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1
Koob, Christopher E. "High temperature fiber optic strain sensing." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-02132009-171339/.
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Weissbach, Joel. "Measuring forces on a hydropower generator using strain gages." Thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256575.
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Increased awareness concerning our energy consumption and its environmentaleffects, has led to a high demand for renewable energies. Hydropower providesaround 40 percent of the electric energy consumed in Sweden today. If energyefficiency and production time were to increase only by some percent in thehydropower plants, vast amounts of additional renewable energy could besupplied to the electric grid. The Hydropower group at Uppsala University usesa hydropower generator to localize and decrease some of the power losses andthe wearing in the generator. New equipment is being tested and evaluated onthe generator. By measuring static and dynamic forces in the generator broaderinsight can be reached during these tests. This thesis describes the development of a system measuring forces on ahydropower generator using strain gages. Each sensor node is equipped withfour strain gages and a signal conditioning circuit. The system measures strain inthe generator, converts it to a voltage signal, amplifies it, filters and transmits it.After calibration of the nodes, forces can be extracted indirectly. This thesisdescribes considerations made during design of the system as well as its differentparts and configurations.
3
Erm, Lincoln P. Ferrarotto Phil. "Development of a five-component strain-gauge balance for the DSTO water tunnel." Fishermans Bend, Vic. : Defence Science and Technology Organisation Air Vehicles Division, 2009. http://hdl.handle.net/1947/10033.
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Mode of access: Internet via World Wide Web. Available at http://hdl.handle.net/1947/10033."November 2009". Available on the DSTO website as at DSTO at :http://dspace.dsto.defence.gov.au/dspace/bitstream/1947/10033/1/DSTO-GD-0597%20PR.pdf
4
Russell, Scott A. "Strain gauge measurements of blade resonance using eddy current excitation in a vacuum spin pit." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FRussell.pdf.
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Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, September 2002.Thesis advisor(s): Raymond P. Shreeve, Garth V. Hobson. Includes bibliographical references (p. 93). Also available online.
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Bennett, K. D. "Optical fiber modal domain sensors for dynamic strain measurement /." This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09162005-115006/.
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Djugum, Richard. "Novel fabrication processes for thin film vapour deposited strain gauges on mild steel." Australasian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070424.115951/index.html.
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Thesis (PhD) - Swinburne University of Technology, School of Engineering and Science, 2006.A thesis submitted for the degree of Doctor of Philosophy, School of Engineering and Science, Swinburne University of Technology, 2006. Typescript. Includes bibliographical references (p. 125-138).
7
Busic, John F. "The design of skin friction gages for measurements in high-speed, short-duration flows." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-10062009-020036/.
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Bennett, K. D. (Kimberly Dean). "Optical fiber modal domain sensors for dynamic strain measurement." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39349.
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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.
9
Resende, Fernanda de Lima e. Sá [UNESP]. "Análise da distribuição de cargas e das forças entre asseno e encosto, na postura sentada adequada." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/97102.
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O objetivo deste trabalho foi estudar a distribuição das cargas no sistema cadeira plataforma de força (C-PF) e verificar se há correlação entre as forças medidas no assento e encosto, na postura sentada adequada. Participaram 38 voluntários, classificados pelo biótipo (32 mulheres e 6 homens): idade média de 43,92 anos, estatura média de 1,60 m e peso corporal médio de 65,10 kgf. Uma cadeira, com células de carga nas partes anterior e posterior do assento e no encosto, e uma plataforma de força mediram a distribuição do peso corporal. Estabeleceram-se várias correlações entre as variáveis (peso corporal, altura, idade, e índice de massa corporal) e as cargas medidas e entre as próprias forças adquiridas. Uma das correlações determinou uma relação entre a força total no assento e a força medida no encosto. A distribuição do peso corporal observada foi: 20,04% na plataforma de força; 45,33% e 30,43%, nas partes anterior e posterior do assento, respectivamente; e 4,20% no encosto. Não houve diferenças estatísticas significativas na comparação das médias dos valores da distribuição do peso corporal tanto entre os sexos como entre os biótipos. Porém, como há diferenças na forma corporal de acordo com os sexos e com os biótipos, houve certa diferença nos valores das forças medidas, no sistema C-PF.
The aim of this study was to study the load distribution in chair-force plate system (CFP) and to verify if there is correlation between measured seat and backrest forces in the adequate sitting posture. 38 volunteers participated of the study, classifieds according to physical types (32 female and 6 male): mean age of 43,92 years old, mean height of 1,60 m and mean body weight of 65,10 kgf. An instrumented office chair with load cells in the anterior and posterior portions of the seat and backrest and a force plate were used to measure the forces and body weight distribution in C-FP system. This study was established many correlations among some variables (body weight, height, age and body mass index) and the measured loads and among the acquired forces. One of these correlations determined a relation among total force measured on seat and acquired force on lumbar backrest. The body weight distribution observed in the C-FP system was: 20,04% in the force plate, 45,33% and 30,43% in the anterior and posterior portions of the seat respectively, and 4,20% in the backrest. There were no statistics significant differences in comparison of values weight distribution averages as between gender as between physical patterns. But, there are some differences in the body shape according to gender and physical patterns, it there was some difference in the values of acquired forces in the C-FP system.
10
COLOSIO, MARCO A. "Uma abordagem da vida em fadiga em barra estabilizadora automotiva considerando defeito superficial fisicamente pequeno." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11143.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
11
Lattimer, Brian Y. "Floating head skin friction gage measurements in supersonic flows." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06302009-040312/.
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Resende, Fernanda de Lima e. Sá. "Análise da distribuição de cargas e das forças entre asseno e encosto, na postura sentada adequada /." Guaratinguetá : [s.n.], 2006. http://hdl.handle.net/11449/97102.
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Orientador: José Geraldo Trani BrandãoBanca: Celso Pinto Morais Pereira
Banca: Marcio Augusto Martin
Resumo: O objetivo deste trabalho foi estudar a distribuição das cargas no sistema cadeira plataforma de força (C-PF) e verificar se há correlação entre as forças medidas no assento e encosto, na postura sentada adequada. Participaram 38 voluntários, classificados pelo biótipo (32 mulheres e 6 homens): idade média de 43,92 anos, estatura média de 1,60 m e peso corporal médio de 65,10 kgf. Uma cadeira, com células de carga nas partes anterior e posterior do assento e no encosto, e uma plataforma de força mediram a distribuição do peso corporal. Estabeleceram-se várias correlações entre as variáveis (peso corporal, altura, idade, e índice de massa corporal) e as cargas medidas e entre as próprias forças adquiridas. Uma das correlações determinou uma relação entre a força total no assento e a força medida no encosto. A distribuição do peso corporal observada foi: 20,04% na plataforma de força; 45,33% e 30,43%, nas partes anterior e posterior do assento, respectivamente; e 4,20% no encosto. Não houve diferenças estatísticas significativas na comparação das médias dos valores da distribuição do peso corporal tanto entre os sexos como entre os biótipos. Porém, como há diferenças na forma corporal de acordo com os sexos e com os biótipos, houve certa diferença nos valores das forças medidas, no sistema C-PF.
