Master of Science / Department of Animal Sciences and Industry / Jeffrey S. Stevenson / Lactating dairy cows from 2 Kansas farms were used to determine the effectiveness of exogenous progesterone in the form of an intravaginal insert (controlled internal drug release; CIDR) in conjunction with an ovulation-synchronization protocol. Cows were enrolled in a Presynch + Ovsynch protocol after parturition, where they received 2 injections of PGF[subscript]2[alpha], 14 d apart (Presynch) beginning between 30 and 36 DIM. Cows (n = 155) detected in estrus after the second PGF[subscript]2[alpha] injection of Presynch were inseminated (early AI). Remaining cows were assigned randomly to be treated with the Cosynch-72 protocol (GnRH 12 d after last Presynch PGF[subscript]2[alpha] injection, PGF[subscript]2[alpha] 7 d after GnRH, and timed AI + GnRH injection 72 h later) and served as controls (n = 159), or to be treated with the Cosynch-72 protocol and receive a progesterone insert (Ovsynch + CIDR; n = 175) for 7 d between GnRH and PGF[subscript]2[alpha]. Blood was collected at d −22 and −10 (relative to TAI at d 0) to determine cycling status based on progesterone concentrations and again at d 11 post AI to determine luteal competency. Treated cows were assigned body condition scores (BCS) on d −22 and −10. Pregnancy status was confirmed by palpation of the uterus per rectum and its contents on d 38 post-timed AI and verified again 4 wk later. Treatment with the progesterone insert increased timed AI pregnancies per AI in Cosynch- 72 + CIDR-treated cows when compared with controls (38 vs. 24%), but did not differ from early AI cows (38%). Pregnancy loss was numerically less in progesterone-treated cows than in controls (4.4 vs. 11.8%). Our study shows that increased pregnancies per AI can be achieved by the use of a progesterone insert in a reduced population of cows not yet inseminated, but treated with a progesterone insert.

Este trabalho avalia o uso de insertos autolubrificantes de pó de aço ferramenta sinterizado para aplicação em ferramentas dos processos de Conformação a Frio. São apresentadas a preparação e a análise de diferentes composições de misturas de pós de aço ferramenta H 13. A Metalurgia do Pó convencional foi utilizada como processo para a obtenção dos insertos do estudo. Foram compactadas e sinterizadas misturas de pó de aço H13 com a adição de percentuais variados do lubrificante sólido Bissulfeto de Molibdênio – MoS2, também em pó, com o objetivo de atribuir propriedades de autolubrificação ao composto. O percentual de lubrificante sólido empregado nas amostras variou de 1% a 5%, com posterior sinterização. Os resultados obtidos no Ensaio de Atrito com anéis de Alumínio AA6351 recozido apresentaram nos insertos autolubrificantes do estudo coeficientes de atrito μ entre 0,10 e 015, menores que os valores μ entre 0,20 e 0,30 obtidos com aço H13 laminado convencional. Também o desgaste abrasivo do ferramental proposto avaliado no Ensaio de Abrasão com Roda de Borracha foi 12% menor quando comparado com o aço ferramenta H13 laminado exposto ao mesmo ensaio. / This study evaluates the use of self-lubricating tool steel powder sintered inserts for use in tools of Cold Forming processes. Preparation and analysis of various compositions of H13 tool steel powder mixtures are presented. The conventional Powder Metallurgy was used as a process for obtaining the study inserts. Were compacted and sintered mixtures of H13 steel powder with the addition of varying percentages of the solid lubricant Molybdenum Disulphide - MoS2, also in powder form, with the purpose of giving self-lubricating properties to the composite. The percentage of solid lubricant used in the samples varied from 1% to 5%, with subsequent sintering. The results of the friction test on AA6351 aluminum rings had friction coefficients μ between 0.10 and 015 with self-lubricating inserts in study, smaller than μ values between 0.20 and 0.30 obtained with the conventional steel H13 laminate. Also, the abrasive wear of the tooling proposed evaluated in the abrasion test with rubber wheel was 12% lower when compared to the H13 tool steel laminate exposed to the same test.

