL-SCALE PUMPING EXPERIMENTS 83 6.1 GENERAL 83 6.2 MIXTURES AND DESIGN PARAMETERS 83 6.3 RESULTS AND DISCUSSION 85 6.3.1 PRESSURE LOSS AND PRESSURE-FLOW RATE CURVES 85 6.3.2 NUMERICAL SIMULATION RESULTS 86 6.3.3 PRESSURE PREDICTION USING MODIFIED NOMOGRAM 88 6.3.4 COMPARISON BETWEEN PREDICTED AND ACTUAL PRESSURE-FLOW RATE CURVES 90 6.4 SUMMARY 92 7 EFFECT OF PUMPING ON FRESH PROPERTIES OF CONCRETE AND FILTRATE FORMATION 95 7.1 GENERAL 95 7.2 MIXTURES DESIGN PARAMETERS 95 7.3 INFLUENCE OF PUMPING ON PROPERTIES OF FRESH CONCRETE 97 7.4 INFLUENCE OF CONCRETE PROPERTIES ON KINETICS OF FILTRATE FORMATION 98 7.5 IMPACT OF FILTRATE AMOUNT ON PUMPABILITY 101 7.6 SUMMARY 104 8 CHALLENGES RELATED TO PUMPING OF CONCRETE 105 8.1 GENERAL 105 8.2 PRIMING GROUT 105 8.3 PIPELINE GEOMETRY 108 8.4 BLOCKAGES 113 8.5 FILLING DEGREE OF PUMP PISTONS 116 8.6 TEMPERATURE CONTROL 117 8.7 VERTICAL PUMPING 118 8.8 CLEANING THE PIPELINE 119 8.9 SUMMARY 120 9 FINAL CONCLUSIONS AND OUTLOOK 121 9.1 GENERAL 121 9.2 CONCRETE FLOW TYPE 121 9.3 LUBRICATING LAYER PROPERTIES 121 9.4 RHEOLOGICAL DEVICES 122 9.5 FILTRATE FORMATION 122 9.6 NUMERICAL SIMULATIONS 122 9.7 MODIFIED NOMOGRAM 123 9.8 RELEVANCE OF PUMPING EXPERIMENTS 123 9.9 INFLUENCE OF PUMPING ON FRESH CONCRETE PROPERTIES 124 9.10 GENERATED DATABASE 124 9.11 IMPROVING NUMERICAL MODEL 124 9.12 TODAY AND TOMORROW 124 BIBLIOGRAPHY 127 APPENDIX A 135 A.1 MATERIALS DESCRIPTION, CHAPTERS 4 AND 5 135 A.2 MATERIALS DESCRIPTION, CHAPTERS 6, 7 AND 8 136 APPENDIX B 137 APPENDIX C 141 LIST OF SELECTED PUBLICATIONS 143 JOURNALS 143 CONFERENCE PAPERS 143 CURRICULUM VITAE 145 / Das Pumpen stellt die effektivste Methode für das Fördern und Einbringen von Frischbeton auf der Baustelle dar. Trotz der in den letzten Jahren erreichten deutlichen Fortschritte auf betontechnologischem Gebiet existieren für die Beurteilung der Pumpbarkeit von Beton bisher weder offiziell gültige Vorschriften noch abgesicherte theoretische Grundlagen, die eine zielsichere Vorhersage des Pumpverhaltens von Normal- als auch Hochleistungsbetonen ermöglichen. Die vorliegende Arbeit schließt entsprechende Wissenslücken und befasst sich gezielt mit dem Pumpen moderner Betone. Grundlegenden Erkenntnisgewinn stellt die Entwicklung einer wissenschaftlich fundierten, baustellengerechten Prüfmethodik zur Charakterisierung und Vorhersage des Pumpverhaltens von Frischbeton dar. Der Untersuchungsfokus richtet sich auf die Wirkung der sich beim Pumpvorgang ausbildenden Gleitschicht. Ein umfangreiches Untersuchungsprogramm gestattet die Erfassung und Quantifizierung der Eigenschaften dieser Schicht. Sie bestimmen infolge deutlicher Reduzierung der Reibung an der Grenzfläche zwischen Rohrwandung und Beton die Betonströmung entscheidend. Bewiesen wird, dass Betonzusammensetzung und rheologische Eigenschaften der Gleitschicht maßgebende Auswirkungen auf den Pumpvorgang haben, da sich die pumpdruckinduzierte Scherspannung in dieser Schicht konzentriert. Weiterhin erfolgt sowohl eine analytische als auch numerische Charakterisierung der Betonströmung im