This master’s thesis deals with design of measurement system for dynamic measurement of bridge sensors. After a short theoretical part, the own concept is introduced. System can provide sampling rate up to 250 kSa/s with 24-bit resolution. The maximum number of samples is about one and a half milion. At first, the design of analog part was made, in this phase of design the digital part is based on evaluation board with ARM Cortex-M7 and external memory. After final choice of appropriate ICs, the analog and digital part will be integrated into one PCB.

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Made available in DSpace on 2016-12-08T17:19:14Z (GMT). No. of bitstreams: 1 Introducao.pdf: 448655 bytes, checksum: 598f8294a6f16ff80e9151c41d1a27f9 (MD5) Previous issue date: 2011-12-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Residual stresses in polymeric parts are a great source of uncertainties for the design of industrial components. They are originated mainly during the injection molding process. Some of the problems related to this phenomenon are reduction to the mechanic strength, cracks propagation and warpage. Many efforts are employed to minimize these residual stresses and, to achieve that, an essential step is its measuring. There are methods and devices already available to measure residual stress in metallic materials, but in the field of polymeric material, many aspects remain unexplored. In the present work, a device to measure strain gage signals was built, which was employed to determine residual stresses according to the most established techniques nowadays. Injection simulation techniques were utilized to estimate the build-up of residual stresses in polymeric test specimens under different manufacturing setups. Statistical analysis was performed to select the most favorable parameters for parts tensioning. Test specimens were fabricated in the selected process conditions. Samples weight measurements confirmed statistically that the process parameters selected have significantly altered the parts final mass. Residual stress measurements were carried out by employing the hole drilling technique in the manufactured specimens, thus being determined tensile residual stresses from 2.7 MPa by 6.2 MPa, in the layers closest to the parts surface. The typical profile for residual stress distribution, as described in literature, was observed in the experiments performed. / Tensões residuais em peças poliméricas são grande fonte de incertezas para o projeto de componentes industriais. São causadas principalmente durante o processo de injeção. Alguns dos problemas relacionados a esse fenômeno são a diminuição da resistência mecânica, surgimento de trincas e empenamento das peças. Muitos esforços são empregados na minimização dessas tensões residuais e, para isso, uma etapa indispensável é a sua medição. Existem métodos e equipamentos já disponíveis para medição de tensões residuais em materiais metálicos, porém, no campo dos materiais poliméricos ainda há muitos aspectos a serem melhor explorados. Neste trabalho foi construído um dispositivo para medição de sinais de extensiometria, o qual foi utilizado para determinação de tensões residuais segundo as técnicas mais utilizadas atualmente para metais. Técnicas de simulação de injeção foram utilizadas para estimar o surgimento de tensões residuais em corpos-de-prova poliméricos sob diversas condições de fabricação. Análise estatística foi realizada para selecionar as condições de fabricação mais propícias ao tensionamento das peças. Corpos-de-prova foram fabricados nas condições de processo selecionadas. Medições de peso das amostras confirmaram estatisticamente que os parâmetros de processo utilizados alteraram significativamente a massa final das peças. Medições de tensões residuais foram realizadas aplicando-se a técnica do furo cego nas amostras fabricadas, determinando-se tensões residuais de tração entre 2,7 MPa e 6,2 MPa, nas camadas próximas às superfície das amostras. O perfil típico de tensões residuais previsto em literatura foi observado nos experimentos realizados.