O presente trabalho apresenta o desenvolvimento de um inserto em aço ferramenta AISI H13 obtido por meio do processo de Metalurgia do Pó com a adição de lubrificante sólido na sua composição, que tem a finalidade de conferir propriedades autolubrificantes ao mesmo. Foram utilizados os pós de MoS2 e de h- BN para promover a redução do coeficiente de atrito. Adicionou-se o lubrificante MoS2 ao pó de aço ferramenta na etapa de mistura dos pós, em concentrações que variaram de 1% a 5%. Da mesma forma, foram confeccionados corpos de prova substituindo o MoS2 por h-BN. Após a compactação de todos os corpos de prova eles foram sinterizados. A mistura com h-BN apresentou grande formação de óxido durante os processos de sinterização e de tratamento térmico, sendo descartada sua utilização para os ensaios de abrasão para verificar desgaste e para os ensaios do anel que determinam o coeficiente de atrito. Conforme as análises realizadas, pode-se observar a formação de fases distintas, com ilhas de lubrificante MoS2 em matriz ferrítica. Utilizou-se o ensaio do anel para determinação do coeficiente de atrito de Coulomb – μ, e anéis de Alumínio como corpos de prova para este ensaio. Os insertos de MoS2 apresentaram ótimos resultados neste ensaio, e foram similares a experimentos realizados por outros pesquisadores que utilizaram o mesmo sistema tribológico deste trabalho - H13 como ferramenta, MoS2 como lubrificante e anéis de Alumínio para conformação. A diferença satisfatória obtida pelo material confeccionado neste estudo em relação aos obtidos da literatura pesquisada está na forma de utilização do lubrificante, que neste caso foi adicionado à matriz pelo processo de Metalurgia do Pó, enquanto que nos trabalhos analisados o lubrificante foi borrifado sobre a matriz. / The present work describes the development of an insert of tool steel AISI H13 obtained by powder metallurgy process with the addition of solid lubricant in the composition, in order to impart self-lubricating properties. MoS2 and h-BN powder were used to promote the reduction of the friction coefficient. It was added MoS2 lubricant with the tool steel powder in the mixing step at concentrations ranging from 1% to 5%. Similarly were prepared specimens replacing MoS2 for h- BN. After compression of the samples they were also sintered. The mixture with h- BN showed extensive formation of oxide during the sintering process and heat treatment, and discarded their use for the abrasion test for wear and ring assays for the determination of the friction coefficient. Through the analysis carried out, were observed the formation of distinct phases with lubricant MoS2 islands in ferritic matrix. The tests for friction in samples with MoS2 showed good results, similar to experiments by other researchers who used the same tribological system of this work - H13 as a tool, MoS2 as a lubricant and aluminum rings for conformation. Satisfactory difference obtained by the material made in this study compared to those obtained from the literature is in the form of use of the lubricant, which in this case was added to the matrix by the powder metallurgy process, whereas in the studies analyzed the lubricant was sprayed onto the matrix.

O objetivo deste trabalho foi propor potenciais misturas de pós para utilização na indústria automotiva, mais especificamente ligas metálicas aplicadas na produção de insertos de assentos de válvulas. A pesquisa foi dividida em etapas como segue a produção via metalurgia do pó: seleção dos componentes para as ligas metálicas estudadas, aquisição e preparo de cada um dos pós metálicos, caracterização física e microscópica dos componentes da mistura, definição das proporções a serem usadas, mistura dos pós constituintes, compactação a frio em prensa uniaxial, sinterização das peças de acordo com ciclo térmico e atmosfera específicos, realização de ensaios de dureza, resistência à compressão radial e análise microestrutural por microscopia de varredura eletrônica. As misturas de pós forma basicamente pó de ferro misturado com aços rápidos, AISI M3/2, D2 e M2. Os insertos produzidos com a liga metálica denominada M3/2 mostraram-se mais vantajosos em relação aos demais por terem apresentado melhor desempenho nos testes de dureza e resistência à compressão radial. / The aim of this study was to propose potential materials for use in the automotive industry, specifically alloys applied in the production of valve seat inserts. The research was divided in steps according to standard powder metallurgy technique: selecting components for the studied alloys, acquisition and preparation of each of the metal powders, physical and microscopic characterization of the components, defining the proportions to be used, a mixture of alloys, compaction in uniaxial presses, sintering the parts according to thermal cycle and specific atmosphere, hardness tests, resistance to radial compression and microstructural analysis using scanning electron microscopy. The powders mixtures were basically iron powder mixed with high-speed steels type AISI M3/2, D2 and M2. The valve seat inserts made with the alloy M3/2 showed to be more advantageous in relation to the other mixtures in terms of hardness and transverse rupture strength.

