M.Ed. (Curriculum Studies) / According to Jansen van Rensburg (1987:62) the watchword in the present-day world is productivity and this necessitates that, that which the student learns must be relevant to particularly the needs of the practice for functional skills. As a result of the above-mentioned, the following questions were posed: * Does the existing Strength of Materials and Structures N5 curriculum conform to scientific justifiable criteria for curriculum development? * Does the contents of strength of Materials and Structures N5 conform to the needs of the Industry? * Is the purpose with the contents clear? To answer the above-mentioned questions a questionnaire was used. R.A. Kruger's evaluation model was used to evaluate the present Strength of Materials and Structures N5 syllabus. The following conclusions, inter alia, were arrived at: * Students who study at Technical Colleges, work mainly with maintenance aspects. A very small percentage indicated that design and drawing aspects are regarded as important in practice. However, the present Strength of Materials and Structures N5 syllabus makes very 1ittle provision for the maintenance of such contents. * Furthermore it was found that there is a particularly great need for practical elucidation of the theory. * The present document (syllabus) does not conform to scientific justifiable criteria. No objectives or aims are reflected in the document. The contents are listed point by point without any order.

Orientador: Américo Bortolazzo Correr / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T02:50:31Z (GMT). No. of bitstreams: 1 Gotti_ValeriaBisinoto_M.pdf: 22569671 bytes, checksum: 63a18f68fe04710cbb552ebb07904779 (MD5) Previous issue date: 2013 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Mestrado / Materiais Dentarios / Mestra em Materiais Dentários

O presente trabalho tem como objetivo analisar as propriedades mecânicas, térmicas, termo dinâmico-mecânicas e morfológicas de compósitos preparados com poliestireno expandido reciclado e pó de madeira. Compósitos com diferentes teores de agente compatibilizante e diferentes teores de pó de madeira foram desenvolvidos em extrusora dupla rosca co-rotante e moldados por injeção. Os resultados obtidos demonstram que o compatibilizante com maior quantidade de anidrido maleico, menor massa molar ponderal média e utilizado em quantidade igual a 2% em massa gerou compósitos com melhores propriedades mecânicas. A melhora na adesão interfacial também foi observada através da análise termo dinâmico-mecânica. Verificou-se aumento no módulo de armazenamento, redução na altura do pico de tan δ e também menor valor do fator de adesão, associado com a maior adesão na região da interface. Para os compósitos desenvolvidos com diferentes teores de pó de madeira a densidade obtida foi semelhante a densidade teórica indicando estar de acordo com a regra das misturas. A utilização de compatibilizante reduziu o teor de vazios dos compósitos. Os resultados obtidos nos ensaios de flexão demonstraram que o módulo de flexão aumenta com a quantidade de carga e também se aproxima do comportamento previsto pela regra das misturas, entretanto os compósitos sem compatibilizante apresentaram redução na resistência a flexão com o aumento do teor de pó de madeira. No ensaio de impacto observou-se redução da resistência ao impacto com a adição de carga, porém os compósitos com compatibilizante apresentaram resultados superiores aos compósitos sem compatibilizante para todos os teores de pó de madeira. Observou-se aumento no módulo de armazenamento, no módulo de perda e também na efetividade do reforço com a adição de pó de madeira. Ocorreu redução na largura e também na altura do pico de tan δ conforme a adição das partículas de madeira, contudo os compósitos com compatibilizante apresentaram redução mais acentuada devido à melhora na adesão interfacial. O modelo teórico para predizer o comportamento do módulo de armazenamento demonstrou proximidade com os valores experimentais para baixos teores de carga. Para tan δ o modelo teórico se mostrou inadequado. As micrografias dos compósitos sem compatibilizante indicaram arrancamento e a presença de vazios entre o pó de madeira e a matriz, entretanto os compósitos com compatibilizante demonstraram maior recobrimento das partículas de madeira pela matriz. A estabilidade térmica dos compósitos com compatibilizante foi reduzida para todos os teores de pó de madeira quando comparada aos compósitos sem compatibilizante. / The present work aims to analyze the mechanical, thermal, dynamicalmechanical thermal properties and morphology of composites based on recycled polystyrene and wood flour. Composites with different types and levels of coupling agent and also with different levels of wood flour were developed in a co-rotating twin-screw extruder and injection molded. The results show that the coupling agent with higher amount of maleic anhydride, lower weight average molecular weight and used in to 2% by weight produced composites with better mechanical properties. The improvement in interfacial adhesion was also observed by dynamical-mechanical thermal analysis. An increase in the storage modulus, decrease in peak height and also lower value of adhesion factor, was observed due to the improved on interfacial adhesion. For the composites developed with different levels of wood flour density obtained was similar to theoretical density indicating that in accordance with the rule of mixtures. The use of coupling agent reduced the concentration of voids in the composites. The flexural modulus increases with the amount of wood flour and also approaches the behavior predicted by the rule of mixtures, however the composites without coupling agent showed reduction in flexural strength. The impact strength decreases with the addition of wood flour, but the composites with coupling agent showed better results than the composite without coupling agent for all levels of wood flour. There was an increase in the storage modulus, loss modulus and also the efficiency of filler with the addition of wood flour. There was a reduction in width and also in peak height of tan δ as the addition of wood particles, composite with coupling agent demonstrated greater reduction due to improved on interfacial adhesion. The theoretical model to predict the behavior of the storage modulus showed proximity with the experimental values for low levels of filler. Theoretical model for tan δ proved inadequate. The micrographs of composites without coupling agent indicated the presence of pulled-out traces and gaps between the wood flour and matrix, however the composites with coupling agent show the strong bonding and good wetting of the fillers by the matrix. The thermal stability of composites with coupling agent was reduced for all levels of wood flour when compared to composites without coupling agent.

