Дисертації з теми "Surface topography-roughness"

Saturn's moon, Titan is a geomorphologically active planetary object, and its surface is influenced by multiple processes like impact cratering, fluvial and aeolian erosion, lacustrine processes, tectonics, cryovolcanism and mantling. Disentangling the processes that compete to shape Titan's landscape is difficult in the absence of global topography data. In this thesis, I utilize techniques in topographic statistics, fractal theory, study of terrestrial analogs and landscape evolution modeling to characterize Titan's topography and surface roughness and investigate the relative roles of surface processes in sculpting its landscape. I mapped the shorelines of 290 North Polar Titanian lakes using the Cassini Synthetic Aperture Radar dataset. The fractal dimensions of the shorelines were calculated via the divider/ruler method and box-counting method, at length scales of (1-10) km and found to average 1.27 and 1.32, respectively. The inferred power-spectral exponent of Titan's topography (β) was found to be ≤ 2, which is lower than the values obtained from the global topography of the Earth or Venus. In order to interpret fractal dimensions of Titan's shorelines in terms of the surficial processes at work, I repeated a similar statistical analysis with 114 terrestrial analogous lakes formed by different processes, using C-band radar backscatter data from the Shuttle Radar Topography Mission (SRTM). I found different lake generation mechanisms on Earth produce 'statistically different' shorelines; however, no specific set of processes could be identified for forming Titanian lake basins. Using the Cassini RADAR altimetry data, I investigated Titan's global surface roughness and calculated median absolute slopes, average relief and Hurst exponent (H) for the surface of Titan. I detected a clear trend with latitude in these roughness parameters. Equatorial regions had the smallest slopes, lowest values of H and smallest intra-footprint relief, compared to the mid-latitudes and polar regions of Titan. I used steady state models of relief generation (tectonic activity) and relief reduction (diffusive mass wasting and advective bedrock channel erosion) to generate synthetic landscapes and simulate Titan's topography. I provided constraints on two environmental variables for Titan that influence surface roughness: diffusivity and erodibility coefficient.

The ongoing interest in bacterial interactions with various surfaces, followed by attachment and subsequent biofilm formation, has been driven by the importance of bacterial activities in number of medical, industrial and technological applications. However, bacterial adhesion to surfaces has not been completely understood due to the complexity of parameters involved. The study presented herein investigates the attachment pattern of nine medically and environmentally significant bacteria belonging to different taxonomic lineages: Firmicutes - Bacillus, Gammaproteobacteria, Alphaproteobacteria and Bacteriodetes. Physicochemical assessment techniques such as contact angle and surface charge measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), confocal microscopy (CLSM), as well as X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) analysis were all employed in order to attain better insight into the factors that influence bacterial interactions with surfaces. Bacterial surface characteristics such as surface wettability and charge in addition to substratum surface wettability, tension, charge and chemistry were also considered. However due to the recent interest in designing micro-textured surfaces with antibacterial and/or antifouling effects the prime was given to the influence of micro- and nano-meter scale surface textures on bacterial adhesion. The interactions between selected bacteria and glass, polymer and optical fibre surfaces were studied. Carefully designed methods for surface modification allowed alteration of the topography of glass, polymer and optical fibre surfaces while maintaining other surface parameters near constant. This allowed isolated assessment of only the effects of surface roughness on bacterial adhesion. Obtained results indicated consistent cellular inclination towards the smoother surfaces for all of the tested species. Enhanced bacterial presence on the smoother surfaces was also accompanied by changes in the bacterial metabolic activity as indicated by the elevated levels of secreted extracellular polymeric materials (EPS) and modifications in the cells morphology. The results indicate that nano-scale surface roughness exert greater influence on bacterial adhesion than previously believed and should therefore be considered as a parameter of primary interest alongside other wellrecognized factors that control initial bacterial attachment.

The topography’s change of surface films Fe/S and Cu/Fe/S was investigated and the diffusive profiles’ analysis of three-layer films Co/Cu/Fe/S was performed after theirs annealing. The influence of mean-square roughness and interdiffusion on a size of giant magnetoresistance (GMR) effect was established. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35308

A computer model based on minimization of the free energy, capable to predict contact angles and spreading transitions between Wenzel and Cassie mode for drops placed on surfaces with different topography were implemented in matlab. Simulations were compared with experiments documented in the literature. These showed that reported transitions between Cassie and Wenzel mode can be explained by minimization of the free energy. In this report, a study on the possibility of constructing water repellent paper surfaces with a combination of treatment with octadecyltrichlorosilane and topography changes, is included.

Diploma thesis deals with elastohydrodynamic lubrication of point contacts, which surfaces are influenced by topography and velocity vector of one rubbing surface is misaligned. Author summarizes knowledge of previously published research articles, which fundamentally enrich current state of knowledge. Diploma thesis contains experimental measurement results of the film thickness and the way of lubrication film formation in elliptical contact for different ellipticity parameters, kinds of rubbing surfaces and angles of the velocity vector. New findings have helped to better understand the behaviour of highly loaded lubricated contacts taking place in machine components and completed the current state of knowledge with results that can be used in next thorough study of this issue.

Traditionally, surface topography measurement was in the domain of quality control of engineering parts. With the advancement of manufacturing technology and affordable computational costs, different types of surfaces are produced with varied shapes and surface textures. These pose significant measurement problems, therefore, surface topography research is gaining momentum to achieve a better control of the surface. Coherence scanning interferometry (CSI) is one of the most common techniques used for measurement of surface topography. It is preferred over tactile and other non-contact techniques since it provides fast and accurate measurement with high vertical (~ 1 nm) and lateral (~1 μm) resolutions over larger areas without any damage to the surface. Essentially, CSI is treated as one dimensional (1D) superposition of the light waves from an object and a reference that generates a three dimensional (3D) interferogram. Secondly, despite the advantages, there is no standard configuration of CSI that can provide absolute surface topography measurement of an engineering part with multiple materials. An effective solution to this problem will be particularly useful in the field of semiconductor and bio-related industries where chips and instruments are made of many materials. In this Thesis, first, the CSI technique is analysed in terms of a wider theoretical framework of 3D linear filtering technique which shows the similarities among other seemingly disparate techniques such as confocal and optical coherence tomography. Due consideration to the spectral characteristic of the source and the effect of numerical aperture are given and important parameters such as vertical and lateral resolutions are computed to compare this theory with standard analysis methods. Additionally, it is shown that the 3D fringe pattern can be considered to be a superposition of a reference field and the scattered field from the top foil-like layer on the top the object. The scattered field from this foil object is dependent on the normal Fresnel reflection coefficients. Therefore, it explains the phase offset and the proportional height offset introduced by different materials, especially, metals. In an object, where multiple materials are present, each material introduces different phase to the fringe pattern and therefore, the surface topography of the entire object is altered. To overcome this problem, the optical polarising properties of the material are exploited. A novel configuration of polarisation sensitive CSI is presented where interferograms with orthogonal circular polarisations are recorded and analysed. The configuration, initially, needs to be calibrated with a material and after that at each point on the object, the refractive index and height offset can be calculated. Therefore, it can be dually used to identify unknown materials present on the object and also to compensate for the height offset introduced by each material to produce absolute surface topography of the entire object. The configuration provides good agreement with ellipsometric results for metals. Additionally, it retains the advantages of high vertical and lateral resolution same as other standard coherence scanning interferometers.

