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1
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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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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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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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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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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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).
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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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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.
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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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Intiang, Jittakant. "Use of triple beam resonant gauges in torque measurement transfer standard." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4500.
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A new torque transfer standard using metallic TBTF resonant sensor was developed to overcome the overload capability problem which occurs with conventional metallic resistance strain gauges. Previous research work, however, has shown that the first prototype of the metallic TBTF resonant sensor was not suitable for use in a torque transfer standard due to its size and subsequent sensitivity to parasitic lateral forces. To maximize the benefits from this sensor, particularly overload capability and long-term stability, in the high accuracy torque measurement application area, there is a need to develop significantly smaller devices. The aim of this thesis is to research through FEA modelling and experimental characterisation the key performance parameters required to produce a miniaturised metallic TBTF resonant sensor that provides better performance when applied in a torque measurement system. For high accuracy any torque transducer using these sensors ought to have low sensitivity to parasitic influences such as bending moments and lateral forces, which can only be achieved with reduced size. The problems with the existing design, key design issues, possible configuration and packaging solutions of the metallic TBTF resonant sensor that could be used for achieving a higher accuracy torque transfer standard are considered. Two designs of miniaturised metallic TBTF resonant sensors, SL20 and SL12, are considered and experimentally investigated. The lateral forces are reduced by 52% for SL20 design and by 80% for SL12 design when compared to the original SL40 design. A torque transducer using the SL20 design was calibrated falling into the Torque Transfer Standard class of accuracy 1 category, uncertainty 0.8%. A torque transducer using the SL12 design was made and calibration showed a class of accuracy 0.5 category, uncertainty 0.2%. The results from this research indicate that the SL12 design is suitable for use in a torque transfer standard. The SL12 design is optimal and the smallest size possible based on the overload capability design criteria requiring the tine cross sectional area to remain constant.
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Costa, Max Dória. "Avaliação da deformação média gerada nos intermediários e na região peri-implantar durante as etapas de confecção da prótese parcial fixa parafusada: análise com strain gauges." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/25/25146/tde-27072011-091402/.
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A adaptação passiva e estabilidade têm se tornado os dois pré-requisitos de maior importância na escolha dos materiais e técnicas de confecção em prótese implantossuportada. A proposta deste trabalho foi avaliar, com auxílio dos strain gauges ou extensômetros lineares elétricos, a deformação média ocorrida nos intermediários e na região peri-implantar mediante a instalação da infraestrutura parafusada durante sete etapas de confecção da prótese parcial fixa. Para a investigação, foi utilizado um modelo experimental homogêneo à base de poliuretano com dois implantes hexágono externo paralelos entre si. Sobre os implantes foram acoplados pilares Multi-unit de 5 mm de altura que receberam na sua superfície três strain gauges dispostos de maneira eqüidistante entre si. Também foram colados na superfície superior do bloco experimental quatro strain gauges para cada implante, posicionados nas faces mesial, distal, vestibular e lingual visando medir as tensões nestas áreas. Os testes foram realizados parafusando os corpos de prova sobre os intermediários utilizando-se para isto um dispositivo eletrônico de torque com força máxima de 10 Ncm. As leituras foram realizadas em sete momentos, obtendo os valores médios de deformação no poliuretano e no intermediário respectivamente: 1) cilindros de cobalto-cromo pré-fabricados usinados como grupo controle (36,4µε e 87,5µε), 2) infraestrutura sobrefundida em monobloco com liga de níquel-cobalto-cromo (340,3µε e 131,4µε), 3) em seguida seccionada com espaço livre para solda (43,2µε e 66,6µε), 4) seccionada com espaço para solda preenchida com resina acrílica quimicamente ativada (Duralay) (74µε e 86,8µε), 5) seccionada e soldada (280µε e 146,2µε), 6) soldada com aplicação de cerâmica (288,7µε e 151,1µε) e 7) finalizada com aplicação do glaze, acabamento e polimento (359,9µε e 197,8µε). Estes resultados mostraram um aumento crescente da deformação média tanto nos intermediários como no poliuretano durante todas as etapas de confecção, com excessão da fundição em monobloco que atingiu altos valores, próximos da prótese finalizada. Desta forma, o procedimento de soldagem diminuiu os níveis de derformação, enquanto a aplicação da cobertura cerâmica, glaze, acabamento e polimento, aumentaram