Made available in DSpace on 2017-06-01T17:57:28Z (GMT). No. of bitstreams: 1 gilberto nery.pdf: 1716064 bytes, checksum: 9c4218702694b75ecbe1b4a033ddafa0 (MD5) Previous issue date: 2006-06-09 / In the Metropolitan Region of Recife some buildings had been constructed where the masonry fulfills function structural been, however, composed of blocks originally confectioned for non load-bearing masonry. This constructive system is regionally known as "coffin buildings". To take handle of the correct evaluation of the conditions of a building like these, it must be considered all the factors that, somehow, has some influence at the stability or durability of it. The present work had as objective to evaluate the influence of the covering mortar in the axial compressive strength of masonry prisms composed of concrete blocks of non load-bearing masonry. The tests had been carried through with prisms of three lined up blocks, where six samples, with fifteen copies each, had been confectioned. To minimize the effect of other variable, all prisms had been confectioned under the same conditions and with identical materials. The samples are: naked blocks; blocks with base to covering; blocks with base to covering and mortar with thicknesses 1,5 cm and 3 cm and traces 1:2:9 (weak) and 1:1:6 (average). The materials had been tested to define its characteristics. All the prisms had been breached at a hydraulical press for to define its respective resistances to the axial compression and the results, later, were statistically treated. It had a considerable increment at the resistance to the compression of the covered prisms and the mortar s resistance revealed influent to the resistance of the prism and the standards of rupture in the majority of the cases / Na Região Metropolitana de Recife foram construídos vários edifícios onde a alvenaria cumpre função estrutural, porém é composta de blocos originalmente confeccionados para vedação. Esse sistema construtivo é conhecido regionalmente como "edifícios caixão". Para se levar a cabo a correta avaliação das condições de um edifício destes, há de se levar em conta todos os fatores que de alguma forma influenciem na estabilidade ou durabilidade do mesmo. O presente trabalho teve como objetivo avaliar a influência da argamassa de revestimento na resistência à compressão de prismas de alvenaria compostos por blocos de vedação de concreto. Os ensaios se realizaram em prismas de 3 blocos alinhados, onde foram confeccionadas 6 amostras com 15 réplicas cada. Para minimizar os efeitos de outras variáveis, todos os prismas foram confeccionados sob as mesmas condições e com materiais idênticos. As amostras são: blocos nus; blocos com chapisco; blocos com chapisco e argamassa com espessuras 1,5 cm e 3 cm e traços 1:2:9 (fraco) e 1:1:6 (médio). Os materiais usados na confecção dos prismas foram ensaiados para definição de suas características. Todos os prismas foram rompidos em prensa hidráulica para definição das respectivas resistências à compressão axial e os resultados, posteriormente, tratados estatisticamente. Houve um incremento considerável nas resistências à compressão dos prismas com revestimento e a resistência da argamassa mostrou-se influenciadora da resistência do prisma e nos padrões de ruptura na maioria dos casos. A aderência do revestimento mostrou-se ponto de fragilidade, principalmente nos prismas com revestimento de 3,0 cm de espessura