Silicon photonics is emerging as a potential field to achieve optical interconnects towards the realization of ultra high bandwidth. The indirect band-gap property of silicon still remains as a big challenge to incorporate silicon photonic active device, for example, silicon-based laser. In the Laboratory of Semiconductor Materials at KTH, a monolithic integration platform based on nano-epitaxial lateral overgrowth (nano-ELOG) technique has been proposed to integrate III-V semiconductor materials with silicon for light source application. The integration process involves uneven surface morphology at different stages. The surfaces of the indium phosphide seed layer on silicon used for ELOG, the mask deposited on it (the silicon/silicon dioxide waveguide) and the ELOG indium phosphide layer grown on it prior to laser growth are often rough. In this thesis work, we have optimized chemical mechanical polishing (CMP) technique in order to achieve an even surface. The same procedure is also necessary to reach the optimal thickness of different layers to enable effective coupling of light from the laser source into the waveguide. CMP of indium phosphide to obtain an average surface roughness of < 1 nm has been optimized by a two-step polishing using different slurries; it results in a step height of ca 3 nm. Similarly the surface of silicon/silicon dioxide “waveguide” has also been optimized with the roughness of ~ 0.5 nm. In the latter case, a step height of 40 nm is retained and this increase with respect to InP is identified to be mainly due to limitations of the polishing machine which is different from that used for indium phosphide. The reduction in step heights with polishing time is analyzed and compared with an existing theoretical model. Our results are in good qualitative agreement with the model. The optimized surface morphology obtained in this work was tested for its suitability for integration. For this evaluation, InP was grown by ELOG in a hydride vapour phase epitaxy reactor with and without CMP of the involved surfaces. The surface after CMP yields layers of better surface morphology with fewer defects as revealed by atomic force microscopy, surface profilometer and cathodoluminescence analysis. The results indicate that the CMP process is useful for monolithic integration for silicon photonics.

Prediction of vehicle disc brake roughness noise is a non-trivial challenge. In fact, neither the source mechanisms, nor the transfer paths are so far well understood. Traditionally, disc brake noise problems are studied as part of the friction-induced noise field, where the source is considered to be a more or less local phenomenon related to the brake disc and brake pad. However, for the roughness noise of interest here this viewpoint is not adequate when attempting to solve the interior noise problem since the transfer of vibro-energy from the brake into the vehicle body is a crucial aspect and plays an important role in the understanding and solution to the problem. The vibroacoustic energy transfer associated with the brake roughness noise is a problem where geometrical complexity and material combinations, including rubber bushings, pose an intricate modelling problem. Additionally, system altering effects from moving parts and loadings are important, e.g. due to the steering or brake systems. In addition, the source mechanisms themselves must also be understood to be able to solve the problem. The current work constitutes a combined experimental and theoretical investigation, aiming at an increased understanding of the source, the transfer paths and how they are a affected by change in the operational state. The experimental study of the vehicle disc brake roughness noise, is based on measurements conducted in a laboratory using a complete passenger car. It is found that the interior noise is a structural-borne broadband noise event well correlated to vehicle speed and brake pressure. The results suggest that the friction source may be divided into vibrations created in the sliding direction and vibrations created normal to the contact plane, where the sliding direction levels appear to be proportional to brake pressure according to Coulomb’s friction law; the vibration level in the normal direction of the contact plane on the other hand has behaviour proportional to Hertz contact theory. The measurements also indicate that the brake force created carried by the suspension system when braking will also alter the vibro-acoustic response of the system. To facilitate the theoretical simulations, an approach for modelling of the suspension system is developed. The vibro-acoustic transfer path model developed is using a modal based on the Craig-Bampton method where a restriction on the coupling modes is suggested. The approach suggested uses undeformed coupling interfaces, to couple structures of fundamentally different stiffness such as may be the case in a vehicle suspension system where for instance rubber bushings are combined with steel linking arms. The approach show great potential inreducing computational cost compared to the classical Craig-Bampton method.
QC 20110913

This paper deals with the analysis of data obtained from the surface of aluminum alloy 7475-T7351 after face milling with a tool inclination of 1°. The theoretical part explains the basic principles of measuring the topography of the surface and instruments that are able to provide relevant data directly from the scanned part. The following part contains the methods of evaluating the information, especially using various types of parameters acquired from ČSN EN ISO standards. The practical part focuses on the data obtained from the sample surface using the Alicona IF-G5. This information determines the character of the surface texture with the tool inclination and the difference between the profile and surface parameters. There is also described surface texture in the tool path and on the edge of the tool path. In the final economic evaluation, the connection between the feed per tooth and the machining price is found.

Stable fixation of implants such as artificial teeth depends on the direct apposition of bone to the implanted material. While endosseous implants were traditionally allowed to "osseointegrate" over several months without carrying load, clinical and experimental data show that prostheses with roughened surfaces allow successful integration when subject to earlier loading and more challenging implant sites. However, to design implant surfaces for an optimal biological response requires an understanding of the mechanism by which roughened surfaces promote osseointegration. Research into this mechanism has, to date, focussed primarily on the response of osteoblastic cells to surface topography in vitro. While these have demonstrated some consistent trends in cell behaviour, the fundamental means by which cells sense and respond to roughness remain unclear. It has been suggested that cell responses to changes in topography may relate to differences in the proteins adsorbed from serum (in vitro). While experimental evidence indirectly suggests that physical features can affect protein adsorption, few studies have examined this with respect to surface roughness, particularly as a mediator of cell responses. To address this issue, cell culture and protein adsorption experiments were conducted on a limited range of surface textures. Titanium samples were ground to produce morphologically similar surfaces with three grades of roughness. A duplicate set of specimens were heated at 600°C for one hour, with the aim of masking potential variations in physicochemical properties with differing degrees of grinding. Osteoblast attachment and proliferation studies were conducted over a short time-frame of 48 hours or less, to highlight the effects of proteins adsorbed from serum rather than secreted by adherent cells. Gel electrophoresis provided a profile of the proteins adsorbed to each surface after 15 minutes, corresponding to the time by which the cells had settled onto the surface. Finally, confocal microscopy was used to examine cell morphology on each surface, and to visualize specific interactions between cellular structures and adsorbed adhesion-mediating proteins. Although the effects were inconsistent, attachment assays showed some indications that fewer cells attached in the first 90 minutes as roughness increased. This inverse cell number-roughness trend was significant at 48 hours; however, the variability in attachment assays prevented reliable separation of attachment and proliferation rate effects. While the reduction in cell number with increasing roughness is consistent with previous reports, it is typically observed at later time points, and thus may be increasingly confounded by contact inhibition and differentiation. Thermal oxidation of the titanium did not impact on osteoblast responses to roughness, although it significantly slowed cell proliferation. The latter result was unexpected on the basis of previous reports. One-dimensional gel electrophoresis revealed no significant differences in the composition of adsorbed layers with variations in roughness. However, as expected on account of wettability changes, the heat-treatment did correspond to significant changes in the adsorption profile. While this was not a highly sensitive analysis, it suggests that the cell responses to roughness changes were not governed by broadscale differences in the proteins initially available to adhering cells. In addition to the composition of the adsorbed layer, the distribution of proteins may also vary with topography. The immunofluorescence methods were not sufficiently sensitive to reveal the distribution of adsorbed adhesion proteins (vitronectin and fibronectin). However, the lack of clear labelling does suggest an absence of large accumulations due to specific topographic features. Further work is required to address this issue conclusively. Observations of cell morphology were consistent with widely-reported contact guidance phenomena on grooved surfaces, with elongation and alignment (with topography) increasing with groove depth. Cell elongation was also enhanced on the more hydrophilic, heat-treated titanium, but this effect diminished over time. Although increased elongation at 90 minutes corresponded to lower cell numbers at 48 hours, no causal relationship has yet been established.

