Note:

An extensometer has been developed to continuously monitor roof extension in underground mines. The extensometer is designed to be installed in the MSHA-mandated test holes in the roof and measures the displacement between an anchorage point at the top of the borehole and the hole in the roof of the excavation. Once installed, the extensometer will report displacement through semi-wireless communications network. The extensometer is hard-wired into the permissible MIDAS datalogger, where results can be obtained wirelessly via the MIDAS user interface. Lab tests have indicated that the device produces displacement data. The device was installed in one underground coal mine to review its effectiveness in the field. / Master of Science

No description available.

No description available.

Report (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Includes bibliographical references (leaf 24). Also available via the Internet.

Techn. University, Diss., 2004--Braunschweig.

As a preliminary starting point for the present study, physical and mechanical properties of polypropylene nanocomposites (PPNCs) for samples received from Queen's University Belfast have been evaluated. Subsequently, polymer/clay nanocomposite material has been produced at Bradford. Mixing and processing routes have been explored, and mechanical properties for the different compounded samples have been studied. Clay intercalation structure has received particular attention to support the ultimate objective of optimising tensile and fracture behaviour of isotropic and die-drawn PPNCs. Solid-state molecular orientation has been introduced to PPNCs by the die-drawing process. Tensile stress-strain measurements with video-extensometry and tensile fracture of double edge-notched tensile specimens have been used to evaluate the Young's modulus at three different strain rates and the total work of fracture toughness at three different notch lengths. The polymer composite was analyzed by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, wide angle x-ray diffraction, and transmission electron microscopy. 3% and 5% clay systems at various compatibilizer (PPMA) loadings were prepared by three different mixing routes for the isotropic sheets, produced by compression moulding, and tensile bars, produced by injection moulding process. Die-drawn oriented tensile bars were drawn to draw ratio of 2, 3 and 4. The results from the Queen's University Belfast samples showed a decrement in tensile strength at yield. This might be explained by poor bonding, which refers to poor dispersion. Voids that can be supported by intercalated PP/clay phases might be responsible for improvement of elongation at break. The use of PPMA and an intensive mixing regime with a two-step master batch process overcame the compatibility issue and achieved around 40% and 50% increase in modulus for 3% and 5% clay systems respectively. This improvement of the two systems was reduced after drawing to around 15% and 25% compared with drawn PP. The work of fracture is increased either by adding nanoclay or by drawing to low draw ratio, or both. At moderate and high draw ratios, PPNCs may undergo either an increase in the size of microvoids at low clay loading or coalescence of microvoids at high clay loading, eventually leading to an earlier failure than with neat PP. The adoption of PPMA loading using an appropriate mixing route and clay loading can create a balance between the PPMA stiffness effect and the degree of bonding between clay particles and isotropic or oriented polymer molecules. Spherulites size, d-spacing of silicate layers, and nanoparticles distribution of intercalated microtactoids with possible semi-exfoliated particles have been suggested to optimize the final PPNCs property.

La connaissance des propriétés mécaniques de la peau humaine in vivo est d’une importance capitale dans de nombreux domaines (médical, cosmétique…). L’objectif de cette thèse est de développer de nouveaux outils pour permettre d’une part au clinicien de caractériser de manière objective les propriétés mécaniques de la peau, et d’autre part d’améliorer la compréhension générale du comportement de cet organe avec le vieillissement. Le premier chapitre est une revue bibliographique de la physiologie et des propriétés physiques de la peau ainsi que des différents moyens d’investigations actuels de ses propriétés. A partir de cette revue, deux axes de recherche sont définis, un axe de sollicitation tangentielle et un axe de sollicitation normale au tissu. Le second chapitre s’intéresse au premier axe de recherche, avec le développement d’une méthode d’indentation dynamique et d’une méthode d’indentation sans contact. Une baisse du module d’Young est trouvée avec l’âge. Le troisième chapitre s’intéresse à l’axe de sollicitation tangentielle, avec une méthode d’extension compression couplant mesures d’efforts et mesures des champs de déplacements de la zone sollicitée. Une approche inverse par un modèle Éléments Finis avec une loi de comportement orthotrope montre à partir des essais réalisés une baisse globale des propriétés mécaniques de la peau avec l’âge. Le quatrième et dernier chapitre relie les deux approches (normale et tangentielle) en comparant les résultats obtenus et tire les perspectives de ces travaux. / The knowledge of the mechanical properties of human skin in vivo is essential for many domains (medical, clinical…). The aim of this thesis is to develop new devices for the clinician in order to perform objective assessment of the mechanical properties of human skin, and also to improve the understanding of the whole mechanical behaviour of this organ with ageing.The first chapter is a bibliography concerning the physiology and the physical properties of the skin and also an overview of the actual devices used for the assessment of these properties. Based on this review, two different ways of stress have been chosen, a normal stress axis and a tangential stress axis to the skin.The second chapter concerns the first way of stress, with the development of a dynamic indentation method and a non contact method. A decrease of the Young modulus is found with ageing.The third chapter concerns a tangential axis of stress, with an extension-compression test using force measurement combined to displacement field measurement of the stressed area. An inverse method using a Finite Element model with an orthotropic law shows that results obtained give a decrease of the mechanical properties of the skin with ageing.The fourth and last chapter links the two different way of stress used with a comparison of results obtained and gives some perspectives of this work.