as deformações.Passive fit and stability have become the most important prerequisites during the choice of materials and techniques to implant-supported prostheses. Therefore, the aim of this study was to verify the mean deformation in abutments and simulated bone tissue around dental implants, with the use of strain gages, during framework screw retention, analyzing seven fabrication stages of the fixed partial denture. For this research, an experimental model based on homogeneous polyurethane with two external hexagon implants parallel to each other, provided with 5 mm height multi-unit abutments. For each, abutment surface received three equidistant strain gauges and the experimental block received upper surface four strain gauges, positioned on the mesial, distal, buccal and lingual aspects. The tests were performed screwing the specimens on the abutment using an electronic torque with 10 Ncm maximum force. The readings were made in seven moments, with abutment and polyurethane mean deformation, respectively: 1) control group: cobalt-chromium prefabricated machined cylinder (36,4µε e 87,5µε), 2) framework fabricated by 1-piece method in nickel-cobalt-chromium alloy (340,3µε e 131,4µε), 3) framework sectioned with space for welding (43,2µε e 66,6µε), 4) weld space filled with chemically activated acrylic resin (Duralay) (74µε e 86,8µε), 5) framework sectioned and soldered (280µε e 146,2µε), 6) framework welded and ceramic application (288,7µε e 151,1µε) and 7) framework concluded applying glaze, finishing and polishing (359,9µε e 197,8µε). The results showed the mean strain increase in abutment and polyurethane over fabrication stages, except that framework fabricated by 1-piece method reached high values close to finished prostheses. Thus, the welding procedure decreased strain levels in simulated bone tissue around dental implants, while ceramic and glaze application, finishing and polishing procedures, increased strain.
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Макуха, З. М. "Використання плівкових наноструктур як чутливих елементів сучасних тензодатчиків." Thesis, Видавництво СумДУ, 2008. http://essuir.sumdu.edu.ua/handle/123456789/4277.
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Narayanan, Soundararajan Hari. "Torque transducer sensitivity study." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-183048.
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A torque transducer or a torque sensor is a device for measuring and recording the torque on a rotating system. Torque transducers usually employ strain gauges to measure the torsional moment applied to a rotating shaft.It is to be noted that for an ideal torque transducer, it should measure only the strain that is caused by a torque. Strain due to bending load should be compensated as per the Wheatstone bridge arrangement. However, because of geometrical tolerances and assembly errors, the compensation doesn’t occur and the measured strain is a resultant of bending loads and axial loads which are undesired to measure the torque associated with the system. An analytical formulation has been developed using Matlab and this thesis gives the generalized indication of the strain due to all the associated loads. The user shall also entire the region where the strain needs to be computed and this knowledge can be useful for placing the strain gauges in the shaft accordingly. Initially, the formulation is based on a standard Torque Transducer used at Atlas Copco and then, a generalized result has been developed. The theoretical formulation is verified using the ProEngineer Mechanica software. The end user shall enter the different loads (if any) along with the geometrical tolerance values and the output will be an indication of the strain at point, strain at a region and sensitivity. The main intention of the thesis is to create a better understanding of the strain associated with the twisting, bending and axial loads and also the geometrical imperfections. The user can also make a decision on the location of strain gauges on a shaft for maximum accuracy. Finally, the differences in error from different possible configurations are compared and a conclusion has been made based on factorial design pertaining to design of experiments.Momentgivare är små sensorer som används för att mäta och registrera vridmomentet på en roterande axel. Momentgivare baseras vanligtvis på trådtöjningsmätare för att mäta vridmomentetet kring axeln de är fixerade på. Det skall noteras att en ideal momentgivare endast bör mäta den yttöjning som uppkommer på grund av ett vridmoment. Den belastning som uppkommer på grund av axelns böjning kompenseras bort med hjälp av en Wheatstonebrygga. Men på grund av geometriska toleranser och monteringsfel kan kompensationen bli felaktig och då påverkas det uppmätta momentet även av böj och axialbelastningar vilket är oönskat. En analytisk modell har utvecklats med hjälp av Matlab och denna rapport undersöker de olika lastfallens bidrag till momentfelet. Användaren kan ange området där yttöjningen skall beräknas och utifrån de beräkningarna bestämma var trådtöjningsgivarna bör placeras. Inledningsvis är beräkningarna baserade på en av Atlas Copcos momentgivare och sedan har generaliserade resultat utvecklats. De teoretiska beräkningarna verifieras med hjälp av programmet ProEngineer Mechanica. Användaren kan ange vilka belastningar som axeln känner samt de geometriska toleransvärdena och modellen beräknar då ytspänningen för den valda regionen. Det huvudsakliga syftet med denna avhandling är att skapa en bättre förståelse av ytspänningen som uppkommer på grund av vridning, böjning och axiella belastningar och även geometriska imperfektioner. Modellen kan också användas för att göra beräkningar som visar var töjningsgivare bör placeras på axeln för maximal precision. Slutligen har de introducerade felet från de olika möjliga konfigurationerna jämförts och en slutsats har dragits baserat på faktorförsök.