Stable fixation of implants such as artificial teeth depends on the direct apposition of bone to the implanted material. While endosseous implants were traditionally allowed to "osseointegrate" over several months without carrying load, clinical and experimental data show that prostheses with roughened surfaces allow successful integration when subject to earlier loading and more challenging implant sites. However, to design implant surfaces for an optimal biological response requires an understanding of the mechanism by which roughened surfaces promote osseointegration. Research into this mechanism has, to date, focussed primarily on the response of osteoblastic cells to surface topography in vitro. While these have demonstrated some consistent trends in cell behaviour, the fundamental means by which cells sense and respond to roughness remain unclear. It has been suggested that cell responses to changes in topography may relate to differences in the proteins adsorbed from serum (in vitro). While experimental evidence indirectly suggests that physical features can affect protein adsorption, few studies have examined this with respect to surface roughness, particularly as a mediator of cell responses. To address this issue, cell culture and protein adsorption experiments were conducted on a limited range of surface textures. Titanium samples were ground to produce morphologically similar surfaces with three grades of roughness. A duplicate set of specimens were heated at 600°C for one hour, with the aim of masking potential variations in physicochemical properties with differing degrees of grinding. Osteoblast attachment and proliferation studies were conducted over a short time-frame of 48 hours or less, to highlight the effects of proteins adsorbed from serum rather than secreted by adherent cells. Gel electrophoresis provided a profile of the proteins adsorbed to each surface after 15 minutes, corresponding to the time by which the cells had settled onto the surface. Finally, confocal microscopy was used to examine cell morphology on each surface, and to visualize specific interactions between cellular structures and adsorbed adhesion-mediating proteins. Although the effects were inconsistent, attachment assays showed some indications that fewer cells attached in the first 90 minutes as roughness increased. This inverse cell number-roughness trend was significant at 48 hours; however, the variability in attachment assays prevented reliable separation of attachment and proliferation rate effects. While the reduction in cell number with increasing roughness is consistent with previous reports, it is typically observed at later time points, and thus may be increasingly confounded by contact inhibition and differentiation. Thermal oxidation of the titanium did not impact on osteoblast responses to roughness, although it significantly slowed cell proliferation. The latter result was unexpected on the basis of previous reports. One-dimensional gel electrophoresis revealed no significant differences in the composition of adsorbed layers with variations in roughness. However, as expected on account of wettability changes, the heat-treatment did correspond to significant changes in the adsorption profile. While this was not a highly sensitive analysis, it suggests that the cell responses to roughness changes were not governed by broadscale differences in the proteins initially available to adhering cells. In addition to the composition of the adsorbed layer, the distribution of proteins may also vary with topography. The immunofluorescence methods were not sufficiently sensitive to reveal the distribution of adsorbed adhesion proteins (vitronectin and fibronectin). However, the lack of clear labelling does suggest an absence of large accumulations due to specific topographic features. Further work is required to address this issue conclusively. Observations of cell morphology were consistent with widely-reported contact guidance phenomena on grooved surfaces, with elongation and alignment (with topography) increasing with groove depth. Cell elongation was also enhanced on the more hydrophilic, heat-treated titanium, but this effect diminished over time. Although increased elongation at 90 minutes corresponded to lower cell numbers at 48 hours, no causal relationship has yet been established.

Surface topography is, generally, composed of many length scales starting from its physical geometry, to its microscopic or atomic scales known by roughness. The spatial and geometrical evolution of the roughness topography of engineering surfaces avail comprehensive understanding, and interpretation of many physical and engineering problems such as friction, and wear mechanisms during the mechanical contact between adjoined surfaces. Obviously, the topography of rough surfaces is of random nature. It is composed of irregular hills/valleys being spatially correlated. The relation between their densities and their geometric properties are the fundamental topics that have been developed, in this research study, using the theory of random fields and the integral geometry.An appropriate random field model of a rough surface has been defined by the most significant parameters, whose changes influence the geometry of its excursion. The excursion sets were quantified by functions known as intrinsic volumes. These functions have many physical interpretations, in practice. It is possible by deriving their analytical formula to estimate the parameters of the random field model being applied on the surface, and for statistical analysis investigation of its excursion sets. These subjects have been essentially considered in this thesis. Firstly, the intrinsic volumes of the excursion sets of a class of mixture models defined by the linear combination of Gaussian and t random fields, then for the skew-t random fields are derived analytically. They have been compared and tested on surfaces generated by simulations. In the second stage, these random fields have been applied to real surfaces measured from the UHMWPE component, involved in application of total hip implant, before and after wear simulation process. The primary results showed that the skew-t random field is more adequate, and flexible for modelling the topographic roughness. Following these arguments, a statistical analysis approach, based on the skew-t random field, is then proposed. It aims at estimating, hierarchically, the significant levels including the real hills/valleys among the uncertain measurements. The evolution of the mean area of the hills/valleys and their levels enabled describing the functional behaviour of the UHMWPE surface over wear time, and indicating the predominant wear mechanisms.

