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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Uma abordagem da vida em fadiga em barra estabilizadora automotiva considerando defeito superficial fisicamente pequeno

COLOSIO, MARCO A. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:48:51Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:09Z (GMT). No. of bitstreams: 1 09601.pdf: 14581150 bytes, checksum: 039930ea0467d8cb98d0f2a68ecb3072 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
32

Análise da contração linear de polimerização de resinas compostas fotopolimerizáveis / Analysis of linear shrinkage of photo-actived composite resins

Brito, Júnia Ribeiro de 18 August 2018 (has links)
Orientador: Cecília Amélia de Carvalho Zavaglia / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-18T19:00:55Z (GMT). No. of bitstreams: 1 Brito_JuniaRibeirode_M.pdf: 3348250 bytes, checksum: 88bd87279275d739ae30a9b4306d65de (MD5) Previous issue date: 2003 / Resumo: A resina composta fotopolimerizável é amplamente utilizada como material dental restaurador tanto em dentes anteriores como em dentes posteriores. Porém, como todo material polimérico, a resina composta também sofre contração devido a sua reação de polimerização. A contração de polimerização das resinas compostas dentais tem sido relatada como causa das falhas na interface dente-restauração, resultando em microinfiltrações de bactérias, com conseqüências negativas para o dente restaurado. O objetivo deste estudo é analisar a contração linear de polimerização de duas resinas compostas fotopolimerizáveis, uma experimental e outra comercial. A experimental foi desenvolvida por Palácio (2003) no DEMA/FEM/UNICAMP. A resina composta comercial é a Z-250/3M. A mudança dimensional que ocorreu durante e após a fotopolimerização foi monitorada durante 5 minutos a partir do instante em que a luz foi ligada. Na metodologia utilizada, os valores da contração linear de polimerização das referidas resinas compostas foram quantificados através da utilização de extensômetros elétricos / Abstract: The composite resin is widely used as a material for the restoration of anterior and posterior teeth. However, like any other polymeric material, the composite resin also presents shrinkage due to it's polymerization reaction. The polymerization shrinkage of dental composite resins has been reported to cause a marginal gap between the cavity wall and the restoration, resulting in bacterial microleakage, with negative consequence for the tooth. The main goal of this study is to analyse the linear shrinkage of two photo-activated dental composite resins. An experimental one, developed by Palacio (2003), and other commercial (Z-250/3M). The measuring time of linear shrinkage was 5 minutes from the start of photoactivation. The dimensional changes which develop during and after the curing of composite resins, were measured by electrical resistance strain gages / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
33

Operation and Calibration Procedures for a Small Four-component Strain Gage Balance

Rasponi, Gary Allen 01 January 1974 (has links) (PDF)
The Florida Technological University four-component strain-gage balance is an internally mounted, half-inch diameter balance capable of measuring four components of load: front and rear normal force, axial force, and rolling moment. Measurement of these components is accomplished by means of sixteen strain gages that are mounted on the balance and wired into four full bridge circuits. When the balance is subjected to a load, the strain gages, through a small resistance change, indicated the strain a balance element is undergoing. This report presents a description of the balance and its support equipment, and outlines specific calibration procedures necessary to their successful implementation. These calibration procedures take two forms: that of calibrating the readout equipment, and that of calibrating the balance itself. Also contained in this report is a method of reducing calibration data into a set of parameters applicable to the balance. To aid in the calibration of the balance, a calibration assembly was designed and built. Two calibration models were designed to facilitate the incremental loading of the balance and the interpretation of the readout data.
34

Optical fiber modal domain sensors for dynamic strain measurement

Bennett, K. D. (Kimberly Dean) 16 September 2005 (has links)
Modern engineering structures often incorporate new materials and complex designs for which existing techniques for nondestructive evaluation prove inadequate, especially for dynamic and in-service measurements. At the same time, optical fiber sensors have been identified as an ideal candidate for embedded and attached measurements of material parameters such as strain, temperature, or state of damage. In particular, sensors based on optical fiber modal interference phenomena have been shown to be capable of highly sensitive detection of static and dynamic strain. This work reviews known applications of modal domain sensing to measurement science to date, and discusses the principles behind the method. A general expression for the intensity distribution emerging from a multimode fiber is formulated, covering both few mode and highly multimode fibers, and new expressions for their sensitivity to both radial and axial strain are derived. Optimized multimode fibers are seen to show an intrinsic phase sensitivity which rivals or even surpasses that of the single mode interferometer, especially in the case of applied radial strain. The use of modal domain sensors for real-time ultrasonic wave transduction is described as a particular application to NDE, with experimental results being presented with regard to acoustic emission monitoring as well as the detection and analysis of shock waves due to impact. Finally, optimization schemes and alternatives for such sensors are addressed, and recommendations for future work are raised. / Ph. D.
35