Abstract: The aim of this study was to study the load distribution in chair-force plate system (CFP) and to verify if there is correlation between measured seat and backrest forces in the adequate sitting posture. 38 volunteers participated of the study, classifieds according to physical types (32 female and 6 male): mean age of 43,92 years old, mean height of 1,60 m and mean body weight of 65,10 kgf. An instrumented office chair with load cells in the anterior and posterior portions of the seat and backrest and a force plate were used to measure the forces and body weight distribution in C-FP system. This study was established many correlations among some variables (body weight, height, age and body mass index) and the measured loads and among the acquired forces. One of these correlations determined a relation among total force measured on seat and acquired force on lumbar backrest. The body weight distribution observed in the C-FP system was: 20,04% in the force plate, 45,33% and 30,43% in the anterior and posterior portions of the seat respectively, and 4,20% in the backrest. There were no statistics significant differences in comparison of values weight distribution averages as between gender as between physical patterns. But, there are some differences in the body shape according to gender and physical patterns, it there was some difference in the values of acquired forces in the C-FP system.
Mestre
13
Bedgar, Kenda J., and Anthony J. Cullison. "FLIGHT TEST INSTRUMENTATION FOR THE ADVANCED HAWKEYE LOADS RISK REDUCTION PROJECT." International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/605029.
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ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, NevadaThis paper is about the installation of the instrumentation system and the strain gages on an E-2C Hawkeye for the Advanced Hawkeye Loads Risk Reduction project. Background information on why this project came about will be given. Explanations on why the existing instrumentation system was modified to the current system will be presented. Anthony Cullison (co-author of this paper) will explain the installation of the strain gages.
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Sprague, Susan, and Andrew Chorney. "A COMPARISON OF METHODS FOR MEASUREMENT OF PRESSURE IN HYDRAULIC LINES." International Foundation for Telemetering, 2000. http://hdl.handle.net/10150/606795.
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International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, CaliforniaThis presentation summarizes a study characterizing strain gages and pressure transducers used to measure the fluid pressure within aircraft hydraulic lines. A series of laboratory calibrations and finite element analyses was performed to demonstrate the quality of data from both pressure transducers and strain gages under variations in both temperature and external strains on the hydraulic lines. Strain gages showed a marked susceptibility to external strains on hydraulic lines, and wide variations in susceptibility to temperature changes. Pressure transducers were found to be relatively immune to both conditions. It is recommended that strain gages be used for trend data only.
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Fung, Wing Wah. "Lightly cemented rubber tire chips as highway pavement sub-base and the use of fiber Bragg's grating (FBG) as instrumentation sensors /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20FUNG.
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Shapiro, Kelli Ann. "Finite-element modeling of a damaged prestressed concrete bridge." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Theses/SHAPIRO_KELLI_19.pdf.
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CIONE, FRANCISCO C. "Medidas de tensões residuais por extensiometria em componentes usados no setor da mobilidade." reponame:Repositório Institucional do IPEN, 2012. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10163.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
18
Malatesta, Enrico. "Analisi sperimentale statica e dinamica del collegamento bullonato dell’assale posteriore di una macchina movimento terra." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Il presente lavoro è stato sviluppato durante il periodo di tirocinio effettuato in KIM, Komatsu Italia Manufacturing S.p.A. (Este, PD). Gli obiettivi del lavoro svolto sono evidenziare eventuali problematiche e verificare la resistenza meccanica dei collegamenti bullonati che uniscono l’assale posteriore della terna WB93R con il relativo telaio. Vengono presentate inoltre le criticità introdotte da un riutilizzo degli elementi di collegamento in seguito al loro disassemblaggio, ad esempio per motivi di manutenzione.
Il metodo di analisi è sperimentale, con utilizzo di estensimetri elettrici collocati primariamente sulla superficie del gambo delle viti determinando così la tensione assiale, la flessione e la torsione.
Successivamente si è passati ai test, che si suddividono in:
• Fase di precarico: per individuare il valore di precarico effettivamente impartito.
• Condizioni operative: vengono svolte e misurate le condizioni di lavoro considerate più gravose. In questo caso si vuole verificare che le sollecitazioni imposte non superino la resistenza meccanica delle viti.
• Fase di sbloccaggio: per individuare il precarico residuo.
Infine si è effettuato il post-processing dei dati raccolti con lo scopo di ottenere le informazioni necessarie. In questa fase sono state quindi evidenziate alcune criticità del comportamento del collegamento indicandone le cause, possibili rimedi e sviluppi futuri del progetto.
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Brito, Júnia Ribeiro de. "Análise da contração linear de polimerização de resinas compostas fotopolimerizáveis." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263516.
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Orientador: Cecília Amélia de Carvalho ZavagliaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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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
20
Hüsken, Maurício. "Instrumentação dos pedais de uma bicicleta de estrada como proposta para análise da força aplicada." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/185797.
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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.
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Anderson, Gregory Lee. "The development of poly(vinylidene fluoride) piezoelectric sensors for measuring peel stresses in adhesive joints." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39881.
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Although bond-normal stresses have been shown to be responsible for the failure of most laboratory adhesive joint geometries, the measurement of these stresses has been accomplished only through the use of very sophisticated optical techniques. In order to develop a more versatile measurement technique, poly(vinylidene fluoride) film was used to develop piezoelectric stress sensors. The sensitivities of the film to normal stresses in the three principal material directions of the orthotropic film were accurately measured using a charge amplifier and a storage oscilloscope. These measured sensitivities comprised the calibration constants of the film.
In order to reduce the detrimental effect on bond strength caused by embedding the low surface energy film into adhesive bondlines, surface treatment methods were investigated using contact angle studies, XPS analysis and 1800 peel and tapered double cantilever beam adhesion specimens. An acid etch using a mixture of acetic, phosphoric and nitric acids was found to greatly improve the bond strengths to an epoxy adhesive without reducing the piezoelectric activity of the film.
The bond-normal stresses in both the elastomeric butt joint and the single lap shear joint were measured using the developed stress sensors. Comparison of the measured stresses with calculated values obtained from closed-form analytical solutions and finite element analysis for the stresses was excellent.
The piezoelectric sensors do have several important limitations. The piezoelectric activity of the film is lost at temperatures above 100°C (210°F). Also, the sensors are only sensitive to dynamic loads. Nonetheless, the sensors provide an accurate means of measuring peel stresses in many adhesive joints of practical interest.Ph. D.
22
Lazarin, Juan Reuben. "Optimum Design of Composite Wing Spar Subjected to Fatigue Loadings." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1816.
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Composites are now being incorporated into aircraft designs because of their high strength to weight ratio compared to traditional metal materials. Due to the complexity of the material, composite parts are presently being over designed to satisfy static and fatigue requirements. A greater understanding of composite fatigue behavior will allow for even greater weight savings leading to increased fuel economy. A critical part of an aircraft that is subjected to fatigue bending loads are its wings. The forces acting on the wings include its lift distribution, powerplant, and fuel which can be carried in the wing body. When in flight these forces repeatedly cause cyclic displacements which could ultimately lead to failure. It is important to design the wing spars which carry the bending loads, to be fatigue resistant so that damage or expensive inspections could be avoided.
