In sliding bearing wear is a very common problem and can be affected by several factors. The wear in a bearing can lead to total failure of the component and lower the lifetime. In a sliding bearing used in a machine in the pulp and paper industry large wear has been detected, but no clear evidence of what the wear depends on. The environment in the machine is strong alkaline (pH 14), a solution of white liquor and lime mud. The penetration of this solution into the bearing might lead to increased wear. A wear study and test were done to see if a better material choice could reduce the wear. In this project an investigation of the wear for seven different bearing materials was done. Two cobalt-based alloy Stellite 6 and Stellite 12, two different precipitation hardened martensitic stainless steel with different number of alloying elements, 17-4PH and Endotec 04. The different metals were welded on the pin with a minimum of 3mm. The other material was three different PEEK polymer composites. PEEK HPV reinforced with carbon fiber, PTFE and graphite. PEEK CA30 with carbon fibers and PEEK GF30 with glass fiber. The method used for the wear test was grinding machine that was reconstructed to a pin-on-disc tribology test. The tests were executed in room temperature with sliding speed of 150rpm and duration of 20 minutes. The metals were tested with the solution of white liquor mixed with lime mud, at two different loading conditions of 300N and 550N. The polymer composites were tested at the load of 300N but with different solution present, white liquor mixed with lime mud and with water. All the pins were sliding against a disc of austenitic stainless steel. Equipment used to investigate the wear mechanisms was a scanning electron microscope. The wear rate was measured by weighing of the pin before and after each test. How the material was affecting the roughness of the austenitic steel countersurface was done with the profilometer. The results of this work showed that both Stellite 6 and Stellite 12 was almost wear resistance in the condition similar to the bearing. Endotec 04 also showed low wear and 17-4PH had the highest of the metals. The dominant wear mechanism seemed to be different severity of adhesive wear. The polymer composite showed all higher wear than the metals, the reason to the high wear rate was harder to decide. It might be a combination between adhesive wear, pulverization of fibers, adsorption of calcium carbonate and matrix/fiber interfacial removal. The alkaline liquid was also believed to increase the wear of the polymer and adhere to some of the metals. The metals seemed to increase the roughness of the countersurface, but the polymers seemed to have more of a polishing effect.

Motivation "Am stetig steigenden Anteil der erneuerbaren Energien, der auf der einen Seite durch die ehrgeizigen Ziele der Politik forciert und auf der anderen Seite durch wirtschaftliche Interessen beflügelt wird, stellt die Windenergie den größten und aussichtsreichsten Bestandteil dar (BMU 2012). Setzt sich der gegenwärtige Trend fort, so ist in den nächsten Jahren mit Multimegawattanlagen im mehrstelligen Megawattbereich zu rechnen."

Hlavní náplní této dizertační práce je výzkum a vývoj nové povrchové vrstvy pro kluzná ložiska na bázi pevných lubrikantů v polyamid-imidové polymerní matrici se zlepšenými tribologckými vlastnostmi. Podklady pro materiálovou kompozici vzešly z expertízy komerčně dostupného povlaku, respektive jeho povrchovou analýzou v mezných operačních podmínkách. Charakterizace mazného oleje před a po tribotestování společně s detailní povrchovou analýzou dala podmínky pro vznik materiálové formulace. Další část práce se zabývá studiem přípravy a vývojem aplikačního nanášení s přípravou polymerní směsi. Nakonec je popsána studie vlivu sulfidu molybdeničitého a grafitu, jakožto pevných lubrikantů pro zlepšení třecích vlastností a hydroxidu vápenatého pro potenciální zpepšení otěruvzdornosti výsledného povrchu pro palikaci kluzných ložisek.

