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An empirically-based classification of lower Paleozoic carbonate-bearing rocks was created for field-based geotechnical applications. Geotechnical parameters were subsequently correlated to that classification. Seven hundred seventy-seven samples were used as the basis for the classification. Thirteen categories based on visual and tactile properties and a hydrochloric acid test were created. Samples were from central, north-central, and south-central Kentucky and represented the majority of Ordovician exposures in the state, and some Mississippian exposures. Few Silurian and Devonian units were included in the sample set. Geotechnical parameters, including density as well as elastic constants (shear and compression wave velocities, Poisson’s ratio, Young’s modulus, and shear modulus), were calculated for 113 representative samples from the classification. Compression strength testing was completed on 29 samples and the slake durability index was calculated for 18 samples. Testing values were correlated to the classification system in an attempt to use the classification as a predictive and comparative tool for geotechnical applications. Despite samples being heterogeneous and isotropic, each of the 13 categories behaved differently and predictably, with the sharpest contrast in siliciclastic and carbonate rocks.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The electromagnetic and mechanical design aspects of optimally designed doublesided rotor radial flux permanent magnet wind generators with non-overlap aircored (iron-less) stator windings are analysed in this thesis. The wind generator is implemented in a battery charging system for use in rural settlements and farms. The optimal generator and system design is based on an accurate analytical model and is confirmed with finite element analysis. It is shown, amongst other things, that the electromagnetic design and surprisingly not the mechanical design, determines the rotor yoke dimensions and, hence, largely the mass and cost of the generator. Alternative battery charging systems are also considered and discussed. / AFRIKAANSE OPSOMMING: Die elektromagnetiese en meganiese ontwerp aspekte van optimaal ontwerpte dubbel-kant rotor radiale vloed permanente magneet windgenerators met nieoorvleuelende lug kern (sonder yster) statorwindings word in hierdie tesis ontleed. Die windgenerator word geplaas in 'n battery-laai stelsel vir gebruik in landelike nedersettings en plase. Die optimale generator en die stelsel ontwerp is gegrond op 'n akkurate analitiese model en is bevestig met eindige element analise. Daar word onder andere getoon dat die elektromagnetiese ontwerp, en nie die meganiese ontwerp, die rotor juk dimensies en dus grootliks die massa en die koste van die generator, bepaal. Alternatiewe battery-laai stelsels word ook oorweeg en bespreek.

Orientador: Yukio Kobayashi / Banca: Carlos Alberto Soufen / Banca: Antônio de Padua Lima Filho / Resumo: A identificação e a qualificação dos constituintes microestruturais de uma junta soldada são de grande importância pela relação que existe entre a microestrutura do cordão e as propriedades mecânicas, particularmente a tenacidade. Trabalhando com variações nos parâmetros de pulso, corrente de pico e tempo de pico, e também na temperatura de pré-aquecimento, foram quantificados os constituintes ferrita acicular e microfases presentes no metal de solda; sendo ambos considerados controladores da tenacidade. Os resultados deste trabalho demonstraram que aumentou a quantidade de ferrita acicular para os menores níveis dos parâmetros de pulso e da temperatura de pré-aquecimento. Quanto às microfases, ocorreu uma redução na quantidade à medida que se elevaram os níveis dos parâmetros de pulso e da temperatura de pré-aquecimento. Observou-se, também, qual foi a influência da velocidade de resfriamento na microestrutura final do metal de solda. Foi utilizado o processo de soldagem a arco elétrico com proteção gasosa, no modo pulsado e arame tubular. A soldagem foi realizada em chapa de aço estrutural de alta resistência e baixa liga (COS-AR 50), com chanfro em "X" e ângulo de 30º. Como metal de adição foi utilizado o arame tubular de fluxo metálico E70C-6M, com diâmetro de 1,2 