Rohr. Nachgewiesen wird, dass sich beim Pumpvorgang betonspezifisch unterschiedliche Strömungsarten einstellen, die bereits bei niedrigen Durchflussmengen definiert sind: Pfropfenströmung in hochduktilen Betonen, partielle Scherung des Kernbetons in Normalbetonen und signifikante Scherung in selbstverdichtenden Betonen. Aus großtechnisch durchgeführten Pumpversuchen gewonnene Ergebnisse werden dem derzeit vorhandenen, verbesserungsbedürftigen Betondruck-Leistungs-Nomogramm zur Einstellung von Parametern an der Betonpumpe gegenübergestellt. Die Vorhersagekapazität des Nomogramms kann durch den Ersatz der Ausbreit- bzw. Setzfließmaßangaben mit Viskositätsangaben der Gleitschicht erweitert und verifiziert werden. Des Weiteren werden baustellenbezogene Herausforderungen im Gesamtprozess des Betonpumpvorgangs, u. a. Vorbereitung der Rohrleitung vor dem Pumpen, Auftreten von Stopfern und Endreinigung exemplarisch dargestellt sowie Empfehlungen für die Praktiker erarbeitet. Schließlich wird der Transfer der in dieser Arbeit entwickelten wissenschaftlich basierten und anwendungsbereiten Methodik als Teil des zukünftigen Konzeptes für die in-situ Rheologie-Überwachung hinsichtlich einer angestrebten vollständigen Automatisierung von Fertigungs- und Einbringprozessen von Beton mit Nachdruck empfohlen.:ZUSAMMENFASSUNG V ABSTRACT VII VORWORT DES HERAUSGEBERS IX DANKSAGUNG XI SYMBOLS XVII INTRODUCTION 1 1.1 FLASHLIGHTS ON HISTORY 1 1.2 MOTIVATION 1 1.3 RESEARCH FIELD 3 1.4 RESEARCH CONCEPT 6 1.5 ECONOMIC RELEVANCE 8 1.6 STRUCTURE AND BOUNDARIES OF THE THESIS 10 STATE OF THE ART 13 2.1 GENERAL 13 2.2 CONCRETE FLOW IN PIPELINE 13 2.3 INFLUENCE OF CONCRETE RHEOLOGY ON PUMPING BEHAVIOUR 16 2.3.1 CEMENT HYDRATION 16 2.3.2 MIXTURE COMPOSITION 17 2.3.2.1 WATER-TO-BINDER RATIO AND PASTE VOLUME 18 2.3.2.2 AGGREGATES 20 2.3.2.3 ADMIXTURES AS PUMPING AIDS 22 2.3.3 HYDRODYNAMIC INTERACTIONS 25 2.3.4 SHEAR HISTORY 27 2.3.5 TEMPERATURE 28 2.4 FORMATION OF LUBRICATING LAYER 30 2.4.1 FLOW-INDUCED PARTICLE MIGRATION 30 2.4.2 PROPERTIES 31 2.4.3 EXPERIMENTAL CHARACTERISATION 32 2.5 BOUNDARY CONDITIONS 32 2.6 PUMPING EQUIPMENT 34 2.7 PRIMING 35 3 APPLIED METHODS 37 3.1 GENERAL 37 3.2 RHEOMETRY 37 3.3 DIRECT DETERMINATION OF PUMPING PRESSURE 40 3.4 SAMPLING AND PRODUCTION OF LUBRICATING MATERIAL 42 3.5 MEASUREMENT OF FILTRATE AMOUNT 45 3.6 ANALYTICAL DETERMINATION OF LUBRICATING LAYER THICKNESS 47 3.7 SMALL-SCALE PUMPING 49 3.8 FULL-SCALE PUMPING 50 3.9 NUMERICAL METHOD 56 3.9.1 MATERIAL MODEL 56 3.9.2 NUMERICAL IMPLEMENTATION 58 4 CHARACTERISATION OF CONCRETE PUMPABILITY 63 4.1 GENERAL 63 4.2 MIXTURE DESIGN PARAMETERS 63 4.3 COMPARISON BETWEEN REFERENCE AND DESIGN MORTARS 65 4.4 RESULTS AND DISCUSSION 65 4.4.1 RHEOLOGICAL BEHAVIOUR OF CONCRETES AND DESIGN MORTARS 65 4.4.2 INFLUENCE OF WALL ROUGHNESS ON RHEOLOGICAL PARAMETERS 67 4.4.3 PREDICTION OF PUMPING PRESSURE 72 4.5 SUMMARY 74 5 LUBRICATING LAYER THICKNESS AND CONCRETE FLOW 75 5.1 GENERAL 75 5.2 MIXTURE DESIGN PARAMETERS 75 5.3 RESULTS AND DISCUSSION 76 5.3.1 CONCRETE FLOW TYPE 76 5.3.2 