[ES] La calidad superficial en las piezas mecanizadas depende del acabado superficial, resultado de las marcas dejadas por la herramienta durante el proceso de corte. Las aproximaciones teóricas tradicionales indican que estas marcas están relacionadas con los parámetros de corte (velocidad de corte, avance, profundidad de corte...), el tipo de máquina, el material de la pieza, la geometría de la herramienta, etc. Pero no todos los tipos de mecanizado y selección de materiales pueden dar un resultado ambiguo. Hoy en día, de manera progresiva, se están utilizando las técnicas de fresado de Alta Velocidad sobre materiales de difícil mecanizado cada vez más. El fresado de Alta Velocidad implica a un considerable número de parámetros del proceso que pueden afectar a la formación topográfica 3D de la superficie. La hipótesis de que los parámetros de rugosidad superficial dependen de las huellas dejadas por la herramienta, determinadas por las condiciones de trabajo y las propiedades del entorno, condujo al desarrollo de una metodología de investigación personalizada. Este trabajo de investigación muestra como la combinación de los parámetros, inclinación del eje de la herramienta, deflexión geométrica de la herramienta y comportamiento vibracional del entorno, influencian sobre el parámetro de rugosidad superficial 3D, Sz. El modelo general fue dividido en varias partes, donde se ha descrito la influencia de parámetros del proceso adicionales, siendo incluidos en el modelo general propuesto. El proceso incremental seguido permite al autor desarrollar un modelo matemático general, paso a paso, testeando y añadiendo los componentes que más afectan a la formación de la topografía de la superficie. En la primera parte de la investigación se seleccionó un proceso de fresado con herramientas de punta plana. Primero, se analiza la geometría de la herramienta, combinada con múltiples avances, para distinguir los principales parámetros que afectan a la rugosidad superficial. Se introduce un modelo de predicción con un componente básico para la altura de la rugosidad, obtenida por la geometría de la herramienta de corte. A continuación, se llevan a cabo experimentos más específicamente diseñados, variando parámetros tecnológicos. Esto empieza con el análisis de la inclinación del eje de la herramienta contra la mesa de fresado. Los especímenes de análisis son muestras con cuatro recorridos de corte rectos con corte en sentido contrario. Las trayectorias lineales con diferentes direcciones dan la oportunidad de analizar la inclinación del husillo de fresado en la máquina. Un análisis visual reveló diferencias entre direcciones de corte opuestas, así como marcas dejadas por el filo posterior de la herramienta. Considerando las desviaciones de las marcas de corte observadas en las imágenes de rugosidad superficial obtenidas a partir de las medidas, se introdujo un análisis sobre el comportamiento dinámico del equipo y de la herramienta de corte. Las vibraciones producen desviaciones en la mesa de fresado y en la herramienta de corte. Estas desviaciones fueron detectadas e incluidas en el modelo matemático para completar la precisión en la predicción del modelo. Finalmente, el modelo de predicción del parámetro de rugosidad Sz fue comprobado con un mayor número de parámetros del proceso. Los valores de Sz medidos y predichos, fueron comparados y analizados estadísticamente. Los resultados revelaron una mayor desviación de la rugosidad predicha en las muestras fabricadas con diferentes máquinas y con diferentes avances. Importantes conclusiones sobre la precisión del equipo de fabricación han sido extraídas y de ellas se desprende que la huella de la herramienta de corte está directamente relacionada con los parámetros de la topografía de la superficie. Además, la influencia de la huella está afectada por la geometría de la herramienta de corte, la rigidez de la herramienta y la precisión del equipo. La geometría de la herramienta conforma la base del parámetro Sz, desviación de la altura de la superficie. Las conclusiones alcanzadas son la base para recomendaciones prácticas, aplicables en la industria.
[CA] La qualitat superficial en les peces mecanitzades depèn de l'acabat superficial, resultat de les marques deixades per l'eina durant el procés de tall. Les aproximacions teòriques tradicionals indiquen que aquestes marques estan relacionades amb els paràmetres de tall (velocitat de tall, avanç, profunditat de tall...), el tipus de màquina, el material de la peça, la geometria de l'eina, etc. Però no tots els tipus de mecanitzat i selecció de materials poden donar un resultat ambigu. Avui en dia, de manera progressiva, s'estan utilitzant les tècniques de fresat d'Alta Velocitat sobre materials de difícil mecanització cada vegada més. El fresat d'Alta Velocitat implica un considerable nombre de paràmetres del procés que poden afectar la formació topogràfica 3D de la superfície. La hipòtesi que els paràmetres de rugositat superficial depenen de les empremtes deixades per l'eina, determinades per les condicions de treball i les propietats de l'entorn, va conduir al desenvolupament d'una metodologia d'investigació personalitzada. Aquest treball de recerca mostra com la combinació dels paràmetres, inclinació de l'eix de l'eina, deflexió geomètrica de l'eina i comportament vibracional de l'entorn, influencien sobre el paràmetre de rugositat superficial 3D, Sz. El model general va ser dividit en diverses parts, on s'ha descrit la influència de paràmetres addicionals del procés, sent inclosos en el model general proposat. El procés incremental seguit permet a l'autor desenvolupar un model matemàtic general, pas a pas, testejant i afegint els components que més afecten a la formació de la topografia de la superfície. En la primera part de la investigació es va seleccionar un procés de fresat amb eines de punta plana. Primer, s'analitza la geometria de l'eina, combinada amb múltiples avanços, per distingir els principals paràmetres que afecten la rugositat superficial. S'introdueix un model de predicció amb un component bàsic per a l'altura de la rugositat, obtinguda a través de la geometria de l'eina de tall. A continuació, es duen a terme experiments més específicament dissenyats, variant paràmetres tecnològics. Això comença amb l'anàlisi de la inclinació de l'eix de l'eina contra la taula de fresat. Els espècimens d'anàlisi són mostres amb quatre recorreguts de tall rectes amb tall en sentit contrari. Les trajectòries lineals amb diferents direccions donen l'oportunitat d'analitzar la inclinació del fus de fresat en la màquina. Una anàlisi visual revelà diferències entre direccions de tall oposades, així com marques deixades pel tall posterior de l'eina. Considerant les desviacions de les marques de tall observades en les imatges de rugositat superficial obtingudes a partir de les mesures, es va introduir una anàlisi sobre el comportament dinàmic de l'equip i de l'eina de tall. Les vibracions produeixen desviacions en la taula de fresat i en l'eina de tall. Aquestes desviacions van ser detectades i incloses en el model matemàtic per completar la precisió en la predicció de el model. Finalment, el model de predicció de el paràmetre de rugositat Sz va ser comprovat amb un major nombre de paràmetres del procés. Els valors de Sz mesurats i predits, van ser comparats i analitzats estadísticament. Els resultats van revelar una major desviació de la rugositat predita en les mostres fabricades amb diferents màquines i amb diferents avanços. Importants conclusions sobre la precisió de l'equip de fabricació han estat extretes i d'elles es desprèn que l'empremta de l'eina de tall està directament relacionada amb els paràmetres de la topografia de la superfície. A més, la influència de la empremta està afectada per la geometria de l'eina de tall, la rigidesa de l'eina i la precisió de l'equip. La geometria de l'eina conforma la base del paràmetre Sz, desviació de l'altura de la superfície. Les conclusions assolides són la base per recomanacions pràctiques, aplicables en la indústria.
[EN] Surface quality of machined parts highly depends on the surface texture that reflects the marks, left by the tool during the cutting process. The traditional theoretical approaches indicate that these marks are related to the cutting parameters (cutting speed, feed, depths of cut...), the machining type, the part material, the tool geometry, etc. But, different machining type and material selection can give a variable result. In nowadays, more progressively, High Speed milling techniques have been applied on hard-to-cut materials more and more extensively. High-speed milling involves a considerable number of process parameters that may affect the 3D surface topography formation. The hypothesis that surface topography parameters depends on the traces left by the tool, determined by working conditions and environmental properties, led to the development of a custom research methodology. This research work shows how the parameters combination, tool axis inclination, tool geometric deflection, cutting tool geometry and environment vibrational behavior, influence on 3D surface topography parameter Sz. The general model was divided in multiple parts, where additional process parameters influence has been described and included in general model proposed. The incremental process followed allows the author to develop a general mathematical model, step by step, testing and adding the components that affect surface topography formation the most. In the first part of the research a milling procedure with flat end milling tools was selected. First, tool geometry, combined with multiple cutting feed rates, is analyzed to distinguish the main parameters that affect surface topography. A prediction model is introduced with a basic topography height component, performed by cutting tool geometry. Next, specifically designed experiments were conducted, varying technological parameters. That starts with cutting tool axis inclination against the milling table analysis. The specimens of analysis are samples with 4 contrary aimed straight cutting paths. Linear paths in different directions give a chance to analyze milling machine spindle axis topography, as well as marks left from cutting tool back cutting edge. Considering the deviations of cutting marks observed in the images of the surface topography obtained through the measurements, the milling equipment and cutting tool dynamical behavior analysis were introduced. Vibrations produce deviations in the milling table and cutting tool. These deviations were detected and included in the mathematical model to complete the prediction model accuracy. Finally, the prediction model of the topography parameter SZ was tested with increased number of process parameters. Measured and predicted SZ values were compared and analyzed statistically. Results revealed high predicted topography deviation on samples manufactured with different machines and with different feed rates. Relevant conclusions about the manufacturing equipment accuracy have been drawn and they state that cutting tool's footprint is directly related with surface topography parameters. Besides, footprint influence is affected by cutting tool geometry, tool stiffness and equipment accuracy.
Logins, A. (2021). High speed milling technological regimes, process condition and technological equipment condition influence on surface quality parameters of difficult to cut materials [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/164122
TESIS