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Saito, Edson Hiroshi. "Medição de tensões em componentes mecânicos utilizando a técnica ESPI." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263913.
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Orientador: Auteliano Antunes dos Santos JuniorDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-16T17:18:43Z (GMT). No. of bitstreams: 1 Saito_EdsonHiroshi_M.pdf: 2483546 bytes, checksum: f0889b176e6cc7896851b8620c53c361 (MD5) Previous issue date: 2010
Resumo: A técnica ESPI, sigla em inglês - Electronic Speckle Pattern Interferometry -, ou ainda, Interferometria Eletrônica por Padrão de Speckle, surgiu em conseqüência do desenvolvimento da metrologia a laser, que possui como característica o chamado efeito speckle. Este efeito é o fenômeno óptico de interferência de ondas eletromagnéticas coerentes - que é o caso do Laser - que possibilita a geração de padrões de franjas de interferência, a partir das quais é possível medir o deslocamento de superfícies e posteriormente calcular as tensões e deformações. Por se tratar de uma metodologia não destrutiva e sensível a pequenos deslocamentos, essa metodologia tem se difundido na indústria para medição de Tensões em componentes mecânicos de formas complexas e como aplicação de apoio para outras técnicas como análise por Elementos Finitos. O objetivo deste trabalho é a aplicação da técnica ESPI em componentes mecânicos fazendo uso de uma metodologia através da qual seja possível estabelecer um procedimento de medição da tensão com confiabilidade. O desafio é estabelecer a adequada aplicação da ferramenta em ambiente industrial, onde há a interferência de ruídos, temperatura, vibração, além de uma adequação de equipamentos de ensaio que pode influenciar diretamente nos resultados de medições. A correta medição das tensões e deformações através de um ensaio não destrutivo e de rápido diagnóstico pode trazer diversos benefício, dentre os quais as cifras gastas em peças destruídas, tempo de medição e economia de mão-de-obra. Os resultados do presente trabalho são a determinação das variáveis influentes na aplicação do ESPI, levantamento das causas raízes dos problemas de medição e, a partir dessas informações, consolidar um procedimento padrão para aplicação em medição de tensões em componentes utilizando a técnica ESPI
Abstract: The ESPI technique - Electronic Speckle Pattern Interferometry - has emerged as a result of the development of laser metrology, which is characterized as the so-called speckle effect. This effect is an optical phenomenon of coherent electromagnetic waves interference - as Laser. It allows the generation of fringes interference from which it can be measured the displacement of surfaces and therefore calculated the stresses and strains. As a no-destructive methodology and being sensible to small displacements, it has being spread out in the industry by measuring Stress and Displacements in complex mechanical components and as a support to Finite Elements Analysis (FEA) and others techniques. The objective of this work is the application of the ESPI technique testing mechanical components making use of a systematic methodology by which it will be able to establish a procedure for measuring stress with reliability. The challenge is to establish the application procedure in the industrial environment, where there are a lot of interferences like noises, temperature variation, vibration etc., besides the fact that the testing equipment to be adapted to static tests can influences in the results. The stress and displacements measurement in a nodestructive test and fast result diagnose can bring a lot of benefits in financial terms serving as a support tool for other testing procedures. The results from this project are the determination of main variables for ESPI application, establishment of root causes in measurements problems using ESPI, and hence consolidate a standard procedure for ESPI application in strain /stress measurement in mechanical components
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
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Koslowsky, Álvaro Acco. "Força aplicada durante a remada na canoagem velocidade." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2014. http://hdl.handle.net/10183/104853.