PREDICTION AND VERIFICATION OF PUMPING PRESSURE 77 5.3.3 QUANTIFICATION OF LUBRICATING LAYER THICKNESS 79 5.4 SUMMARY 82 6 FULL-SCALE PUMPING EXPERIMENTS 83 6.1 GENERAL 83 6.2 MIXTURES AND DESIGN PARAMETERS 83 6.3 RESULTS AND DISCUSSION 85 6.3.1 PRESSURE LOSS AND PRESSURE-FLOW RATE CURVES 85 6.3.2 NUMERICAL SIMULATION RESULTS 86 6.3.3 PRESSURE PREDICTION USING MODIFIED NOMOGRAM 88 6.3.4 COMPARISON BETWEEN PREDICTED AND ACTUAL PRESSURE-FLOW RATE CURVES 90 6.4 SUMMARY 92 7 EFFECT OF PUMPING ON FRESH PROPERTIES OF CONCRETE AND FILTRATE FORMATION 95 7.1 GENERAL 95 7.2 MIXTURES DESIGN PARAMETERS 95 7.3 INFLUENCE OF PUMPING ON PROPERTIES OF FRESH CONCRETE 97 7.4 INFLUENCE OF CONCRETE PROPERTIES ON KINETICS OF FILTRATE FORMATION 98 7.5 IMPACT OF FILTRATE AMOUNT ON PUMPABILITY 101 7.6 SUMMARY 104 8 CHALLENGES RELATED TO PUMPING OF CONCRETE 105 8.1 GENERAL 105 8.2 PRIMING GROUT 105 8.3 PIPELINE GEOMETRY 108 8.4 BLOCKAGES 113 8.5 FILLING DEGREE OF PUMP PISTONS 116 8.6 TEMPERATURE CONTROL 117 8.7 VERTICAL PUMPING 118 8.8 CLEANING THE PIPELINE 119 8.9 SUMMARY 120 9 FINAL CONCLUSIONS AND OUTLOOK 121 9.1 GENERAL 121 9.2 CONCRETE FLOW TYPE 121 9.3 LUBRICATING LAYER PROPERTIES 121 9.4 RHEOLOGICAL DEVICES 122 9.5 FILTRATE FORMATION 122 9.6 NUMERICAL SIMULATIONS 122 9.7 MODIFIED NOMOGRAM 123 9.8 RELEVANCE OF PUMPING EXPERIMENTS 123 9.9 INFLUENCE OF PUMPING ON FRESH CONCRETE PROPERTIES 124 9.10 GENERATED DATABASE 124 9.11 IMPROVING NUMERICAL MODEL 124 9.12 TODAY AND TOMORROW 124 BIBLIOGRAPHY 127 APPENDIX A 135 A.1 MATERIALS DESCRIPTION, CHAPTERS 4 AND 5 135 A.2 MATERIALS DESCRIPTION, CHAPTERS 6, 7 AND 8 136 APPENDIX B 137 APPENDIX C 141 LIST OF SELECTED PUBLICATIONS 143 JOURNALS 143 CONFERENCE PAPERS 143 CURRICULUM VITAE 145

Dentro da seqüência natural de testes para validar o uso do biodiesel (éster etílico) misturado ao óleo diesel em maiores proporções no Brasil, este trabalho teve o objetivo de estudar os efeitos do uso de uma mistura combustível B10 (com concentração de 10% em volume de biodiesel diluído em óleo diesel) na degradação do óleo lubrificante de um motor de ignição por compressão, aspirado, de 1,9 L e de injeção indireta. Acoplado a um dinamômetro, o motor foi submetido à condição de velocidade constante de 2.500 rpm, sob carga variável, e abastecido com três combustíveis diferentes: óleo diesel puro, B10 de biodiesel de soja e B10 de biodiesel de soja e nabo forrageiro. Cada combustível alimentou o motor durante 30 horas. Para determinar a degradação resultante, selecionaram-se as propriedades do óleo lubrificante usado em cada etapa para serem analisadas (viscosidade, contaminação por água e presença de elementos). Os resultados revelaram que o uso de 10% volume dos dois tipos de biodiesel na mistura combustível não causou variação significante na concentração de elementos e nas propriedades físico-químicas do óleo lubrificante. / Adding to an ongoing sequence of tests aimed at validating the use of biodiesel (ethyl ester) mixed with diesel in higher proportions in Brazil, this study was conducted to investigate the