Ce présent travail de thèse porte sur l’étude du potentiel d’un traitement de surface par laser femtoseconde comme étape de substitution aux traitements réalisés actuellement lors de la métallisation de polymère. Pour cela, l’étude des modifications chimiques et morphologiques induites par traitement laser femtoseconde ainsi que leurs influences respectives sur les propriétés d’adhérences et de mouillabilités de la surface polypropylène sont présentées. Une revue bibliographique met en évidence la faisabilité d’une modification contrôlée de la surface du polypropylène après traitement laser femtoseconde. De plus, ces modifications engendrent une évolution démontrée des propriétés de mouillage qui peuvent répondre à certaines demandes industrielles. Après traitement laser femtoseconde, la surface traitée répond de différentes manières à la sollicitation en fonction de ses propriétés intrinsèques. Les expériences d’impacts localisés et de surfaces nous ont conduits à observer trois stades de modifications topographiques pour les conditions étudiées : un phénomène d’incubation, d’accumulation et d’ablation. Ce dernier a fait l’objet d’une étude plus approfondie. De manière générale, on observe deux régimes d’ablation linéaires pour l’ensemble des densités de puissance étudiées lorsque l’on étudie la profondeur d’ablation en fonction du nombre d’impulsion et le volume d’ablation en fonction de la densité de puissance cumulée. Enfin, nous montrons que les liaisons présentes en surface après traitement sont dépendantes de deux facteurs ; la densité de puissance cumulée utilisée et l’environnement de travail. Sachant que les modifications topographiques obtenues sont de types multi-échelles, les résultats ont été analysés sur la base des modèles de Wenzel (1936) et de Cassie-Baxter (1944) relatifs à la théorie du mouillage de surfaces rugueuses. Les résultats expérimentaux et leurs corrélations avec les paramètres de rugosités 3D calculés à différentes échelles ont été traités par une analyse statistique. On observe alors un comportement mixte avec un contact intime de la goutte sur les sommets des aspérités (modèle de Wenzel) et un contact hétérogène (airpolypropylène) à une échelle mésoscopique (état « fakir » décrit par le modèle de Cassie-Baxter). Toutefois, la situation où la goute repose sur le sommet des structures (CB) n’est pas toujours stable. Nous avons étudié la transition de l’état CB à l’état W par des expériences d’évaporation. On observe que cette transition est fortement dépendante de la chimie de surface dont la contribution est prépondérante sur les propriétés d’adhérence métal/PP. En contrôlant cette propriété, il est alors possible de répondre à une problématique industrielle de galvanoplastie (adhérence augmenté par le traitement laser) ou d’électroformage (adhérence faible permettant une réplication de bonne qualité des motifs)
This work presents the potential of a femtosecond laser surface treatment as an alternative step of pretreatments during the metallization of polymer. To do this, the study of chemical and morphological modification induced by femtosecond laser treatment and their respective influences on the properties of adhesion and wettability of polypropylene surface are presented. A literature review highlights the feasibility of a controlled surface modification after femtosecond laser treatment of polypropylene (PP). In addition, it is known that these modifications changes the wetting properties and can be used to meet industrial applications development. After femtosecond laser treatment, the treated surface responds to the solicitation with different morphological comportment according to its intrinsic properties. Experiences of localized impacts and surfaces us to observe three stages of topographic changes to the conditions studied: an incubation phenomenon of accumulation and ablation. The ablation phenomenon is further study. Generally, two linear ablation regime is observed for all power densities examined when considering the depth of ablation as a function of the pulse number and the ablation volume according to the accumulated power density. Finally, we show that the bonds present on the surface after treatment are dependent on two factors: the accumulated power density used and the working environment. Knowing that topographic obtained is multi-scales, the results were analyzed on the basis of models Wenzel (W)(1936) and Cassie–Baxter (CB) (1944) which explain the theory of wetting of rough surfaces. The experimental results and their correlations with 3D roughness parameters calculated at different scales were treated by statistical analysis. We observe a mixed model behavior with intimate contact of the drop on the tops of the asperities (Wenzel model) and a heterogeneous contact (air - PP) in a mesoscopic scale (state " fakir " described by the Cassie -Baxter model). However, this situation where the drop sits on the top of asperities (CB) is not always the most stable. We have studied the transition between the CB state and the W state by evaporation experiments. It is observed that this transition is strongly dependent on the surface chemistry whose contribution is much greater than the adhesion properties metal / PP. If controlling this property, it is possible to obtain two industrial applications: electroplating (increased adhesion by laser treatment) or electroforming (low adherence to replicate the topography)

O processo de estampagem é influenciado por diferentes variáveis, tais como, propriedades mecânicas e rugosidade da chapa, lubrificação do blank, coeficiente de atrito entre o blank e a ferramenta, parâmetros da prensa (força relativamente constante e velocidade), bem como variações nas ferramentas de conformação (deformação elástica). Este trabalho se dedica a investigação da influência do atrito entre a ferramenta e o blank. Em particular, será investigado o desenvolvimento de padrões artificiais de rugosidade de chapas metálicas (textura de superfície). O foco do presente trabalho é o estudo, em condições industriais, da inter-relação entre topografia superficial caracterizada pelos parâmetros de rugosidade 2D e 3D e estampabilidade de chapas de aço para painéis automotivos. Diferentes texturas superficiais de chapas de aço foram analisadas em termos de estampabilidade (medido pelo deslocamento do blank durante a estampagem) e tentativamente relacionadas com os parâmetros de rugosidades (2D e 3D) obtidos na chapa antes de estampar. Algumas tendências relevantes foram estabelecidas entre estes parâmetros. Os resultados aqui apresentados estão em concordância com publicações recentes mostrando uma clara relação entre estes parâmetros e que trabalhos futuros são necessários.
The stamping process is influenced by several variables such as sheet mechanical properties and roughness, blank lubrication, friction coefficient, press parameters (press force and speed), as well as variations in the forming tools (elastic strain). This work is dedicated to study the influence of friction between the tool and the blank. In this sense, it is necessary to study the development of artificial roughness patterns of sheet metals (surface textures). The aim of this research work is to study the inter-relationship, using the surface topography characterized by 2D and 3D roughness parameters and the formability of steel sheets for automotive panels. Different surface textures of sheet metal have been evaluated in terms of formability (measured by material flow during the process stamping) and tentatively related to roughness parameters (2D and 3D) obtained in the sheet metal prior to stamping. Some relevant tendencies have been established amongst these parameters. The results presented here are in accordance with other recently published research work showing that there is a clear relationship between these parameters, and that further detailed studies are needed.

