Dissertations / Theses on the topic 'Strain Gauge analysis'

This project is centred on an ongoing trailer component failure problem at the STEELBRO New Zealand Ltd due to cracks. In this research the problem has been systematically approached using ANSYS finite element analysis software. The approach involves investigation of the problem and structural analysis of the trailer subjected to two types of service conditions. The service conditions are simulated in ANSYS which involved CAD and finite element modelling of the trailer, and then the finite element model is validated experimentally by strain gauges and geometrically by ANSYS element shape checking capability. The finite element model subjected to static structural analysis confirmed the crack locations and indicated the cause of the failure. Further fatigue analysis on one of the loading condition revealed it’s potential to cause failure at the crack locations. Finally, this research concludes with a proposal of revised component design to overcome the failure at the crack locations and recommendations for further analysis on the trailer.

Orientador: Renato Sussumu Nishioka
Banca: Wirley Gonçalves Assunção
Banca: Alysson Noriyuki Kajishima Konno
Banca: Eduardo Shigueyuki Uemura
Banca: Osvaldo Daniel Andreatta Filho
Resumo: O objetivo deste estudo foi avaliar, por meio da extensometria, a distribuição de tensões ao redor de implantes em função dos diferentes locais para carregamento, tipo de coifa (plástica ou usinada) e configuração (linear e compensada). Para tanto, em um bloco de poliuretano, foram posicionados paralelos entre si e com uma configuração linear, implantes auto-rosqueáveis de hexágono externo, com dimensões de 3,75 X 13mm, a uma distancia de 7mm, de centro a centro. Em um outro bloco a fixação do meio foi deslocada em 2mm para gerar uma configuração compensada (offset). Pilares protéticos Micro-unit, com 3mm de cinta foram instalados sobre as fixações. Com duas matrizes em aço inoxidável foram confeccionados 10 enceramentos para cada bloco, distribuídos da seguinte forma: 5 para coifa plástica e 5 para coifas usinadas (n=5). A seguir esses padrões foram fundidos com uma liga de Co-Cr. Quatro extensômetros (strain gauges) foram colados na superfície superior de cada bloco tangenciando a plataforma de cada fixação. Um carregamento de 30kg durante 10s foi feito em cinco posições (A, B, C, D, E), sendo repetido três vezes para aquisição dos dados (em με) pela aparelho condicionador de sinais. Os dados obtidos foram submetidos a análise de variância (ANOVA) e teste de Tukey (p<0,05). Como conclusão da análise dos resultados obtidos pudemos observar que não houve diferença na utilização de coifas plásticas e usinadas, que não houve diferença entre as configurações linear e compensada; havendo diferença estatisticamente significante para os locais de carregamento
Abstract: The aim of this study was to evaluate, using strain gauge, the load distribution surround the implants according differents loading sites, coping types (plastic and machined) and configuration (linear and offset). In one polyurethane block, three cylindrical implants with external hexagon (3.75mm x 13mm) were fixed parallel with 7mm between their centers in a linear configuration. In another block the midle implant was positioned in a 2mm offset. Micro-units abutments with 3mm of metallic neck were fixed. With two metallics matrix, it was manufactured 10 wax patterns for each block, distributed in the following form: 5 for plastic copings and 5 for machined copings (n=5). After, patterns were casted in cobalt-chromium alloy. Four strain gauges were positioned on the upper surface of each polyurethane model around the implants. An axial load of 30kg within 10 seconds in five positions (A, B, C, D, E), with three repetead measurements for data aquisition (in με) by the multichanel bridge machine. The datas were submitted to ANOVA and Tukey test (p<0.05). Such as conclusion from the obtained data treatment: there was no difference between the plastic and machined copings, there was no difference between the linear and offset configuration; there was statiscal significance only with the differents loading sites.
Doutor

There is no established method of measuring load accurately in a threaded connection at working temperatures exceeding 500°C. At these conditions conventional methods can not be used due to the sensitivity of the instruments and it is suggested that a non contact method should be used. The laser strain gauge was developed by the Loughborough University Optical Research Group and it is a non contact way of measuring surface strain. With the help of finite element analysis (FEA) a special nut was developed that can be used to measure the load on the connection by relating the surface strain of the nut to the load. Experimental work later revealed that due to the threads sticking in the connection there is hysteresis present between the load and surface strain relationship. To eliminate the hysteresis a new part was added to the connection which could be used to relate the surface strain on it to the load without any hysteresis. This new part was a specially designed washer with three grooves to allow easy access for the user to measure the surface strain using the laser strain gauge. Part of the design specification was that the load has to be determined to an accuracy of 0.5%. Using sensitivity analysis the washer was analysed in terms of how manufacturing imperfections affect the accuracy of the load measuring device. The results revealed that to achieve the required 0.5% accuracy the washer would have to be manufactured to very tight tolerances. To achieve these tight tolerances the manufacturing process would not be cost effective so it was proposed that individual calibration is required for each load measuring washer. Tests showed that with sufficient calibration the specially designed washer and the laser strain gauge can be combined and used as an accurate non contact load measuring device. As it is a non contact method it can be used in extreme environments including high temperatures. This thesis describes how background research, finite element analysis and experimental testing were used to develop the load measuring washer. Also it is shown, how in-depth sensitivity analysis was used to determine the accuracy of the prototype and that how manufacturing imperfections influence the working life of a threaded connection.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O objetivo deste estudo foi avaliar, por meio da extensometria, a distribuição de tensões ao redor de implantes em função dos diferentes locais para carregamento, tipo de coifa (plástica ou usinada) e configuração (linear e compensada). Para tanto, em um bloco de poliuretano, foram posicionados paralelos entre si e com uma configuração linear, implantes auto-rosqueáveis de hexágono externo, com dimensões de 3,75 X 13mm, a uma distancia de 7mm, de centro a centro. Em um outro bloco a fixação do meio foi deslocada em 2mm para gerar uma configuração compensada (offset). Pilares protéticos Micro-unit, com 3mm de cinta foram instalados sobre as fixações. Com duas matrizes em aço inoxidável foram confeccionados 10 enceramentos para cada bloco, distribuídos da seguinte forma: 5 para coifa plástica e 5 para coifas usinadas (n=5). A seguir esses padrões foram fundidos com uma liga de Co-Cr. Quatro extensômetros (strain gauges) foram colados na superfície superior de cada bloco tangenciando a plataforma de cada fixação. Um carregamento de 30kg durante 10s foi feito em cinco posições (A, B, C, D, E), sendo repetido três vezes para aquisição dos dados (em με) pela aparelho condicionador de sinais. Os dados obtidos foram submetidos a análise de variância (ANOVA) e teste de Tukey (p<0,05). Como conclusão da análise dos resultados obtidos pudemos observar que não houve diferença na utilização de coifas plásticas e usinadas, que não houve diferença entre as configurações linear e compensada; havendo diferença estatisticamente significante para os locais de carregamento
The aim of this study was to evaluate, using strain gauge, the load distribution surround the implants according differents loading sites, coping types (plastic and machined) and configuration (linear and offset). In one polyurethane block, three cylindrical implants with external hexagon (3.75mm x 13mm) were fixed parallel with 7mm between their centers in a linear configuration. In another block the midle implant was positioned in a 2mm offset. Micro-units abutments with 3mm of metallic neck were fixed. With two metallics matrix, it was manufactured 10 wax patterns for each block, distributed in the following form: 5 for plastic copings and 5 for machined copings (n=5). After, patterns were casted in cobalt-chromium alloy. Four strain gauges were positioned on the upper surface of each polyurethane model around the implants. An axial load of 30kg within 10 seconds in five positions (A, B, C, D, E), with three repetead measurements for data aquisition (in με) by the multichanel bridge machine. The datas were submitted to ANOVA and Tukey test (p<0.05). Such as conclusion from the obtained data treatment: there was no difference between the plastic and machined copings, there was no difference between the linear and offset configuration; there was statiscal significance only with the differents loading sites.