This thesis presents methods to statistically quantify data from fastener vibration life tests. Data from fastener vibration life tests with secondary locking features of threaded inserts is used. Threaded inserts in three different configurations are examined: no locking feature, prevailing torque locking feature, and adhesive locking feature. Useful composite plots were developed by extracting minimum preloads versus cycles from test data. Minimum preloads were extracted due to the overlapping of varying test data and because the minimum preload is of most interest in such tests. In addition to composite plots, descriptive statistics of the samples were determined including mean, median, quartiles, and extents. These descriptive statistics were plotted to illustrate variability within a sample as well as variability between samples. These plots also reveal that characteristics of loosening for a sample, such as preload loss and rates of preload loss, are preserved when summarizing such tests. Usually fastener vibration life tests are presented and compared with one test sample, which is why statistically quantifying them is needed and important. Methods to predict the sample population have been created as well. To predict populations, tests to determine the distribution of the sample, such as probability plots and probability plot correlation coefficient, have been conducted. Once samples were determined to be normal, confidence intervals were created for test samples, which provides a range of where the population mean should lie. It has been shown that characteristics of loosening are preserved in the confidence intervals. Populations of fastener vibration life tests have never before been presented or created. The evaluation of loosening has been conducted for fastener vibration life tests in the past with plots of one test sample; however, in this work statistically quantified results of multiple tests were used. This is important because evaluating loosening with more than one test sample can determine variation between tests. It has been found that secondary locking features do help reduce the loss of preload. The prevailing torque secondary locking feature is found to be more effective as preload is lost. The best secondary locking feature has been found to be the adhesive.

High Pressure Die Casting (HPDC) is low-cost technique for the mass production of complex, non-ferrous parts. Despite its benefits such as dimensional accuracy, surface quality and high production rate / some mechanical drawbacks limit use of HPDC in production of critical parts especially under dynamical loads. This study aims to improve impact resistance and surface hardness of die cast parts by means of tool steel inserts. These inserts act as a barrier between the impactor and die casting alloy, in order to avoid surface deformation and reduce stress localization which leads crack formation. Except the impact surface, whole insert is embedded into the die casting alloy by placing them on specially machined die casting molds prior to the metal injection. The mentioned method was evaluated by mechanical test and micro-examinations which were applied on AISI D2 tool steel inserted A518.0, A413.2 and Zamak5 alloy samples. To see the effect of inserts on energy absorbance under single destructive loads, both monolithic (conventional) and inserted (produced by mentioned technique) samples were subjected to Charpy impact test. In order to observe its behavior under non-destructive, cyclic, low velocity impacts / a dedicated real rifle part was produced by this method and tested in the real service loads. Explicit Finite Elemental Analysis was also carried out to understand how the inserts increases the energy absorbance and protect the die cast body by simulating both destructive and non-destructive impact loads. In addition to these, micro-examinations were also conducted especially on insert-die casting alloy interface for chemical and physical interactions, defects and stability. In regards of experimental findings, mechanical feasibility of the method was achieved. It was proved that steel inserts improve energy absorbance, stress distribution and impact-surface hardness of die cast products.

Tekinimas yra vienas iš svarbiausių metalo apdirbimo būdų detalių gamyboje. Tekinimo įrankis turi ypač didelę reikšmę šiame procese, jis pjaunamąsias savybes praranda dėl pjaunančiųjų briaunų ištrupėjimo, pjaunančiojo pleišto plastinės deformacijos ir ypač dėl peilio darbinio paviršių dilimo. Norint parinkti optimalius pjovimo rėžimus ir įrankius, reikia nustatyti pagrindinius veiksnius, turinčius įtakos tam procesui. Tad gamybinėje įmonėje atlikti aliumininių detalių apdirbimo, smulkiagrūdžio karbido tekinimo plokštelėmis stebėjimai, norint išsiaiškinti pagrindinius veiksnius turinčius įtakos plokštelių nusidėvėjimui. Buvo pasirinktos trys plokštelės, kurios dirbo skirtingais režimais. Užfiksuoti plokštelių išdirbiai, bei nudilimo tipai pagal plokštelių viršūnių pakitimus. Iš gautų duomenų nustatyta, kad daugiausia įtakos plokštelių nusidėvėjimui turi abrazyvinis, difuzinis ir adhezinis dilimai. / Turning is the most popular in metal working and cutting tool has big dispose in this work. The durability of the cutting tool depends of the tool accuracy, quality, of the setting parameters, of the cutting regime and the formation of motion. The cutting tool loses its quality for the following reasons: cracking of the cutting edges; plastic deformation of the cutting tool and most important cutting tool working edge attrition. In the production facility was during the observation after aluminum parts production, where they were processed fine grain carbide turning plates. For research the main factors for affecting the plates wear. Three plates were chosen, which worked in different operating modes. Was recorded plates output and types of wear, by geometry changing of plates head. From the data obtained revealed that the main influencing the wear plate wear is abrasive, diffuse, and adhesive wear.