Orientador: Paulo Roberto Gardel Kurka / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T16:26:05Z (GMT). No. of bitstreams: 1 Iizuka_EduardoKenji_M.pdf: 15704991 bytes, checksum: d25013321bbe7f7be9760b4235125e16 (MD5) Previous issue date: 2006 / Resumo: O trabalho apresenta os resultados obtidos na simulação numérica e medição extensométrica de peneiras vibratórias de alta capacidade. Para o estudo numérico utilizou-se o software MSC.FEA 2005 que é uma integração dos softwares MSC.Patran e MSC.Nastran, obtendo-se resultados de tensão de von Mises apresentados na forma de gráficos e tabelas. Nas medições experimentais foram empregados extensômetros do tipo roseta 45° que possibilitaram a determinação das tensões principais e consequentemente a tensão de von Mises dos pontos instrumentados. Os valores de tensão de von Mises numéricos e experimentais formam comparados resultando em uma diferença média satisfatória de 8,4% considerando-se a complexidade do equipamento analisado. Os resultados deste trabalho são importantes para os futuros projetos de peneiras vibratórias de alta capacidade, visando garantir a integridade física do equipamento / Abstract: The work presents the results of numerical simulation and strain gage measurements for high capacity vibrating screens. MSC.FEA 2005 software that is an integration of the MSC.Patran and MSC.Nastran softwares was used to get the numerical results of von Mises stress, which is presented in charts and tables formo Strain gages type rosette 45° were used on experimental measurements and allowed the determination of principal stress hence von Mises stress, in the analyzed points. Numerical and experimental values of stress were compared and resulted into an 8.4% mean difference, which is a satisfactory result considering the complexity of the equipment. The results presented in this work create an important base to future designs of high capacity vibrating screens, aiming at the physical integrity of the equipment / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica

This thesis deals with the use of the electronic measuring systems for monitoring structures. The first part of this work is focused on mapping the available measuring systems for monitoring deformations and strains, from the point of their measurement accuracy, the real advantages and disadvantages, including examples of monitoring of constructions. In the second part were selected measuring systems for monitoring strains and deflection interest structure. Subsequently, the measuring system with online recording into the tested roof structure was installed and the loading test was performed. Obtained data were compared with other two independent measurements. In the last part of the thesis, the measured values of each independent measurements were compared together, and with the values calculated from the mathematical model. The achieved results show that the installed monitoring system is capable to reliably measure deformation of the structure in real time and thus to warn the building administrator against the potential danger in advance.

Innovative multifunctional materials are essential to many new sensor applications. Piezoresistive nano-composites make up a promising class of such materials that have the potential to provide a measurable response to strain over a much wider range than typical strain gages. Commercial strain gages are currently dominated by metallic sensors with a useable range of a few percent strain at most. There are, however, many applications that would benefit from a reliable wide-range sensor. These might include the study of explosive behavior, instrumentation of flexible components, motion detection for compliant mechanisms and hinges, human-technology interfaces, and a wide variety of bio-mechanical applications where structural materials may often be approximated as elastomeric. In order to quantify large strains, researchers often use optical methods which are tedious and difficult. This thesis proposes a new material and technique for quantifying large strain (up to 40%) by use of piezoresistive nano-composite strain gages. The nano-composite strain gage material is manufactured by suspending nickel nano-strands within a biocompatible silicone matrix. Study and design iteration on the strain gage material requires an improved understanding of the electrical behavior and conduction path within the material when strained. A percolation model has been suggested for numerical approximations, but has only provided marginal results for lack of data. Critical missing information in the percolation model is the nano-strand cluster size, and how that size changes in response to strain. These data are gathered using a dynamic technique in the scanning electron microscope called voltage contrast. Cluster sizes were found to vary in size by approximately 6% upon being strained to 10%. A feasibility study is also conducted on the nano-composite to show its usability as a strain gage. High Displacement Strain Gages (HDSGs) were manufactured from the nano-composite. HDSGs measured the strain of bovine ligament under prescribed loading conditions. Results demonstrate that HDSGs are an accurate means for measuring ligament strains across a broad spectrum of applied deformations.