Wing models were be made from composite materials with a NACA 0016 airfoil shape, chord length of 9.25”, and a span of 15.25”. The C – channel spars were located at 22% and 72% of the chord. Strain gages on the wing model were used to measure strain at different locations. Static test were conducted on the specimens in order to validate a finite element analysis(FEA) model to be used for simulations. Overall, the strain measurements on the leading edge from two of the wings matched the model within 9% of the simulation results. Additional spar designs were then analyzed to determine the optimal one for static and fatigue bending loads. The wings were fatigue tested under displacement control at a test frequency. A model 8801 servo-hydraulic Instron machine and Wave Matrix software was used to fatigue the wings. After 100,000 cycles the test would be deemed a success and concluded.
23
RICARDO, LUIZ C. H. "Estimativa da vida sob fadiga de amplitude variavel de um componente mecanico." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10779.
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Dissertacao [Mestrado]
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
24
Muller, John Francis. "Serviceability of prestressed concrete railway sleepers." Thesis, Queensland University of Technology, 1985. https://eprints.qut.edu.au/36475/1/36475_Muller_1985.pdf.
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In 1984, prestressed concrete members of a left hand, trial 1 in
16 concrete sleepered turnout were subjected to strain gauge
measurements under coal traffic in Central Queensland. However,
the results were inadequate to permit finalisation of standards
for sleepers generally. Consequently, strain gauges were
installed across the entire rail seat cross-sections of eight
standard sleepers in 1985 to ascertain the effects of artificially
produced rail defects on prestressed concrete sleeper performance
under coal traffic conditions. This operation was carried out
in 1985 and the results analysed by the author in conjunction
with finite element analyses of a sleeper model using the SAP IV
programme available at the Queensland Institute of Technology
Computer Centre, Brisbane. Both field strain results and finite
element analyses indicated clearly that distributions of strains
and stresses are nonlinear across the rail seat cross-section.
Whilst simple bending theory has normally been used for sleeper
analysis, caution is required due to the increasing stress
gradients towards the outer fibres both top and bottom. Criteria
for design of prestressed concrete sleepers for traffic speeds
below 100 km/h have now been able to be finalised. Other
aspects such as bond development of prestressing tendons, dynamic
test performance under accelerated load testing and track buckling
considerations are encompassed. Special sleeper types are
also discussed.
25
Koyuncu, Atayil. "Acquisition Of Field Data For Agricultural Tractor." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/2/12607237/index.pdf.
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During the operations of an agricultural tractor, front axle and front axle support encounter the worst load conditions of the whole tractor. If the design of these components is not verified by systematic engineering approach, the customers could face with sudden failures. Erkunt Agricultural Machinery
Company, which is located in Ankara, has newly designed and manufactured the front axle support of its agricultural tractors. In this study, the design of 2WD (Wheel Drive) Erkunt Bereket Agricultural Tractor’
s front axle support has been verified by developing a verification method, which involves testing the tractor on a special test track and field and together with the computer aided engineering analysis, in order to prevent such failures in the lifetime of the tractor. For this purpose, a strain gage data acquisition system has been designed to measure the strain values on the component, while the tractor is operating on a test track and field. The locations of the strain gages have been determined by simulating the selected design load cases through finite element method. Measuring the maximum strains for the front axle support that have been experienced by the tractor while operating, the stress values have been calculated and the design safety has been investigated considering the material&
#8217
s tensile strength. Secondly, the fatigue life of the component regarding the acquired strain data has been predicted. These processes have led the company to verify the design of the front axle support.
26
Hoffman, Benjamin R. "Six-Component Load Cell Design for Use in Force Measurement Platforms." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1383950379.
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Chytil, Jan. "Statická zatěžovací zkouška nosné konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227811.
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Subject of the thesis is experimental verification of load capacity of construction for storage coal by using load test. In the first part, the analysis of sorts of load tests is made and its execution in causality with standard regulations. Further possible options of bringing test load are described and also the method of evaluation of static load test. Second part looks into the analysis of means of measurement which can be used to determine required quantity. Final part is dedicated to realization and evaluation of the load test on material construction followed by comparison of experimental values with values established on a model of construction created by using computing program.
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Crevatin, Andrea. "A novel approach to the experimental study of thermoplastic composities fatigue behaviour." Doctoral thesis, Università degli studi di Trieste, 2009. http://hdl.handle.net/10077/3135.
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2007/2008Si tratta della messa a punto di un nuovo metodo di indagine per la descrizione del comportamento a fatica di materiali plastici compositi. Il lavoro è stato completato con la formulazione di un modello matematico in grado di descrivere il comportamento dei materiali.
XXI Ciclo
1973
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Marae, Djouda Joseph. "Caractérisation optique des déformations à l'échelle nanométrique." Thesis, Troyes, 2016. http://www.theses.fr/2016TROY0005/document.
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La mesure des déformations de la microstructure est importante pour l’étude des propriétés et le contrôle des structures. Nous proposons deux approches nouvelles de caractérisation de déformations nanométriques. Elles utilisent des nanoparticules (NPs) d’or déposées à la surface des matériaux. Dans la première approche, les réseaux de NPs sont déposés par lithographie électronique. Lors d’essais de traction uniaxiale dans un microscope électronique à balayage les images prises à de chargements successifs permettent de suivre le déplacement de NPs qui jouent le rôle de nanojauges. L’analyse des champs cinématiques obtenus à partir des images MEB révèle des phénomènes de plasticité au sein de la microstructure et les hétérogénéités de déformations. La méthode a été appliquée aux aciers inoxydables austénitique et duplex austéno-ferritique. Elle a été couplée à la technique de diffraction des électrons rétrodiffusés. Les mécanismes de déformations locaux ont été mis en évidence. Dans la seconde approche, nous essayons de tirer parti des propriétés optiques de NPs afin de suivre l’évolution de déformations à la surface des matériaux. Les NPs supportent un plasmon localisé de surface dont la résonance est fonction de la taille, de la forme des NPs ou de l’indice optique du milieu environnant. Sa position spectrale dépend aussi de la distance inter-NPs. Notre étude a été limitée à des polymères. Un dispositif permettant de réaliser les mesures d’extinctions au cours de la traction a été développé. Les premiers essais constituent la preuve expérimentale de ce conceptThe strain measurement at the microstructure is important for the properties study and structure control. We propose two new approaches of strain characterizations at nanoscale. They are based on the use of gold nanoparticles (NPs) arrays deposited on the surface of materials.In the first approach, arrays of NPs are deposited by the electron beam lithography technique. During in situ tensile test inside a scanning electron microscope, the images of the array are progressively recorded. The treatment of these images gives access to 2D strain tensor components and NPs played the role of nanogauges. The strains at components of the microstructure and the heterogeneities of plastic deformations are evidenced. This method was coupled to the electron backscatter diffraction technique. The local deformation mechanisms can then be highlighted. In the second approach, we try to take advantage of optical properties of gold NPs to track the strain evolutions at the surface of materials. Gold NPs support localized surface plasmon that resonance is function of size and shape of NPs or of the surrounding medium. In addition, plasmon resonance also depends to NPs separation. We therefore sought to determine whether the displacements of NPs during tensile test may be monitored optically. The study was limited to the case of polymers. An experimental set up was developed to carry extinction measurement during a tensile test. These first tests constitute experimental proof of this concept. The spectral variations were analyzed to determine the performance of the optical strain-sensor proposed
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Au, Daniel Tak Yin. "Evaporation cast thin film carbon nanotube strain gauges." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44860.