mm. / Abstract: The identification and qualification of the microstructural constituents present in the welded joint are very important for the relationship between the microstructure of the weld beads with the mechanical properties, particularly toughness. Working with variations of pulse parameters, peak current and peak time, and also preheating temperature, had been quantified the constituents acicular ferrite and microphases present in weld metal; being both considered controllers of toughness. The results of this work demostrated that greater amounts of acicular ferrite had been occurred in the lowest levels of pulse parameters and preheating temperature. As for microphases, it has a reduction of the amount with the increase of pulse parameters and preheating temperature. It was observed, also, the influence of the cooling speed in the final microstructure of the weld metal. The samples were welded by the metal gas arc welding, using pulsed arc and tubular wire. As metal base was used HSLA structural steel plate (COS-AR 50), with "X"-groove and bevel angle 30º. The addition metal was the tubular metal-cored wire "E70C-6M" with diameter of 1.2 mm. / Mestre

A utilização do aço ASTM A 335 P91 tem sofrido um aumento considerável, especialmente em função da necessidade de materiais com maior resistência à fluência para aplicações em unidades de utilidades (geração de vapor) e de processo. Por ser um material de difícil soldabilidade, diversos problemas são enfrentados durante a construção das unidades e, posteriormente, durante manutenção, geralmente em função de problemas de soldagem oriundos da fase de fabricação e construção. As normas de projeto e construção utilizadas internacionalmente vêm sofrendo adaptações a fim de melhorar a utilização deste material, mas seus requisitos ainda apresentam importantes lacunas em relação às principais práticas recomendadas pela literatura técnica mais atual. Visando uma melhor utilização deste material, obtendo juntas soldadas com propriedades mecânicas e metalúrgicas mais consistentes, o presente trabalho foi desenvolvido avaliando-se a influência de parâmetros de soldagem energia de soldagem e temperatura de tratamento térmico pós-soldagem (TTPS) sobre as propriedades mecânicas e metalúrgicas, incluindo resistência à fluência, de juntas soldadas de aço ASTM A 335 P91. Foram testadas nove juntas soldadas, combinando três níveis de energia de soldagem com três temperaturas de TTPS. Os resultados obtidos indicam que é possível ter melhor controle sobre as propriedades deste material, desde que se opere com níveis mais restritos de energia de soldagem e maiores temperatura de TTPS, observando-se as limitações pertinentes, especialmente no que tange à temperatura crítica de transformação Ac1. / The use of ASTM A 335 P91 has been increased considerably specially because of the need for materials with higher creep resistance for power generation (nuclear and thermoelectric) and oil and gas processing applications. As this is a material with poor weldability, several issues are faced during construction of these unities, and later during maintenance usually associated with welding problems originated in the fabrication and construction phase. The design and construction codes most used worldwide are receiving important revisions targeting to enhance the use condition of this material but its requirements still show important lacks when compared to the main practices recommended by the more recent technical literature. Aiming a better usage of this material obtaining sound welded joints with more consistent metallurgical and mechanical properties, this work was developed assessing the influence of some welding parameters welding heat input and temperature of post-­weld heat treatment (PWHT) on the metallurgical and mechanical properties, including creep strength, of welded joints of ASTM A 335 P91 steel. Nine welded joints were submitted to testing, combining three different levels of welding heat input with three different PWHT temperatures. The results show that it is possible to have a better control over the properties of this material since it is used lower welding heat inputs combined to higher PWHT temperatures, taking care about the limitations regarding the critical transformation temperature Ac1.