Increasing demands for lower emissions from heavy trucks and buses creates new demands on the components in the engine. One such component is the journal bearing which is used at many positions in the engine. Implementing a start-stop system in a truck engine leads to that the crankshaft journal bearing gets worn out too quickly. A journal bearing is a sliding bearing with a constant flow of oil. When the journal starts rotating an oil film is formed between the bearing and the journal, separating the journal from the bearing surface when the rotational speed is high enough. When this happens a hydrodynamic oil film is formed. During start and stop the bearing and journal passes through boundary and mixed lubrication regimes. The increase in starts and stops leads to a vast increase in the time that the bearing is experiencing boundary and mixed lubrication. During these regimes the journal comes in contact with the bearing surface and eventually leads to wear. This thesis has compared two new materials provided by Höganäs AB with an existing bearing as a reference material. The new materials were laser cladded onto bearing shells and sent to Scania for grinding and testing. The thought was to use a start-stop test rig at KTH that simulates start-stop cycles. The reference bearings were first run in the test rig, but when the shells with the new materials arrived it turned out that they would not fit in the test rig. This created the need for a new test method on a short notice and a reciprocating tribometer at Scania was chosen. The tribometer underwent a number of modifications to be able to fit the samples. Five tests with each new material and the reference material were carried out. The tests ran for 60 minutes except for a long term test that ran for 600 minutes. The results showed that the material designated “S”, which had a solid lubricant, had a coefficient of friction similar to the reference material, but produced less wear and could handle a higher load. The thesis has also proved that the start-stop test rig at KTH works well and can deliver reliable results. / På grund av skärpta miljökrav för tunga lastbilar och bussar ökar kraven på motorns komponenter. En av dessa komponenter är radialglidlager som används på många platser i motorn. Implementering av start-stoppsystem i en lastbilsmotor leder till att vevaxellagren slits ut i förtid. Ett radialglidlager är ett glidlager med ett kontant tillflöde av olja. När axeln börjar rotera skapas det en oljefilm mellan lagerytan och axeln. När rotationshastigheten är tillräckligt hög bär oljefilmen lasten och separerar axeln och lagerytan. Då har det bildats en fullfilm. Under start och stopp passerar lagret genom smörjregimerna gränsskiktssmörjning och blandsmörjning. Ökningen av start och stopp leder till en stor ökning av tiden som lagret upplever gränsskiktsoch blandsmörjning. Under dessa regimer är axeln och lagerytan i kontakt vilket leder till nötning. Detta examensarbete har jämfört två nya material från Höganäs AB med ett existerande lager som referens. De två nya materialen påsvetsades på lagerskålar och skickades till Scania för att slipas och testas. Tanken var att använda en start-stopprigg på KTH som simulerar startstoppcykler. Till att börja med kördes referenslagren i riggen, men när lagerskålarna med de nya materialen levererades visade det sig att de inte passade i testriggen. Detta innebar att en ny testmetod behövdes tas fram med kort varsel och valet föll på en reciprocerande tribometer på Scania. Tribometern var tvungen att modifieras för att proverna skulle passa. Fem test med varje material utfördes. Varje test tog 60 minuter, förutom ett långtidstest som kördes under 600 minuter. Resultaten visade att materialet kallat ”S”, vilket inkorporerade ett fast smörjmedel, hade en friktionskoefficient som liknade referensmaterialets, men producerade mindre nötning och klarade av en högre last. Examensarbetet har också kunnat påvisa att start-stoppriggen på KTH fungerar väl och kan leverera konsekventa resultat.

This master thesis is focused to make education exercise on simulation equipment, tilting pad apparatus and air bearing apparatus. Exercise are, for better understanding problems, completed about exercise measurement viscosity. Were to be proposed three separate exercise for exercising, which were to be well – tried. Measured data from stations for sliding bearing will students confront with computed data. To every exercise are created instructions for exercising, educational presentation and poster to arrangement.