This master´s thesis deals with determination of pressure in the pipe using foil strain gauge. It is calculation of the pressure from the measured strain. The main purpose of this work is devise mathematical-technological models to determinate internal pipe pressure from longitudinal deformation. Devised models were used on data from realized experiment and results were compared with real value of pressures in pipes. This thesis contains three models which were mutually compared. Sensitivity analysis were done on two of these models. Thesis also contains opening research of strain gauge problematics. Description of basic knowledge of physical objects mechanic with focusing on shells also belongs to this theoretical part.

Cold Central Plant Recycling (CCPR) has been used by many state highway agencies to save material, money, time, and energy in pavement construction and rehabilitation. The objectives of this thesis were to: (1) perform an instrumented verification analysis, (2) evaluate the response and performance of two pavement configurations with a CCPR base layer through accelerated pavement testing (APT), and (3) construct models using mechanistic-empirical pavement design software for comparison with the APT results. The pavement configurations featured a 5-inch CCPR mixture with either a 3-inch or 1.5-inch SM-9.5D surface mixture. Each section was instrumented with strain gauges, pressure cells, and thermocouples. A heavy vehicle simulator (HVS) was used to load three replicate test sections in each lane, with the temperature controlled at 39°C at a depth of 1.5 inches. Results from the instrument verification analysis showed that the strain gauges and pressure cells used in the experiment recorded pavement responses with a high degree of repeatability. In addition, the loading condition variables (speed, wheel load, and tire inflation pressure) affected the response following the expected trends and did not affect the repeatability of the instruments. The average CV of all strain gauge and pressure cell signals was approximately 0.009 or 0.9%, and 0.004 or 0.4%, respectively. In terms of the rutting comparison, the sections with the 3-inch surface layer outperformed the sections with the thinner 1.5-inch surface layer. However, the age of the pavement at the start of testing significantly affected the rutting performance. After adjusting for the pavement age at the time of testing, the section with the thicker surface showed approximately half of the rutting of the section with the thinner surface. The results from preliminary ME Design analysis indicate that the software cannot model the studied APT sections using the default material properties and calibration factors available at the time of analysis. In particular, the software does not seem to be prepared to model the CCPR materials.
Master of Science