Le laminage à chaud de l’acier inoxydable est une étape du procédé de fabrication agissant significativement sur la qualité de surface des produits. Les nuances ferritiques stabilisées sont largement utilisées dans les applications automobiles et de décoration mais sont concernées par le phénomène de collage à chaud. Ces nuances, ayant des résistances élevées en corrosion sèche et en fluage, sont riches en éléments tels que le Cr, le Nb ou le Ti, limitant aussi l’oxydation des brames lors du laminage. Or, l’oxydation maitrisée de la brame permet de protéger la surface du métal de tout contact direct avec les cylindres de laminage.Afin de comprendre l’initiation du collage, une première campagne d’étude sur la topographie et la dégradation de l’état de surface des cylindres a été réalisée. Il a été mis en évidence que l’initiation du collage ne serait pas du à des rayures d’usure en surface des cylindres et dont la profondeur serait supérieure à la couche d’oxyde, car la probabilité que la profondeur d’une rayure de cylindre soit plus importante que la couche d’oxyde est très faible.Ensuite, un banc d’essai reproduisant les conditions tribologiques de l’emprise du laminoir a été conçu afin de mieux appréhender les mécanismes à l’origine du collage. Etant donné l’importance de l’état de surface des brames et des cylindres, ce banc d’essai a permis de travailler sur des échantillons pris en production, permettant d’étudier la surface oxydée des tôles. Cette deuxième campagne d’étude a mis en évidence l’importance des oxydes de silicium sur l’adhérence partielle de la couche d’oxyde, ainsi que la relative hétérogénéité en épaisseur et en composition chimique
Hot rolling of stainless steel is one of the most important steps in manufacturing process regarding surface quality of the product. Stabilised ferritic stainless steels are widely used in automotive and cosmetic appliances but are also concerned by sticking phenomenon. These grades, having high dry corrosion and creep resistance, are enriched in specific chemical elements such as Cr, Nb or Ti, limiting also slab oxidation during hot rolling. Nevertheless, the mastered oxidation of slab surface is a way to protect metal surface from direct contact with rolls.In order to better understand initiation of sticking, a first campaign was based on topography and rolls surface state wear analysis. This study revealed that sticking initiation is not due to the presence of roll scratches which depth is higher than oxide layer thickness. Indeed, the probability that roll scratches are deeper than oxide layer thickness is very low.In a second time, a pilot was designed, reproducing tribological conditions of a roll bite, to better understand mechanisms that initiate sticking. Keeping in mind the importance of rolls and slab surface state, this pilot is able to use specimen taking from industrial products, having the original oxide layer surface. This second study highlighted the major role of silicium oxides on scale adherence and the high heterogeneity of this scale layer in thickness and in chemical composition

Dans le cadre de ce travail, la génération des surfaces produites par le procédé de fusion laser sur lit de poudre LPBF a été étudiée. Le LPBF est un procédé de fabrication additive qui peut conduire à de nouvelles opportunités (fabrication de structures complexes avec canaux internes, structures lattices). Ce procédé attire donc une attention considérable en particulier dans l'industrie aéronautique. Une étude de l’influence des paramètres primaires du procédé LPBF sur la génération des surfaces a été réalisée. Au cours de cette étude, la relation entre la rugosité des surfaces supérieures et latérales et la densité du matériau a été établie. Cela a permis de déterminer la première fenêtre de paramètres optimaux.Une analyse de la dispersion de la rugosité et la reproductibilité du procédé ont ensuite été réalisées. Cette analyse a révélé une importante dispersion de la rugosité, notamment d'une face à l'autre. En conséquence, des recommandations sur les mesures de surface ont été proposées.L'effet de différents paramètres secondaires est également étudié afin de mieux comprendre la génération de la surface latérale et de l'optimiser. Cette étude a montré que les compensations et les réglages de contour sont des paramètres clés qui peuvent contribuent à la réduction de la rugosité des surfaces latérales. Sur la base des résultats de ces études, la rugosité a pu être diminuée d’un Sa de 40 µm à un Sa de 10 μm.Enfin, cette thèse présente une nouvelle approche de modélisation de génération des topographies des surfaces latérales. L’approche est basée sur la géométrie du cordon (rayons de courbure). Elle permet de prendre en compte la position des cordons et des couches et prédit la rugosité pour différentes stratégies de lasage et paramètres de compensation
In the current study, surface generation during additive manufacturing (AM), especially the laser powder bed fusion (LPBF) process was studied. LPBF is a progressive process that can lead to new opportunities, such as applications that require complex structures (internal channels or lightweight lattice structures). It has therefore attracted considerable attention, which has led to research and development in many industries, particularly in the aerospace industry.A surface generation study to optimize surface roughness and material density by examining the influence of the primary LPBF process parameters was therefore performed. During this study, the relationship between the roughness of the top and side surfaces and the density of the material was established. This made it possible to determine the first window of optimal parameters.An analysis of the roughness dispersion and process reproducibility were then carried out. This analysis revealed a significant roughness dispersion, especially from one side to the other. As a result, recommendations on surface measurements have been proposed.The effect of different process options (secondary parameters) are also studied in order to better understand the generation of the side surface and optimize it. This study showed that compensations and contour settings are key parameters that can help reduce the side surface roughness. Indeed, the geometric positioning of the different weld tracks is an important issue that must be addressed to reduce surface roughness. Based on the results of this study, it is possible to reduce the average surface roughness Sa from 40 to 10 μm.Finally, this thesis presents a new approach to modeling side surfaces roughness (at 0°). The approach is based on the weld track geometry (radii of curvature). It allows to take into account the weld tracks and layers position in relation to each other and thus to predict the roughness for different scanning strategies, compensation parameters

The aim of this research work is to study the inter-relationship, under controlled industrial conditions, among skin pass reductions, surface topography characterized by 2D and 3D roughness parameters, stampability and painted surface finish quality for automotive steel sheet stampings. Different surface textures obtained from cold rolling finishing have been evaluated in terms of paint appearance (rating and spectral curve) and tentatively related to roughness parameters (2D and 3D) obtained from the cold finished sheets. Some relevant tendencies have been established amongst these parameters. The results presented here are in accordance with other recently published research showing that there is a clear relationship between these parameters, and that further detailed studies are needed.
O foco do presente trabalho é o estudo, em condições industriais, da inter-relação entre grau de redução do passe de acabamento, topografia superficial caracterizada pelos parâmetros de rugosidade 2D e 3D, estampabilidade e aparência de pintura de chapas de aço para painéis automotivos. Diferentes texturas superficiais de chapas de aço foram analisadas em termos de aparência de pintura (rating e curvas espectrais) e tentativamente relacionadas com os parâmetros de rugosidades (2D e 3D) obtidos na chapa antes de estampar. Algumas tendências relevantes foram estabelecidas entre estes parâmetros. Os resultados presentes aqui estão de acordo com publicações recentes mostrando uma clara relação entre estes parâmetros e que trabalhos futuros ainda são necessários.

Our research focuses on re-using a waste a material, cross-linked polyethylene abbreviated XLPE, which is a widely used coating for wires. XLPE is strong and has excellent thermal properties due to its chemical structure - what leads to the significance of recycling this valuable polymer. Properties of XLPE include good resistance to heat, resistance to chemical corrosion, and high impact strength. A wire is usually composed of a metal core conductor and polymeric coating layers. One creates a new coating, including little pieces of recycled XLPE in the lower layer adjacent to the wire, and virgin XLPE only in the upper layer. Industries are often wasting materials which might be useful. Mostly, some returned or excess products could be recycled to create a new type of product or enable the original use. This method helps cleaning the waste, lowers the costs, and enhances the income of the manufacturing company. With the changing of the thickness of the outer layer, the roughness changes significantly. Moreover, different processing methods result in surfaces that look differently.

