Connu dans son principe depuis les années 30, le procédé de toilage a surtout débouché industriellement chez le constructeur automobile américain Chrysler. Il était le premier à mettre au point des appareils permettant un usinage mécanisé pour un processus de fabrication jusque là manuel. L'usinage de superfinition par toilage a conquis ensuite une large audience sous l'impulsion des travaux de l'allemand Karl Wiek en 1950. L'objectif de ce travail était de préciser l'action de toilage en liaison avec l'intervention des variables process ainsi que les caractéristiques principales des processus physiques mis en jeu dans la superfinition des métaux. Dans la synthèse bibliographique, nous avons montré les insuffisances des travaux scientifiques sur l'usinage par toilage qui ramènent la connaissance du procédé à un boisseau de faits empiriques montrant l'intervention critique d'un certain nombre de variables du process. Afin de mieux cerner les mécanismes physiques qui régissent l'usinage par film abrasif, nous avons introduit une approche tribo-énergétique utilisant le couplage des mesures physiques in situ et des expertises de retour d'essais de toilage. Reprenant alors méthodiquement les connaissances de conception des technologies de toilage, nous avons développé un banc d'essai original basé sur un test de toilage où tous les paramètres limites sont donnés par les conditions de service (essai de service). Les mécanismes physiques entrant en jeu dans le toilage du matériau usiné et au niveau de l'interface toile/pièce ont été ainsi discutés. Aussi les interventions des variables process examinées avec effet d'échelle ont été précisées. Bien que le toilage agit par écrêtement de rugosité et par formation de micro-copeaux, la structure du film abrasif, caractérisée par un pouvoir de logement élevé, semble freiner voire transformer cette action de coupe en phénomène de frottement et de labourage. Par ailleurs, la ductilité et l'homogénéité microstructurale du matériau usiné semble conditionner, entre autres phénomènes, l'épaisseur de la couche écrouie et l'endurance de la surface toilée. Nous avons présenté aussi des résultats originaux qui montrent, par une approche multi-échelles de la topographie de surface, l'effet d'échelle de rugosité sur l'intervention des variables process. Celui-ci conditionne fortement la stabilité du process de toilage et permet de mieux préciser la qualité tribologique de surface en terme du besoin fonctionnel.

Aggregate properties influence different aspects of asphalt pavement performance. Aggregate polishing characteristics are directly related to pavement surface frictional properties and thus to skid resistance. Aggregate resistance to degradation (abrasion and breakage) is another important property that influences pavement performance. Aggregate degradation could take place during production due to plant operations and during compaction, leading to change in aggregate characteristics and mix properties. In addition, aggregate resistance to degradation is important in mixes such as Stone Matrix Asphalt (SMA) and Open Graded Friction Course (OGFC) that rely on stone-to-stone contacts among coarse aggregates. Some aggregates in these mixes fracture due to the high stresses at contact points. Many test methods exist for measuring aggregate polishing and degradation, but a critical review of these methods reveals that they suffer from being time consuming, are unable to differentiate between aggregates with distinct resistance to polishing, or unable to differentiate between aggregate resistance to abrasion and breakage. New methodologies are needed to give better assessment of aggregate resistance to polishing, abrasion, and breakage. The thesis presents the development of new methods for measuring aggregate resistance to polishing, abrasion, and breakage. These methods rely on measurements using the Aggregate Imaging System (AIMS) and Micro-Deval. The new method for measuring aggregate resistance to polishing monitors change in aggregate texture as a function of polishing time. As such, it provides the initial texture, rate of polishing, and final texture. The new method for measuring aggregate degradation is capable of distinguishing between breakage and abrasion. In this method, abrasion is defined as the reduction in aggregate angularity, while breakage is defined by fracture of particles. The new methods are shown to be rapid and accurate, and they require reasonable training. Since both AIMS and Micro-Deval are used in the new methods, it was necessary to evaluate the repeatability of these two methods. Measurements using two AIMS units and two Micro-Deval machines were used to assess the variability. There was no statistical difference between the measurements of the two AIMS units or between the measurements of the two Micro-Deval units.

This study considered using a relatively new method to study soil-tool wear which could drastically reduce the time and associated costs of traditional wear studies. The goal was to utilize discrete element method (DEM) simulations to recreate the results of a circular soil bin test in order to develop a relationship that could be used to predict wear under different conditions. Through the application of DEM, simulations could be used to study different materials or designs intended to result in improved wear performance.<p> Three replications of aluminum cylindrical bars were worn during 400 km of travel in a circular soil bin. Wear was quantified by measuring the change in radius of the cylinders at 18-degree intervals around their circumference. Mass data were also obtained to provide an overall average of wear occurring on the bar and to validate the radii measurements.<p> The DEM simulations were executed using EDEM software. Conditions present in the physical soil bin trials were simulated by recreating components in the soil bin and incorporating soil properties that were directly measured, using representative soil samples. Forces exerted on the bar by the soil and the relative velocities between the soil and tool were used to generate a relationship to predict wear of the bar. The wear equation was verified using a portion of the experimental data from the soil bin.<p> The wear model showed promise in predicting the amount of wear recorded in the soil bin through the application of DEM-predicted compressive forces and relative velocities between the tool and soil particles. The Archard equation for wear was modified to create a non-linear equation. Plotting the measured wear against the wear predicted from the fitted equation produced a trendline with a slope of 0.65. Although a perfect correlation would have produced a slope of 1, the model was able to predict a large portion of the wear that occurred. Refinement of the model could further be achieved with changes in the design of the geometry used in the simulation and through verification of force predictions with experimental data. Because of the variable nature of wear, additional replications of tools in the soil bin would have increased the number of data points available to create the model and reduced the impact of outlying data. With these recommended improvements, the wear model has the ability to very accurately predict the wear of a cylindrical bar.