A material study was conducted on two types of cored composite materials used in shipbuilding: a GRP/Balsa Cored sandwich and a GRP/PVC Foam Cored sandwich. The two materials were tested in the Cone Calorimeter and the LIFT Apparatus to obtain data on ignitability, heat release rate, mass loss rate, and smoke production. The observed phenomena of delamination, melting and charring of the core materials, and edge effects are discussed in the context of how they affect test results. The ignition data analysis method specified in ASTM E 1321 "Standard Test Method for Determining Material Ignition and Flame Spread Properties" and Janssens' "improved" method of analysis were both used to derive effective material properties of the test materials. These two analysis methods are shown to produce different material property values for critical irradiance for ignition, ignition temperature, and the effective thermal property, $k ho c$. Material properties derived using Janssens' method are shown to be more consistent between the two test materials and the two different test methods; they were also shown to be better predictors of time to ignition when compared to actual test data. Material properties are used as input to Quintiere's fire growth model in order to evaluate their affect on time to flashover predictions in the ISO 9705 Room/Corner test scenario. Recommendations are made for future testing of cored composite materials, ignition data analysis methods, predictive fire growth models, and other work with composite materials. ** This copy contains no figures or appendices **

Afin d'améliorer la coulabilité de certaines nuances d'acier, du calcium est ajouté pour modifier et contrôler la nature des inclusions d'oxydes et des sulfures présentes dans l'acier. Grâce au traitement au calcium, les inclusions solides provoquant l'obstruction des buses de coulée sont converties en inclusions liquides qui ne bouchent pas les buses. L'injection du fil fourré est devenue l'une des technologies de pointe pour les ajouts de calcium, car elle offre une récupération de calcium plus élevée que d'autres méthodes et son fonctionnement est simple et peu coûteux. Ce travail est divisé en deux axes principaux. La première clarifie les mécanismes de dissolution du fil fourré lors de son injection dans le métal liquide. La deuxième traite du transport du calcium une fois qu'il est libéré dans l'acier, ainsi que de la modification chimique des inclusions par cet élément. Le premier axe s'articule autour de DissolFil, un modèle numérique décrivant les phénomènes thermiques présents au cours du processus d'injection d'un fil fourré dans un bain d'acier liquide. Celui-ci est complété par une étude expérimentale de l'immersion de fils fourrés dans des bains d'acier statiques utile à la validation du modèle. Les résultats de simulation ont mis en évidence l'importance de la vitesse d'injection du fil en tant que paramètre à adapter en fonction de la conception du fil et de la surchauffe du bain d'acier afin d'optimiser la profondeur de libération du calcium dans la poche. Le deuxième axe comprend un modèle de dissolution et du transport du calcium dans une poche d'acier et la modification des inclusions, couplant la mécanique des fluides et la thermodynamique à l'aide des codes de calcul Ansys Fluent (mécanique des fluides) et CEQCSI (thermodynamique). Le modèle a été validé à partir des prélèvements d’acier réalisés lors d’essais industriels spécifiques. Nous montrons que le transfert de masse en couche limite à partir des bulles de calcium vers l'acier liquide est le mécanisme dominant pour la dissolution du calcium. De plus, la modification globale des inclusions solides et liquides dépend fortement du mélange et de l'homogénéisation de la poche et de la composition chimique de l'acier / In order to improve the castability of some steel grades, calcium is added to the liquid steel to modify and control the nature of oxide and sulphide inclusions present in the steel. As a result of the treatment with calcium solid inclusions that provoke clogging of the casting nozzles are converted into liquid ones that do not clog the nozzles. Cored wire injection has matured as one of the leading technologies to perform calcium additions since it offers a higher calcium recovery than other methods and its operation is simple and inexpensive. This work, divided into two main axes, clarifies the mechanisms of dissolution of the cored wire during its injection, the dissolution and transport of calcium once it has been released into the steel ladle, and the chemical modification of inclusions by this element. The first axis revolves around DissolFil, a numerical model describing the thermal phenomena occurring during the process of injection of a cored wire into a liquid steel bath. In parallel, an experimental study of immersion of cored wires into quiescent steel baths that was carried out with the aim of validating the model. The simulation results put into evidence the importance of the wire injection velocity as the operating parameter that needs to be tailored as a function of the wire design and steel bath superheat in order to optimize the release depth of calcium in the steel ladle. The second axis comprises a model of dissolution and transport of calcium in the steel ladle and inclusion modification, coupling fluid-dynamics and thermodynamics by using the Ansys Fluent (fluid-dynamics) and CEQCSI (thermodynamics) calculation codes. The model was validated with data from steel samples obtained in dedicated industrial trials. We highlight boundary layer mass transfer from calcium bubbles into the liquid steel as the dominant calcium dissolution mechanism. Furthermore, the global modification of solid inclusions into liquid ones depends strongly on the mixing and homogenization in the ladle and the steel chemical composition