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A remada em Canoagem Velocidade se caracteriza por ser um movimento bilateral, cíclico e simétrico, sendo que a propulsão é gerada, principalmente, pelos membros superiores. Não estão claros os aspectos relacionados à assimetria entre os hemicorpos da remada e, quanto a esta influência, o desempenho no deslocamento de caiaques de Canoagem Velocidade. O presente estudo teve como objetivos quantificar e comparar a quantidade de força aplicada à água, em atletas de diferentes níveis de desenvolvimento, bem como estabelecer a relação entre essas variáveis e o desempenho durante a execução de um teste máximo de 200 m em um caiaque individual de Canoagem Velocidade. Foram avaliados 90 atletas, com idade entre 10 a 40 anos, sendo que os mesmos foram subdivididos em três grupos, de acordo com seu nível de desenvolvimento: Iniciantes, Intermediários e Avançados. Foi encontrado que atletas de nível de desenvolvimento mais avançado eram os mais velhos, mais altos, mais pesados, mais experientes e mais rápidos que os atletas dos níveis menos avançados (p<0,001). Os atletas dos níveis de desenvolvimento mais avançado também produziram mais força que os seus pares de nível Intermediário e Iniciantes. Contudo, não foram encontradas diferenças significantes tanto para a diferença entre os lados, bem como quanto à dominância lateral foi levada em consideração. Além disso, não foi encontrada relação entre diferença na produção de força entre os lados direito e esquerdo e o desempenho em 200m. Por outro lado, a força máxima apresentou correlação negativa significante (r=-0,92, ES – quase perfeito) com desempenho em 200 m. Por fim, foi verificado que o equipamento utilizado apresentou reprodutibilidade aceitável para mensurar a força em atletas de Canoagem Velocidade. Foi concluído que tanto características morfofisiológicas e técnicas em atletas de Canoagem Velocidade apresentam desenvolvimento contínuo, de acordo com tempo e quantidade de prática na modalidade.Sprint Kayak stroke can be characterized as a bilateral, cyclic and symmetrical movement, where the propulsion lies mainly on the upper body. It is not clear, however, whether the stroke asymmetry affects Sprint Kayak performance. Therefore, this study aimed to quantify and compare force production amongst three developing level as well as to establish the relationships between force production and difference in left/right force production in those three different developing levels and 200 m performance in Sprint Kayak athletes. 90 athletes with ages ranging from 10 to 40 years volunteered for this study. They were allocated into three different groups based on developing level: Beginner, Intermediate and Advanced. Athletes of more advanced levels were older, taller, heavier, more experienced and faster than their lower level counterparts (p<0,001). Athletes from more advanced level also produced higher force scores than the intermediate and beginner levels. However, the force difference as well as lateral dominance were not different. Moreover, it was not found relationship between the difference and performance over 200 m. On the other hand, maximal force presented significant correlation with 200 m performance (r=-0,92 ES – nearly perfect). Finally, it was verified that the equipment used to measure force was reprodutible. In conclusion, morfophysiological and technical characteristics of Sprint Kayak athletes present a continuous development, according to time and amount of practice.
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Lashore, Michael. "Mathematical Model Validation of a Center of Gravity Measuring Platform Using Experimental Tests and FEA." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1467.
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This thesis sets out to derive an analytical model for a center of gravity (CG) measuring platform and examines its validity through experimental testing and Finite Element Modeling. The method uses a two-stage platform tilting process to first locate the planar CG coordinates and then find the third CG coordinate normal to the platform. An uncertainty model of the measuring platform was also developed, both CG and uncertainty models were implemented in the form of a MATLAB code. A load cell sizing task was also added to the code to assist the Integration Engineers at Jet Propulsion Laboratory in selecting load cells to design their own version of the CG Platform. The constructed CG Platform for this project used an array of six strain gauges, four C2A-06-062LT-120 Tee Rosettes and two C2A-06-031WW-120 Stacked Rosettes. They were bonded onto the legs of three truss shaped bipods. Results from the Platform Tilting Tests could not be used to validate the CG model as the measured CG and weight values found from the experimental tests contained a considerable amount of error. The errors in the Platform Tilting Tests are believed to stem from the initial errors observed during the bipod rod and strain gauge calibration tests. As an alternative, an FE model of the CG measuring platform was created as another means of validation. The math model of the CG measuring platform was successfully validated by showing that there was less than a 0.01% different between the bipod loads predicted from the MATLAB code and the FE model. Using the FEM generated loads as inputs into the CG code to calculate a CG matched the initial point mass or CG created in the FE model within a 0.01% difference. To validate the CG model even further, another test should be performed using a CG Platform prototype instrumented with load cells to generate new experimental data and compare them with the results from the FE model.