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This work describes the research performed on synthesising and measuring the gauge factor of evaporation cast thin film carbon nanotube strain gauges. The main characteristics pursued of the strain gauges are inexpensive, easily manufactured and reasonably sensitive. Carbon nanotubes have exhibited a high gauge factor due to their intrinsic piezoresistivity and were incorporated into evaporation cast films to try to take advantage of the high sensitivity. Another direction taken to improve the sensitivity is alignment of carbon nanotubes in the thin film.
Previous work produced an evaporation cast carbon nanotube strain gauge with a relatively high gauge factor. However, it was not reproducible and the research encompassed extends from the previous work. A number of ink compositions with different carbon nanotube and surfactant loadings were used to synthesise thin films of carbon nanotubes on a polyimide substrate. Variations of evaporation casting were used to decrease the evaporation rate in attempts of carbon nanotube alignment through a self-organising liquid crystal phase during evaporation. Other methods of inkjet printing and air flow evaporation casting were also attempted to achieve alignment. Electrical connections using a conductive polymer and metal wires were fabricated onto the samples for electrical measurements. A four-point probe resistance measurement under the application of strain was used to elicit the gauge factors.
The strain gauge design was modified from previous work for more reliable electrical connections and for higher applied strains. A procedure for electrical measurements coupled with the application of strain was devised and the gauge factors achieved varied between 0.1 and 4.0 with a median of 1.1 ±0.1. The median gauge factor was reproducible and exhibited by several samples fabricated with different types of evaporation casting. The decrease in evaporation rate did not result in either alignment or relatively high gauge factors. In general, alignment was not achieved with the other methods of air flow evaporation and inkjet printing.
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Johnson, Timothy Michael. "Strain Monitoring of Carbon Fiber Composite with Embedded Nickel Nano-Composite Strain Gage." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2622.
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Carbon fiber reinforced plastic (CFRP) composites have extensive value in the aerospace, defense, sporting goods, and high performance automobile industries. These composites have huge benefits including high strength to weight ratios and the ability to tailor their properties. A significant issue with carbon fiber composites is the potential for catastrophic fatigue failure. To better understand this fatigue, there is first a huge push to measure strain accurately and in-situ to monitor carbon fiber composites. In this paper, piezoresistive nickel nanostrand (NiNs) nanocomposites were embedded in between layers of carbon fiber composite for real time, in situ strain monitoring. Several different embedding methods have been investigated. These include the direct embedding of a patch of dry NiNs and the embedding of NiNs-polymer matrix nanocomposite patches which are insulated from the surrounding carbon fiber. Also, two different polymer matrix materials were used in the nanocomposite to compare the piezoresistive signal. These nanocomposites are shown to display repeatable piezoresistivity, thus becoming a strain sensor capable of accurately measuring strain real time and in-situ. This patch has compatible mechanical properties to existing advanced composites and shows good resolution to small strain. This method of strain sensing in carbon fiber composites is more easily implemented and used than other strain measurement methods including fiber Bragg grating and acoustic emissions. To show that these embedded strain gages can be used in a variety of carbon fiber components, two different applications were also pursued.
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Belknap, Eric. "Mechanical characterization of SAW-based sensors for wireless high temperature strain measurements." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1306949369.
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Шумакова, Наталія Іванівна, Наталия Ивановна Шумакова, Nataliia Ivanivna Shumakova, and О. В. Слиненко. "Тензодатчики на основі плівкових матеріалів." Thesis, Видавництво СумДУ, 2005. http://essuir.sumdu.edu.ua/handle/123456789/17765.
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Zheng, Yulan. "Characterisation and development of novel thick film strain gauges." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/47490/.
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The strain gauge is a physical sensor, in which the influence of an externally applied strain causes the resistance to undergo a reversible change. It can be applied to the measurement of force, pressure, and displacement etc. The thick film strain gauge is relatively new however and has been seen to have many advantages. System zero (offset) and system gain (sensitivity) are key characteristics of the strain gauges. Hence intensive research was carried out to study these two aspects of different construction types of thick film strain gauges, i.e. X-plane and Z-plane strain gauges. Different fabrication parameters of these devices were studied for their effect on the characteristic. Temperature characteristics of both of these types of devices were examined as a measure of system zero stability. Combinations of resistor thickness, construction materials and geometric parameters of these types of devices were noticed to affect their temperature behavior. These observations would undoubtedly facilitate the achievement of good TCR matching between resistors in practical application. A programme of explanatory theory to understand these observations has been submitted, which comprises strain analysis and conduction mechanism study. Loading characteristics of Z-plane strain gauges have also been studied to explore the potential of this type of device.
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Baradoy, Daniel Alexander. "Composition Based Modaling of Silicone Nano-Composite Strain Gauges." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5483.
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In this work a review of the technology surrounding high deflection strain sensing with an emphasis on that of a recently developed nickel nano-composite strain sensor is presented. A new base silicone material was identified for the nickel nano-composite strain sensor that improves its mechanical stiffness and conductive properties. A previously identified cyclic creep concern was mitigated through preconditioning and the use of adhered backing materials. Through a block design experiment the strain/resistance curves for the strain sensors were characterized over a wide range of nano-filler material compositions. An analytical model was developed based on observation that the resistance of the sensors follows a log-normal response with respect to applied strain. The model demonstrated high fidelity in representing the resistance-strain relationship of the sensors yielding an average R2 value of .93. A standard least squares statistical analysis confirmed strong relationships between curve fit parameters of the modified log-normal model and additive volume fractions with significance at the .05 level for each case. A suitable strain gauge composition was selected for a specific application: a fetal monitoring device. A prototype belt was developed that is worn over the abdomen to detect deflections cause by labor contractions and other fetal movements. Simulation testing on the device was performed and the device was found to be a feasible option for fetal monitoring.
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Anderson, Matthew Francis. "Parametric investigation of strain gauges in structural damage detection." Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2436.
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Vibration-based damage detection (VBDD) methods are used to detect damage in structural members non-evasively. This investigation began with two objectives: to prove a VBDD method could detect damage using strain gauges both analytically and experimentally, and to then use that method to determine the distance from a damaged area that strain gauges could be effective. Work began simultaneously using finite element software and physical experiments. It was determined that a VBDD method could detect damage with strain gauges in both settings. A parametric study was then completed that used probabilistic methods to identify an effective range for strain gauges over the length of the structural member.
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Almarghalani, Maan. "Design and characterization of polymeric strain gauges for biomedical applications." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52523.
