Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 90-93).

O assentamento passivo tem sido considerado um dos mais importantes requisitos para o sucesso de próteses implanto-suportada. Este estudo in vitro investigou a deformação do intermediário de prótese implantosuportada após o aperto do parafuso tanto do cilindro de Paládio-Prata como de Cobalto-Cromo. Um modelo mestre foi usado para simular uma mandíbula humana com cinco implantes. Extensômetros foram colados nas faces mesial e distal de cada intermediário para registrar as deformações causadas pelos cilindros após o aperto dos parafusos. Os intermediários foram montados sobre as réplicas dos implantes e os parafusos foram apertados com um torque de 20 Ncm e as leituras foram gravadas. Após este passo, os parafusos tanto dos cilindros de Paládio-Prata como de Cobalto-Cromo foram apertados com um torque de 10 Ncm e as leituras também foram gravadas. Estas medições foram repetidas por cinco vezes. O teste estatístico de Mann-Whitney foi aplicado aos resultados. Nenhuma diferença estatística foi encontrada entre as tensões geradas tanto pelos cilindros de Paládio-Prata como os de Cobalto-Cromo. No entanto, existiram diferenças com relação à qualidade da tensão. A deformação gerada pelo aperto dos parafusos dos cilindros de Cobalto-Cromo foi de compressão e o aperto dos parafusos dos cilindros de Paládio-Prata gerou forças de compressão e tração. / Passive fit has been considered one of the most important requirements for the success of implant supported prostheses. This in vitro study investigated the abutment deformation of an implant-supported prosthesis after screw tightening of palladium-silver and cobalt-chromium prosthetic cylinder. A master model was used to simulate a human mandible with five implants. The Strain gauges were attached on the sides of each abutment to capture deformations because of the cylinders screws after was tightened. The abutments were mounted onto implant replicas and the screws were tightened to a 20 Ncm torque, and the readings were recorded. After this step, palladiumsilver and cobalt-chromium prosthetic cylinders were tightened to a 10 Ncm torque and the readings were recorded. The measurements were repeated five times. Mann-Whitney statistical test was applied to the results. No statistical differences were found between the deformation generated by palladium-silver and cobalt-chromium prosthetic cylinders. However, there were differences relative to the quality of the strain. The deformation generated by screw tightness of the cobalt-chromium prosthetic cylinders was compressive while palladium-silver prosthetic cylinders generated compressive and tensile strain.

Pressure measurement using a strain gauge bonded with epoxy adhesive to a metallic mechanical support has been, and still is, extensively employed, however, for some applications the use of an epoxy is inadequate, especially when temperatures exceed 120C. There is therefore particular interest in the use of thin film techniques to vacuum deposit strain gauges directly on metallic substrates. Such devices are highly cost effective when produced in large quantities due to the manufacturing techniques involved. This makes them ideally suited for use in large-volume products such as electronic weighing scales and pressure transducers. In this thesis, new techniques for fabricating thin film vapour deposited strain gauge transducers on metal substrates for application as novel pressure sensors in the fastener industry are developed. Clearly, for a vapour deposited strain gauge to function correctly, it is essential that it be deposited on a defect free, high quality electrically insulating film. This was a significant challenge in the present study since all available physical vapour deposition (PVD) equipment was direct current (DC) and insulators of around 4 um thick were needed to electrically isolate the strain gauges from metal. As a result, several methods of depositing insulators using DC were developed. The first involved the use of DC magnetron sputtering from an aluminium target to reactively deposit up to 4 um thick AlN. DC magnetron discharges suffer arc instability as the AlN forms on the target and this limits the maximum thickness that can be deposited. Consequently, the arc instability was suppressed manually by increasing argon gas flow at the onset of arcing. Although the deposited AlN showed a high insulating resistance, it was found that the breakdown voltage could significantly increase by (a) utilising a metallic interlayer between the thin film insulator and the metallic substrate and (b) annealing in air at 300C. A second deposition method involved the use of DC magnetron sputtering to deposit modulated thin film insulators in which an aluminium target was used to reactively deposit alternating layers of aluminium nitride and aluminium oxide. These films showed significant increases in average breakdown voltage when the number of layers within the composite film was increased. The third method involved the deposition of AlN thin film insulators using partially filtered cathodic arc evaporation with shielding. Initially, AlN was deposited under partially filtered conditions to obtain a relatively thick (~ 4 um) coating then, while still depositing under partially filtered conditions, a smooth top coating was deposited by using a shielding technique. The deposition of metal macroparticles is an inherent problem with cathodic arc deposition and shielding is one form of macroparticle filtering. Such particles are highly undesirable in this study as they are electrically conductive. A fourth coating technique for depositing insulators on steel was based on thermal spray technology. Insulating films of Al2O3 were plasma sprayed and then polished to thereby fabricate viable electrical insulators for vapour deposited strain gauges. With respect to depositing strain gauges two methods were employed. The first involved the sputter deposition of chromium through a shadow mask to form a strain gauge with gauge factor sensitivity of around 2. The second used cathodic arc evaporation to fabricate a multi-layered strain gauge composed of alternating CrN and TiAlN layers that yielded a gauge factor of around 3.5. The technique achieves better compatibility between gauge and insulator by allowing a wider selection of materials to form the gauge composition. Finally, a novel pressure sensor in the form of a load cell was developed that consisted of a chromium strain gauge on a steel washer electrically insulated with AlN thin film. The load cell showed good performance when tested under compressive load.