This study examines the lapping machining process used during the manufacturing of polycrystalline diamond compacts (PDCs). More specifically, it is aimed at improving the productivity of the process by developing a better understanding of the parameters that affect the material removal rate (MRR) and MRR uniformity of lapped PDC samples. Experiments that focused on several controllable lapping parameters were performed to determine to what extent they affected the process. It was determined that the MRR can be modeled with the Preston equation under certain ranges of pressure and speed. It was also found that using a hard and rigid sample holder produces higher MRRs than soft and flexible sample holders. The results have also shown that MRRs in excess of 300 micrometers per hour can be achieved while using 10 grams of diamond abrasive per PDC per hour of lapping. The productivity of the lapping process can also be improved by placing the maximum allowed PDC samples in a concentric circle on the edge of the sample holder. The MRR uniformity between samples lapped on the same sample holder was found to be dependent on the sample holder material. This thesis is composed of six chapters. The first chapter introduces the need for PDC's as extreme cutting tools, the manufacturing process of PDC's, and the lapping process. The second chapter discusses the motivation behind this research and the primary objectives that were established. The third chapter details the materials and the experimental procedure, and the fourth chapter presents the results. The fifth chapter discusses the results, and the sixth chapter presents conclusions and information on possible future work.

This study considered using a relatively new method to study soil-tool wear which could drastically reduce the time and associated costs of traditional wear studies. The goal was to utilize discrete element method (DEM) simulations to recreate the results of a circular soil bin test in order to develop a relationship that could be used to predict wear under different conditions. Through the application of DEM, simulations could be used to study different materials or designs intended to result in improved wear performance.<p> Three replications of aluminum cylindrical bars were worn during 400 km of travel in a circular soil bin. Wear was quantified by measuring the change in radius of the cylinders at 18-degree intervals around their circumference. Mass data were also obtained to provide an overall average of wear occurring on the bar and to validate the radii measurements.<p> The DEM simulations were executed using EDEM software. Conditions present in the physical soil bin trials were simulated by recreating components in the soil bin and incorporating soil properties that were directly measured, using representative soil samples. Forces exerted on the bar by the soil and the relative velocities between the soil and tool were used to generate a relationship to predict wear of the bar. The wear equation was verified using a portion of the experimental data from the soil bin.<p> The wear model showed promise in predicting the amount of wear recorded in the soil bin through the application of DEM-predicted compressive forces and relative velocities between the tool and soil particles. The Archard equation for wear was modified to create a non-linear equation. Plotting the measured wear against the wear predicted from the fitted equation produced a trendline with a slope of 0.65. Although a perfect correlation would have produced a slope of 1, the model was able to predict a large portion of the wear that occurred. Refinement of the model could further be achieved with changes in the design of the geometry used in the simulation and through verification of force predictions with experimental data. Because of the variable nature of wear, additional replications of tools in the soil bin would have increased the number of data points available to create the model and reduced the impact of outlying data. With these recommended improvements, the wear model has the ability to very accurately predict the wear of a cylindrical bar.

Aggregate properties influence different aspects of asphalt pavement performance. Aggregate polishing characteristics are directly related to pavement surface frictional properties and thus to skid resistance. Aggregate resistance to degradation (abrasion and breakage) is another important property that influences pavement performance. Aggregate degradation could take place during production due to plant operations and during compaction, leading to change in aggregate characteristics and mix properties. In addition, aggregate resistance to degradation is important in mixes such as Stone Matrix Asphalt (SMA) and Open Graded Friction Course (OGFC) that rely on stone-to-stone contacts among coarse aggregates. Some aggregates in these mixes fracture due to the high stresses at contact points. Many test methods exist for measuring aggregate polishing and degradation, but a critical review of these methods reveals that they suffer from being time consuming, are unable to differentiate between aggregates with distinct resistance to polishing, or unable to differentiate between aggregate resistance to abrasion and breakage. New methodologies are needed to give better assessment of aggregate resistance to polishing, abrasion, and breakage. The thesis presents the development of new methods for measuring aggregate resistance to polishing, abrasion, and breakage. These methods rely on measurements using the Aggregate Imaging System (AIMS) and Micro-Deval. The new method for measuring aggregate resistance to polishing monitors change in aggregate texture as a function of polishing time. As such, it provides the initial texture, rate of polishing, and final texture. The new method for measuring aggregate degradation is capable of distinguishing between breakage and abrasion. In this method, abrasion is defined as the reduction in aggregate angularity, while breakage is defined by fracture of particles. The new methods are shown to be rapid and accurate, and they require reasonable training. Since both AIMS and Micro-Deval are used in the new methods, it was necessary to evaluate the repeatability of these two methods. Measurements using two AIMS units and two Micro-Deval machines were used to assess the variability. There was no statistical difference between the measurements of the two AIMS units or between the measurements of the two Micro-Deval units.