effects of utilizing a B10 fuel mixture (10% volume biodiesel diluted in diesel) on the degradation of lubricating oil in an aspirated, indirect-injection, 1.9 L compression-ignition engine. Coupled to a dynamometer, the engine was operated at a constant speed of 2,500 rpm under variable load and run with three types of fuel: pure diesel, B10 soy biodiesel, and B10 soy and fodder turnip biodiesel. Each type of fuel fed the engine for 30 hours. To determine the resulting degradation, selected properties of the lubricating oil used in each run were analyzed (viscosity, contamination by water and presence of elements). The results revealed that the use of a 10% volume of either type of biodiesel in the fuel mixture did not lead to significant variation in the concentration of elements or in the physico-chemical properties of the lubricating oil.

Dentro da seqüência natural de testes para validar o uso do biodiesel (éster etílico) misturado ao óleo diesel em maiores proporções no Brasil, este trabalho teve o objetivo de estudar os efeitos do uso de uma mistura combustível B10 (com concentração de 10% em volume de biodiesel diluído em óleo diesel) na degradação do óleo lubrificante de um motor de ignição por compressão, aspirado, de 1,9 L e de injeção indireta. Acoplado a um dinamômetro, o motor foi submetido à condição de velocidade constante de 2.500 rpm, sob carga variável, e abastecido com três combustíveis diferentes: óleo diesel puro, B10 de biodiesel de soja e B10 de biodiesel de soja e nabo forrageiro. Cada combustível alimentou o motor durante 30 horas. Para determinar a degradação resultante, selecionaram-se as propriedades do óleo lubrificante usado em cada etapa para serem analisadas (viscosidade, contaminação por água e presença de elementos). Os resultados revelaram que o uso de 10% volume dos dois tipos de biodiesel na mistura combustível não causou variação significante na concentração de elementos e nas propriedades físico-químicas do óleo lubrificante. / Adding to an ongoing sequence of tests aimed at validating the use of biodiesel (ethyl ester) mixed with diesel in higher proportions in Brazil, this study was conducted to investigate the effects of utilizing a B10 fuel mixture (10% volume biodiesel diluted in diesel) on the degradation of lubricating oil in an aspirated, indirect-injection, 1.9 L compression-ignition engine. Coupled to a dynamometer, the engine was operated at a constant speed of 2,500 rpm under variable load and run with three types of fuel: pure diesel, B10 soy biodiesel, and B10 soy and fodder turnip biodiesel. Each type of fuel fed the engine for 30 hours. To determine the resulting degradation, selected properties of the lubricating oil used in each run were analyzed (viscosity, contamination by water and presence of elements). The results revealed that the use of a 10% volume of either type of biodiesel in the fuel mixture did not lead to significant variation in the concentration of elements or in the physico-chemical properties of the lubricating oil.

No description available.