Hollow section members are widely used in industrial applications for the design of many machine and structural components. These components are often fabricated at lower cost by welding rather than by casting or forging. For instance, in agricultural machinery, the hollow tubes are typically connected together through welding to form T-joints. Such T-joint connections are also employed in other engineering applications such as construction machinery, offshore structures, bridges, and vehicle frames. In this dissertation, the behaviour of tubular T-joint connections, in particular square hollow section (SHS)-to-SHS T-joints, subjected to static and cyclic loads is studied both experimentally and numerically. The techniques used for the fabrication of the T-joint connections can affect their strengths to different degrees. With modern advances in manufacturing technologies, there are many alternatives for the fabrication of the T-joint connections. For instance, in recent years, the use of the laser beam has become increasingly common in industrial applications. From a manufacturing point of view, the T-joint connections can be fabricated by using traditional mechanical cutting or laser cutting techniques. Currently, for the fabrication of the T-joint connections, the straight edge of one tube is cut using mechanical tools (e.g., flame cutting) and then welded to the body of the other tube. A major contribution of this research work is investigating the feasibility of using laser cutting to produce welded square hollow-section T-joints with similar or higher fatigue strengths than their conventional mechanical cut counterparts. For this purpose, a total of 21 full-scale T-joint samples, typical of those found in the agricultural machinery, are included for the study. Finite Element (FE) models of the T-joints manufactured with the different cutting techniques are also developed and the FE results are verified with the experiments. The results of the numerical and experimental study on the full-scale T-joint samples show that the fatigue strength of the samples that are manufactured with laser cutting is higher than those fabricated with conventional mechanical cutting. From a structural analysis view point, despite of the wide use of tubular T-joint connections as efficient load carrying members, a practical but yet simple and accurate approach for their design and analysis is not available. For this purpose, engineers must often prepare relatively complicated and time consuming FE models made up of shell or solid elements. This is because unlike solid-section members, when hollow section members are subjected to general loadings, they may experience severe deformations of their cross-sections that results in stress concentrations in the connections vicinity. One of the objectives/contributions of this research work is the better understanding of the behaviour of SHS-to-SHS T-joint connections under in-plane bending (IPB) and out-of-plane bending (OPB) loading conditions. Through a detailed Finite Element Analysis (FEA) using shell and solid elements, the stiffness and stress distribution at the connection of the tubular T-joints are obtained for different loading conditions. It is observed that at a short distance away from the connection of the T-joints, the structure behaves similar to beams when subjected to loadings. The beam like stresses cease to be valid only in the vicinity of the connection. Therefore, several parameters are defined to recognize the joints stress concentrations and the bending stiffness reduction. These parameters permit the accurate modelling of the tubes and the T-connection by simple beam elements with certain modifications. The models consisting of beam elements are significantly easier to prepare and analyze. Through several numerical examples, it is shown that the modified beam models provide accurately all important information of the structural analysis (i.e. the stresses, displacements, reaction forces, and the natural frequencies) at substantially reduced computational effort in comparison with the complicated Finite Element (FE) models built of shell or solid elements. Another contribution of this research work is the FE modelling of the weld geometry and its effect on the stresses at the vicinity of the connection. The results of the FE modelling are verified through a detailed experimental study. For the experimental study, two test fixtures with hydraulic actuators capable of applying both static and cyclic loadings are designed and used. Strain gauges are installed at several locations on full-scale T-joint samples to validate the developed FE models. It is shown that the membrane stresses which occur at the mid-surface of the tubes remain similar regardless of the weld geometry. The weld geometry only affects the bending stresses. It is also shown that this effect on bending stresses is highly localized and disappears at a distance of about half of the weld thickness away from the weld-toe. To reduce the stress concentrations at the T-joint, plate reinforcements are used in a number of different arrangements and dimensions to increase the load carrying capacity of the connection.