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Wagner, Stefan [Verfasser], Max Christian [Akademischer Betreuer] Lemme, Wilfried [Akademischer Betreuer] Mokwa, and Frank [Akademischer Betreuer] Niklaus. "2D materials for piezoresistive strain gauges and membrane based nanoelectromechanical systems / Stefan Wagner ; Max Christian Lemme, Wilfried Mokwa, Frank Niklaus." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1181193214/34.
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Шуляренко, Д. О., and А. С. Овруцький. "Тензорезистивні властивості плівкових наносистем на основі пермалою та срібла як чутливих елементів тензодатчиків." Thesis, Сумський державний університет, 2018. http://essuir.sumdu.edu.ua/handle/123456789/67874.
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Величина магнітоопору залежить від таких факторів як матеріал компонент плівкової системи, метод та умови отримання, процеси дифузії та фазоутворення, інтервал термовідпалювання та ін. Детальне дослідження тензорезистивного ефекту в плівкових наносистемах відкриває перспективу створення на їх основі не тільки тензорезисторів і тензодатчиків, а й багатофункціональних сенсорів для одночасного контролю декількох фізичних параметрів.
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Dokoupil, Pavel. "Nejistota měření přetvoření a mechanického napětí pomocí odporových tenzometrů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-371773.
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The dissertation thesis deals with the determination of uncertainty of strain measurement and the stress using resistance strain gages. You can find two methods to define the uncertainty in the thesis, GUF and MMC, and both are applied for measurements carried out with resistance strain gages. Definition of the measurement uncertainty was set for the strain measured by uniaxial and biaxial strain gages. The uncertainty of the stress was defined for linear strain gages, T Rosettes and Rosettes. There were universal mathematic-technical models defined to measure strain and stress, these models can be used either for standard and special measurements i.e. high-temperature, or for measurements in radiation field. Each part of the strain uncertainty and stress is analyzed from the point of view of a size of uncertainty and a form of probability of the function that strain and stress can adopt. The maximum focus was dedicated to the mistakes influencing measured strain like strain gage properties, installation and operating influences, external influences, time effects and the influence of the measured object. There are two mistakes influencing the stress described and analyzed in the thesis, the mistake of the Young’s modulus of elasticity and the mistake of the Poisson’s ratio. The thesis is conceived as a complex of information related to the measurement uncertainties using the resistance strain gages and methods of defining the measurement uncertainty in a way that the experimenter can apply the gained info and methods in the required measurements. The final chapters give representative examples to define measurement uncertainties for uniaxial and biaxial stress applying GUF and MMC method. The thesis also includes the experiment that compares measured values of strain, stress and measurement uncertainties, using several different types of strain gages at different temperatures, with theoretical calculation of strain and with stress. The experiment was carried out using the displacement sensor that works on an elementary principle of bending load.
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Bortolotto, Marina Schnaider. "Bender elements, ultrasonic pulse velocity, and local gauges for the analysis of stiffness degradation of an artificially cemented soil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/172327.
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A rigidez a pequenas deformações e sua respectiva degradação são informações cruciais para se determinar parâmetros de projeto mais precisos. Apesar de sua importância, estas propriedades não são usualmente investigadas. Assim, o objetivo do presente trabalho foi de estudar a degradação da rigidez da areia de Osório artificialmente cimentada por meio de diferentes métodos de laboratório. A escolha por um material cimentado ocorreu baseada em apelos ambientais, econômicos e técnicos. O presente estudo também objetiva desenvolver e validar um sistema de Bender Elements (BE), que forneça resultados confiáveis na avaliação da degradação do solo. Pares de BE foram construídos para serem utilizados em testes de bancada e ensaios triaxiais. Além disso, um amplificador de sinal, assim como scripts foram desenvolvidos especialmente para a interpretação dos dados no domínio do tempo. O aumento da rigidez durante o processo de cura foi avaliado por meio da velocidade de onda cisalhante, medida pelos BE e por um equipamento de ondas ultrassônicas (UPV), sob condições de pressão atmosférica. Ensaios de degradação da rigidez, por sua vez, foram conduzidos em uma câmara triaxial especialmente modificada para a instalação dos BE Após sete dias de cura atmosférica, os corpos-de-prova foram cisalhados no equipamento triaxial modificado enquanto mudanças de rigidez eram obtidas por meio de testes de BE e instrumentação interna. Os resultados demonstraram que o sistema BE desenvolvido foi bem sucedido na avaliação da rigidez do solo estudado. A comparação entre os resultados