Die Arbeit untersucht den Einfluss von von radialen, im Zahngrund auslaufenden Schmierölbohrungen auf die Zahnfußtragfähigkeit außenverzahnter Stirnräder durch theoretische und experimentelle Untersuchungen. Es werden Formeln entwickelt, die ohne zeitaufwändige Berechnungen eine sichere Beurteilung des Einflusses von Schmierölbohrungen auf die Zahnfußtragfähigkeit ermöglichen. Dazu wird ein Einflussfaktor Y_OeB ermittelt, welcher die einfache Integration in vorhandene Berechnungsstandards erlaubt. Als Vorlage dient dabei die Berechnung der Zahnfußtragfähigkeit nach DIN 3990 / ISO 6336, die durch diesen Faktor ergänzt werden kann. Neben experimentellen Versuchen zum Einfluss der geometrischen Größen Zahnfußausrundungsradius und Bohrungsdurchmesser werden auch verschiedene Parameter wie die Kranzdicke, zusätzliche Torsionsbelastungen (z. B. an Sonnenwellen), die Wärmebehandlung und die Belastungsart (Schwell- oder Wechsellast) berücksichtigt. Darüber hinaus betrachtet die Arbeit das Verhalten verschiedener Werkstoffe bei Vorhandensein einer Schmierölbohrung. Sie liefert des Weiteren einen Erklärungsansatz zum Einfluss der Schmierölbohrungen auf die Zahnfußtragfähigkeit auf Basis der Veränderung der Eigenspannungsverteilung im Zahnfußgebiet durch die radiale Bohrung und bietet dafür auch ein Modell zur qualitativen Berechnung der Eigenspannungsverteilung auf Basis der FE-Methode an.

The discovery and subsequent synthesis of metal containing fullerenes- IFS (Inorganic Fullerene-like Structures) by R. Tenne et al. has generated considerable scientific interest with great potential impact in many industrial application areas such as lubrication. The lubrication mechanism (tribofilm formation) via exfoliation and deposition of the atomic layers from this cage-like IF-particles was revealed and demonstrated first by this research group. The incorporation of the nanoparticles into lubricants (oils, greases) is however not straightforward. When two surfaces are sliding against each other and a lubricant is used, a thin layer (tribofilm) is formed on the contact area. The friction reducing effects of the nanoparticles can be altered or hindered by certain additives that are used in lubricative oils. The effects of such additives on the tribological behavior of the nanoparticles are investigated by analyzing the tribofilms formed on the worn surfaces using energy-dispersive X-ray spectroscopy in a scanning electron microscope. Another challenge of nanoparticles in lubricants is the penetration of the nanoparticles into the contact zone. A possible solution of this problem is briefly discussed. A modified burnishing technique can be used to coat sliding metallic surfaces with a friction reducing tribofilm. The morphology and composition of these tribofilms was investigated with analytical electron microscopy techniques. In the second part of the thesis electron microscopy was used to investigate the material transfer. Titanium is an elements with high adhesive ability to the counter surface, it displays poor tribological properties in sliding metallic contacts. This can lead to material transfer and consequently severe surface damage. The cold formation and machining of titanium, thus can lead rapid tool wear and poor surface finish. Electron microscopy techniques were used to study the mechanism of titanium transfer to different counter surfaces.