A 6082 aluminium alloy has been characterized with regard to the influence of surface roughness on fatigue strength.

Fatigue life testing of smooth specimens was used to establish reference curves for the material in extruded and forged T6 condition. The extruded material was found to have better fatigue strength than the forged material, although the cyclic stress-strain response was similar for both. The forged material was tested in T5, T6 and T7 tempers, showing no significant difference in fatigue strength.

Surface roughness was created by circumferential grinding of cylindrical test specimens, and the surface topography was measured using a white light interferometry microscope. The measurements proved to be accurate, although errors were observed for certain surface features. Residual stresses were quantified by X-ray diffraction. Compressive residual stresses of around 150 MPa were found in both rough and smooth specimens. Load cycling did not significantly alter the surface residual stresses.

Stress solutions ahead of all major surface grooves were found using a linear elastic material model. Estimates of cyclic stresses and strains were calculated in the notch roots using different Neuber corrections of the linear solution. The results were compared to finite element analysis employing a bilinear kinematic hardening model. A generalized version of the Neuber correction was found to be within 20% of the nonlinear finite element results.

Several empirical models for the notch sensitivity factor were investigated. These were found to be unable to describe the notch influence on fatigue life and initiation life. In order to follow this approach, it was recommended that different test specimens should be used where the short fatigue crack growth could be monitored.

It was shown that microstructural fracture mechanics theories could be used to estimate the fatigue limit of rough surfaces. In some cases, initiation from material defects or weaknesses would override the influence of surface geometry. In one specimen, the initiation appeared to have started as at a de-bonded grain, while in other cases, initiation was thought to have started at larger second phase particles embedded in notch roots. Further work in this area should focus on statistical descriptions of surface roughness, inherent material defects, and their interaction.

This work seeks to understand past and present surface conditions on the Moon using two different but complementary approaches: topographic analysis using high-resolution elevation data from recent spacecraft missions and forward modeling of the dominant agent of lunar surface modification, impact cratering. The first investigation focuses on global surface roughness of the Moon, using a variety of statistical parameters to explore slopes at different scales and their relation to competing geological processes. We find that highlands topography behaves as a nearly self-similar fractal system on scales of order 100 meters, and there is a distinct change in this behavior above and below approximately 1 km. Chapter 2 focuses this analysis on two localized regions: the lunar south pole, including Shackleton crater, and the large mare-filled basins on the nearside of the Moon. In particular, we find that differential slope, a statistical measure of roughness related to the curvature of a topographic profile, is extremely useful in distinguishing between geologic units. Chapter 3 introduces a numerical model that simulates a cratered terrain by emplacing features of characteristic shape geometrically, allowing for tracking of both the topography and surviving rim fragments over time. The power spectral density of cratered terrains is estimated numerically from model results and benchmarked against a 1-dimensional analytic model. The power spectral slope is observed to vary predictably with the size-frequency distribution of craters, as well as the crater shape. The final chapter employs the rim-tracking feature of the cratered terrain model to analyze the evolving size-frequency distribution of craters under different criteria for identifying "visible" craters from surviving rim fragments. A geometric bias exists that systematically over counts large or small craters, depending on the rim fraction required to count a given feature as either visible or erased.

In tribology engineering, friction control is a significant challenge. The interacting surfaces of mechanical components are typically designed for best efficiency during tribological operations and are primarily achieved through adequate lubrication. In these applications, breakage of the lubricant films between these contacting components can cause surface damage. In extreme-sliding interactions, this can lead to seizure and scuffing. Scuffing is a severe form of wear observed in lubricated sliding interactions. Hence, lubrication effectiveness becomes an important tribological factor that can regulate friction and wear. It is well known that the materials used in engineering applications are subjected to a range of manufacturing processes and surface finishing methods, resulting in surfaces with varying roughness and topographies. This can have a significant impact on a lubricant's ability to lubricate. Hence, understanding the influence of surface topography and roughness on lubrication, friction, and wear has always been an imperative area of high research interest. The entire experimental studies show that the surface topography and roughness synergistically influence lubrication, friction, and scuffing. The work also shows that selective determination of topography and roughness ranges can prevent scuffing and improve the efficiency of interacting tribo-components in practical engineering applications

The artificial knee and hip joints comprise a polymer-metal tribological system where soft polymers slide against hard metallic surfaces. When a polymer slides on it, the micro hard asperities remove the polymers in the form of debris. Numerous investigations discovered that the shapes and sizes of polymer debris have a major impact on the functionality and life of the artificial knee and hip joints. The counter surface topography is one of the various parameters influencing debris morphology. Hence, researchers created various surface topographies on metallic surfaces and studied their influence on debris morphology. However, debris generation is a complex process. It depends on various interrelated processes such as deformation mechanisms, adhesion, transfer film formation and debris entrapment. Friction is the source of stress, causing deformation and wear. Friction has two components: the ploughing component and the adhesion component. One or both components participate in the wear and debris generation. The researchers previously found a relationship between surface topography and the two components of friction. However, previous research is lacking or ambiguous in describing how the wear rate and debris morphology are linked with the counter surface topography. Hence, this thesis tries to correlate surface topography and wear and debris morphology. The two friction components are used to explain the obtained correlation. The explanation may contribute to understanding the basic wear and debris generation mechanisms. For the present study, various kinds of surface topography with varying roughness were created on SS316L steel plates. Wear experiments of various polymers with different physical and mechanical properties were performed against the prepared surface topographies. The wear rate was calculated from the LVDT data. The adhesion and ploughing components of friction were calculated from the friction data of the wear experiments under dry and lubricated conditions. The size and aspect ratio of the generated debris were measured using digital image analysis software. The underlying wear and debris generation mechanisms were analysed by examining the worn pin surface and the sliding tracks using a Scanning Electron Microscope. The major underlying mechanisms were ploughing, adhesion, plastic deformation, debris trapping, and debris rolling. The experimental results show that the roughness does not affect the wear rate, debris size, or aspect ratio. However, surface topography significantly affects the wear rate, debris size, and debris aspect ratio. The results are explained by analysing the variation of adhesion and ploughing components with the surface topographies. The ploughing component finds to be varied with surface topography. However, the adhesion component finds to remain independent of the kinds of surface topography. The results conclude that the ploughing component of friction primarily dictates the wear rate with a proportional relationship. However, the adhesion component of friction primarily dictates the transfer film formation, debris entrapment and its rolling. This provides a reducing effect on effective wear. The debris morphology results show that, in the absence of the adhesion, debris size has a proportional relationship with the ploughing component. The size of the debris has an inverse relationship with the ploughing component of friction when adhesion is present. The ploughing and adhesion together generate smaller debris than ploughing alone. The results also conclude that the aspect ratio of debris has a proportional relationship with the ploughing component of friction. However, the adhesion and ploughing together produce debris with a larger aspect ratio than ploughing alone produces.

