In an effort to increase machining efficiency and minimize costs, research into tool condition monitoring (TCM) systems has focused on developing methods to allow for unmanned machining. For drilling processes, such systems typically use indirect approaches to monitoring the tool condition by measuring spindle torque and feed force as well as vibrations including acoustic emission (AE – mechanical vibrations faster than 100 kHz). This project aimed to advance the state-of-the-art in the area of TCM by developing a method to detect sudden tool failures in large diameter (> 25 mm) indexable insert drills. This project was a continuation of the research conducted by Mr. R. Griffin (a former MSc student), who developed a model capable of predicting long term wear trends in indexable insert drills [1]. Notably, his model was unable to react to sudden tool breakage due to tool chipping, which was addressed by this project as presented in this thesis. In order to develop and train models able to detect sudden tool failure, an experiment was developed and installed in the field of the industry partner of this project. The experiment’s main feature was a pair of AE sensors added to the existing torque and force sensors. On this setup, experiments were conducted by drilling 2251 holes in workpieces using indexable insert drills with or without the insert breaking. When drilling holes without the insert breaking, the holes were named as good ones; and when drilling holes with the insert breaking they were named as bad holes. During the drilling process, data was collected from current sensors attached to the spindle motor and feed motor as well as from an AE sensor on the spindle and on the workpiece. From the signals from the spindle motor current and feed motor current sensors, algorithms were developed to identify and divide the signals of drilling a hole into different sections of the drilling cycle (i.e. entrance, steady-state, exit, etc.). Steady-state time-domain features were extracted from the sensor signals measured for all holes drilled in the experiments and the extracted features were used to train and test the classifier models. These models were cross validated to determine which type of model was the best fit for the drilling data collected. The results from the classifier models show that most of the classifiers tested have the ability to identify sudden tool breakage based on the data recorded in the present study, with varying degrees of success. The naïve Bayes classifier was able to detect the most failures but suffered from a large number of falsely detected failures. Both the classification tree and linear discriminant analysis classifiers had lower failure detection rates than the naïve Bayes classifier, but did not suffer from the same amount of false positives; as such, these two classifiers had higher overall classification rates than the naïve Bayes. These results suggest that classification tree and linear discriminant analysis methods are better suited for the drilling application and that the time-domain features should be complemented by others, such as the features extracted from the frequency domain, to accurately diagnose the tool condition. Future research should focus on extracting frequency and time-frequency domain features as these features might contain more information on tool condition. In addition, methods of examining features at the entrance and exit of the holes should be investigated as these two points in the drilling cycle are the most prone to sudden tool failure.

The analysis of pile behavior is a complex problem due to the diversity of the phenomena governing the soil behavior and particularly that of the neighboring soil. The objective of this work was to develop a valid modeling tool to evaluate piles' behavior under axial loads by developing a pertinent mechanical model supported in a robust finite element program which would successfully reproduce the soil behaviour under extreme monotonic and cyclic shear strain. This is done to allow for the numerical modelling of the installation procedure of pile foundations and continued loading of high amplitude cyclic paths. In order to model the installation phase of a monotonic, jacked or dynamic pile foundation some issues must be addressed. Finite deformations take place whilst the pile is put in place requiring an adjustment in the mechanical formulation of the model at the interface level to take into account that the small deformations (rotations and strain) hypothesis is no longer valid. Moreover, the constitutive model must take into account the physical behaviour of the soil when subjected to high order of magnitude displacements. This includes the phenomenon of grain breakage, also referred to as particle crushing, which greatly influences the volumetric behaviour of soil as thus reflecting of shear stress mobilization. The elastoplastic ECP model has therefore been enhanced by introducing an internal variable taking into account the breakage mechanism. The thermodynamic admissibility criteria are verified for the original and revised constitutive models. Both monotonic and pseudo-dynamic installation procedures were numerically simulated and the results thoroughly analysed. Finally, the cyclic shear resistance degradation at the pile shaft is a commonly occurring phenomenon during continued cyclic loading of pile foundation (friction fatigue). The constitutive modelling of this phenomenon, however, is not a straightforward matter. The stress path followed by the thin layer at the soil-pile interface level is known to be directly related to the volumetric behaviour due to the boundary conditions of the problem. A comprehensive analysis of all the components of the behaviour of soil during this stage was object of study in this work.