Made available in DSpace on 2017-06-01T17:57:34Z (GMT). No. of bitstreams: 1 larissa_marques_cunha_cabral.pdf: 1240575 bytes, checksum: 527cd5d555a68768c684554d8e1cccd1 (MD5) Previous issue date: 2014-06-09 / The work involved studying the behavior and adjustment of dosage diagram of concrete with respect to static and dynamic elastic modulus. Furthermore, it compares the models of the static elastic modulus based on the compressive strength, German, European, American and Brazilian ABNT NBR 6118 (2014) prediction - Design of Concrete Structures: procedure. Two concrete were produced with different consistency; plastic and other fluid (selfcompacting). Three traits were developed for each consistency, totaling six traits. These dosages were as varying the water / cement and cement consumption; the rebate was kept constant. A comparative analysis of the experimental results with those predicted by some standards was carried out to evaluate the level of accuracy of the same. ACI 318 (2014) was the standard that had their closest results compared to NBR 6118 (2014). Have the Eurocode and DIN 1045 standards -2 showed similar results. And the standard fib CEB - 2010, showed overestimated values in relation to other standards. Thus, we can say that the determination of elasticity of the concrete module proved consistent with the materials and dosages used. However, it is very sensitive to the composition of the trace variable, even when kept the materials. The compressive strength is one of the variables that affect the results. However, it also has great influence to change the nature of the coarse aggregate and the relative folder / coarse aggregate, for example. The dynamic ultrasonic waves through the module was also measured and compared with the static module, showing a rapid and non-destructive option to evaluate the modulus of elasticity of the concrete. / O trabalho em questão estuda o comportamento e adequação do diagrama de dosagem do concreto com relação ao módulo de elasticidade estático e dinâmico. Além disso, compara os modelos de previsão do módulo de elasticidade estático baseados na resistência à compressão das normas americana, alemã, européia, fib e a brasileira ABNT NBR 6118 (2014) - Projeto de Estruturas de Concreto: procedimento. Foram produzidos dois concretos com consistências distintas; uma plástica e outra flúida (auto adensável). Foram desenvolvidos três traços para cada consistência, totalizando assim seis traços. Essas dosagens tiveram como variáveis a relação água/cimento e o consumo de cimento; o abatimento foi mantido constante. Uma análise comparativa entre os resultados experimentais com os valores previstos por algumas normas foi realizada, avaliando o nível de precisão das mesmas. A ACI 318 (2014) foi a norma que teve seus resultados mais próximos em relação a NBR 6118 (2014). Já as normas EUROCODE 2 (2004) e DIN 1045 apresentaram resultados semelhantes. E a norma fib CEB 2010, apresentou valores superestimados em relação às demais normas. Assim, é possível afirmar que a determinação do módulo de elasticidade do concreto se mostrou coerente com os materiais e dosagens utilizadas. Contudo, é uma variável muito sensível à composição do traço, mesmo quando mantidos os materiais. A resistência à compressão é uma das variáveis que interfere nos resultados. Entretanto, tem também grande influência a variação da natureza dos agregados graúdos e a relação pasta/agregado graúdo, por exemplo. O módulo dinâmico através de ondas ultrassônicas, também foi medido e comparado com o módulo estático, mostrando-se uma opção rápida e não destrutiva de avaliar o módulo de elasticidade do concreto.