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The market need for organic materials to be used in sensor design has increased with the growing interest in organic printed electronics. Therefore, it is important to find and investigate the piezoelectric and piezoresistive properties of organic materials through the use of alternative rapid fabrication techniques. Poly(3,4- ethylenedioxythiophene) poly(styrenesulfonate), commonly known as PEDOT:PSS, a conductive polymer widely used in organic electronics, can be possibly used as piezoresistive element to measure the strain on flexible substrate electronics. Using PEDOT:PSS and other metallic inks such as silver, the goal of this work is use alternative microfabrication technologies to deposit PEDOT:PSS on flexible substrates and then to use these methods to design strain gauges. The targeted biomedical applications of the designed strain gauges vary from rehabilitation devices to smart biomedical monitoring systems. In this work, PEDOT:PSS strain gauges are initially designed using aerosol jet deposition on a flexible polyamide substrate. The technology has proved to be very powerful in depositing lines with thickness less than 1um. In order to reduce the initial resistance of the strain gauges, it is desirable to increase the thickness of the structure. For this reason, laser micromachining etching is used to fabricate PEDOT:PSS strain gauges. The designed structures have been tested mechanically and electrically in order to measure their gauge factors to longitudinal and transversal mechanical strains. The resultant longitudinal gauge factor varied in the range of -1 and 2, while little change in the resistance was noticed for transversal characterization. Using the same fabrication method, silver paint strain gauges are designed and characterized to have a high longitudinal gauge factor approximated to be higher than 10. The silver paint gauge factor barely responded to transversal actuation. While the variability of the PEDOT:PSS strain gauges results seemed to be an issue, the reproducibility of silver ink strain gauges proved the viability of the technological fabrication process presented in this work.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Philip-Chandry, Rekha. "Fluid flow measurement using electrical and optical fibre strain gauges." Thesis, Liverpool John Moores University, 1997. http://researchonline.ljmu.ac.uk/5565/.
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The design, development and calibration of three flow sensors to measure the speed and direction of fluid flow is presented in this thesis. The force exerted by the fluid flow on the sensors are measured using strain gauges. Multidirectional fluid flow measurement has been made possible by vectorial addition of the orthogonal flow components. The fluid speed and direction are generated irrespective of each other. Electrical resistance strain gauges are used as the force measuring device for the first version of the flow meter. These strain gauges are bonded to the four longitudinal surfaces of a square-sectioned, elastic, rubber cantilever having a drag element attached to its free end. An attempt has been made to optimise the shape and dimensions of the elastic beam to obtain a constant drag co-efficient over a wide flow range. Calibration of the electrical strain gauge flow sensor has been performed in a wind tunnel to measure air flow. The sensor has a repeatability of 0.02%, linearity within 2% and a resolution of 0.43 m/s. The most noteworthy feature of the flow sensor is its quick response time of 50 milliseconds. The sensor is able to generate a measurement of flow direction in two dimensions with a resolution of 3.6". Preliminary measurements in a water tank enabled the speed of water to be measured with a resolution of 0.02 m/s over a range from 0 to 0.4 m/s. An optical fibre strain sensor has been designed and developed by inserting grooves into a multimode plastic optical fibre. As the fibre bends, the variation in the angle of the grooves causes an intensity modulation of the light transmitted through the fibre. A mathematical model has been developed which has been experimentally verified in the laboratory. The electrical strain gauge was replaced by the fibre optic strain gauge in the second version of the flow sensor. Two dimensional flow measurement was made possible by attaching two such optical fibre strain gauges on the adjacent sides of the square sectioned rubber beam. The optical fibre flow sensor was successfully calibrated in a wind tunnel to generate both the magnitude and direction of the velocity of air. The flow sensor had a repeatability of 0.3% and measured the wind velocity up to 30 M/s with a magnitude resolution of 1.3 m/s and a direction resolution of 5.9'. The third version of the flow sensor has used the grooved optical fibre strain sensor by itself without the rubber beam to measure the fluid flow. Wind tunnel calibration has been performed to measure two dimensional wind flow up to 35 m/s with a resolution of 0.96 m/s.
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Remington, Taylor David. "Biomechanical Applications and Modeling of Quantum Nano-Composite Strain Gauges." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4407.
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Biological tissues routinely experience large strains and undergo large deformations during normal physiologic activity. Biological tissue deformation is well beyond the range of standard strain gauges, and hence must often be captured using expensive and non-portable options such as optical marker tracking methods that may rely upon significant post-processing. This study develops portable gauges that operate in real time and are compatible with the large strains seen by biological materials. The new gauges are based on a relatively new technique for quantifying large strain in real-time (up to 40 %) by use of a piezoresistive nano-composite strain gauge. The nano-composite strain gauges (NCSGs) are manufactured by suspending nickel nanostrands within a biocompatible silicone matrix. The conductive nickel filaments come into progressively stronger electrical contact with each other as the NCSG is strained, thus reducing the electrical resistance that is then measured using a four-probe method. This thesis summarizes progress in the understanding, design and application of NCSGs for biomechanical applications. The advanced understanding arises from a nano-junction-level finite element analysis of gap evolution that models how the geometry varies with strain in the critical regions between nickel particles. Future work will incorporate this new analysis into global models of the overall piezoresistive phenomenon. The improvements in design focused on the manufacturing route to obtain a reliable thin and flexible gauge, along with a modified connection and data extraction system to reduce drift issues that were present in all previous tests. Furthermore, a pottable data logging system was developed for mobile applications. Finally, a method of analyzing the resultant data was formulated, based upon cross-correlation techniques, in order to distinguish between characteristic wave-forms for distinct physical activities. All of these improvements were successfully demonstrated via a gait-tracking system applied to the insole of standard running shoes.
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Carpes, Felipe Pivetta. "DESENVOLVIMENTO DE UM SISTEMA DE PEDAIS DINAMOMÉTRICOS PARA AVALIAÇÃO BIOMECÂNICA NO CICLISMO." Universidade Federal de Santa Maria, 2006. http://repositorio.ufsm.br/handle/1/8416.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe assessment of pedal forces is one of the more sophisticated methods applied on the sports sciences to accomplish cycling performance tests. With information of pedal forces the pedaling technique is evaluated based on the ability of the cyclists to produce and apply forces on the pedals. Several variables concerning the performance can be monitored with the application of instrumented pedals, but there is a lack of studies that consider the differences between the lower limbs on the force generation, what can occur due instrumentation limitation on the laboratories because the instrumented pedal are not commercial available and it is manufactured by research laboratories. The purpose of this study was to develop an instrumented pedals system that permit the evaluation of the pedal forces for each lower limb, with characteristics that no modify the normal pattern of pedaling and able to be used on different bicycle geometries and cycle ergometers. For the instrumentation, spindles of two (right and left) Shimano SPD pedals were modified to mounting 8 strain-gage sensors on each spindle, disposed on two rows and connected on two Wheatstone complete-bridges to measure strain in response to horizontal (Fx, tangential bridge) and vertical loads (Fz, normal bridge). With the spindles mounted on the pedal body, a piece for connection with the crank was manufactured. These pieces (right and left) are the house for ball bearings that permit the movement of the pedal relative to crank and not commit the strain-gages wires. These pieces permit the application of the pedal on different bicycles and cycle ergometers. The system was calibrated and presents a linear relationship between the load applied and the signal output from the full-bridges that monitor the horizontal and vertical efforts on the spindles. A calibration matrix was developed to transform the output signal to force magnitudes, and also an interference matrix was mounted to correct the mechanical interference between the horizontal and vertical measures. For the two pedals, the hysteresis was lower than 0,60%. For the right pedal, the sensitivity of the normal bridge was 2.5 mV/N, the tangential bridge present sensitivity of 2.6 mV/N. The left pedal presents a sensitivity of 2.4 mV/N and 2.7 mV/N for normal and tangential bridges, respectively. The resolution of the system was, for both pedals, lower than 0.5 N, while the error calculated from the calibrated data was 1% for the right normal bridge and 2% for the right tangential bridge and left normal and tangential bridges. It can be concluded that the system present characteristics that permits the application on the athlete s evaluations due the low error, satisfactory resolution and good linearity observed between the applied loads and the signal output on the normal and tangential full-bridges.