Coarse aggregate is often one of the largest volume occupying components in a portland cement concrete system. With increases in transportation costs and depletion of many of the aggregate sources currently in use the need to reevaluate the performance of aggregates in concrete has arisen. Current aggregate testing requirements for many organizations have not been updated in decades, even with the advancements in aggregate testing equipment that are currently available. This research project investigates current used and potential test methods for evaluating coarse aggregate for use in portland cement concrete. Testing focused on determining the most appropriate aggregate property to evaluate and then determining the correlation to mechanical concrete properties. Relationships between potential aggregate tests and currently used aggregate tests were evaluated to determine if compatible relationships between methods were evident. For this purpose concrete mixtures were made at a fixed aggregate volume to establish if a link was evident between aggregate test properties and concrete. To establish a link between laboratory and real world performance field sites with known distress were visited to better establish limits for aggregate testing requirements. Results obtained provided the basis for recommendations for testing requirements and limits to be used for aggregates in portland cement concrete. / text

Railway track ballast fouling is an ongoing issue without a clear understanding regarding either the cause for generation or the source of the fouling materials. This study was conducted to determine what physical processes are likely causing ballast fouling, where in the track sub-structure fouling material is concentrating, and what factors affect the severity of ballast fouling. A field investigation on a CN railway track was conducted in Joliette, QC during undercutting maintenance operations. Data for in-situ ballast, sub-ballast, and subgrade samples were gathered from a series of trenches excavated through the track embankment. The geotechnical and mineralogical characteristics of a selected set of ballast samples were gathered through a regime of laboratory testing. Grain size distribution data for the select samples was collected from sieve and hydrometer testing. Three sets of LA abrasion tests were conducted on both in-situ and freshly quarried ballast rock to determine the degradation characteristics of the various ballast types. The petrographic analysis of the sample types was conducted using bulk hand sample characterization, thin-section analysis, and X-Ray Diffraction Analysis. The petrographic, grain size, and LA abrasion combined analysis indicated that ballast fouling was primarily caused through degradation of the ballast. The fouling material within the ballast pores was sourced to the abraded pieces of ballast that had degraded over time through XRD and grain size distribution analysis. It was found with statistical confidence that ballast layers with harder, structureless rock types have less fouling material form within the ballast void spaces compared to ballast rock types that are soft on the Mohs hardness scale or have planes of weakness due to structural factors. Analysis of the grain size data also showed that ballast fouling was generally concentrated within the section of the ballast layer directly underlying the steel rail, within the topmost parts of the ballast layers. Overall it was recommended that the effects of chemical degradation on ballast rock types and the historical operational duration of ballast be incorporated into future ballast fouling studies. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2011-09-27 10:01:46.141

The aim of this research was to investigate the interaction of abrasion and corrosion on rings and liners from marine diesel engines using high sulphur residual fuels. Pure corrosion effects were simulated in a sealed vessel containing emulsified lubricant and acid. Graphite was found to stimulate corrosion of ferrite but phosphide eutectic and iron carbide remained unattacked. A reciprocating test was used to combine the mechanisms of abrasion and corrosion which have been identified as producing normal wear in marine engines. The severity of the mechanisms were balanced to produce surfaces similar to those often encountered over the centre of an engine stroke. Two engine tests, specified to compare the type and extent of wear using high and low sulphur fuels, showed that an increase in corrosion resulting from increased fuel sulphur was not directly responsible for a measured increase in top ring wear rate. Corrosion was thought to dissolve the ferritic phases to release hard phases into the system which intensified abrasion of the surfaces. It was also possible that phosphide eutectic was left at a sufficiently high level above the surface by corrosion of the matrix to cause direct abrasion of the ring. Throughout the experimental work particular emphasis was placed on examination and interpretation of the interaction of corrosion and abrasion in lubricated acidified environments.

Copies of author's previously published articles inserted. / Bibliography: leaves 136-155. / xxi, 180 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Examines tooth-to-tooth contact under controlled experimental conditions that simulate bruxism. Focuses on the wear characteristics of enamel and factors influencing the nature and extent of human enamel wear. / Kaidonis, John Aristidis / Thesis (Ph.D.)--University of Adelaide, Dept. of Dentistry, 1995?