[pt] O objetivo dessa dissertação é propor protocolos estatísticos alternativos ao atual praticado pela American Society for Testing and Materials (ASTM) para a determinação do desempenho dos laboratórios participantes de Ensaios de Proficiência (EP) utilizando estatística robusta. A participação em EP é um requisito compulsório à conformidade nas certificações e acreditações para laboratórios de ensaio e calibração. O Programa de EP da ASTM considera o valor de consenso para prover os escores dos participantes. O modelo para estimar os escores, ZASTM, se baseia na média amostral (valor designado, VD) e no desvio padrão amostral (desvio padrão para a proficiência, DPP). Neste cenário, há necessidade de tratamento exaustivo dos dados, motivação para este estudo, incluindo o tratamento de outliers e a investigação de existência de distribuição normal (Gaussiana). Neste estudo, os protocolos propostos (nIQR e MADe) consideram o emprego de estatísticas robustas, mais resistentes à presença de outliers, os quais ocasionam desvios da normalidade desejada. Os resultados da comparação do protocolo ASTM com os protocolos propostos, em dados da matriz de óleos lubrificantes, reportados ao provedor ASTM, revelam haver diferença entre as médias ou entre as variâncias dos escores produzidos pelos diferentes protocolos ao nível de 5 porcento de significância, ocasionando mudança na classificação do desempenho dos laboratórios. Conclui-se que os protocolos estatísticos alternativos propostos apresentaram a vantagem de dispensar o tratamento de outliers e a investigação da distribuição dos dados, sendo que o protocolo MADe ainda apresentou redução na incerteza de medição associada ao valor designado por consenso. / [en] The objective of this dissertation is to propose statistical protocols that are alternative to the current one applied by the American Society for Testing and Materials (ASTM) to determine the performance of participants laboratories of Proficiency Testing (PT) by using robust statistics. Participation in PT is a mandatory requirement for compliance in certifications and accreditations for testing and calibration laboratories. The ASTM EP Program employs the consensus value to provide the participants scores. The method for estimating the scores, ZASTM, is based on the sample data mean (assigned value, AV) and the sample data standard deviation (standard deviation for proficiency assesment, SDPA). In this case, it is necessary an exhaustive treating of the data, motivation for this study, including the treatment of outliers and the investigation of existence of normal distribution (Gaussian). In this study, the proposed protocols (nIQR and MADe) consider the application of robust statistics, which are more resistant to the presence of outliers, which cause deviations from the desired normality. The results of the ASTM protocol comparison with the proposed protocols in the lubricant oil matrix data reported to the ASTM provider show a difference between the means or between the variances of the scores produced by the different protocols at the 5 per cent level of significance, causing variation in the classification of laboratory performance. It is concluded that the proposed alternative statistical protocols had the advantage of dispensing the outliers treatment and the investigation of the data distribution, and the MADe protocol still showed reduction in the measurement

Silver is a precious metal that has traditionally been used for jewellery and money. It also possesses desirable properties such as being corrosion resistant and having good electrical conductivity, resulting in its use for industrial applications. Furthermore, it is also recognised for its tribological properties in non-cost prohibitive applications. Silver can be used as a surface coating and can be deposited using an electroplating process. The utilisation of silver as a surface coating is advantageous and sustainable, as the substrate material properties are enhanced while usage of silver is kept to a minimum. On the other hand, electroplating has been used for over a century. It is a process which is able to produce a layer of uniform and dense coating that adheres well to the substrate metal, thus modifying the properties of the substrate. It benefits from being relatively low cost and is scalable. Silver is electroplated onto stainless steel threaded compression fittings to prevent galling. Traditional silver electroplating, which contains the use of cyanide as a complexing agent in the electroplating bath, is still in use within industry, even to this day. Cyanide, in its various forms can be poisonous, toxic and even lethal, which presents a risk during the silver electroplating process. Furthermore, the toxic wastes created during the cyanide silver electroplating process are detrimental to the environment. The aim of this work is to develop a self-lubricating non-cyanide silver PTFE composite coating suitable for use in threaded compression fittings of the ferruled type. The composite can be considered self-lubricating when