Hollow section members are widely used in industrial applications for the design of many machine and structural components. These components are often fabricated at lower cost by welding rather than by casting or forging. For instance, in agricultural machinery, the hollow tubes are typically connected together through welding to form T-joints. Such T-joint connections are also employed in other engineering applications such as construction machinery, offshore structures, bridges, and vehicle frames. In this dissertation, the behaviour of tubular T-joint connections, in particular square hollow section (SHS)-to-SHS T-joints, subjected to static and cyclic loads is studied both experimentally and numerically. The techniques used for the fabrication of the T-joint connections can affect their strengths to different degrees. With modern advances in manufacturing technologies, there are many alternatives for the fabrication of the T-joint connections. For instance, in recent years, the use of the laser beam has become increasingly common in industrial applications. From a manufacturing point of view, the T-joint connections can be fabricated by using traditional mechanical cutting or laser cutting techniques. Currently, for the fabrication of the T-joint connections, the straight edge of one tube is cut using mechanical tools (e.g., flame cutting) and then welded to the body of the other tube. A major contribution of this research work is investigating the feasibility of using laser cutting to produce welded square hollow-section T-joints with similar or higher fatigue strengths than their conventional mechanical cut counterparts. For this purpose, a total of 21 full-scale T-joint samples, typical of those found in the agricultural machinery, are included for the study. Finite Element (FE) models of the T-joints manufactured with the different cutting techniques are also developed and the FE results are verified with the experiments. The results of the numerical and experimental study on the full-scale T-joint samples show that the fatigue strength of the samples that are manufactured with laser cutting is higher than those fabricated with conventional mechanical cutting. From a structural analysis view point, despite of the wide use of tubular T-joint connections as efficient load carrying members, a practical but yet simple and accurate approach for their design and analysis is not available. For this purpose, engineers must often prepare relatively complicated and time consuming FE models made up of shell or solid elements. This is because unlike solid-section members, when hollow section members are subjected to general loadings, they may experience severe deformations of their cross-sections that results in stress concentrations in the connections vicinity. One of the objectives/contributions of this research work is the better understanding of the behaviour of SHS-to-SHS T-joint connections under in-plane bending (IPB) and out-of-plane bending (OPB) loading conditions. Through a detailed Finite Element Analysis (FEA) using shell and solid elements, the stiffness and stress distribution at the connection of the tubular T-joints are obtained for different loading conditions. It is observed that at a short distance away from the connection of the T-joints, the structure behaves similar to beams when subjected to loadings. The beam like stresses cease to be valid only in the vicinity of the connection. Therefore, several parameters are defined to recognize the joints stress concentrations and the bending stiffness reduction. These parameters permit the accurate modelling of the tubes and the T-connection by simple beam elements with certain modifications. The models consisting of beam elements are significantly easier to prepare and analyze. Through several numerical examples, it is shown that the modified beam models provide accurately all important information of the structural analysis (i.e. the stresses, displacements, reaction forces, and the natural frequencies) at substantially reduced computational effort in comparison with the complicated Finite Element (FE) models built of shell or solid elements. Another contribution of this research work is the FE modelling of the weld geometry and its effect on the stresses at the vicinity of the connection. The results of the FE modelling are verified through a detailed experimental study. For the experimental study, two test fixtures with hydraulic actuators capable of applying both static and cyclic loadings are designed and used. Strain gauges are installed at several locations on full-scale T-joint samples to validate the developed FE models. It is shown that the membrane stresses which occur at the mid-surface of the tubes remain similar regardless of the weld geometry. The weld geometry only affects the bending stresses. It is also shown that this effect on bending stresses is highly localized and disappears at a distance of about half of the weld thickness away from the weld-toe. To reduce the stress concentrations at the T-joint, plate reinforcements are used in a number of different arrangements and dimensions to increase the load carrying capacity of the connection.