An artificial Neural Network (ANN) system has been developed that can analyse aircraft flight data to provide a reconstruction of the aerodynamic loads experienced by the aircraft during flight, including manoeuvre, buffet and distributed loading. For this research data was taken from the International Follow-On Structural Test Project (IFOSTP) F/A-18 fatigue test conducted by the Royal Australian Air Force and Canadian Forces. This fatigue test involved the simultaneous application of both manouevre and buffet loads using airbag actuators and shakers. The applied loads were representative of the actual loads experienced by an FA/18 during flight tests. Following an evaluation of different ANN types an Ellman network with three linear layers was selected. The Elman back-propagation network was tested with various parameters and structures. The network was trained using the MATLAB 'traingdx' function with is a gradient descent with momentum and adaptive learning rate back-propagation algorithm. The ANN was able to provide a good approximation of the actual manoeuvre or buffet loads at the location where the training loads data were recorded even for input values which differ from the training input values. In further tests the ability to estimate distributed loading at locations not included in the training data was also demonstrated. The ANN was then modified to incorporate various methods for the calculation and prediction of output error and reliability Used in combination and in appropriate circumstances, the addition of these capabilities significantly increase the reliability, accuracy and therefore usefulness of the ANN system's ability to estimate aircraft loading.To demonstrate the ANN system's usefulness as a fatigue monitoring tool it was combined with a formulae for crack growth analysis. Results inficate the ANN system may be a useful fatigue monitoring tool enabling real time monitoring of aircraft critical components using existing strain gauge sensors.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais
The widening of the root canal increases its fracture risk and is not clear yet, the influence of the materials and techniques used to restore these teeth. The aim of this study was to evaluate the effect of different posts and restorative techniques in the fracture resistance, fracture mode and root strain in canals excessively widened. One hundred thirty five standardized bovine roots, with similar dimensions and endodontically treated, were randomly divided in 9 groups (n=15) with the root canals prepared with 10 mm depth and 1.5 mm diameter. All roots received ferrule in the coronal ending with 0.5 mm depth and 2 mm extension. The roots of two reference groups were reconstructed with nickel-chromium metallic cast post-and-core (NMF) and glass fiber post (PFV) with composite resin core. For the experimental groups (weakened roots - wc groups), the root canals were over prepared additionally with the depth of 9 mm and the diameter increased to approximately 3,5 mm. Then the roots were restored with metallic cast post-and-core (wcNMF); glass fiber post (wcPFV); glass fiber post associated with accessory glass - ap - fiber post (wcPFVap); direct composite resin - cr - in the medial and cervical thirds after luting the post (wcPFVcr); direct composite resin associated with accessory posts in the medial and cervical thirds, after luting the post (wcPFVcrap); the post was reembased indirectly with composite resin - icr - (wcPFVicr); the post was reembased indirectly with composite resin associated with accessory posts (wcPFVicrap). All posts were fixed with chemical resinous cement, the core was made with composite resin and the roots restored with metallic crown. The samples were submitted to 3x105 mechanical fatigue cycles of 50 N load and fracture resistance measured in a mechanical testing machine with tangential load application (135º). Five samples of each group received two strain gauges adhered in the mesial and buccal surfaces of the root, 1mm below the cervical crown ending, in the center of the tooth, to measure roots strain under continuous 0 to 100 N loading. Fracture mode was classified in accordance to the degree of destruction of the dental structure, in catastrophic or repairable. The data were submitted to ANOVA (2x2)l to one-way and Tukey´s test (α=0.05). The factorial analysis demonstrated significant decrease of the fracture resistance and catastrophic failures for the wcNMF group. Roots widened canals restored with composite resin and/or accessory fiber posts result in fracture resistance values similar to NMF group, however, these demonstrated more repairable fracture. The strain-gauge analysis didn t present significant differences in the superficial strain of the root. Fiber glass post associated with composite resin or with accessory fiber glass posts, seems to be more indicated as alternative to metallic cast post-and-core in weakened roots, because of the lower risk of catastrophic fractures.
O alargamento do canal aumenta o risco de fratura dentária e ainda não está clara a influência dos materiais e técnicas empregados para restaurar dentes com estas características. Assim, o objetivo deste estudo foi avaliar o efeito de diferentes pinos e técnicas restauradoras na resistência à fratura, padrão de fratura e deformação de raízes com canais excessivamente alargados. Foram empregadas 135 raízes bovinas com dimensões semelhantes, tratadas endodonticamente, aleatoriamente divididas em 9 grupos (n= 15). Os canais foram preparados com 10 mm de profundidade e 1,5 mm de diâmetro e as raízes receberam preparo com férula de 0,5 mm de profundidade e 2 mm de extensão. Dois grupos de referência foram restaurados com retentores intraradiculares metálicos fundidos em níquel-cromo (NMF) e pino de fibra de vidro (PFV) com núcleo de preenchimento em resina composta. Para os demais grupos, os canais radiculares foram alargados na profundidade de 9 mm e o diâmetro aumentado para ±3,5 mm, padronizando a espessura de dentina remanescente em 0,5mm no terço coronário da raiz. Os canais alargados (ca) foram então restaurados com, núcleo metálico fundido (caNMF); pino de fibra de vidro (caPFV); pino de fibra de vidro associado a pinos de fibra de vidro acessórios (caPFVpa); preenchimento direto com resina composta nos terços médio e cervical após cimentação do pino (caPFVrd); preenchimento direto com resina composta associado a pinos acessórios, após cimentação do pino (caPFVrdpa); pino reembasado com resina composta de forma indireta (caPFVri); pino reembasado com resina composta de forma indireta associado a pinos acessórios (caPFVripa). Todos os procedimentos de cimentação foram realizados com cimento resinoso de ativação química, os núcleos de preenchimento em resina composta e as raízes restauradas com coroa total metálica. As amostras foram submetidas a 3x105 ciclos de fadiga mecânica de 50N de carga. Em cinco amostras de cada grupo, dois extensômetros foram aderidos à raiz, um na mesial e outro na vestibular, 1 mm abaixo do limite cervical da coroa, no centro do dente, para mensurar a deformação das raízes sob carregamento contínuo de 0 a 100N. A resistência à fratura (N) das amostras foi então medida em máquina de ensaio mecânico com aplicação de carga tangencial (135º). Os dados foram submetidos à análise de variância fatorial (2x2), para comparar o efeito do tipo de retentor em função do tipo de raiz, e em fator único, para avaliar os métodos de preenchimento, seguido pelo teste de Tukey (α=0,05). O padrão de fratura foi classificado de acordo com o grau de comprometimento da estrutura dentária em catastrófica ou reparável. A análise estatística fatorial demonstrou significativa redução da resistência à fratura e falhas catastróficas para o grupo caNMF. Valores de resistência comparável ao grupo NMF e padrão de fratura reparável foram obtidos em raízes com canais alargados, sempre que a resina composta ou pinos de fibra acessórios foram utilizados. Não houve diferença significante na deformação externa da raiz entre os grupos estudados. Pode-se concluir que o uso de pinos de fibra de vidro, associado ao preenchimento com resina composta e/ou pinos de fibra de vidro acessórios, parece ser mais indicado como alternativa ao núcleo metálico fundido em raízes fragilizadas, devido ao menor risco de fraturas catastróficas.
Mestre em Odontologia

Fundação de Amparo a Pesquisa do Estado de Minas Gerais
The presence of bone loss is related to changes in the biomechanical behavior of endodontically treated teeth. The purpose of this study was to evaluate the effect of alveolar bone loss, ferrule presence and post type on the biomechanical behavior of endodontically treated maxillary canines restored with all-ceramic crowns. For the experimental analysis, forty upper human canines were selected and divided into 8 experimental groups according 3 treatment variations: bone support, without or with 5.0 mm of bone loss; ferrule presence, with or without 2.0mm of ferrule; and post type, restored with cast post and cores or glass fiber post. The restored canines were loaded at a 15- degree angle, and the deformation was measured using strain gauges placed on the buccal and proximal root surfaces. Strain results were analyzed by 3- way-ANOVA and Tukey HSD tests (α=.05). For the finite element analysis, eight 3-D models were created, following the same variations of the experimental analysis. The models were analyzed using the maximum principal stress criteria for stress distribution analysis. The presence of ferrule decreased significantly the buccal and proximal strain. The type of post showed slightly influence on the stress distribution. The presence of bone loss increased significantly the stress concentration and strain values in both regions mainly on root dentin and surrounding cortical bone. Can be possible to conclude that the presence of a ferrule improved the mechanical behavior, irrespective of the type of post. The 5.0mm of bone loss increased significantly the stress concentration and the strain on the root dentin.
A perda de inserção óssea está relacionada a mudanças no comportamento biomecânico de dentes tratados endodonticamente. O objetivo deste estudo foi avaliar o efeito da perda óssea alveolar, da presença de remanescente coronário e do tipo de retentor intra-radicular no comportamento biomecânico de caninos tratados endodonticamente e restaurados com cora em cerâmica pura. Para a análise experimental, quarenta caninos superiores foram selecionados e divididos em 8 grupos experimentais (n=10), de acordo com três fatores em estudo: suporte ósseo, ausência e presença de 5.0mm de perda óssea; remanescente coronário, ausência e presença de 2.0mm de remanescente coronário; e tipo de retentor, núcleo moldado e fundido e pino de fibra de vidro. Os caninos foram restaurados com cora em cerâmica pura reforçada por disilicato de lítio. As amostras foram submetidas ao carregamento de compressão a 15º em relação ao longo eixo do dente, e a deformação mensurada por extensômetros fixados nas superfícies radiculares vestibular e proximal. Os valores de deformação foram submetidos a Análise de variância fatorial 2X2X2 seguido pelo teste Tukey HSD (α=0,05). Para a análise de elementos finitos, oito modelos foram criados, simulando as mesmas variáveis da análise experimental. Todas as estruturas foram consideradas homogêneas e isotrópicas, a exceção do pino de fibra de vidro, considerado ortotrópico. Foi utilizado o critério de máxima tensão principal para análise de distribuição de tensões. A presença do remanescente coronário diminuiu significativamente a deformação vestibular e proximal. O tipo de pino mostrou pequena influência na distribuição de tensões. A presença da perda óssea aumentou significativamente a concentração de tensões, principalmente na dentina radicular e no osso cortical, e os valores de deformação em ambas as regiões mensuradas. Pode-se concluir que a presença de remanescente coronário dentinário melhorou o comportamento biomecânico, independente do tipo de pino. A presença da perda óssea alveolar de 5.0mm aumentou significativamente os valores de deformação e a concentração de tensões na dentina radicular.
Mestre em Odontologia

Comprehensive analysis of the ringcore method used for the determination of the residual stresses in mechanical components is presented in this thesis. Principles, advantages, disadvantages and applicability of this semidestructive experimental method are discussed too. At the same time the ringcore method is compared with the hole drilling method, which is used more frequently. All aspects of the ringcore method are analyzed by the finite element method. FE simulations, performed on the universal numerical model, verified principles of the integral method and the incremental strain method. FE simulations also provided basic information for the uncertainty analysis, which significantly affects the accuracy of the residual stress measurement. The main goal, which the present work deals with, is to create a global overview of all ringcore methods´ aspects elaborated in a clear and complex form.