In the present work, the breakage of wastewater particles in orifice flow is investigated through numerical simulations. Using maximum strain rate along particle paths as the breakage criterion, breakage is predicted using computational fluid dynamics. The numerical simulations confirm that nominal orifice strain rate cannot explain the higher particle breakage in single-orifice systems compared to that of multi-orifice systems, instead particle breakage was found to correlate well with the maximum strain rates in the system. On the issue of effect of initial particle location on breakage, numerical modeling shows that particles travelling along the centerline are suspected to break less than those travelling near the wall. However, experiments designed to study the breakage of particles injected at various radial locations proved inconclusive. Finally, results suggest that while single orifice systems are ideal for strong particles, multi-orifice systems may be more effective in breaking weak particles.

In the present work, the breakage of wastewater particles in orifice flow is investigated through numerical simulations. Using maximum strain rate along particle paths as the breakage criterion, breakage is predicted using computational fluid dynamics. The numerical simulations confirm that nominal orifice strain rate cannot explain the higher particle breakage in single-orifice systems compared to that of multi-orifice systems, instead particle breakage was found to correlate well with the maximum strain rates in the system. On the issue of effect of initial particle location on breakage, numerical modeling shows that particles travelling along the centerline are suspected to break less than those travelling near the wall. However, experiments designed to study the breakage of particles injected at various radial locations proved inconclusive. Finally, results suggest that while single orifice systems are ideal for strong particles, multi-orifice systems may be more effective in breaking weak particles.

Submitted by Pedro Augusto Grava da Silva null (pedroagrava@gmail.com) on 2017-08-31T20:44:35Z No. of bitstreams: 1 Dissertação Mestrado - Pedro Augusto Grava da Silva.pdf: 2172440 bytes, checksum: 060031f8bfdf62d96e69dee0cad48a65 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-09-01T14:47:36Z (GMT) No. of bitstreams: 1 silva_pag_me_bauru.pdf: 2172440 bytes, checksum: 060031f8bfdf62d96e69dee0cad48a65 (MD5) / Made available in DSpace on 2017-09-01T14:47:36Z (GMT). No. of bitstreams: 1 silva_pag_me_bauru.pdf: 2172440 bytes, checksum: 060031f8bfdf62d96e69dee0cad48a65 (MD5) Previous issue date: 2017-07-12 / Item merged in doublecheck by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-12-07T18:03:54Z Item was identical to item(s): 152464, 152368 at handle(s): http://hdl.handle.net/11449/151521, http://hdl.handle.net/11449/152148 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Esta dissertação teve como objetivos a investigação da resistência e do recrescimento de flocos, produzidos durante a floculação de água destinada ao abastecimento, e foi dividida em duas etapas. Em primeiro lugar a resistência de agregados à quebra induzida por distúrbio hidrodinâmico foi investigada por meio de três técnicas macroscópicas de medição, a saber: fator de resistência (FR), a tensão local (σ) e o coeficiente de resistência do floco (γ). Num segundo momento a capacidade de recuperação do tamanho dos agregados foi investigada. O diâmetro estável (d) e o parâmetro característico da função de distribuição de tamanho de agregados (β) foram utilizados para analisar o processo refloculação após a quebra induzida dos agregados. Para obtenção das variáveis de interesse, foi utilizado método não intrusivo de análise de imagem e equipamento baseado em dispersão de luz. As águas de estudo foram preparadas em laboratório a partir de solução de ácido húmico (água tipo 1) e suspensão de caulinita (tipo 2), e coaguladas por dosagem de sal de alumínio em região do mecanismo de varredura. A floculação ocorreu em gradientes de velocidade médios (G) entre 20 e 120 s-1, e a ruptura ocorreu sob condições controladas com Gquebra de 800 s-1 por 10 segundos. Após a ruptura, a condição inicial foi reestabelecida para análise da recuperação de tamanho do agregado. Os resultados mostraram, para as duas água de estudo, uma tendência crescente para FR em resposta ao aumento de G. A mesma tendência foi observada para γ o que pode indicar que condições elevadas de agitação produzem flocos mais resistentes. Os resultados da análise da refloculação apontaram que o agregado não recupera totalmente seu tamanho, tanto para os flocos de Al-ácido húmico como para os de Al-caulinita. Para água tipo 1, o diâmetro estável dos agregados diminuiu de 332 μm antes da quebra, para 157 μm após a recuperação, e de 233 para 132 μm na água tipo 2, utilizando G de 20 s-1. O parâmetro β que exprime a distribuição de tamanho dos agregados, também apontou para uma diminuição geral do tamanho dos agregados, de forma que após a quebra a distribuição foi deslocada para as faixas de classificação de menor tamanho. / This dissertation has aimed to investigate the strength and re-growth during the flocculation of drinking water, and was divided into two steps. The first one was investigate the rupture of floc caused by shear induced forces through three macroscopic techniques, namely: strength factor (FR), the average strength per unit area at the plane of rupture (σ) and the floc strength coefficient (γ). The second one was investigate the re-growth ability of flocs. The stable diameter (d) and the characteristic parameter of the aggregate size distribution function (β) were used to analyze the re-growth process after the induced breakage of the aggregates. The method was based on a non-intrusive image analysis monitoring technique and a light scattering equipment. The study waters were prepared in laboratory from humic acid solution (water type 1) and kaolinite suspension (type 2) and coagulated by dosing aluminum salt in the region of the “sweep flocculation” mechanism. The flocculation occurred for average velocity gradients (G) from 20 to 120 s-1 and the breakage occurred under controlled conditions for Gquebra of 800 s-1 for 10 seconds. After breakage, the initial condition was re-established for aggregate size recovery analysis. For the two study waters the results showed an increasing trend for FR in response to the increase of G. The same trend was observed for γ which may indicate that high agitation conditions produce more resistant flocs. The reflocculation analysis results showed that the aggregate did not fully recover its size, both for the aliquots of Al-humic acid and those of Al-kaolinite. The stable diameter of the aggregates for water type 1 decreased from 332 μm before breakage, to 157 μm after recovery, and from 233 to 132 μm in water type 2, using G of 20 s-1. The parameter β expressing the aggregate size distribution also pointed to a general decrease in aggregate size, so that after the breakage the distribution was shifted to the smaller size ranges. / 33004056089P5