High entropy alloys (HEAs) is a concept wherein alloys are constructed with five or more elements mixed in equal proportions; these are also known as multi-principle elements (MPEs) or complex concentrated alloys (CCAs). This PhD thesis dissertation presents research conducted to develop precipitation-hardenable high entropy alloys using a much-studied fcc-based equi-atomic quaternary alloy (CoCrFeNi). Minor additions of aluminium make the alloy amenable for precipitating ordered intermetallic phases in an fcc matrix. Aluminum also affects grain growth kinetics and Hall-Petch hardenability. The use of a combinatorial approach for assessing composition-microstructure-property relationships in high entropy alloys, or more broadly in complex concentrated alloys; using laser deposited compositionally graded AlxCrCuFeNi2 (0 < x < 1.5) complex concentrated alloys as a candidate system. The composition gradient has been achieved from CrCuFeNi2 to Al1.5CrCuFeNi2 over a length of ~25 mm, deposited using the laser engineered net shaping process from a blend of elemental powders. With increasing Al content, there was a gradual change from an fcc-based microstructure (including the ordered L12 phase) to a bcc-based microstructure (including the ordered B2 phase), accompanied with a progressive increase in microhardness. Based on this combinatorial assessment, two promising fcc-based precipitation strengthened systems have been identified; Al0.3CuCrFeNi2 and Al0.3CoCrFeNi, and both compositions were subsequently thermo-mechanically processed via conventional techniques. The phase stability and mechanical properties of these alloys have been investigated and will be presented. Additionally, the activation energy for grain growth as a function of Al content in these complex alloys has also been investigated. Change in fcc grain growth kinetic was studied as a function of aluminum; the apparent activation energy for grain growth increases by about three times going from Al0.1CoCrFeNi (3% Al (at%)) to Al0.3CoCrFeNi. (7% Al (at%)). Furthermore, Al addition leads to the precipitation of highly refined ordered L12 (γ′) and B2 precipitates in Al0.3CoCrFeNi. A detailed investigation of precipitation of the ordered phases in Al0.3CoCrFeNi and their thermal stability is done using atom probe tomography (APT), transmission electron microscopy (TEM) and Synchrotron X-ray in situ and ex situ analyses. The alloy strengthened via grain boundary strengthening following the Hall-Petch relationship offers a large increment of strength with small variation in grain size. Tensile strength of the Al0.3CoFeNi is increased by 50% on precipitation fine-scale γ′ precipitates. Furthermore, precipitation of bcc based ordered phase B2 in Al0.3CoCrFeNi can further strengthen the alloy. Fine-tuning the microstructure by thermo-mechanical treatments achieved a wide range of mechanical properties in the same alloy. The Al0.3CoCrFeNi HEA exhibited ultimate tensile strength (UTS) of ~250 MPa and ductility of ~65%; a UTS of ~1100 MPa and ductility of ~30%; and a UTS of 1850 MPa and a ductility of 5% after various thermo-mechanical treatments. Grain sizes, precipitates type and size scales manipulated in the alloy result in different strength ductility combinations. Henceforth, the alloy presents a fertile ground for development by grain boundary strengthening and precipitation strengthening, and offers very high activation energy of grain growth aptly suitable for high-temperature applications.

This project is centered around the use of finite element analysis for developing a beam for a new type of motor used in a screening machine. Essentially the main purpose of the developed beam is to transfer vibrations to the screen machine that it will be attached to. Since the machine operates on vibrations from the motor, the beam was to be designed with material fatigue in mind, which demanded examination of stresses in the welded joints of the beam. Concepts were generated with a specification of requirements as a basis, and the concepts were then analysed with finite element analysis. The results from this analysis were compared and a final design choice was selected. Since the beam will be subjected to varying fatigue loads, an S-N curve was needed to gain information of the material’s cyclic stress versus life. Most S-N curves are accessible through literature or databases, however, there are some materials that do not have an S-N curve available. If that is the case then the designer has the option to estimate one using ultimatetensile strength and the material’s fatigue limit. Hence, an S-N curve was estimated in this project.

Through a series of carefully designed experiments, characterization and some modeling tools, this work is aimed at studying the role of thermal profiles on different microstructural zones and associated properties like strength and corrosion through a variation of weld parameters, thermal boundary conditions and material temper. Two different alloys belonging to the Al-Cu and Al-Cu-Li system in different temper conditions- peak aged (T8) and annealed (O) were used. A 3D-thermal pseudo mechanical (TPM) model is developed for the FSW process using heat transfer module in COMSOL Multiphysics and is based on a heat source wherein the temperature dependent yield shear stress is used for the heat generation. The precipitation and coarsening model is based on the Kampmann and Wagner theoretical framework and accounts for the competition between the various nucleation sites for both metastable and equilibrium precipitates. The model predicts different precipitate mean radius and volume fraction for the various zones in the friction stir welded material. A model for the yield strength is developed which considers contributions from different strengthening mechanisms. The predictions of the each models have been verified against experimental data and literature. At constant advance per rotation, the peak temperature decreases with a decrease in traverse speed and increases with an increase in tool rotation. Weld properties were significantly affected by choice of thermal boundary conditions in terms of backing plate diffusivity. Weld conditions with a higher peak temperature and high strain rate results in more dissolution of precipitates and fragmentation of constituent particles resulting in a better corrosion behavior for the weld nugget. For a peak aged temper of 2XXX alloys, the weld nugget experiences dissolution of strengthening precipitates resulting in a lower strength and the Heat affected zone (HAZ) experiences coarsening of precipitates. For an annealed material, both the weld nugget and HAZ experiences dissolution of precipitates with an increase in strength in the weld nugget.