Modern construction practices require proper knowledge to predict concrete pumping pressure, especially in high-volume and high-rise applications. Despite the progress made over the last decades, the spread of concrete pumping to high-rise construction has been hampered by the lack of standardized operating procedures and performance criteria. By and large, the guidelines available today focus predominantly on pumping Conventional Vibrated Concrete (CVC), while ambiguity still surrounds pumping Self-Consolidating Concrete (SCC) and other types of Highly-Workable Concrete (HWC). This PhD dissertation focuses on the fundamental principles relevant to the flow of high-strength SCC in pumping pipes, and it aims to develop methods to predict and reduce the required pumping pressure. The flow pattern of SCC in pipes is analytically investigated, providing a numerical approach to predict the pumping pressure based on the properties of both concrete and the lubrication layer, the pipe diameter, and the flow rate. The analytical results are further validated through full-scale pumping tests executed at the laboratory of the Université de Sherbrooke. Through this phase 26 optimal concrete mixtures were pumped in a 30-m pumping circuit to investigate the interactions between the concrete properties and pressure loss. The same tests are also employed to empirically correlate pressure loss with rheological and tribological properties of concrete at different flow rates. The resulting correlations furnish instrumental models capable of computing pressure loss for a wide range of concrete properties. In another application, the experimental results are analyzed to identify the influence of pumping on concrete properties with time. Full-scale pumping results are statistically analyzed in order to establish a quantitative description of the most influential parameters governing the concrete flow in pipes. As a result, concrete pipe flow is statically modeled, allowing the computation of pressure loss at different flow rates based on the the rheological and tribological properties of the concrete and the pipe diameter. Another statistical model is derived to calculate the pressure loss as a function of the V-funnel flow time, granting the advantage of predicting the pressure loss on job sites without the need for complex rheological and tribological measurements. In light of the research findings of the previous phases, a new simple test method called the pipe flow test (PFT) is developed in the context of this research, specifically for predicting pipe flow pressure loss. With preceding research phases as insights, the final stage of this project is directed toward mix design optimization faced with the challenge of reducing the pumping pressure and meeting the strength requirements of high-strength SCC. Ultimately, the research findings emanating from this investigation provide practical guidelines and conclusive models to predict and reduce pumping pressure for a wide scope of concrete mixtures and pipe diameters.

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.

São realizadas análises teóricas e experimentais do atrito nos processos de forjamento a frio, através do ensaio de compressão do anel. Os modelos de atrito de Amonton-Coulomb (μ), atrito interfacial (m) e de Levanov (f) são investigados com auxílio de softwares comerciais de simulação de processos de forjamento. Diferentes condições de lubrificação foram aplicadas para o aço baixa liga 16MnCr5 e a liga de alumínio AA6351 nas condições recozido e encruado. O atrito foi analisado, utilizando os softwares MSC.Superforge e Qform, em função dos resultados obtidos e as condições de lubrificação e estado do material. Valores paramétricos do atrito adquiridos através de correlação teórico-experimental são condizentes com a literatura, indicando a relação do atrito com o material de trabalho, inclusive com seu grau de encruamento. Os modelos de atrito m e f apresentaram maior sensibilidade com relação ao estado do material. / Experimental and theoretical analyses of friction in cold forging process are evaluated by means of the ring compression test. Friction models from Amonton- Coulomb (μ), interfacial friction (m) and Levanov’s model (f) are investigated by aid of numerical simulation software. Different lubricants are applied for low carbon steel alloy 16MnCr5 under annealed and work-hardened conditions. Friction is analyzed by means of lubricant and material conditions using MSC.Superforge and Qform numerical simulation softwares. Acquired frictional parameter values obtained by theoretical-experimental correlation agree with literature, showing friction’s relationship with workpiece material and its hardening level. Friction models m and f presented better sensitivity when concerning the material’s hardening level.

Les contraintes économiques et environnementales toujours plus exigeantes tendent à réduire la quantité de lubrifiant utilisée dans les systèmes mécaniques. Il en résulte des épaisseurs de film de l’ordre du nanomètre dans les zones de contact, laissant seulement quelques couches de molécules de lubrifiant pour assurer la séparation des surfaces. Pour relever ce défi, de nouveaux fluides sont à l’étude tels que les liquides ioniques qui présentent un formidable potentiel en tant que lubrifiants. Grâce à la Dynamique Moléculaire, la réponse rhéologique d’un liquide ionique à différentes sollicitations de température, pression et cisaillement est tout d’abord caractérisée en détail. Avec l’appui d’essais expérimentaux, l’aptitude du liquide ionique à lubrifier des films minces est confirmée. Cette étude a également permis de jeter un nouveau regard sur les modèles analytiques classiques utilisés en rhéologie. Le liquide ionique en situation de nano-confinement entre deux surfaces représentatives d’un contact acier-acier est ensuite étudié. Les effets combinés du glissement à la paroi, de la rhéofluidification et de l’élévation de température apportent des éléments de réponse pour expliquer la saturation de la contrainte de cisaillement aux fortes sollicitations. Enfin, l’influence de différents revêtements de surface limitant grandement le frottement est analysée. Selon le matériau utilisé, des régimes de lubrification très différents surviennent avec un glissement du fluide à la paroi parfois prédominant. L’utilisation de surfaces polaires impacte également fortement la réponse des contacts lubrifiés par un liquide ionique. / Increasing economic and environmental constraints tend to reduce the amount of lubricant used in mechanical systems. This results in nanometric film thicknesses in the contact areas, leaving only a few layers of lubricant molecules to ensure the separation of the surfaces. To meet this challenge, new fluids are being considered such as ionic liquids which feature a great potential as lubricants. Through Molecular Dynamics simulations, the rheological response of an ionic liquid to different conditions of temperature, shear and pressure is first characterized in detail. The ability of the ionic liquid to lubricate thin films is confirmed. Besides, this study goes back over the classic analytical models used in rheology. The ionic liquid is then nanoconfined between two representative surfaces of a steel-steel contact. The combined effects of wall slip, shear-thinning and temperature rise provide answers to explain the saturation of the shear stress. Finally, the influence of different low friction surface coatings is analyzed. According to the material used, very different dynamical behaviors occur. Moreover, it is shown that the use of polar surfaces significantly impacts the response of ionic liquid lubricated contacts.