Instrumentação dos pedais de uma bicicleta de estrada como proposta para análise da força aplicada

Hüsken, Maurício January 2018 (has links)
Com o crescimento do ciclismo como opção para lazer, meio de transporte e, principalmente, esporte voltado à competição, estudos mais aprofundados fizeram-se necessários visando à maximização do desempenho de atletas de alto nível. De forma complementar, muitos são os desenvolvimentos na área de sistemas de instrumentação com o objetivo primordial de possibilitar a medição e a caracterização dos diversos parâmetros de interesse dos pesquisadores na área do ciclismo. Tendo em vista o surgimento de diversos sistemas comerciais que permitem realizar a medição de grandezas como força e potência mecânica gerada pelo ciclista, este trabalho propôs instrumentar e caracterizar as medições provenientes dos pedais e pedivelas de uma bicicleta de estrada com a finalidade de, posteriormente, compará-las com base em métodos estatísticos adequados. Em função das limitações mecânicas inerentes à bicicleta e presentes no movimento de rotação nos pedais e pedivelas, foram criados sistemas completamente independentes, com alimentações elétricas feitas por baterias, e a sincronização para o início das aquisições, através de módulos ZigBee. Os ensaios contaram com a participação de dez voluntários, os quais foram responsáveis por gerar vinte sprints de dados, cada, que serviram para avaliar estatisticamente e concluir, por meio de Análises de Variância, que as forças aplicadas pelos ciclistas se diferenciaram significativamente para pelo menos uma das células de carga. / Cycling has grown as a leisure activity, means of transport and mainly as a professional sport. Therefore, deeper studies and research aiming at maximizing the performance of high-level athletes have been made necessary. Additionally to such studies, the area of instrumentation schemes has developed seeking to make possible the measuring and characterization of several parameters for researchers interested in cycling. Regarding the vibrant surging of systems that allow the measuring of magnitudes such as the forces and mechanical power generated by the cyclist, the present research aims at implementing and characterizing the measuring deriving from pedals and crankset for a road bicycle so as to analyze the results with appropriate statistic methods. Considering the mechanical limitations inherent to the bicycle the movement of pedals and crankset independent electrical systems charged by batteries were created, as well as the synchronization for the beginning of data acquisitions through ZigBee modules. Ten volunteers participated on the practices. They generated twenty sprints of data each. Such data served to statistically evaluate and conclude, based on variance analysis, that the power applied by the cyclists are significantly different for one of the load cell.
36

Design of a load cell for triaxial force measurement in walking

Clarke, Robert Gregory January 1981 (has links)
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 91-92. / by Robert Gregory Clarke. / B.S.
37

Strain measurement of composite materials using fibre optic sensors /

Furlong, Peter Andrew Caskey. January 1900 (has links)
Thesis (M.App.Sc.) - Carleton University, 2007. / Includes bibliographical references (p. 166-174). Also available in electronic format on the Internet.
38

Aspectos da deformacao do aluminio em ensaios de tracao

QUADROS, NEY F. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:31:55Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:40Z (GMT). No. of bitstreams: 1 02238.pdf: 7874589 bytes, checksum: 2508ea5b8a12f7656ab705c285fb99b3 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
39

Analise experimental de um modelo de V.P.C.P. para reator nuclear

VALLIN, CELSO 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:30:35Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:00Z (GMT). No. of bitstreams: 1 01112.pdf: 4081809 bytes, checksum: 8bc8c990027f72b27ae11db41cc3b5b6 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
40

Medidas de tensões residuais por extensiometria em componentes usados no setor da mobilidade / Measurements of residual stresses with strain gages for components used in the mobility sector

CIONE, FRANCISCO C. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:35:29Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:35Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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