Submitted by Alisson Mota (alisson.davidbeckam@gmail.com) on 2015-06-26T19:00:09Z No. of bitstreams: 1 Dissertação - Antonio Wesley Carvalho de Oliveira.pdf: 14382471 bytes, checksum: 51e491c08eb16a03973ecbf929d4a9e6 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-29T15:53:37Z (GMT) No. of bitstreams: 1 Dissertação - Antonio Wesley Carvalho de Oliveira.pdf: 14382471 bytes, checksum: 51e491c08eb16a03973ecbf929d4a9e6 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-29T18:06:00Z (GMT) No. of bitstreams: 1 Dissertação - Antonio Wesley Carvalho de Oliveira.pdf: 14382471 bytes, checksum: 51e491c08eb16a03973ecbf929d4a9e6 (MD5) / Made available in DSpace on 2015-06-29T18:06:00Z (GMT). No. of bitstreams: 1 Dissertação - Antonio Wesley Carvalho de Oliveira.pdf: 14382471 bytes, checksum: 51e491c08eb16a03973ecbf929d4a9e6 (MD5) Previous issue date: 2010-01-10 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The process of new product development is split-up basically in five stages: identification of opportunity and concept development, planning and product specification, development and engineering process of the product, testing and evaluations, and ram-up. The testing stage allows guaranteeing that the new product is reliable and is in accordance with customer needs. In this phase, the engineering group checks if the product is conform through experimental tools. One of these tools is the sensor generally used to measure deformation known as strain gauge. Although the strain gauges have large application, the usage of very strong quicksetting adhesive to fix the strain gauge on the body can compromise the results of the measurement. A proposal to cover the problems related to the placement of the strain gauge is to print the strain gauge on the surface of the body to be analyzed though of printing method of ink that has metal nanoparticles. The printing process consists in to deposit drops of suspension extremely thin onto the surface of a flexible polymer film. As objective, this work evaluated the performance of the printed strain gauge, obtained by silver conductive ink, above surface of flexible material. Thereunto, it was described the characteristics of the conventional strain gauge and printed strain gauge, apply the strain gauge conventional and printed on the surface of an flexible polymeric material through conventional placement methods and ink-jet print methods, compare the characteristics and measurement of strain gauge conventional and printed by mechanical tests: tensile strength and flexural, and evaluate the advantage and disadvantage of the printed strain gauge. The results obtained by the new concept of strain gauge presented very satisfactory by the experimental tests. / O processo de desenvolvimento de novos produtos dividi-se basicamente em cinco etapas: identificação de oportunidade e desenvolvimento do conceito, planejamento e especificação do produto, desenvolvimento e processo de engenharia do produto, teste e avaliação, e início da produção. A etapa de teste permite assegurar que o novo produto é confiável e está de acordo com as necessidades do cliente. Nesta etapa, a engenharia avalia se o produto está conforme por meio de ferramentas experimentais. Uma destas ferramentas é o transdutor comumente utilizado para medir deformações conhecido como extensômetro. Embora os extensômetros apresentem ampla aplicação, a utilização da cola para fixação na superfície do corpo pode comprometer os resultados de uma medição. Uma proposta para os problemas relacionados à fixação do extensômetro é imprimir o extensômetro na superfície do corpo a ser analisado por meio de impressão de tintas que utilizam nanopartículas metálicas. O processo de impressão consiste em depositar gotas de suspensão extremamente finas na superfície de um corpo flexível polimérico. Como objetivo, este trabalho avaliou a performance do extensometro impresso, obtido por meio de impressão de tinta condutiva de prata, sobre a superfície de um material flexível. Para isso, descrevem-se as características do extensometro convencional e do extensometro impresso, aplica-se o extensometro convencional e o impresso na superfície de um material polimérico flexível por meio dos métodos convencionais de fixação e impressão de nano-partículas condutivas respectivamente, comparam-se as características e medições dos extensômetros convencional e impresso por meio de ensaios mecânico: de tração e flexão, e avaliam-se as vantagens e desvantagens do extensômetro impresso. Os resultados obtidos pelo novo conceito de extensômetro apresentaram-se bastante satisfatórios nas avaliações experimentais.