In recent times, light gauge cold-formed steel sections have been used extensively in residential, industrial and commercial buildings as primary load bearing structural components. This is because cold-formed steel sections have a very high strength to weight ratio compared with thicker hot-rolled steel sections, and their manufacturing process is simple and cost-effective. However, these members are susceptible to various buckling modes including local and distortional buckling and their ultimate strength behaviour is governed by these buckling modes. Fire safety design of building structures has received greater attention in recent times due to continuing loss of properties and lives during fires. Hence, there is a need to fully evaluate the performance of light gauge cold-formed steel structures under fire conditions. Past fire research has focused heavily on heavier, hot-rolled steel members. The buckling behaviour of light gauge cold-formed steel members under fire conditions is not well understood. The buckling effects associated with thin steels are significant and have to be taken into account in fire safety design. Therefore, a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the distortional buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research program more than 115 tensile coupon tests of light gauge cold-formed steels including two steel grades and five thicknesses were conducted at elevated temperatures. Accurate mechanical properties including the yield strength, elasticity modulus and stress-strain curves were all determined at elevated temperatures since the deterioration of the mechanical properties is one of the major parameters in the structural design under fire conditions. An appropriate stress-strain model was also developed by considering the inelastic characteristics. The results obtained from the tensile coupon tests were then used to predict the ultimate strength of cold-formed steel compression members. In the second phase of this research more than 170 laboratory experiments were undertaken to investigate the distortional buckling behaviour of light gauge coldformed steel compression members at ambient and elevated temperatures. Two types of cross sections were selected with various thicknesses (nominal thicknesses are 0.6, 0.8, and 0.95 mm) and both low and high strength steels (G250 and G550 steels with minimum yield strengths of 250 and 550 MPa). The experiments were conducted at six different temperatures in the range of 20 to 800°C. A finite element model of the tested compression members was then developed and validated with the help of experimental results. The degradation of mechanical properties with increasing temperatures was included in finite element analyses. An extensive series of parametric analyses was undertaken using the validated finite element model to investigate the effect of all the influential parameters such as section geometry, steel thickness and grade, mechanical properties and temperature. The resulting large data base of ultimate loads of compression members subject to distortional buckling was then used to review the adequacy of the current design rules at ambient temperature. The current design rules were reasonably accurate in general, but in order to improve the accuracy further, this research has developed new design equations to determine the ultimate loads of compression members at ambient temperature. The developed equation was then simply modified by including the relevant mechanical properties at elevated temperatures. It was found that this simple modification based on reduced mechanical properties gave reasonable results, but not at higher temperatures. Therefore, they were further modified to obtain a more accurate design equation at elevated temperatures. The accuracy of new design rules was then verified by comparing their predictions with the results obtained from the parametric study. This thesis presents a description of the experimental and numerical studies undertaken in this research and the results including comparison with simply modified current design rules. It describes the laboratory experiments at ambient and elevated temperatures. It also describes the finite element models of cold-formed steel compression members developed in this research that included the appropriate mechanical properties, initial geometric imperfections and residual stresses. Finally, it presents the details of the new design equations proposed for the light gauge coldformed steel compression members subjected to distortional buckling effects at elevated temperatures.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The aim of this study was to evaluate the effect of two cavity preparation on fracture resistande of two CAD/CAM ceramic on Finite Element Analysis, Coronal deformation, Fracture Resistance and Fracture Mode over human molar teeth restored with esthetic indirect restoration. Forty-eight human molars were select and randomly divided into the following four groups (n=12): Group 1: conventional onlay (with occlusal and proximal box), leucite glass ceramic (IPS-Empress CAD, Ivoclar Vivadent); group 2: conservative onaly (without occlusal and proximal box), leucite glass ceramic (IPS-Empress CAD, Ivoclar Vivadent); group 3: convencional onlay, lithium-disilicate glass ceramic (IPS e.max CAD, Ivoclar Vivadent); group 4: conservative onlay, lithium-disilicate glass ceramic (IPS e.max CAD, Ivoclar Vivadent). Cuspal deformation (μS) was measured at 100N and Maximum fracture load by strain gauges (n = 7 teeth), Fracture Resistance (N) was measured by axial compression test and Fracture mode were recorded based on the degree of tooth structure and restoration damagemin four types (n = 12 teeth) and the Stress distributions was mesasure for all groups on Finite Element Analysis. The CS, Fracture resistance and Fracture mode were statistically analyzed using Tukey test and ANOVA two-way (p = 0.05). The Coronal deformation (CD) at 100N the Tukey s test showed that leucite ceramic restorations had significantly higher deformation than lithium-disilicate ceramic restorations, irrespective of cavity preparation (P<0.001). At maximum fracture load showed that lithium-disilicate ceramic restorations had significantly higher deformation than leucite ceramic restorations, irrespective of cavity preparation (P<0.001). The Fracture resistance and Fracture mode showed that the presence of box had no significant effect for leucite ceramic restoration (P=0.375), however the presences of box on disilicate ceramic restorations reduced significantly the fracture resistance (P<0.001). The disilicate ceramic restorations had significantly higher fracture resistance than leucite ceramic restoration (P <0.001) irrespective of cavity preparation. Fracture mode distributions showed that the leucite disilicate ceramic resulted in more severe fracture mode irrespective of cavity preparation. Whithin the limitations of this study, it was observed that the conservative onlay increase fracture resistence and the complex restored with a leucite-reinforced ceramics has less coronal deformation and fracture mode.
O objetivo deste estudo foi avaliar o efeito da morfologia do preparo cavitário na distribuição de tensões, comportamento biomecânico e resistência à fratura de molares restaurados indiretamente por dois sistemas cerâmicos. Quarenta e oito terceiros molares inferiores hígidos e com formas semelhantes extraídos foram divididos em 4 grupos (n=12) resultantes da combinação de dois fatores em estudo: 1- tipo de sistema cerâmico: Leucita (IPS-Empress CAD, Ivoclar Vivadent Ltda) e Dissilicato de Lítio (IPS e.max CAD, Ivoclar Vivadent Ltda); 2- Protocolo restaurador: onlay convencional e onlay conservador. A deformação coronal (μS) na carga de 100N e carga máxima a fratura foi medida por strain gauges (n= 7). A resistência à fratura (N) foi medida pelo teste de compressão axial e o modo de falha foi avaliado de acordo a destruição da estrutura dental e restauração em quatro tipos (n=12) e a distribuição de tensões foram analisadas em quatro grupos pelo método de análise de Elementos Finitos. A deformação coronal (DC), resistência à fratura (RF) e modo de falha (MF), foram analisados estatisticamente usando análise de variância ANOVA two-way e Teste de Tukey (p˂0,05). A análise de variância ANOVA two-way mostrou que a DC, em uma carga de 100N, apenas o fator restauração cerâmica (p<0,001) teve efeito significativo, na qual a cerâmica reforçada por leucita teve significantemente maior deformação que a cerâmica reforçada por dissilicato de lítio (p<0,001). Além disso, os preparos feitos com caixas proximal e oclusal resultaram em uma deformação similar do preparo sem as caixas (p<0,001). Na carga máxima à fratura apenas o fator tipo de cerâmica (p<0,001) tiveram efeito significativo no teste de RF, na qual as restaurações de dissilicato de lítio tiveram maior deformação que a leucita (p<0,001). Os testes de RF, mostraram que a presença das caixas não teve efeito significativo nas cerâmicas reforçadas por leucita (p=0,375), enquanto que a presença das caixas proximais e oclusais nas restaurações de cerâmica reforçada por dissilicato de lítio tiveram diminuição significativa na RF (p<0,001). As cerâmicas de dissilicato de lítio tiveram significantemente maior RF do que as cerâmicas de leucita (p<0,001). E no MF, a restaurações de dissilicato de lítio resultaram em fraturas mais catastróficas independente da geometria do preparo cavitário. De acordo com as limitações deste estudo in vitro e computacional, foi observado que o preparo mais conservador aumenta a resistência à fratura e o complexo restaurador com cerâmica reforçada por leucita teve menor deformação coronal e menor modo de falha.
Mestre em Odontologia