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.

In past studies, several techniques have been employed to create microscopic features on relatively simple surfaces. Of these, lithography-based techniques have proven effective at manufacturing large fields of deterministic microasperities and microcavities on planar and cylindrical substrates. The present study focuses on adapting UV-lithography to a more complex substrate. Machined from stainless steel, a conical mold insert introduces an interesting geometry designed for the injection molding of radial lip seal elastomer. The distinct shape of this mold insert poises unique challenges to a conventional lithography procedure. Spray application is investigated as a feasible means to deposit layers of photoresist on the surface. An appropriate masking element is designed and created to facilitate transfer of a particular pattern via UV exposure. A clamping technique is implemented to align and secure the photomask. These techniques are incorporated into a three-day process, and results are obtained through optical microscopy and light interferometry. By applying Design of Experiments (DOE) and Analysis of Variance (ANOVA), significant process variables are indentified. Based on these findings, refinements to the process are enabled and future considerations are made evident.

Les collisionneurs de particules sont des outils indispensables pour l'étude et la compréhension des lois fondamentales de la physique. Le plus grand accélérateur de particules jamais construit, le Large Hadron Collider (LHC), installé au CERN, est un accélérateur circulaire de type synchrotron à faisceaux contrarotatifs. Dans le LHC, les dipôles supraconducteurs en Nb-Ti génèrent une induction maximale de 8,3 T et les particules ont une énergie de collision de 14 TeV. La communauté scientifique souhaiterait des collisions à plus hautes énergies, ce qui nécessitera l'utilisation de dipôles à inductions magnétiques plus élevées. Le supraconducteur Nb3Sn est une option pour les dipôles générant jusqu'à 14 T environ. Une possible augmentation de l'énergie de collision du LHC de 14 TeV à 33 TeV est actuellement en discussion. Ce niveau d'énergie nécessitera l'utilisation de supraconducteurs à haute température (HTS) ayant des inductions irréversibles bien supérieures à celles du Nb3Sn et du Nb-Ti. A basse température les conducteurs YBCO présentent des inductions irréversibles et des densités de courant critique très élevées. Au nominal, les aimants supraconducteurs d'accélérateur fonctionnent à des courants de l'ordre de 10-20 kA. Ce niveau de courant bien supérieur aux capacités individuelles de transport des conducteurs HTS requerra l'utilisation de câbles supraconducteurs multibrins. Dans cette thèse, une formulation analytique fournissant une estimation de l'induction ultime des dipôles HTS est dérivée et la possibilité de générer des inductions supérieures à 20 T est démontrée. Le concept de câble transposé Robel à fort courant − introduit en 2006 pour les conducteurs YBCO − a jusqu'alors été caractérisé à 77 K, en induction propre. Mon travail expérimental pionnier a conduit à la première caractérisation réussie de câbles Roebel à 4,2 K et sous des inductions allant jusqu'à 9,6 T. Les forts courants critiques (12 kA) et les densités de courant critique (>1,1 kA/mm2) démontrent le potentiel de ces câbles pour des applications dans les aimants d'accélérateur à haute induction. Les câbles caractérisés ont atteint leur courant critique avec une distribution inégale de courant entre les brins. La principale raison de cette répartition déséquilibrée a été identifiée comme étant due à une résistance de contact non homogène aux jonctions. Mon travail novateur a permis de développer des outils numériques et expérimentaux universels qui permettent de quantifier et d'évaluer les performances des câbles HTS pour les aimants d'accélérateur.