A medida das forças envolvidas na pedalada é uma das mais sofisticadas metodologias aplicadas nas ciências do esporte para avaliação da técnica de pedalada. A técnica de pedalada é avaliada com base na habilidade dos ciclistas em produzir e aplicar força aos pedais. Diversas variáveis de controle de desempenho podem ser monitoradas com a aplicação de pedais instrumentados. No entanto, observa-se que um pequeno número de estudos considera as diferenças entre os membros na capacidade de gerar força, o que possivelmente ocorre devido a limitações de instrumentação, pois pedais instrumentados são normalmente unilaterais e construídos por laboratórios de pesquisa, não sendo disponíveis comercialmente. O objetivo deste estudo foi desenvolver um sistema de pedais instrumentados que possibilitem o monitoramento das forças aplicadas nos pedais direito e esquerdo, com características que não modifiquem o padrão normal de movimento e que possam ser utilizados em diferentes bicicletas e ciclo ergômetros. Para a instrumentação, os eixos dos pedais (direito e esquerdo) modelo Shimano SPD para ciclismo mountain-bike foram modificados a fim de que fossem montados 8 extensömetros em cada eixo e dispostos em duas colunas e conectados em duas pontes de Wheatstone completas, sendo uma para o monitoramento da deformação do eixo decorrente da força aplicada no sentido horizontal e outra para medir a deformação decorrente das forças aplicadas no sentido vertical ao plano do pedal. Com o eixo fixo ao corpo do pedal, uma peça foi especialmente desenvolvida para abrigar rolamentos que permitem a conexão e o movimento relativo do pedal com o pé-de-vela, a fim de permitir a montagem dos fios dos extensômetros. Esta peça permite o uso do sistema de diferentes bicicletas e ciclo ergômetros. O sistema foi calibrado e apresentou relação linear entre as cargas aplicadas e as tensões de saída nas pontes de Wheatstone que monitoram esforços horizontais e verticais em ambos os pedais. Uma matriz de calibração foi desenvolvida para a conversão das tensões em magnitudes de força, assim como uma matriz de interferência foi montada para corrigir o acoplamento entre as medidas verticais e horizontais devido ao desalinhamento entre os sensores. Para ambos os pedais a histerese foi menor que 0,6%. Para o pedal direito, a sensibilidade na ponte normal foi de 2,5 mV/N e na ponte tangencial foi de 2,6 mV/N. Para o pedal esquerdo a sensibilidade foi de 2,4 mV/N e 2,7 mV/N para a ponte normal e tangencial respectivamente. A resolução do sistema, para ambos os pedais, foi sempre menor que 0,5 N, enquanto que o erro estimado a partir da matriz de calibração foi de 1% para a ponte normal direita e 2% para a ponte tangencial direita, e pontes normal e tangencial esquerdas. Conclui-se que o sistema apresentou características estáticas que permitem sua aplicação prática na avaliação de atletas devido ao baixo erro, satisfatória resolução e linearidade observada entre as cargas aplicadas e as tensões de saída nas pontes tangenciais e normais.
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Martineau, Adin Douglas. "Estimation of Knee Kinematics Using Non-Monotonic Nanocomposite High-Deflection Strain Gauges." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7037.
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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.
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Vella, David. "Narrow gates, strait ways : the postmodern sacred and the icon." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/39623/.
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This study compares two prevalent notions in postmodern philosophy and critical-cultural theory: the sacred and the icon. On the one hand, the sacred has often been described as the exposure to an abyssal reality that is completely foreign to human perception and control. This deeply subversive event is presented through two of its most influential thinkers, Georges Bataille and Maurice Blanchot. On the other hand, the icon marks the experience of a sensitivity to the singular selfhood of the other. It comprises a loving receptivity to its unique identity, in particular the identity of the human or divine stranger who is excluded or victimized by human narratives and structures. Intrinsic to the ethical scene, as I show through Emmanuel Levinas and Richard Kearney, is an interaction rather than a subjugation of the subject by the other. This project seeks to present the similarities and differences between the sacred and the icon. In particular, it calls for a certain relationship between them, allowing both to be observed in each other’s respective light. Both are thus re-examined through their relation to each other. Moreover, this bond is seen to be ethically significant for either phenomenon and it helps redefine the sacred and the icon in a manner that is closer to actual experience. It also perceives either one in terms of a practical efficacy. To exemplify these views, the Christian mystical experience known as the ‘passive dark night of the soul’ is explored insofar as it constitutes one of the most radical instances of the icon. Crucial to this relationship is its exposure of the possible shortcomings and misjudgements of previous conceptions of the sacred. A potential new role for the sacred is indicated: a function that is at once more ethical and constructive. Above all, the underlying concern of this study is the very nature of this interaction of the two extremes. Throughout, it shows this affiliation as dialectical by nature. Between the sacred and the icon, a process of a mutual coinciding and estranging takes place.
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El, Kabbami Ibrahim Sami Mahmond. "Influence of abnormal femoral torsion on patellofemoral joint. Measurement by using strain gauges." Doctoral thesis, Universitat Autònoma de Barcelona, 2004. http://hdl.handle.net/10803/4266.
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Djugum, Richard, and n/a. "Novel fabrication processes for thin film vapour deposited strain gauges on mild steel." Swinburne University of Technology, 2006. http://adt.lib.swin.edu.au./public/adt-VSWT20070424.115951.
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Pressure measurement using a strain gauge bonded with epoxy adhesive to a metallic
mechanical support has been, and still is, extensively employed, however, for some
applications the use of an epoxy is inadequate, especially when temperatures exceed
120C. There is therefore particular interest in the use of thin film techniques to
vacuum deposit strain gauges directly on metallic substrates. Such devices are highly
cost effective when produced in large quantities due to the manufacturing techniques
involved. This makes them ideally suited for use in large-volume products such as
electronic weighing scales and pressure transducers. In this thesis, new techniques for
fabricating thin film vapour deposited strain gauge transducers on metal substrates for
application as novel pressure sensors in the fastener industry are developed.