Human knee kinematics, especially during gait, are an important analysis tool. The current "gold standard" for kinematics measurement is a multi-camera, marker-based motion capture system with 3D position tracking. These systems are accurate but expensive and their use is limited to a confined laboratory environment. High deflection strain gauges (HDSG) are a novel class of sensors that have the potential to measure kinematics and can be inexpensive, low profile, and are not limited to measurements within a calibrated volume. However, many HDSG sensors can have a non-linear and non-monotonic response. This thesis explores using a nanocomposite HDSG sensor system for measuring knee kinematics in walking gait and overcoming the non-monotonic sensor response found in HDSGs through advanced modeling techniques. Nanocomposite HDSG sensors were placed across the knee joint in nine subjects during walking gait at three speeds and three inclines. The piezoresistive response of the sensors was obtained by including the sensors in a simple electrical circuit and recorded using a low-cost microcontroller. The voltage response from the system was used in four models. The first two models included a physics-based log-normal model and statistical functional data analysis model that estimated continuous knee angles. The third model was a discrete linear regression model that estimated the inflection points on the knee flexion/extension cycle. Finally, a machine learning approach helped to predict subject speed and incline of the walking surface. The models showed the sensor has the capability to provide knee kinematic data to a degree of accuracy comparable to similar kinematic sensors. The log-normal model had a 0.45 r-squared and was unsuitable as a stand-alone continuous angle predictor. After running a 10-fold cross validation the functional data analysis (FDA) model had an overall RMSE of 3.4° and could be used to predict the entire knee flexion/extension angle cycle. The discrete linear regression model predicted the inflection points on the knee kinematics graph during each gait cycle with an average RMSE of 1.92° for angle measures and 0.0332 seconds for time measures. In every estimate, the discrete linear regression model performed better than the FDA model at those points. The 10-fold cross validation of the machine learning approach using the discrete voltages could predict the categorical incline 90% of the time and the RMSE for the speed model was 0.23 MPH. The use of a HDSG as a knee kinematics sensor was shown as a viable alternative to existing motion capture technology. In future work, it is recommended that a calibration method be developed that would allow this sensor to be used independent of a motion capture system. With these advancements, this inexpensive and low profile HDSG will advance understanding of human gait and kinematics in a more affordable and scope enhancing way.

Cold-formed steel members have been widely used in residential, industrial and commercial buildings as primary load bearing structural elements and non-load bearing structural elements (partitions) due to their advantages such as higher strength to weight ratio over the other structural materials such as hot-rolled steel, timber and concrete. Cold-formed steel members are often made from thin steel sheets and hence they are more susceptible to various buckling modes. Generally short columns are susceptible to local or distortional buckling while long columns to flexural or flexural-torsional buckling. Fire safety design of building structures is an essential requirement as fire events can cause loss of property and lives. Therefore it is essential to understand the fire performance of light gauge cold-formed steel structures under fire conditions. The buckling behaviour of cold-formed steel compression members under fire conditions is not well investigated yet and hence there is a lack of knowledge on the fire performance of cold-formed steel compression members. Current cold-formed steel design standards do not provide adequate design guidelines for the fire design of cold-formed steel compression members. Therefore a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research, a detailed review was undertaken on the mechanical properties of light gauge cold-formed steels at elevated temperatures and the most reliable predictive models for mechanical properties and stress-strain models based on detailed experimental investigations were identified. Their accuracy was verified experimentally by carrying out a series of tensile coupon tests at ambient and elevated temperatures. As the second phase of this research, local buckling behaviour was investigated based on the experimental and numerical investigations at ambient and elevated temperatures. First a series of 91 local buckling tests was carried out at ambient and elevated temperatures on lipped and unlipped channels made of G250-0.95, G550-0.95, G250-1.95 and G450-1.90 cold-formed steels. Suitable finite element models were then developed to simulate the experimental conditions. These models were converted to ideal finite element models to undertake detailed parametric study. Finally all the ultimate load capacity results for local buckling were compared with the available design methods based on AS/NZS 4600, BS 5950 Part 5, Eurocode 3 Part 1.2 and the direct strength method (DSM), and suitable recommendations were made for the fire design of cold-formed steel compression members subject to local buckling. As the third phase of this research, flexural-torsional buckling behaviour was investigated experimentally and numerically. Two series of 39 flexural-torsional buckling tests were undertaken at ambient and elevated temperatures. The first series consisted 2800 mm long columns of G550-0.95, G250-1.95 and G450-1.90 cold-formed steel lipped channel columns while the second series contained 1800 mm long lipped channel columns of the same steel thickness and strength grades. All the experimental tests were simulated using a suitable finite element model, and the same model was used in a detailed parametric study following validation. Based on the comparison of results from the experimental and parametric studies with the available design methods, suitable design recommendations were made. This thesis presents a detailed description of the experimental and numerical studies undertaken on the mechanical properties and the local and flexural-torsional bucking behaviour of cold-formed steel compression member at ambient and elevated temperatures. It also describes the currently available ambient temperature design methods and their accuracy when used for fire design with appropriately reduced mechanical properties at elevated temperatures. Available fire design methods are also included and their accuracy in predicting the ultimate load capacity at elevated temperatures was investigated. This research has shown that the current ambient temperature design methods are capable of predicting the local and flexural-torsional buckling capacities of cold-formed steel compression members at elevated temperatures with the use of reduced mechanical properties. However, the elevated temperature design method in Eurocode 3 Part 1.2 is overly conservative and hence unsuitable, particularly in the case of flexural-torsional buckling at elevated temperatures.