Particles exist in great abundance in nature, such as in sands and clays, and they also constitute 75% of the materials used in industry (e.g., mineral ores, formulated pharmaceuticals, dyes, detergent powders). When a load is applied to a bulk assembly of soil particles, the response of a geomaterial at the bulk (macro) scale, originates from the changes that take place at the particle scale. If particle breakage occurs, the shape and size of the particles comprising the bulk are changed; this induces changes in the contact network through which applied loads are transmitted. As a result, changes at the micro-scale can significantly affect the mechanical behaviour of a geomaterial at a macro-scale. It is therefore unsurprising that the mechanisms leading to particle breakage are a subject of intense research interest in several fields, including geomechanics. In this thesis, particle breakage of two dry granular materials is studied, both experimentally and numerically. The response of the materials is investigated under different stress paths and in all the tests grain breakage occurs. High resolution x-ray computed micro-tomography (XCT) is used to obtain 3D images of entire specimens during high confinement triaxial compression tests and strain controlled oedometric compression tests. The acquired images are processed and measurements are made of the temporal and spatial evolution of breakage, local variations of porosity, volumetric and shear strain and grading. The evolution and spatial distribution of quantified breakage including the resulting particle size distribution for the whole specimen and for specific areas, are presented and further related to the localised shear and volumetric strains that developed in the specimens. In addition, the discrete element method (DEM) was used to provide further micro-mechanical insight of the underlying mechanisms leading to particle breakage. Classical DEM simulations, using a Hertz-Mindlin contact model and non-breakable spheres, was first deployed to study the initiation and likelihood of particle breakage under oedometric compression. Moreover, a bonded DEM model was used to create clumps that represent each particle and simulate breakage of particles under single particle compression. The DEM model parameters were obtained from results of single particle compression test and the models were validated against the quantitative 3D information of the micro-scale, acquired from the XCT analysis.