Clearly, for a vapour deposited strain gauge to function correctly, it is essential that it be
deposited on a defect free, high quality electrically insulating film. This was a
significant challenge in the present study since all available physical vapour deposition
(PVD) equipment was direct current (DC) and insulators of around 4 um thick were
needed to electrically isolate the strain gauges from metal. As a result, several methods
of depositing insulators using DC were developed. The first involved the use of DC
magnetron sputtering from an aluminium target to reactively deposit up to 4 um thick
AlN. DC magnetron discharges suffer arc instability as the AlN forms on the target and
this limits the maximum thickness that can be deposited. Consequently, the arc
instability was suppressed manually by increasing argon gas flow at the onset of arcing.
Although the deposited AlN showed a high insulating resistance, it was found that the
breakdown voltage could significantly increase by (a) utilising a metallic interlayer
between the thin film insulator and the metallic substrate and (b) annealing in air at
300C. A second deposition method involved the use of DC magnetron sputtering to
deposit modulated thin film insulators in which an aluminium target was used to
reactively deposit alternating layers of aluminium nitride and aluminium oxide. These
films showed significant increases in average breakdown voltage when the number of
layers within the composite film was increased. The third method involved the
deposition of AlN thin film insulators using partially filtered cathodic arc evaporation
with shielding. Initially, AlN was deposited under partially filtered conditions to obtain
a relatively thick (~ 4 um) coating then, while still depositing under partially filtered
conditions, a smooth top coating was deposited by using a shielding technique. The
deposition of metal macroparticles is an inherent problem with cathodic arc deposition
and shielding is one form of macroparticle filtering. Such particles are highly
undesirable in this study as they are electrically conductive. A fourth coating technique
for depositing insulators on steel was based on thermal spray technology. Insulating
films of Al2O3 were plasma sprayed and then polished to thereby fabricate viable
electrical insulators for vapour deposited strain gauges.
With respect to depositing strain gauges two methods were employed. The first
involved the sputter deposition of chromium through a shadow mask to form a strain
gauge with gauge factor sensitivity of around 2. The second used cathodic arc
evaporation to fabricate a multi-layered strain gauge composed of alternating CrN and
TiAlN layers that yielded a gauge factor of around 3.5. The technique achieves better
compatibility between gauge and insulator by allowing a wider selection of materials to
form the gauge composition. Finally, a novel pressure sensor in the form of a load cell
was developed that consisted of a chromium strain gauge on a steel washer electrically
insulated with AlN thin film. The load cell showed good performance when tested under
compressive load.
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Mercado, Ervin N. "Use of carbon nano-fiber foams as strain gauges to detect crack propagation." Thesis, Monterey, California: Naval Postgraduate School, 2015. http://hdl.handle.net/10945/45907.
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Approved for public release; distribution is unlimitedThis thesis focuses on testing the feasibility of using carbon nanofiber foams as strain gauge material to detect crack propagation in aluminum structures. We produced the tridimensional carbon nanofiber foams using a process that exposed palladium catalyst particles to a fuel rich oxygen/ethylene mixture at moderate temperatures in a tubular furnace. The microstructure of the foam generated was characterized using a scanning electron microscope to determine diameter and distribution of the fibers within the foam. Sections of the foam, electrically isolated, were attached to aluminum tensile specimens. Simultaneous mechanical and electrical measurements were conducted on the aluminum-foam fixtures. The mechanism responsible for the conductivity values seems to be related to the number of contacts established between all fibers as the foam was compressed or stretched during tensile tests, as opposed to the electrical properties of the individual fibers. The design of the foam sensor and the way it is attached to the aluminum plates presented challenges that will need to be further addressed. The data showed a correlation between strain levels in the aluminum probes and the resistivity detected in the foam, confirming that the later can be employed as a sensor to monitor the structural integrity of the former.
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Costa, Max Doria. "Análise da deformação gerada nos intermediários e na região óssea peri-implantar sob diferentes condições de carga em prótese parcial fixa parafusada." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/25/25146/tde-03022016-100412/.
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O sucesso a longo prazo dos implantes tem como fatores críticos a incidência e a transferência de estresses mecânicos sobre a prótese, intermediários, implantes e destes para o tecido ósseo adjacente, devendo cada parte deste sistema ser submetido somente a forças às quais estão aptos a receber. A proposta deste trabalho foi avaliar a deformação gerada nos intermediários e na região óssea peri-implantar diante da aplicação de cargas funcionais e parafuncionais em prótese parcial fixa de três elementos parafusadas sobre dois implantes. Para este trabalho, foi utilizado um modelo experimental homogêneo à base de poliuretano, simulando o tecido ósseo, com dois implantes do tipo hexágono externo paralelos que receberam intermediários do tipo multi-unit. Na superfície de cada intermediário foram instalados três sensores (strain gauges), capazes de medir a microdeformação dispostos de maneira eqüidistante entre si. Na região óssea simulada, foram instalados quatro sensores para cada implante, posicionados nas faces mesial, distal, vestibular e lingual. A aplicação da carga estática de 300N foi realizada em uma máquina de ensaios universais. As leituras foram realizadas em quatorze momentos para todos os corpos de prova, variando o direcionamento da carga (axial e inclinada à 30 graus) e simulando ainda sete diferentes pontos de aplicação de carga (1- pilar mesial, 2 - pôntico, 3- pilar distal, 4- simultaneamente no pilar mesial, pontico e pilar distal, 5- no pilar mesial e distal, sem contato no pôntico, 6- no pilar mesial e no pôntico, 7- no pilar distal e no pôntico). Os resultados mostraram que a direção da carga interferiu na magnitude e distribuição da microdeformação, de forma que, no osso simulado, os valores encontrados na carga axial se encontraram dentro da tolerância fisiológica independente do local de aplicação de carga. Observou-se uma distribuição mais uniforme quando a carga foi aplicada simultaneamente nos pilres mesial, pôntico e pilar distal. Por outro lado, valores de microdeformação acima do limite de tolerância foram observados para a carga inclinada e nesta situação o local de aplicação teve influência na microdeformação, com valores extremamente elevados e sem uniformidade na distribuição, devendo o carregamento oblíquo ser evitado.Long-term success with implants has some critical factors such as incidence and transmission of mechanical stress to the prosthesis, abutments, and implants to the adjacent bone tissue. Each part of the system should be subjected to loads under its strength limit. The purpose of the present study was to evaluate abutment and peri-implant bone tissue strains during functional and parafunctional loads application in a three-unit screw-retained fixed prosthesis supported by two implants. In order to simulate the bone tissue, an experimental model made of homogeneous polyurethane was used wherein two external hexagon implants were placed parallel to each other, provided with multi-unit abutments. On the surface of each abutment three sensors (strain gauges) were positioned equidistant to each other to measure microstrains. The simulated bone around each implant received four strain gauges, positioned on the mesial, distal, buccal and lingual aspects. The tests were performed applying a 300N static load on a universal testing machine. The readings were made at fourteen moments for each specimen, changing load direction (axial and 30 degrees oblique) and also simulating seven different points of load application (1- mesial abutment, 2- pontic, 3- distal abutment, 4- simultaneously on the mesial abutment, pontic and distal abutment, 5- mesial and distal abutment (no pontic contact), 6- mesial abumtent and pontic, 7- distal abutment and pontic. The results showed that the load direction significantly influenced the magnitude and distribution of microstrains, so that for the simulated bone, the values found during axial load were within the physiological threshold independent of the point of load application; however, a more uniform distribution was observed when force was applied simultaneously on the mesial abutment, pontic and distal abutment. Furthermore, microstrain values above the tolerance limits were observed during oblique load, and for this condition, the point of load application significantly influenced the microstrains, with extremely high values and non-uniform distribution for all load conditions tested. Therefore, oblique loading must be avoided.