En las últimas precipitaciones suscitadas en nuestra región Lambayeque, específicamente en el distrito de Mórrope, nos alarmado, más aún en el fenómeno Yaku, registrado en este año. Frente a ello, esta investigación tuvo por objetivo mejorar la resistencia del adobe a efectos de las lluvias e inundaciones, utilizando el Yeso y la Poña de Algarrobo que actualmente se incinera. Para ello, primero se conoció las propiedades y composición de los materiales y elementos a adicionar; posteriormente, se obtuvo una muestra patrón de adobe; después de ello, se obtuvieron los porcentajes óptimos tanto para Yeso y Poña de Algarrobo y finalmente, se procesaron y analizaron los datos para cuantificar los resultados. Dentro de nuestros resultados se obtuvieron que adicionándole 6% Poña de Algarrobo y 9% de Yeso al adobe patrón, la resistencia a la compresión se incrementa en 59.54%, la tracción en 15.85%, la flexión en 15.69%, la compresión de murete en 28.40%, la tracción diagonal de murete en 26.09%, la tracción del mortero en 60.00%, la erosión en 58.05%, la succión se redujo la desintegración parcial, la inmersión se redujo la desintegración total y en la inundación simulada aumentó la resistencia a la absorción y capilaridad. Por lo tanto, se ha llegado a concluir que al adobe tradicional incorporándole 6% de Poña de Algarrobo y 9% de Yeso, mejora sus propiedades físicas y mecánicas incrementando la resistencia al agua. / In the latest rainfall in our Lambayeque department, specifically in the Mórrope district, we were alarmed, even more so in the Yaku phenomenon, registered this year. Faced with this, this research aimed to improve the resistance of adobe to the effects of rains and floods, using the Yeso and the Poña of Algarrobo that is currently incinerated. For this, first the properties and composition of the materials and stabilizers were known; subsequently, a standard sample of adobe was obtained; after that, the optimal percentages were obtained for Yeso and Poña of Algarrobo and finally, the data was processed and analyzed to quantify the results. Among our results, we obtained that by adding 6% Poña de Algarrobo and 9% Yeso to the standard adobe, the resistance to compression increases by 59.54%, the traction by 15.85%, the bending by 15.69%, the compression of the wall by 28.40 %, diagonal wall traction in 26.09%, the traction of mortar by 60.00%, erosion in 58.05%, suction reduced partial disintegration, immersion reduced total disintegration and in simulated flooding increased resistance to absorption and capillarity. Therefore, it has been concluded that incorporating 6% Poña de Algarrobo and 9% Yeso to traditional adobe increases its physical and mechanical properties, increasing its resistance to water.

En la actualidad se observa que el comportamiento de los parachoques de los vehículos sufre fisuras y aumentan los esfuerzos, ya que estos son elaborados con plásticos los cuales tienen muy baja resistencia, de tal forma que cuando sufren un impacto frontal, el vehículo termina muy afectado poniendo en riesgo la vida de las personas. Por ello, surgieron los parachoques con materiales compuestos los cuales tienen mayor resistencia que los plásticos y cercana a los metales. Por esta razón el objetivo de este trabajo es modelar y analizar un parachoques con Materiales Compuestos de Jute/Epoxi, Kenaf/Epoxi y Sisal/Epoxi utilizando las ecuaciones de la Energía Cinética, el Teorema de Cantidad de Movimiento y la Energía de Deformación, para así calcular la energía interna que se genera a la hora del impacto frontal, y realizar una comparación de los tres MC bajo la normativa GB17354-1998 y la directiva 96/79/CE del Parlamento Europeo. Además, se realizó la simulación de choque frontal del parachoques con los tres Materiales Compuestos (Jute/Epoxi, Kenaf/Epoxi y Sisal/Epoxi) propuestos en esta tesis, para así, evaluar los Esfuerzos, Deformaciones, Desplazamientos y el Factor de Seguridad mediante gráficos, utilizando el software SolidWorks. Y resultado de ello se obtuvo que el Material Compuesto de Sisal/Epoxi es el más Resistente y Seguro con respecto a los dos Materiales Compuesto (Jute/Epoxi y Kenaf/Epoxi).