In this work, measurements and simulations were used to investigate the effects of grinding wheel topography on the geometric aspects of the grinding process. Since existing methods for measuring the grinding wheels were either not accurate enough or could only measure a small portion of a grinding wheel, a novel grinding wheel measurement system was developed. This system consists of a white light chromatic sensor, a custom designed positioning system and software. The resulting wheel scanning system was capable of measuring an entire grinding wheel with micron level accuracy. The system was used to investigate the effects of fine, medium and course dressing on grinding wheel surface topology and the resulting workpiece surface. New techniques were also developed to simulate metal removal in grinding. The simulation software consisted of a stochastic wheel model, dressing model and metal removal model. The resulting software could determine the uncut chip thickness, contact length for every cutting edge on a grinding wheel as well as the resulting surface roughness of the grinding wheel. The simulation was validated by comparing the wheel model used in the simulation to grinding wheel measurements and by comparing the simulated surface finish to the measured surface finish. There was excellent agreement between the predicted and experimentally measured surface topology of the workpiece. The results suggested that only 22 to 30% of the cutting edges exposed on the grinding wheel are active and that the average grinding chip is as much as 10 times thicker and 5 times shorter than would be produced by a grinding wheel with a regular arrangement of cutting edges as assumed by existing analytical approaches.

W rozprawie przedstawiono zagadnienie pomiaru i charakteryzacji topografii powierzchni miękkich soczewek kontaktowych metodami: mikroskopii sił atomowych (AFM) i mikroskopii konfokalnej. Głównymi celami pracy były: analiza parametrów statystycznych popularnych soczewek kontaktowych oraz opracowanie jednolitej procedury pomiarowej topografii powierzchni soczewek kontaktowych za pomocą mikroskopu AFM. W głównym eksperymencie zmierzono topografię powierzchni siedmiu soczewek silikonowo-hydrożelowych. Potwierdzono tezę, iż rodzaj materiału oraz zastosowane procedury obróbki powierzchni wpływają na topografię powierzchni soczewek. Udowodniono, że soczewki nowszej generacji wykazują mniejszą chropowatość w porównaniu do soczewek starszej generacji. Zbadano także wpływ zastosowanej sondy AFM na pomiar topografii powierzchni soczewek. Poprzez modyfikację powierzchni sondy z wykorzystaniem trimetoksy(propylo)silanu osiągnięto możliwość zobrazowania topografii powierzchni materiału, który z uwagi na silne przyciąganie typowej sondy krzemowej do powierzchni próbki uniemożliwiał obrazowanie w trybie semikontaktowym (tapping). Ważnym aspektem pracy jest zrozumienie procesu osadzania się depozytów na powierzchni soczewek w trakcie ich użytkowania. W pracy zbadano topografię powierzchni zarówno soczewek nowych jak i używanych, w celu określenia jakie zmiany występują w trakcie ich codziennego użytkowania. W eksperymencie porównano powierzchnię soczewek używanych w trybie ciągłym oraz soczewek poddawanych codziennej pielęgnacji. Soczewki używane w trybie ciągłym wykazywały większą chropowatość w zestawieniu z soczewkami nowymi, co nie jest oczywiste z uwagi na to, że w przypadku niektórych typów soczewek osady mogą zmniejszać chropowatość poprzez wypełnienie zagłębień. Poddawanie soczewek codziennej procedurze czyszczenia wpływało na zmniejszenie chropowatości powierzchni w porównaniu do soczewek noszonych w trybie ciągłym niemniej ich powierzchnia wykazywała znaczące różnice w porównaniu do soczewek nieużywanych. Zbadano również zmiany w topografii powierzchni soczewek jednodniowych, które następują wskutek użytkowania. Podobnie jak w przypadku soczewek miesięcznych powierzchnia różniła się w porównaniu do nowej soczewki, niemniej z uwagi na krótszy czas noszenia obserwowane zmiany były mniejsze w porównaniu do soczewek miesięcznych. Zbadano także możliwość charakteryzacji topografii powierzchni soczewek kontaktowych z użyciem mikroskopii konfokalnej. Użycie tego typu mikroskopu jest tańsze i mniej inwazyjne niż w przypadku AFM, potencjalnie umożliwia też śledzenie zmian w trakcie użytkowania. Analizie poddano obrazy – rozkłady maksymalnej odpowiedzi optycznej. Uzyskane wyniki świadczą o tym, że istnieje związek pomiędzy chropowatością powierzchni soczewek a odpowiedzią optyczną, jednakże nie jest możliwe użycie powszechnie stosowanych globalnych wskaźników statystycznych do oceny i porównania chropowatości powierzchni soczewek. W pracy podjęto próbę opracowania wskaźnika związanego z chropowatością powierzchni soczewek kontaktowych z użyciem odpowiedzi optycznej uzyskanej za pomocą mikroskopu konfokalnego. Jednakże, wstępna analiza wykazała, iż mimo dostrzegalnej różnicy w obrazach z mikroskopu konfokalnego, globalne wskaźniki statystyczne, stosowane podczas analizy obrazów z AFM nie znajdują zastosowania w analizie obrazów z mikroskopu konfokalnego. Dodatkowo, wykonano analizę granulometryczną obrazów z mikroskopu konfokalnego, która dała niejednoznaczny wynik, co sugeruje, że wskaźnik związany z chropowatością powierzchni powinien być rozwijany z użyciem bardziej zaawansowanych metod lokalnej analizy obrazów lub innych narzędzi numerycznych.
In the dissertation, the problem of measurement and characterization of surface topography of soft contact lenses using atomic force microscopy (AFM) and confocal microscopy was studied. The main goals of the work were: to analyze statistical parameters of popular contact lenses and to develop a uniform procedure for measuring contact lens surface using AFM. In the main experiment surface topography of seven silicone-hydrogel lenses was measured. A hypothesis was confirmed that material type and surface treatment process influence the surface topography. It was proved that new generation lenses exhibit smaller roughness that older ones. The impact of the type of AFM probe on surface topography measurements was also investigated. As a result of modification of the probe surface using trimethoxy(propyl)silane, the ability to visualize the surface topography of the material has been achieved, which, due to the strong attraction of the probe to the surface was not possible in the tapping mode with standard silicone probe. An important aspect analyzed in the dissertation was to understand the process of accumulation of deposits on the lens surface during wear. In the work the surface topography of both new and used lenses were investigated to analyze changes that occur during daily use. In the experiment the lens surfaces were compared for two regimes of care: continuous operation and lenses subjected to daily care. The lenses used in the continuous regime exhibited higher roughness in comparison with the new lenses. This result is not obvious since for certain lens types lower roughness is achieved during use because of deposits that fill gaps in the surface. The measurement of lenses subjected to the daily procedure of cleaning resulted in lower surface roughness when compared with lenses in the continuous regime of operation. In the case of both care procedures the roughness was still higher than in the case of new lenses. Changes in the surface topography of one-day contact lens that result from the wear were also investigated. Similarly to monthly lenses for one-day lenses the surface topography changes were observed but at the same time were smaller than for monthly lenses due to shorter time of operation. The possibility of characterization of the surface topography of contact lenses using confocal microscopy was also investigated. The use of this type of microscope is cheaper and less invasive than of AFM, and potentially allows to inspect changes during the daily use. The images were analyzed that are distributions of maximum optical response. The obtained results show that there is a relationship between the surface roughness of the lenses and the optical response, however, it is not possible to use the commonly used global statistical parameters to evaluate and compare the surface roughness of the lenses. An attempt was made to develop a parameter related to the surface roughness of contact lenses using the optical response obtained with a confocal microscope. However, preliminary analysis showed that despite the visual differences between the images, the global statistical parameters used in the analysis of the AFM images are not applicable to the analysis of confocal microscopic images. Additionally, granulometric analysis of the confocal microscope images was performed, which gave an inconclusive result, suggesting that the index related to surface roughness should be developed using more advanced local image analysis methods or other numerical tools.