Inúmeras são as vantagens da utilização de instrumentos rotatórios de níquel-titânio no preparo químico-cirúrgico, como por exemplo, melhor modelagem dos canais curvos e uma diminuição significativa no tempo de trabalho. Todavia, a maior preocupação no uso desses instrumentos tem sido a sua fratura, principalmente, por sua ocorrência estar ligada a diferentes fatores. O objetivo do presente estudo foi avaliar a influência da velocidade de rotação e do número de usos, no tempo de trabalho e na ocorrência de fraturas de instrumentos de dois sistemas rotatórios de níquel-titânio (K3 e RaCe), em canais simulados com mesmo ângulo de curvatura. Foram avaliados os instrumentos 25/.04 dos dois sistemas nas velocidades de 180, 350, 600 rpm ao instrumentarem 5 mm referentes à curvatura dos canais simulados. Para cada velocidade foram utilizadas limas com 1, 2 e 3 usos. Um contra-ângulo foi adaptado a um dispositivo calibrado para realizar movimentos padronizados de penetração nos canais simulados. Foram mensurados: o tempo necessário para instrumentar a curvatura do canal e a quantidade de fraturas ocorridas. Os resultados obtidos foram submetidos a ANOVA sendo em seguida empregado o teste de Tukey (&#945;=5%). Sob as condições desse experimento, o aumento da velocidade diminuiu o tempo de instrumentação em ambos os sistemas. Os instrumentos RaCe prepararam o canal em menor tempo do que os instrumentos K3 nas velocidades de 350 e 600 rpm (p<0,05), não havendo diferença em 180 rpm (p>0,05). Ocorreu maior número de instrumentos fraturados nas velocidades de 180 e 600 rpm para o sistema RaCe e de 600 rpm para o K3, e nenhuma fratura na velocidade de 350 rpm para ambos. O número de usos não influenciou o tempo de trabalho para nenhum sistema (p>0,05), porém, o número de fraturas aumentou proporcionalmente ao aumento do número de usos, exceto na velocidade de 350 rpm na qual não ocorreram fraturas. Os instrumentos RaCe apresentaram maior índice de fratura para a velocidade de 180 rpm (30%) do que para 600 rpm (13,33%). A velocidade de 350 rpm foi a mais segura para os instrumentos de ambos os sistemas. / Use of nickel-titanium rotary instruments has many advantages like better shaping of curved canals and lower working time. However, instrument fracture has always been a serious concern in root canal treatment because it involves a lot of factors. The aim of this study was to evaluate the influence of rotational speed and number of uses on the preparation time and incidence of fractures of K3 and RaCe instruments, using simulated root canals with the same angle of curvature. Nickel-titanium 25/.04- tapered instruments of both rotary systems were tested at 180, 350 and 600 rpm during shaping of 5 mm curvature’s extent. The files were used 3 times in each rotational speed. A contra-angle electric handpiece was mounted on a machine that was calibrated to deliver a constant penetration movement. Working time and incidence of fractures were measured. The results were analyzed statistically using a one-way analysis of variance with a post-hoc Tukey test (&#945;=5%). Under the conditions of this study, higher rotational speeds reduced preparation time for both rotary systems. RaCe instruments showed lower preparation time than K3 instruments at 350 and 600 rpm (p<0,05). There was no significant difference at 180 rpm (p>0,05). There was a higher incidence of fractures at 180 and 600 rpm for RaCe instruments and at 600 rpm for K3 instruments. No file breakage occurred at 350 rpm for both instruments. Preparation time was not influenced significantly by the frequency that the files were used (p>0,05). Incidence of fractures increased with an increase in the number of file usage, unless at 350 rpm in which none of the files fractured. At 180 rpm, RaCe instruments showed a higher incidence of breakage than at 600 rpm. Rotational speed of 350 rpm was the safest for both kind of instruments tested in this study.

In this study the breakage mechanics of brittle glass marbles was investigated. The pro-cess was to firstly investigate them in laboratory environment. The marbles or specimens was loaded until a crushing breakage occurred in a single point load test called Single Sphere Point load test in this document. From the test we could derive the crushing load, the deformation and strain, the tensile strength and other parameters needed for the second part of this work. Namely the numerical modelling, here we investigated the specimen with the Discrete Element method or DEM for shorts. The software used was an open sourced software created in MATLAB called DICE2D. Since the software was developed to only include the mathematical part of the numerical model several re-coding processes were needed, with other words the creation of add-ons to the software. The add-ons were automatic code created in Python where the user now are able to create a geometrical model for the specimen that the software can interpret. There were two add-ons created in order to generate a geometry, called the circumference method and the random generation method, i.e. different methods of creating a geometry. The first method, the circumference method creates circumferences filled with smaller particles with the same radii, then moves a step inward to the specimens center and fills another circumference until the center is reached. The second method, the random method generates particles positioned randomly inside the specimen with a random radii, created such that the radius of the particles is chosen with an interval, were the user can choose the smallest and the largest particle radius. It was found that both these add-ons were of great use with different purposes in mind. The circumference method was able to create a brittle material where the deformations were low. The random method also created a brittle material but since the particles were randomly positioned there also was empty space created such that the deformations were larger than the one found in the laboratory environment, since the empty space between the particles was closed before the plastic deformation could occur. Hence the second method of generation is more relevant for concrete and rock mechanics since in these cases this is the actual process, where the micro-cracks first closes then the elastic and plastic deformation occurs [Martin, 1993]. The first method, the circumference method is of great use when investigating the elastic deformations since here the particles are in contact. Thus creating the scenario for granular particles, In this thesis however the circumference method was used in order to create a solid specimen. For future use this add-on should be used in order such that each particle simulates an actual grain. The results found with both of these methods follows the results found in the laboratory test for the crushing load. But the incremental increase of force when the load is applied on the specimen was not able to be simulated. It is believed that the software is having difficulties to simulate brittle material due to the small deformations and the large loads.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21355号 / 工博第4514号 / 新制||工||1703(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 KIM Chul-Woo, 教授 杉浦 邦征, 講師 張 凱淳 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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