Machines operating in dusty environments, such as mining and civil works, are prone to premature failure, leading to production losses. To address this problem, this research project examines the interaction between solid contaminants and the bearing micro-geometry, in lubricated surface contacts. In particular, it seeks to identify anti-wear additives that are effective in reducing wear under abrasive conditions, making machine elements more dirt tolerant. In general, the influence of antiwear additive is so small that it is difficult to isolate it. Manufactures often make claims about their antiwear products, which are difficult to verify. Hence, there is a need to characterising the antiwear additives available with a well-defined parameter, making it easier for consumers to compare the efficacy of various additives, and be able to select the most suitable additive for a given environment. Effect of micro-geometry parameters such as radial clearance, out-of-roughness and surface roughness was examined and a Film Shape Factor (FSF) – also termed gamma ratio – has been proposed for ensuring adequate separation of journal bearings operating in hydrodynamic lubrication regime, where the out-of-roundness values are higher than the surface roughness values. In this research, an experimental study has been conducted on journal bearings, to examine the influence of five antiwear additives on the bearing wear and micro-geometry. The test additives were provided by the industry partner without revealing their chemical identity or composition; however, these included some of the most commonly used antiwear additives. The tests were performed under three conditions: pure base oil, base oil containing contaminants, and base oil containing contaminants treated with five different additives. The experiments were aimed at choosing one wear measuring technique that evaluates the performance of an individual additive reliably, and based on this technique the additives were characterised. To achieve these objectives, a multi-wear parameter approach (MWPA) was developed, which employed three main wear measurement methodologies, i.e. weight loss, micro-geometry and particle counts –to examine the effect of the antiwear additives. Minimum oil film thickness was also measured to study the lubrication status in the bearing contacts. The MWPA helped in comparing different wear measuring methods, and in selecting the most reliable one. This approach also helped in developing short duration wear tests, thereby saving time, while still getting reliable results without repeating these. Wear experiments were performed on seven sets of bronze bearings and steel sleeve shafts. The test contaminant was 16 micron Aluminium oxide Al2O3 powder mixed in oil with 4% concentration by weight. These solid contaminants were treated with five different antiwear additives to study their influence on the bearings. Bearings were operated such that the minimum oil film thickness in the bearing was equal to the size of the contaminants. These tests were run for a constant sliding distance of 7536m. The results showed that most of the wear measuring techniques do not suit heavily contaminated test conditions. However, the out-of-roundness technique proved to be the most reliable and practical. Based on this technique a methodology was developed which gave a wear characteristic number (N). A unique value of N can be derived for each additive, thereby ranking the additives for their efficacy. The finding of this research provides a better understanding of the methodologies used for measuring wear in journal bearings subjected to dusty environments, and examines the efficacy of each one of these. The wear characteristic number (N) can be used by manufacturers with support from international standards organisations, so that the users can confidently choose the most appropriate antiwear additive for their application. Machines operating in a dusty environment, such as mining industry and civil works are prone to premature failure with subsequent production losses. In response to this problem, this research project examines the interaction between solid contaminant particles and the lubricant film micro-geometry in lubricated surface contacts. In particular, it seeks to identify lubricant anti-wear additives, which are effective in reducing wear under abrasive conditions and thus making machine elements more dirt tolerant.

Motivation "Am stetig steigenden Anteil der erneuerbaren Energien, der auf der einen Seite durch die ehrgeizigen Ziele der Politik forciert und auf der anderen Seite durch wirtschaftliche Interessen beflügelt wird, stellt die Windenergie den größten und aussichtsreichsten Bestandteil dar (BMU 2012). Setzt sich der gegenwärtige Trend fort, so ist in den nächsten Jahren mit Multimegawattanlagen im mehrstelligen Megawattbereich zu rechnen."

Wave ocean energy is a source of renewable energy which is gaining interest in the modern world. In contrast to other well-researched renewable energy sources such as wind energy, wave ocean energy is under the development phase. Governments around the world are encouraging the research of harnessing wave energy. As of now, there are different concepts to harness energy from waves. Tribological components are one of the main aspects that need attention in these wave energy converters. The moving components such as bearings can be the life-determining component of the entire device. This thesis provides conceptual solutions to adapt an existing start-stop bearing test rig to the conditions of wave energy converters. The test rig can test different bearing sused in the wave energy converters. The new design intends to provide scaled wave energy conditions. These conditions are mainly influenced by the oscillating movement of the bearings, the complex load condition and the salty environment. Since the testing of bearings in wave energy converters is in the initial stage, modular designs are implemented to test different types of bearings. / Se filen