Thesis (M.S. in Operations Research)--Naval Postgraduate School, June 2010.
Thesis Advisor(s): Buttrey, Samuel E. ; Second Reader: Whitaker, Lyn R. "June 2010." Description based on title screen as viewed on July 15, 2010. Author(s) subject terms: F/A-18, fatigue life expended (FLE), linear regression, Naval Air Systems Command (NAVAIR), prediction, S-Plus, strain gage, wing root fatigue. Includes bibliographical references (p. 53). Also available in print.

The importance of fire safety design has been realised due to the ever increasing loss of properties and lives caused by structural failures during fires. In recognition of the importance of fire safety design, extensive research has been undertaken in the field of fire safety of buildings and structures especially over the last couple of decades. In the same period, the development of fire safety engineering principles has brought significant reduction to the cost of fire protection. However the past fire research on steel structures has been limited to heavier, hot-rolled structural steel members and thus the structural behaviour of light gauge cold-formed steel members under fire conditions is not well understood. Since cold-formed steel structures have been commonly used for numerous applications and their use has increased rapidly in the last decade, the fire safety of cold-formed steel structural members has become an important issue. The current design standards for steel structures have simply included a list of reduction factors for the yield strength and elasticity modulus of hot-rolled steels without any detailed design procedures. It is not known whether these reduction factors are applicable to the commonly used thin, high strength steels in Australia. Further, the local buckling effects dominate the structural behaviour of light gauge cold-formed steel members. Therefore an extensive research program was undertaken at the Queensland University of Technology to investigate the local buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. The first phase of this research program included 189 tensile coupon tests including three steel grades and six thicknesses to obtain the accurate yield strength and elasticity modulus values at elevated temperatures because the deterioration of the mechanical properties is the major parameter in the structural design under fire conditions. The results obtained from the tensile tests were used to predict the ultimate strength of cold-formed steel members. An appropriate stress-strain model was also developed by considering the inelastic mechanical characteristics. The second phase of this research was based on a series of more than 120 laboratory experiments and corresponding numerical analyses on cold-formed steel compression members to investigate the local bucking behaviour of the unstiffened flange elements, stiffened web elements and stiffened web and flange elements at elevated temperatures up to 800°C. The conventional effective design rules were first simply modified considering the reduced mechanical properties obtained from the tensile coupon tests and their adequacy was studied using the experimental and numerical results. It was found that the simply modified effective width design rules were adequate for low strength steel members and yet was not adequate for high strength cold-formed steel members due to the severe reduction of the ultimate strength in the post buckling strength range and the severe reduction ratio of the elasticity modulus to the yield strength at elevated temperatures. Due to the inadequacy of the current design rules, the theoretical, semi-empirical and empirical effective width design rules were developed to accurately predict the ultimate strength of cold-formed steel compression members subject to local buckling effects at elevated temperatures. The accuracy of these new design methods was verified by comparing their predictions with a variety of experimental and numerical results. This thesis presents the details of extensive experimental and numerical studies undertaken in this research program and the results including comparison with simply modified effective width design rules. It also describes the advanced finite element models of cold-formed steel compression members developed in this research including the appropriate mechanical properties, initial imperfections, residual stresses and other significant factors. Finally, it presents the details of the new design methods proposed for the cold-formed steel compression members subject to local buckling effects at elevated temperatures.

A material’s Coefficient of Thermal Expansion (CTE) is a valuable physical property, particularly for structural fiber reinforced composites that are routinely used in satellite/aerospace applications. Satellite space structures are routinely designed with a high degree of dimensional and thermal stability. Designing and verifying for near zero CTE performance is a common design requirement. The CTE is routinely a physical property with known values for common materials. However, the strength, stiffness and CTE properties on a multi-ply graphite fiber reinforced laminate composite can be tailored to specific engineering requirements. Because of this, a method of verification (testing) is routinely performed to ensure these requirements are met.

A rigidez a pequenas deformações e sua respectiva degradação são informações cruciais para se determinar parâmetros de projeto mais precisos. Apesar de sua importância, estas propriedades não são usualmente investigadas. Assim, o objetivo do presente trabalho foi de estudar a degradação da rigidez da areia de Osório artificialmente cimentada por meio de diferentes métodos de laboratório. A escolha por um material cimentado ocorreu baseada em apelos ambientais, econômicos e técnicos. O presente estudo também objetiva desenvolver e validar um sistema de Bender Elements (BE), que forneça resultados confiáveis na avaliação da degradação do solo. Pares de BE foram construídos para serem utilizados em testes de bancada e ensaios triaxiais. Além disso, um amplificador de sinal, assim como scripts foram desenvolvidos especialmente para a interpretação dos dados no domínio do tempo. O aumento da rigidez durante o processo de cura foi avaliado por meio da velocidade de onda cisalhante, medida pelos BE e por um equipamento de ondas ultrassônicas (UPV), sob condições de pressão atmosférica. Ensaios de degradação da rigidez, por sua vez, foram conduzidos em uma câmara triaxial especialmente modificada para a instalação dos BE Após sete dias de cura atmosférica, os corpos-de-prova foram cisalhados no equipamento triaxial modificado enquanto mudanças de rigidez eram obtidas por meio de testes de BE e instrumentação interna. Os resultados demonstraram que o sistema BE desenvolvido foi bem sucedido na avaliação da rigidez do solo estudado. A comparação entre os resultados do BE e UPV não foi conclusiva no que se refere à dependência do solo à frequência. A degradação do módulo obtida por ambas as metodologias apresentou uma adequada concordância para o corpo-deprova com menor quantidade de cimento. Módulos obtidos por BE foram pouco maiores que os obtidos por medidas internas. Ainda, a interpretação no domínio do tempo dos resultados de BE para corpos-de-prova cimentados, especialmente durante ensaios triaxiais, foi difícil de ser executada, reforçando a necessidade de se combinar diferentes métodos de interpretação quando BE forem utilizados.
Stiffness at small strains and its respective degradation are crucial information to determine more precise design parameters. Despite their importance, these properties are not usually investigated. Thus, the objective of the present work was to study the stiffness degradation of artificially cemented Osorio sand by means of different laboratory methods. The choice for a cemented material was based on environmental, economic, and technical appeals. The present study also aimed to develop and validate a Bender Elements (BE) system that can provide reliable results in the evaluation of soil degradation. BE pairs were built for bench and triaxial tests. In addition, a signal amplifier, as well as scripts were specially developed for the interpretation of data in the time domain. Increase in stiffness during the curing process was evaluated by shear wave velocity measured by BE and an ultrasonic pulse wave velocity (UPV) equipment under atmospheric pressure conditions. Stiffness degradation tests were conducted in a specially modified triaxial chamber for BE installation After seven days of atmospheric curing, specimens were sheared in the modified triaxial equipment, while stiffness changes were obtained by BE tests and internal instrumentation. The results showed that the developed BE system was capable of successfully evaluating the studied soil. The comparison between BE and UPV results was not conclusive regarding soil dependence on frequency. Shear module degradation obtained with the two methodologies presented an adequate agreement for the specimen with the smaller amount of cement. Shear moduli obtained with BE were slightly larger than those obtained with internal measurements. Also, BE results interpretation in the time domain for cemented specimens, especially in the triaxial tests, was difficult to perform, reinforcing the need to combine different interpretation methods when BE are used.