Orientador: Gilberto de Magalhães Bento Golçaves / Banca: Carlos Elias da Silva Junior / Banca: Geraldo Luiz Palma / Resumo: Este trabalho avaliou as ocorrências mecânicas, macro e microestrutural em metal de solda de juntas de aço estrutural temperado e revenido, soldadas pelo processo a arco elétrico com proteção gasosa (GMAW) de 80%Ar-20%CO2, em modo convencional e pulsado, utilizando eletrodo de alma metálica ("metal cored"), designação AWS E70C-6M. As soldas foram realizadas em dois passes, um por lado de juntas preparadas com chanfro duplo "V"60º. Para uma mesma energia teórica de soldagem, comparativamente verificou-se aumentos nas eficiências de deposição e térmica do processo para a soldagem com arco pulsado, além de uma maior influência na diluição do metal de base e nas características geométricas dos cordões. Entretanto, foi constatada maior resistência mecânica para os metais de solda obtidos em modo convencional, atribuído à ocorrência de um refinamento microestrutural mais intenso nesta condição de soldagem. A expectativa desta contribuição é de que disponibilize maiores informações em metalurgia da soldagem para atender principalmente o segmento de fabricação de equipamentos e sistemas mecânicos aplicados a serviços abrasivos / Abstract: This study evaluated the mechanical, macro and microestrurtural events on metal weld joints of quenched and tempered structural steel, welded by eletric arc process with protective gas (GMAW) of 80% Ar-20% CO2 in conventional and pulsed mode using metal cored electrode, designation AWS E70C-6M. The welds were made in two passes, one on each side of joints prepared with 60º double "V" bevel. For a given theoretical energy welding, comaratively there was increases in the efficiencies of deposition and thermal for pulsed arc welding process, and a greater influence on the dilution of the base metal and the geometrical characteristics of the cords. However, was observed a higher mechanical strength for a weld metals obtained in conventional manner, attributed to the occurrence of an intense microstructural refinement in this welding condition. The expectation of this contribution is to make evailable more information on welding metallurgy to meet especially the segment of manufacturing equipment and mechanical systems applied to abrasive services / Mestre

Made available in DSpace on 2014-06-11T19:28:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-17Bitstream added on 2014-06-13T19:57:37Z : No. of bitstreams: 1 sarni_mij_me_bauru.pdf: 941928 bytes, checksum: 4ead015efe149db89a0c631bd5132b8b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho avaliou as ocorrências mecânicas, macro e microestrutural em metal de solda de juntas de aço estrutural temperado e revenido, soldadas pelo processo a arco elétrico com proteção gasosa (GMAW) de 80%Ar-20%CO2, em modo convencional e pulsado, utilizando eletrodo de alma metálica (metal cored), designação AWS E70C-6M. As soldas foram realizadas em dois passes, um por lado de juntas preparadas com chanfro duplo V60º. Para uma mesma energia teórica de soldagem, comparativamente verificou-se aumentos nas eficiências de deposição e térmica do processo para a soldagem com arco pulsado, além de uma maior influência na diluição do metal de base e nas características geométricas dos cordões. Entretanto, foi constatada maior resistência mecânica para os metais de solda obtidos em modo convencional, atribuído à ocorrência de um refinamento microestrutural mais intenso nesta condição de soldagem. A expectativa desta contribuição é de que disponibilize maiores informações em metalurgia da soldagem para atender principalmente o segmento de fabricação de equipamentos e sistemas mecânicos aplicados a serviços abrasivos / This study evaluated the mechanical, macro and microestrurtural events on metal weld joints of quenched and tempered structural steel, welded by eletric arc process with protective gas (GMAW) of 80% Ar-20% CO2 in conventional and pulsed mode using metal cored electrode, designation AWS E70C-6M. The welds were made in two passes, one on each side of joints prepared with 60º double V bevel. For a given theoretical energy welding, comaratively there was increases in the efficiencies of deposition and thermal for pulsed arc welding process, and a greater influence on the dilution of the base metal and the geometrical characteristics of the cords. However, was observed a higher mechanical strength for a weld metals obtained in conventional manner, attributed to the occurrence of an intense microstructural refinement in this welding condition. The expectation of this contribution is to make evailable more information on welding metallurgy to meet especially the segment of manufacturing equipment and mechanical systems applied to abrasive services