Thesis (Ph. D.)--University of Hong Kong, 1983.

xiii, 75 p. : ill. (some col.) / Uplift rates associated with 12 episodic tremor and slip events on the Cascadia Subduction Zone occurring between 1997 and 2010 have been determined from hourly water level records from 4 NOAA tide gauges (Neah Bay, Port Angeles, Port Townsend, and Seattle). Displacements inferred from water levels generally agree with displacements inferred from modeling GPS data. Examination of uplift between events shows an inter-event deformation rate approximately equal in magnitude, with ETS events, on average, releasing strain accumulated between events, suggesting that ETS is consistent with the elastic rebound theory. Additionally, while the GPS record only extends to the late 1990s and the tremor record includes only recent decades for Cascadia, tidal records in the Pacific Northwest and around the world span many decades. Thus, by showing that ETS can be resolved in tidal records we open up the possibility that tidal records could be used to study ETS where other tools are not available. This thesis contains unpublished coauthored material. / Committee in charge: Dr. David A. Schmidt, Chair; Dr. Ray J. Weldon, Advisor; Dr. Dean Livelybrooks, Member

Orientador: Auteliano Antunes dos Santos Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T17:18:43Z (GMT). No. of bitstreams: 1 Saito_EdsonHiroshi_M.pdf: 2483546 bytes, checksum: f0889b176e6cc7896851b8620c53c361 (MD5) Previous issue date: 2010 / Resumo: A técnica ESPI, sigla em inglês - Electronic Speckle Pattern Interferometry -, ou ainda, Interferometria Eletrônica por Padrão de Speckle, surgiu em conseqüência do desenvolvimento da metrologia a laser, que possui como característica o chamado efeito speckle. Este efeito é o fenômeno óptico de interferência de ondas eletromagnéticas coerentes - que é o caso do Laser - que possibilita a geração de padrões de franjas de interferência, a partir das quais é possível medir o deslocamento de superfícies e posteriormente calcular as tensões e deformações. Por se tratar de uma metodologia não destrutiva e sensível a pequenos deslocamentos, essa metodologia tem se difundido na indústria para medição de Tensões em componentes mecânicos de formas complexas e como aplicação de apoio para outras técnicas como análise por Elementos Finitos. O objetivo deste trabalho é a aplicação da técnica ESPI em componentes mecânicos fazendo uso de uma metodologia através da qual seja possível estabelecer um procedimento de medição da tensão com confiabilidade. O desafio é estabelecer a adequada aplicação da ferramenta em ambiente industrial, onde há a interferência de ruídos, temperatura, vibração, além de uma adequação de equipamentos de ensaio que pode influenciar diretamente nos resultados de medições. A correta medição das tensões e deformações através de um ensaio não destrutivo e de rápido diagnóstico pode trazer diversos benefício, dentre os quais as cifras gastas em peças destruídas, tempo de medição e economia de mão-de-obra. Os resultados do presente trabalho são a determinação das variáveis influentes na aplicação do ESPI, levantamento das causas raízes dos problemas de medição e, a partir dessas informações, consolidar um procedimento padrão para aplicação em medição de tensões em componentes utilizando a técnica ESPI / Abstract: The ESPI technique - Electronic Speckle Pattern Interferometry - has emerged as a result of the development of laser metrology, which is characterized as the so-called speckle effect. This effect is an optical phenomenon of coherent electromagnetic waves interference - as Laser. It allows the generation of fringes interference from which it can be measured the displacement of surfaces and therefore calculated the stresses and strains. As a no-destructive methodology and being sensible to small displacements, it has being spread out in the industry by measuring Stress and Displacements in complex mechanical components and as a support to Finite Elements Analysis (FEA) and others techniques. The objective of this work is the application of the ESPI technique testing mechanical components making use of a systematic methodology by which it will be able to establish a procedure for measuring stress with reliability. The challenge is to establish the application procedure in the industrial environment, where there are a lot of interferences like noises, temperature variation, vibration etc., besides the fact that the testing equipment to be adapted to static tests can influences in the results. The stress and displacements measurement in a nodestructive test and fast result diagnose can bring a lot of benefits in financial terms serving as a support tool for other testing procedures. The results from this project are the determination of main variables for ESPI application, establishment of root causes in measurements problems using ESPI, and hence consolidate a standard procedure for ESPI application in strain /stress measurement in mechanical components / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