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-30T12:54:06Z No. of bitstreams: 2 Dissertação - Aleones José da Cruz Junior - 2016.pdf: 10954784 bytes, checksum: 8944f42a69c5b4dd439d7460fa35ae41 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-30T12:54:28Z (GMT) No. of bitstreams: 2 Dissertação - Aleones José da Cruz Junior - 2016.pdf: 10954784 bytes, checksum: 8944f42a69c5b4dd439d7460fa35ae41 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-30T12:54:28Z (GMT). No. of bitstreams: 2 Dissertação - Aleones José da Cruz Junior - 2016.pdf: 10954784 bytes, checksum: 8944f42a69c5b4dd439d7460fa35ae41 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-08-19 / In the last few years there have been increasing demands for more elaborated foundations projects, therefore, numerical tools and Geotechnical design methodologies have been developed. However, these solutions need to be confirmed, which is possible through direct measuring of the elements, achieved through instruments. Diverse research applied instrumentations to the load transfer problem under controlled conditions of the field and laboratory, however, there are few studies that aimed the application of a global instrumentation, of the construction as a whole, and for a longer period of time with greater durability of the sensors. In this regard, this work had the main objective to come up with a methodology for a versatile and durable instrumentation of piled foundations in order to verify the load distribution transmitted by the pillars to the ends of the piles from the making of the sensors to the load test application to measure loads at full scale. The use of strain gages for construction of the instruments has been set. The sensors were fabricated and calibrated using the physical space and equipment of PPGECON-UFG, using criteria and specific procedures for this research. Prototypes were developed in scale models, small columns of concrete, in order to reach the best arrangement of the sensors, performing load and performance of instrumentation simulations. A construction was determined as a case study where it was performed instrumented static load test at several levels, using the developed sensors. The sensors developed by performance tests proved to be durable and accurate, and the immersion sensor shown a closer behavior to the concrete through load tests. However, performance tests have shown to be more susceptible to setting time and curing phenomena of the concrete. For application in columns, it was found that the sensors manufactured showed good performance when compared to calculated values of elastic modulus compound. Sensors applied to the load test were able to obtain the distribution of loads at different levels, separating portions of the lateral friction resistance per layer, and the unit shear stress of soil layer. From these results it was found the maximum shear stress in the surface layer and it was possible to compare with semi-empirical methods of load capacity and bridging charge-discharge curve. Proving that the installation of instrumentation in the load test, even without occurrence of break, is used to verify the performance of the test pile, knowing additional parameters and confirming the geotechnical design. / Nos últimos anos ocorreram demandas crescentes por projetos de fundações mais elaborados e para tal têm sido desenvolvidas ferramentas numéricas e metodologias de projeto geotécnico. Todavia, estas soluções precisam ser confirmadas, o que é possível através de medidas diretas sobre os elementos, conseguidas por meio de instalações de instrumentos. Variadas pesquisas aplicaram instrumentações ao problema de transferência de carga em condições controladas de campo e laboratório, no entanto, são poucas pesquisas que buscaram a aplicação de uma instrumentação global, da obra como um todo, e por um período maior de tempo com maior durabilidade dos sensores. Nesse contexto, este trabalho teve o objetivo principal de propor uma metodologia para instrumentação versátil e duradoura de fundações estaqueadas, a fim de verificar a distribuição das cargas transmitidas pelos pilares até as pontas das estacas, a partir da confecção dos sensores até a aplicação em provas de carga para medir cargas em escala real. Foi definido o uso de extensômetros elétricos para construção dos instrumentos. Os sensores foram confeccionados e calibrados utilizando o espaço físico e equipamentos do Programa de Pósgraduação em Geotecnia Estruturas e Construção Civil (PPGECON), utilizando critérios e procedimentos específicos para esta pesquisa. Foram desenvolvidos protótipos em modelos reduzidos, pilaretes de concreto, a fim de verificar a melhor condição de disposição dos sensores, realizando simulações de carga e de desempenho das instrumentações. Foi definida uma obra para estudo de caso, onde foi executada prova de carga estática instrumentada em vários níveis, usando os sensores desenvolvidos. Mediante testes de desempenho os sensores mostraram ser duráveis e precisos, sendo que o sensor de imersão mostrou um comportamento mais próximo ao comportamento do concreto através de testes de carga. No entanto, os testes de desempenho mostraram ser mais suscetíveis a fenômenos de pega e cura do concreto. Para aplicação em pilares, foi verificado que os sensores confeccionados mostraram bom desempenho quando comparados aos valores calculados de módulo de elasticidade composto. Os sensores aplicados na prova de carga conseguiram obter a distribuição das cargas nos vários níveis, separando parcelas de resistências de atrito lateral por camada, e as tensões cisalhantes unitárias por camada de solo. A partir destes resultados verificou-se a tensão cisalhante máxima na camada superficial e foi possível comparar com métodos semi-empíricos de capacidade de carga e de extrapolação da curva carga-recalque. Comprovando que a instalação da instrumentação na prova de carga, mesmo sem ocorrência da ruptura, serve para verificar o desempenho da estaca ensaiada, conhecendo parâmetros adicionais e confirmando o dimensionamento geotécnico.