Målet med detta examensarbete är att ersätta den tidigare lösningen av sensorfingret med andra komponenter, eller hitta en annan sensor med motsvarande funktion. Arbetet har begränsats av att ESAB vill ha ett mekaniskt finger för användarvänlighetens skull. Efter en förundersökning av olika typer av sensorer har vi valt att använda oss av trådtöjningsgivare som sensorer till det mekaniska sensorfingret. I och med detta val behövde vi även komma med ett teoretiskt förslag på en mekanisk upphängning av sensorfingret. Vi har byggt upp två separata Wheatstonebryggor med varsin instrumentförstärkare (INA125). Utsignalen från bryggorna är relativt liten och behövde förstärkas cirka 2000 gånger. Nollbalansering av bryggorna har skett manuellt med potentiometrar men vi har även gett ett förslag på en lösning där nollbalansering kan ske med ett enkelt knapptryck. Knappen är placerad på upphängningen på ett sådant sätt att man inte kan trycka oavsiktligt på knappen. Resultatet av arbetet är en uppkoppling på en experimentplatta samt förslag på hur upphängningen och sensorfingret designmässigt kan se ut. För vidare arbetsgång behövs en prototyp för att testa livslängden och ta reda på vilken känslighet som är mest optimal. / The goal with this degree project was to find a solution with different components to the existing design, or find a sensor with similar function that could replace the previous design of the sensor finger. Our work has been limited by ESAB due to the user friendly mechanical design of the previous sensor finger. After examining different sensors we choose to use strain gages as sensors for the mechanical sensor finger. With this choice we also needed to suggest a theoretical design for a mechanical attachment of the sensor finger. We have designed two separate Wheatstone bridges with separate instrumental amplifiers (INA125). The output signals from the bridges are relatively small and need to be amplified around 2000 times. The zero balancing of the bridges has been done manually with potentiometers but we have also suggested a solution where the zero balancing can be performed by a push-button. The button is placed where you cannot push it unintentionally. The result of this degree project is a circuit on a veroboard, a designing proposal for the attachment and the sensor finger. In order to further develop this design it would be necessary to build a prototype to evaluate its life span and find the optimal sensitivity.

<p>Målet med detta examensarbete är att ersätta den tidigare lösningen av sensorfingret med andra komponenter, eller hitta en annan sensor med motsvarande funktion.</p><p>Arbetet har begränsats av att ESAB vill ha ett mekaniskt finger för användarvänlighetens skull. Efter en förundersökning av olika typer av sensorer har vi valt att använda oss av trådtöjningsgivare som sensorer till det mekaniska sensorfingret. I och med detta val behövde vi även komma med ett teoretiskt förslag på en mekanisk upphängning av sensorfingret.</p><p>Vi har byggt upp två separata Wheatstonebryggor med varsin instrumentförstärkare (INA125). Utsignalen från bryggorna är relativt liten och behövde förstärkas cirka 2000 gånger.</p><p>Nollbalansering av bryggorna har skett manuellt med potentiometrar men vi har även gett ett förslag på en lösning där nollbalansering kan ske med ett enkelt knapptryck. Knappen är placerad på upphängningen på ett sådant sätt att man inte kan trycka oavsiktligt på knappen.</p><p>Resultatet av arbetet är en uppkoppling på en experimentplatta samt förslag på hur upphängningen och sensorfingret designmässigt kan se ut.</p><p>För vidare arbetsgång behövs en prototyp för att testa livslängden och ta reda på vilken känslighet som är mest optimal.</p> / <p>The goal with this degree project was to find a solution with different components to the existing design, or find a sensor with similar function that could replace the previous design of the sensor finger.</p><p>Our work has been limited by ESAB due to the user friendly mechanical design of the previous sensor finger. After examining different sensors we choose to use strain gages as sensors for the mechanical sensor finger. With this choice we also needed to suggest a theoretical design for a mechanical attachment of the sensor finger.</p><p>We have designed two separate Wheatstone bridges with separate instrumental amplifiers (INA125). The output signals from the bridges are relatively small and need to be amplified around 2000 times.</p><p>The zero balancing of the bridges has been done manually with potentiometers but we have also suggested a solution where the zero balancing can be performed by a push-button. The button is placed where you cannot push it unintentionally.</p><p>The result of this degree project is a circuit on a veroboard, a designing proposal for the attachment and the sensor finger.</p><p>In order to further develop this design it would be necessary to build a prototype to evaluate its life span and find the optimal sensitivity.</p>