Orientador: Kamal Abdel Radi Ismail / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-14T07:39:10Z (GMT). No. of bitstreams: 1 Iano_MarcosChogi_D.pdf: 40621209 bytes, checksum: d971e987a0e70601a78ccb0bd1587e8e (MD5) Previous issue date: 2009 / Resumo: Instrumentos de monitoramento como termômetros, multímetros, voltímetros, manômetros, etc, são imprescindíveis para o controle e confiabilidade de um processo. No entanto, não muito raramente, os cuidados para o perfeito funcionamento destes instrumentos são colocados em segundo plano ou negligenciados. Os resultados destes descuidos, em um primeiro momento, são variações no processo e em um cenário mais negativo, interrupção e possíveis acidentes. Neste estudo, procurou-se analisar os efeitos da temperatura e do tempo de utilização nos elementos sensores de manômetros que utilizam tubo de Bourdon. Para induzir e acelerar estes efeitos montou-se uma bancada de testes composta de um reservatório onde os manômetros foram submergidos e submetidos a variações de temperatura por tempos determinados e um sistema de controle da pressão exercida sobre os manômetros. Tanto no inicio, quanto ao final de cada bateria de solicitação, os manômetros foram re-calibrados. Deste modo, geraram-se parâmetros para comparações e subsídios para se determinar os erros relativos dos instrumentos, oriundos da deterioração dos elementos sensores. Com base nos resultados alcançados puderam-se determinar, de forma a orientar os usuários de instrumentos/sistemas similares, os erros relativos esperados em cada faixa de temperatura, pressão e tempo de utilização destes instrumentos, além de auxiliá-lo na determinação do período ideal para calibrações e conhecimento de sua vida útil. / Abstract: Systems monitoring instruments like thermometers, multimeters, voltmeters, manometers, etc, are of such importance to monitor and processes reliability controlling. However, it's uncommon to have the due cares for their perfect operation being in certain moments put in second place or neglected. The results of those improper cares are the process variation and afterwards a more negative/imprecise scenario, unexpected interruption and worse possible accidents. In this study, it was analyzed the effect of temperature and time when using sensing elements like manometers which use Bourdon tube. To induce and accelerate these effects one work-bench tests was built consisting of a reservoir where the manometers were submerged and submitted under temperature variation to certain pre-determined times and a pressure controlling system on the manometers inserted. Within each pre-determined test sequence as the manometers were re-calibrated. Based on the obtained results this work gives subsidies to determine the deriving relative errors due to the sensing elements deterioration., moreover assist the user on the expected relative errors in each band of temperature, pressure and time, beyond of that determinate the ideal calibration period to obtain a known useful instrument lifetime. / Doutorado / Termica e Fluidos / Doutor em Engenharia Mecânica

This thesis sets out to derive an analytical model for a center of gravity (CG) measuring platform and examines its validity through experimental testing and Finite Element Modeling. The method uses a two-stage platform tilting process to first locate the planar CG coordinates and then find the third CG coordinate normal to the platform. An uncertainty model of the measuring platform was also developed, both CG and uncertainty models were implemented in the form of a MATLAB code. A load cell sizing task was also added to the code to assist the Integration Engineers at Jet Propulsion Laboratory in selecting load cells to design their own version of the CG Platform. The constructed CG Platform for this project used an array of six strain gauges, four C2A-06-062LT-120 Tee Rosettes and two C2A-06-031WW-120 Stacked Rosettes. They were bonded onto the legs of three truss shaped bipods. Results from the Platform Tilting Tests could not be used to validate the CG model as the measured CG and weight values found from the experimental tests contained a considerable amount of error. The errors in the Platform Tilting Tests are believed to stem from the initial errors observed during the bipod rod and strain gauge calibration tests. As an alternative, an FE model of the CG measuring platform was created as another means of validation. The math model of the CG measuring platform was successfully validated by showing that there was less than a 0.01% different between the bipod loads predicted from the MATLAB code and the FE model. Using the FEM generated loads as inputs into the CG code to calculate a CG matched the initial point mass or CG created in the FE model within a 0.01% difference. To validate the CG model even further, another test should be performed using a CG Platform prototype instrumented with load cells to generate new experimental data and compare them with the results from the FE model.