The diploma thesis is focused on the measurement of forces acting between the tire and the road. There is an outline of tire and tire models problematic in the opening part. In the following part, the rear right suspension of the formula student car was mounted with strain gauges and the data logging system was described. There is also a multi-body model of the rear axle created in Adams/Car and SAMS software, that is able to calculate forces acting between the tire and the road, taking the measured forces in the suspension, rocker position, and throttle position into consideration. After a series of calibrations and verification measurements, the measurement on the test track was made, with data analysis focused on forces acting between the tire and the road.

Les itinéraires routiers supportant un nombre élevé de véhicules lourds ont habituellement des structures de chaussées épaisses et peu déformables. A ce jour, l’évaluation de l’état structurel réalisée au moyen d’appareils de mesure de déflexion (déflectographe ou curviamètre) et les relevés de dégradation sont souvent insuffisants pour détecter le début d’endommagement des structures épaisses. Afin de mesurer de façon plus précise et en continue, la réponse mécanique de la chaussée, des sections autoroutières ont été instrumentées au moyen de capteurs spécifiques (jauges, sondes de température et géophones) qui constituent un moyen d’auscultation complémentaire. L’exploitation des mesures sous trafic réel génère cependant une grande quantité des données et une variabilité des mesures qui conduisent à proposer une procédure originale de tri des signaux. Le traitement des mesures des jauges permet d’analyser les variations réelles des déformations en prenant en compte les variations journalières et saisonnières des paramètres environnementaux. Une modélisation avec différentes hypothèses de comportement aux interfaces des différentes couches de la chaussée est ensuite proposée, ce qui permet d’améliorer la compréhension du comportement mécanique de la chaussée sous trafic réel. Le traitement des mesures des géophones permet de remonter à la mesure de la déflexion qui représente la capacité portante de la chaussée. L’utilisation des différents géophones permet également d’identifier les silhouettes des poids-lourds et d’estimer leur vitesse ainsi que leur position latérale. Ces travaux répondent à une demande très actuelle des gestionnaires d’ouvrages, qui souhaitent disposer d’outils pour le monitoring dans le temps de leurs infrastructures
Recently, the roads supporting a great number of heavy vehicles usually have a thick and little deformable structure. To evaluate the pavement performances, deflection measurement devices have been used. However, these measurements are not accurate and the degradation detection is not enough to detect the start of pavement damage.In order to obtain more accurate and continuous mechanical pavement measurements, highway sections were instrumented with specific sensors (temperature probes, strain gages, geophones). However, the measurements analysis under real traffic generates a great number of data and a variability of measurements. Therefore, this problem requires an original signal sorting process. The study of strain measurements allows analyzing real strain variations which take in account the daily and seasonal variations of environment parameters.Modelling calculations with different assumptions were carried out afterward in order to obtain the best prediction for the mechanical pavement behavior. The study of geophone measurements allows measuring pavement deflections which represent pavement bearing capacity. In addition, different geophones were used to characterize heavy vehicle silhouettes, vehicle speeds and their lateral positions. The thesis work meets the expected requirement of construction managers to monitor continuously their infrastructures under real traffic

碩士
輔仁大學
織品服裝學系碩士在職專班
105
The posture and movement detection of textiles are increasingly designed for sports training, medical rehabilitation, entertainment, military ... and divers industries. Current products with posture detection textiles are mostly attachment of electronic components and textile, which need to take time to wear the heavy equipment or need to be operated in spicific spaces. In order to solve this problem, novel posture detection textiles and other wearable sensor products have come to the world. Compared with other wearable detectors, posture detection textiles can fit closely with the human body, and thus more flexible and more comfortable during the measurement, and without being limited by the space. This study is based on the patent analysis of the strain gauge technology of posture detection textiles, which concludes the development trend of attitude detection textile technology and strain sensing materials by analyzing the non-patent literature cited in the patent information. The patent analysis shows that the sensing technology of posture detection textiles has step towards the integration in textiles. The citation analysis shows that the major international electronics manufacturers have set up their patent portfolios in sports training, game entertainment, data processing … etc.. Broad integrations and applications are expected for posture detection textiles in game entertainment, mobile APP, digital data analysis and processing technology. From the analysis of non-patent literature, it shows that the materials of posture detection textiles are mainly from semiconductor elements, flexible materials, conductive materials and conductive fiber, among which, conductive materials are major. The development of conductive materials is mainly by nano-materials technology, including carbon nanotubes, carbon nanotubes composite materials, carbon nanotubes film, nano-fiber membrane, nano-silver, etc. We could anticipate the future posture detection textiles would be super light and thin which bring no burden for the wearers.