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Neto, Rafael Tobias Moretti. "Determinação de níveis ótimos de passividade em prótese sobre implante em função da deformação dos intermediários." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/25/25135/tde-04092007-143032/.
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O assentamento passivo tem sido considerado um dos mais importantes requisitos para o sucesso de próteses implanto-suportada. Este estudo in vitro investigou a deformação do intermediário de prótese implantosuportada após o aperto do parafuso tanto do cilindro de Paládio-Prata como de Cobalto-Cromo. Um modelo mestre foi usado para simular uma mandíbula humana com cinco implantes. Extensômetros foram colados nas faces mesial e distal de cada intermediário para registrar as deformações causadas pelos cilindros após o aperto dos parafusos. Os intermediários foram montados sobre as réplicas dos implantes e os parafusos foram apertados com um torque de 20 Ncm e as leituras foram gravadas. Após este passo, os parafusos tanto dos cilindros de Paládio-Prata como de Cobalto-Cromo foram apertados com um torque de 10 Ncm e as leituras também foram gravadas. Estas medições foram repetidas por cinco vezes. O teste estatístico de Mann-Whitney foi aplicado aos resultados. Nenhuma diferença estatística foi encontrada entre as tensões geradas tanto pelos cilindros de Paládio-Prata como os de Cobalto-Cromo. No entanto, existiram diferenças com relação à qualidade da tensão. A deformação gerada pelo aperto dos parafusos dos cilindros de Cobalto-Cromo foi de compressão e o aperto dos parafusos dos cilindros de Paládio-Prata gerou forças de compressão e tração.Passive fit has been considered one of the most important requirements for the success of implant supported prostheses. This in vitro study investigated the abutment deformation of an implant-supported prosthesis after screw tightening of palladium-silver and cobalt-chromium prosthetic cylinder. A master model was used to simulate a human mandible with five implants. The Strain gauges were attached on the sides of each abutment to capture deformations because of the cylinders screws after was tightened. The abutments were mounted onto implant replicas and the screws were tightened to a 20 Ncm torque, and the readings were recorded. After this step, palladiumsilver and cobalt-chromium prosthetic cylinders were tightened to a 10 Ncm torque and the readings were recorded. The measurements were repeated five times. Mann-Whitney statistical test was applied to the results. No statistical differences were found between the deformation generated by palladium-silver and cobalt-chromium prosthetic cylinders. However, there were differences relative to the quality of the strain. The deformation generated by screw tightness of the cobalt-chromium prosthetic cylinders was compressive while palladium-silver prosthetic cylinders generated compressive and tensile strain.
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Calkins, Thomas B. "Nanocomposite High Displacement Strain Gauges for use in Human-Machine Interfaces: Applications in Hand Pose Determination." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2627.
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Conductive nanocomposites are finding many uses as multi-functional materials. One recent development involves the creation of high displacement strain gauges, which have potential applications in a variety of engineering roles. The piezoresistive nature of the gauges makes possible their strain sensing capability. The intent of this research is to show that specific High Displacement Strain Gauges can successfully be used in one human-machine interface application that will demonstrate their potential for a range of other human-machine interface applications. This will be shown in the development of these sensors to accomplish hand pose determination. The flexible and inexpensive gauges are attached to several locations on a glove. It is then shown that by linking this glove with software, the position of the hand can be interpreted into the letters of the American Sign Language alphabet. This use of this nanocomposite sensor establishes the potential for future applications. Issues such as accuracy of response, cyclability, recalibration and reliability are discussed. A design of experiments is accomplished in order to evaluate the effects of modification of the gauges in order to overcome these issues. This work develops the potential of these sensors for use in human-machine interface applications such as computer games, remote controls, robotics, prosthetics and virtual reality applications.
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Ayranci, Cagri. "Development and testing of a Long Gage Strain (LGS) sensor for concrete structure instrumentation." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26844.
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Reinforced Concrete (RC) is the most commonly used structural material in civil engineering applications. RC structures have long term service lives under normal loading conditions; however, overload due to misuse or statistically remote events such as earthquakes may create damages that, if not detected on time, may eventually cause failure. Hence, it is important to monitor RC structures to take necessary precautions and save human lives. A L&barbelow;ong G&barbelow;age S&barbelow;train (LGS) sensor has been developed to monitor these structures. While it has been developed with concrete applications in mind, the new sensor can be used in a variety of applications, including measuring strains in pipelines, steel structures, and the like. The proposed sensor system has very low cost compared to the commercially available competing systems. Prototypes of the proposed strain sensors have been built and tested to calibrate the sensors and to prove their accuracy, repeatability, and to assess their reliability prior to in-situ concrete experiments. In-situ tests of the proposed sensors embedded into a reinforced concrete beam have been carried out. The steel rebars in the beam are also instrumented with commercial short gage length strain gages in order to compare the strain outputs of the strain gages to that of the proposed strain sensor. Results prove the accuracy, and reliability of the proposed strain sensor.
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Cordaro, Nicholas Michael. "Accelerated bone bonding to calcium phosphate ceramic coated strain gauges: An experimental and computational study." Thesis, The University of Arizona, 2000. http://hdl.handle.net/10150/278724.
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Calcium phosphate ceramic (CPC) coated strain gauges have been used for long term in vivo bone strain measurements but require 6 to 9 weeks for sufficient bonding. PepTite2000™, OP-1, TGF-β1, Ca₂SO₄·2H₂O, and an endothelial cell layer with and without TGF-β1 were examined as enhancements to accelerate bone to CPC bonding. Young male Sprague-Dawley rats were implanted with gauges for three weeks and calcein labeled. Following euthanasia, their femurs were explanted and mechanically tested. Histology was completed. Optical Coherence Tomography (OCT) was studied as an alternative to histology. A finite element analysis (FEA) examined bone to gauge strain transfer. Mechanical testing indicated increased sensing accuracy with TGF-β1 and OP-1 enhancements versus unenhanced gauges. PepTite2000™ and endothelial enhanced gauges displayed lower sensing accuracy and contained vasculature near CPC. TGF-β1 increased bonding with endothelial cells. Ca₂SO₄·2H₂O inhibited bone bonding. OCT unsuccessfully imaged bone to CPC contact. FEA identified geometric and material parameters for improved gauge design.