The presentation describes the development of a new mountain bicycle pedal with a special magnetic safety locking mechanism by means of the finite element method (FEM). It starts with a description of the predecessor mountain bike pedal “Enduro” from magped GmbH and sets out the development objectives for the new pedal named “Enduro2”. The complete development activities like load determination and load assumptions, FEM analysis of the initial draft, subsequent optimization steps for strength improvement and mass reduction, bearing design and analysis, and prototype testing are described. The presentation ends with a chapter about creating computer generated images for marketing material of the pedal. The presentation is structured as follows: 1. Introduction: -Description of the predecessor mountain bike pedal “Enduro1” by magped GmbH -The magnetic safety locking mechanism -Overview of the magped GmbH product portfolio -Short magped GmbH company presentation -Development objectives and initial design draft of the successor pedal model “Enduro2” 2. Determination of the load cases for design & optimization: -Loads for bicycle pedals acc. to DIN ISO 4210 -Chosen load cases and qualification test program 3. Strength analysis and weight optimization of the pedal axis: -Pre-optimization steps -Optimized shape: Theoretical consideration of the pedal axis -Optimized design description -Obtained mass reduction -User tips for shape / notch stress optimization -Comparison with the axis of a competitor 4. Strength analysis and weight optimization of the pedal body: -Challenges in pedal body design -Computed load cases -Design result and mass savings 5. Bearing design and analysis: -Sliding bearing layout -Ball bearing layout: Bearing forces computation by FEM due to over-determined system -Description of the Creo Simulate FEM model -Bal bearing life span 6. Product testing: -Test program performed by the zedler-institute -Testing of the first test batch of pedals with hollow bored axis -Testing of the first test batch of pedals without hollow bored axis 7. Realized mass savings: -Magped Enduro1 and Enduro2 on the balance and comparison with the magped Gravel pedal 8. Creation of marketing material for the final product: -Still image creation -Photorealistic rendering containing FEM loading sequences / Der Vortrag beschreibt die Entwicklung eines neuen Mountainbike-Pedals mit einer speziellen magnetischen Sicherheitsverriegelung mittels der Finite-Elemente-Methode (FEM). Er beginnt mit einer Beschreibung des Vorgänger-Mountainbike-Pedals 'Enduro' der magped GmbH und legt die Entwicklungsziele für das neue Pedal mit dem Namen 'Enduro2' dar. Die gesamten Entwicklungsaktivitäten wie Lastermittlung und Lastannahmen, FEM-Analyse des ersten Entwurfs, nachfolgende Optimierungsschritte zur Festigkeitsverbesserung und Massenreduzierung, Lagerauslegung und -analyse sowie Prototypentests werden beschrieben. Die Präsentation endet mit einem Kapitel über die Erstellung computergenerierter Bilder für die Verwendung in Marketingmaterial des Pedals. Gliederung des Vortrages: 1. Einleitung: -Beschreibung des Vorgänger-Mountainbike-Pedals 'Enduro1' der magped GmbH -Die magnetische Sicherheitsverriegelung des Pedals -Überblick über das Produktportfolio der magped GmbH -Kurze Firmenpräsentation der magped GmbH -Entwicklungsziele und erster Designentwurf des Nachfolgemodells 'Enduro2' 2. Ermittlung der Lastfälle für Design & Optimierung: -Belastungsfälle für Fahrradpedale nach DIN ISO 4210 -Ausgewählte Lastfälle und Qualifikations-Testprogramm 3. Festigkeitsanalyse und Gewichtsoptimierung der Pedalachse: -Vor-Optimierungsschritte -Optimierte Form: Theoretische Betrachtung der Pedalachse -Beschreibung der optimierten Form -Erzielte Massenreduzierung -Anwendertipps zur Form- / Kerbspannungsoptimierung -Vergleich mit der Achse eines Wettbewerbers 4. Festigkeitsanalyse und Gewichtsoptimierung des Pedalkörpers: -Herausforderungen bei der Konstruktion von Pedalkörpern -Berechnete Lastfälle -Konstruktionsergebnis und Gewichtseinsparung 5. Lagerkonstruktion und -analyse: -Auslegung der Gleitlager -Auslegung der Kugellager: Berechnung der Lagerkräfte durch die FEM aufgrund des statisch überbestimmten Systems -Beschreibung des Creo Simulate FEM-Modells -Lebensdauer der Kugellager 6. Produktprüfung: -Testprogramm, durchgeführt durch das zedler-Institut -Erprobung der ersten Versuchscharge von Pedalen mit hohlgebohrter Achse -Prüfung der ersten Versuchscharge von Pedalen ohne hohlgebohrte Achse 7. Realisierte Masseneinsparung: -Magped Enduro1 und Enduro2 auf der Waage und Vergleich mit dem magped Gravel-Pedal 8. Erstellung von Marketingmaterial für das Endprodukt: -Erstellung von computergenerierten Fotos -Fotorealistisches Rendering mit FEM-Belastungssequenzen