碩士
國立臺灣大學
臨床牙醫學研究所
99
Objectives: The stress around implants has been considered to affect the prognosis of implant therapy. The purpose of this study was to evaluate the effects of platform switching on the peri-implant bone strain in dental implants with external and internal connections, with strain gauge technique, under three different loads: the central vertical load, the lingual vertical load, the horizontal load. The other purpose was to evaluate whether increasing the degree of horizontal offset resulted in decreasing the peri-implant bone strain. Methods: Four types of implant：external hex connection and internal hex connection platform implant（OSSEOTITE® Parallel Walled Implants, BIOMET 3i, Palm Beach Gardens,USA）, length 13㎜ with different diameter 5.0 ㎜, 6.0 ㎜, were embedded in a 20 x 22 x 70 mm (width x height x length) epoxy resin block. Four strain gauges (EA-00-031CE-350) were bonded on resin surface adjacent to the buccal, mesial , lingual , and distal side of the implant platform. A CAD-CAM 10 x 10 x 11.5 ㎜ (width x length x height) tetragonal column customized abutments was fabricated. Three types of load were applied (vertical loads at two locations:the central vertical load, the lingual vertical load, and a horizontal load) with three different intensities (10N, 30 N and 50N). Each load was repeated 10 times and the data from the strain gauge were recorded and analyzed. Results: 1. Under the central vertical load, the platform switching design did not change peri-implant bone strain tendancy significantly. 2. Under the lingual vertical load, there was a tendency that the platform switching design decreased peri-implant bone strain. The greater amount of horizontal shifting, the smaller the peri-implant bone strain. When the applied load was larger, the tendency of reduced bone strain became more statistically significant. 3. Under the horizontal load, the trend was similar to that under lingual vertical load. 4. There was a difference between external hex connection and internal hex connection groups. Under the off-axis load, the reduction percentage of peri-implant bone strain in platform switching group of the internal hex connection group was not as large as that of the external hex connection. Conclusions: The data suggested that under off-axis load, there was a trend that the platform switching design decreased peri-implant bone strain in both external and internal connection groups. The greater amount of horizontal shifting, the smaller the peri-implant bone strain. When the applied load was larger, the tendency become more statistically significant. However, the reduction percentage in peri-implant bone strain in platform switching group of the internal hex connection group was not as large as that of the external hex connection under the off-axis force application.

Introdução: A literatura informa que a variação da inclinação cuspídea tem influência na deformação do ligamento periodontal, tanto a nível apical como cervical. Esta deformação parece estar relacionada com lesões dentárias e trauma oclusal, assim como o aumento e agravamento da periodontite. Objetivo: Estudo in vitro da deformação radicular nas porções cervical e apical através da variação da inclinação cuspídea na presença de duas cargas estáticas axiais e não-axiais. Materiais e métodos: Selecionaram-se aleatoriamente 6 pré-molares mandibulares. O ligamento periodontal e o osso cortical foram simulados de acordo com o módulo de elasticidade. Nas regiões apical e cervical foram colocados 2 extensómetros para determinar as deformações resultantes de uma carga estática axial e outra a 45º em relação longo eixo dentário, com uma intensidade de 50N. Os dados foram analisados utilizando p = 0,05. Resultados: Os valores de deformação máximo e mínimo, foram registados através da aplicação da força não-axial, com 4,80μm na região cervical e 0,01μm na região apical. A média da deformação cervical foi de 0,59μm para forças axiais e 1,5μm para forças não-axiais, enquanto que para a região apical registaram-se deformações de 0,49μm e 0,13μm, para as mesmas forças. A inclinação cuspídea tem influência na deformação registada a nível apical, contudo não foram registadas diferenças significativas a nível cervical. Verificou-se ainda que existem diferenças significativas na deformação radicular com aplicação de forças axiais e não-axiais. Conclusão: A inclinação cuspídea tem influência na deformação radicular na porção apical, no entanto, o mesmo não se verifica na região cervical. Forças não-axiais criaram uma deformação cervical significativamente maior do que as forças axiais. A nível apical, o inverso foi verificado. Há todo o interesse em aprofundar o estudo de forma a compreender quais as diferenças e poder estimar a deformação radicular com a variação da inclinação cuspídea.
Introduction: Literature established that cusp inclination influences periodontal ligament strain, apical and cervically. This strain appears to be related with dental lesions and occlusal trauma, as well as increase of periodontitis. Objective: In vitro study of cervical and apical portions of dental root through variation of cusp inclination, in the presence of axial and non-axial static loads. Materials and methods: 6 mandibular premolars were randomly selected. Periodontal ligament and cortical bone were simulated based on their elastic modulus. Two strain gauges were placed in the cervical and apical portions to determine resulting strains from a static load of 50N, axial and 45º with the tooth’s long axis. Data was analyzed using p = 0,05. Results: Maximum and minimum strain values were registered applying non-axial loads, with cervical value being 4,80μm and an apical value of 0,01μm, respectively. Cervical mean strain was 0,59μm for axial loads and 1,5μm for non-axial loads, while apical mean strains were 0,49μm and 0,13μm for the same loads. Cusp inclination influences apical strain, however significant differences were not found cervically. Significant differences in root strain were identified between axial and non-axial loads. Conclusion: Cusp inclination influences root strain apically, however, the same does not apply to cervical region. Non-axial loads increased cervical strain significantly when compared to axial loads. Apically, the opposite was verified. This study ought to be continued to understand the differences and to estimate radicular strain with variations of cusp inclination.

碩士
大葉大學
機械工程研究所碩士班
96
In this work, differential strain-gauged pressure transducers and their sensing elements have been studied in detail. As a sensing element is pressurized, it becomes deformed and the bonded strain-gages extend and shorten. The electrical resistances of the strain-gages change as a result. Then, employing the electrical bridge circuits composed of the strain gauges, the output voltage is used to determine the pressure difference that is to be measured. Of the sensing elements, the finite element technique and optimization process provide analysis in designing three appropriate types of sensing elements of particular pressure difference ranges. Stress limit is imposed to obtain the optimal sizes of the sensing elements.

碩士
大葉大學
機械工程研究所碩士在職專班
95
This study is mainly aimed at the design, analysis, fabrication, and testing of a strain-gauged extensometer normally required on a mechanical tensile or compressive test. First of all, an elastic sensing member, which utilizes the properties of a cantilever beam, is designed and subjected to finite element analysis using the commercial software COSMOSWORKS. Strain gauges are designed to be bounded on the appropriate locations of the members to form a full Wheatstone bridge. In order to obtain an output voltage as large as possible to ensure the measuring accuracy of this extensometer, different sets of design dimensions of the beam are taken for analysis. The stress limit is considered, and the final dimensions are determined. An extensometer is then fabricated and tested. The test data show that the results obtained based on the finite element analysis are consistent with the test results.

Several standardized courses for Formula SAE (FSAE) testing are introduced and described with sufficient detail to be reproduced by any Formula SAE team. Basic analysis methods for the courses are given as well as explanations of how those analyses could be used. On-car data from the Global Formula Racing (GFR) SAE cars is used to verify the analysis methods, give estimates to unknown variables, and show the relevance of the standard testing courses. Using the courses and methods described in this paper should allow standardized comparison of FSAE car performance, as well as provide a method to verify simulations and evaluate changes in vehicle performance from tuning. Instrumentation of all suspension member forces with strain gauge load cells is shown to be an extremely powerful tool for measuring vehicle performance and quantifying vehicle dynamic characteristics. The design and implementation of strain gauge load cells is described in detail to provide a template for reproducing similar results in other vehicles. Data from the GFR 2011 FSAE car is used throughout the paper to: show the design process for making effective suspension member load cells, show the calibration processes necessary to ensure quality data is collected, illustrate the calculation of suspension corner forces, and show the effectiveness of measuring vehicle dynamic characteristics with this technique. Using the methods described in this paper should provide data that allows a more complete and thorough understanding of on-car vehicle dynamics. This data may be used to validate vehicle models.
Graduation date: 2012