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.

To ensure that manufactured cartridges is safe to use, a tensile test is performed. The frictional force between the bullet and the case is required according to Normas standard to be between 15 – 75 Kg. Variations of the frictional force, with values outside of the standard had been noted by Norma Precision without understanding the cause. The aim of this report was to investigate and evaluate possible causes of the variations measured by tensile tests, difference between extreme values and to find a solution to what can be done to prevent the variations. Two different cases and three different bullets were used by request from Norma in the scope of this report. Different combinations of the bullets and cases was tested by alternating process parameter, surfaces and loading procedures. The loaded cartridges went through tensile tests to investigate differences. Bullets and cases with extreme values from the measured frictional force were chosen for further investigation in SEM and profilometer. To be able to draw further conclusions four different simulation models was created in Abaqus and different parameters was calculated. The dimensions and shape of the bullet resulted as the cause of changes of the tensile test curves. The smallest frictional force was found to differ from the largest by a change in wear mechanism from mainly abrasive ploughing to cutting and adhesion that caused transfer of material from the bullet to the case. The change in wear mechanism was found to be caused by an increased bullet diameter. The loading procedure was found to cause variations in plastic deformation on the neck of the case and damage the bottom of the bullet. The loading procedure was assumed to have the largest impact on the variations in frictional force. To minimize the variations the central axis of the case was suggested to be in line with the central axis of the bullet.

São realizadas análises teóricas e experimentais do atrito nos processos de forjamento a frio, através do ensaio de compressão do anel. Os modelos de atrito de Amonton-Coulomb (μ), atrito interfacial (m) e de Levanov (f) são investigados com auxílio de softwares comerciais de simulação de processos de forjamento. Diferentes condições de lubrificação foram aplicadas para o aço baixa liga 16MnCr5 e a liga de alumínio AA6351 nas condições recozido e encruado. O atrito foi analisado, utilizando os softwares MSC.Superforge e Qform, em função dos resultados obtidos e as condições de lubrificação e estado do material. Valores paramétricos do atrito adquiridos através de correlação teórico-experimental são condizentes com a literatura, indicando a relação do atrito com o material de trabalho, inclusive com seu grau de encruamento. Os modelos de atrito m e f apresentaram maior sensibilidade com relação ao estado do material. / Experimental and theoretical analyses of friction in cold forging process are evaluated by means of the ring compression test. Friction models from Amonton- Coulomb (μ), interfacial friction (m) and Levanov’s model (f) are investigated by aid of numerical simulation software. Different lubricants are applied for low carbon steel alloy 16MnCr5 under annealed and work-hardened conditions. Friction is analyzed by means of lubricant and material conditions using MSC.Superforge and Qform numerical simulation softwares. Acquired frictional parameter values obtained by theoretical-experimental correlation agree with literature, showing friction’s relationship with workpiece material and its hardening level. Friction models m and f presented better sensitivity when concerning the material’s hardening level.

This thesis aims to design a test equipment for positive change the adhesion contact between the wheel and the rail head. This can be achieved by changing the size of the coefficient of friction, which are eliminated negative effects accompanying the operation of the rail transport (acoustic emissions and excessive wear). Reducing friction must not be compromised traction or braking. Equipment ranks among to Top of Rail systems where as medium is used the friction modifier. The study includes an overview of available types of friction modifiers and applicators Top of rail system. The design of the applicator is built based on the off-board system that is placed in front of the arc track with a small radius of curvature.