a concentration of 8% or more by volume of the self-lubricating PTFE substance is incorporated. My original contribution to knowledge is firstly the successful development and characterisation of a self-lubricating non-cynanide Ag-PTFE coating on stainless steel without a strike resulting in improved CoF of 0.06 from the CoF of 0.6 based on an unlubricated surface. Secondly is the application of a non-cyanide Ag-PTFE MMC for threaded compression fittings. Thirdly is the characterisation of the make-up process of threaded compression fittings through the proposed use of the torque-angle slope in assessing coating performance for threaded compression fittings during make-up. Conclusions that can be drawn for the work are that the performance non-cyanide Ag-PTFE coating exceeded the performance of the pure Ag coating made using the same non-cyanide process. Moreover, the performance of the Ag-PTFE coating shows promising results when compared to the performance of the commercial silver cyanide coating. As a viable replacement to the current silver cyanide process, the self-lubricating non-cyanide Ag-PTFE coating, will improve the working conditions and have a positive contribution to the environment. Moreover, a thinner coating with has the potential to reduce raw material usage and electroplating waste disposal costs.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-11-13Bitstream added on 2014-06-13T19:55:36Z : No. of bitstreams: 1 lago_df_me_ilha.pdf: 2600686 bytes, checksum: 82a754d34e90e3dd82ddaab84ab68958 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Todo sistema ou equipamento mecânico está sujeito a processos de deterioração. Esta deterioração leva ao aparecimento de defeitos que podem atrapalhar a continuidade e qualidade do serviço (produção). Uma quebra não prevista traduz-se por uma parada brusca, levando geralmente a grandes prejuízos e a perda de tempo de produção. Para evitar paradas inesperadas eficientemente e reduzir os custo de manutenção são utilizadas técnicas de manutenção preditiva. Entre todas as técnicas existentes, as mais importantes na manutenção de redutores são a análise de vibrações e a análise de partículas de desgaste. A determinação da severidade, modos e tipos de desgaste em máquinas pode ser feita pela identificação da morfologia, acabamento superficial, coloração, natureza, quantidade e tamanho das partículas encontradas em amostras de óleo ou graxas. Pela análise do sinal vibratório é possível tomar decisões de intervir ou não na operação da máquina, aumentando a disponibilidade e confiabilidade da mesma. A integração destas técnicas tem o potencial para revolucionar práticas industriais e proporcionar para as companhias um significante alívio econômico. Para estudo destas duas técnicas, neste trabalho foi construída uma bancada experimental com o propósito de se realizar a manutenção preditiva em um redutor de velocidades. O Sistema foi posto para funcionar até o limite de utilização. Foram utilizados lubrificantes recomendados pelo fabricante do redutor, lubrificantes com contaminação líquida em várias porcentagens e lubrificantes com contaminação sólida em duas porcentagens. Foram observadas que para baixas rotações a análise de partículas foi vantajosa em relação à análise de vibrações e que a contaminação por água, embora tenha ocasionado uma maior oxidação do sistema, proporcionou menor desgaste do que o lubrificante sem contaminação. / Every system or mechanical equipment is subject to deterioration processes. This deterioration takes to the apparition of defects that can disturb the continuity and quality of the service (production). One break not foreseen translates for an abrupt stop, usually taking to great damages and waste of time of production. For avoid unexpected stops efficiently and reduce the cost, predictive maintenance techniques are used. Among all the existent techniques, the most important in the maintenance of reducers are vibration analysis and wear particle analysis. The determination of the severity, wear modes and types in machines can be done through the identification of the morphology, surface finishing, coloration, nature, quantity and size of the particles found in oil samples or lubricating greases. Vibration Analysis is one of the oldest techniques in the maintenance. By vibration sign analysis it is possible to make decisions of intervening or not in the machine operation, improving its availability and reliability. The integration of these techniques has the potential to revolutionize industry practices and provide a significant industrial economic relief. For the study of these two techniques, in this work, an experimental bench was built with the purpose of doing the predictive maintenance in a reducer. The System was put to work until the limit. It was observed that for low rotations the wear particle analysis were advantageous in relation to the vibration analysis and for oil with water contamination, although causing a larger oxidation in the system, a smaller wear than the lubricant without contamination was provided.