do BE e UPV não foi conclusiva no que se refere à dependência do solo à frequência. A degradação do módulo obtida por ambas as metodologias apresentou uma adequada concordância para o corpo-deprova com menor quantidade de cimento. Módulos obtidos por BE foram pouco maiores que os obtidos por medidas internas. Ainda, a interpretação no domínio do tempo dos resultados de BE para corpos-de-prova cimentados, especialmente durante ensaios triaxiais, foi difícil de ser executada, reforçando a necessidade de se combinar diferentes métodos de interpretação quando BE forem utilizados.Stiffness at small strains and its respective degradation are crucial information to determine more precise design parameters. Despite their importance, these properties are not usually investigated. Thus, the objective of the present work was to study the stiffness degradation of artificially cemented Osorio sand by means of different laboratory methods. The choice for a cemented material was based on environmental, economic, and technical appeals. The present study also aimed to develop and validate a Bender Elements (BE) system that can provide reliable results in the evaluation of soil degradation. BE pairs were built for bench and triaxial tests. In addition, a signal amplifier, as well as scripts were specially developed for the interpretation of data in the time domain. Increase in stiffness during the curing process was evaluated by shear wave velocity measured by BE and an ultrasonic pulse wave velocity (UPV) equipment under atmospheric pressure conditions. Stiffness degradation tests were conducted in a specially modified triaxial chamber for BE installation After seven days of atmospheric curing, specimens were sheared in the modified triaxial equipment, while stiffness changes were obtained by BE tests and internal instrumentation. The results showed that the developed BE system was capable of successfully evaluating the studied soil. The comparison between BE and UPV results was not conclusive regarding soil dependence on frequency. Shear module degradation obtained with the two methodologies presented an adequate agreement for the specimen with the smaller amount of cement. Shear moduli obtained with BE were slightly larger than those obtained with internal measurements. Also, BE results interpretation in the time domain for cemented specimens, especially in the triaxial tests, was difficult to perform, reinforcing the need to combine different interpretation methods when BE are used.
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Бурик, І. П., Ю. М. Бабкін, Максим Миколайович Іващенко, Максим Николаевич Иващенко, Maksym Mykolaiovych Ivashchenko, Олександр Іванович Лєпіхов, Александр Иванович Лепихов, and Oleksandr Ivanovuch Liepikhov. "Підвищення надійності вибухозахисних систем при застосуванні плівкових тензодатчиків." Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47175.
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Забезпечити надійну безпеку персоналу шахт по всій мережі гірничих виробок
можна шляхом гасіння спалахів метану або вугільного пилу безпосередньо в зоні їх
виникнення. Для цього потрібні спеціальні засоби з примусовою подачею гасильного
матеріалу в осередок спалаху (вибуху) у момент його виникнення.
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Herranz, Alvarez Juan F. "Minimisation of the wire position uncertainties of the new CERN vacuum wire scanner." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/398303.
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The particle production of an accelerator is characterised by the accelerated species of particles, by their number and energy. The particle rate is determined by the production cross section, a natural constant and the accelerator dependent parameter luminosity. The luminosity is proportional to the number of particles in each beam and inversely proportional to the particle beam transverse dimensions. The luminosity increases with the particle beam density and therefore the probability of interactions too. To optimize the transverse beam sizes, profile monitors are used to measure parameter depending changes.
Different monitors can provide beam transversal profile measurements (Wire Scanners, Synchrotron Light Monitors, Rest Gas Profile Monitors), however the wire scanner monitor is considered to be the most accurate of all monitors. Wire scanner instruments measure the transverse beam density profile in a particle accelerator by means of moving a thin wire in an intermittent manner.
In the next years the luminosity of the Large Hadron Collider (LHC) will be significantly increased and more accurate beam profile measurement will necessary. The new performance demands a wire travelling speed up to 20 m.s-1 and a position measurement accuracy of the order of few micros. The existing wire scanners does not reach the new requirements as their accuracy achieved is limited by the motorization, the angular position measurement system located outside of the vacuum vessels and the vibration of the thin carbon wire which has been identified as one of the major error sources reducing the knowledge of the wire position. Therefore the development of a new device whose accuracy meets the new requirements was mandatory.
This thesis work aims to provide suitable inputs for the design and operation of this new fast wire scanner in order to minimize the uncertainties in the wire position. To accomplish the aims the understanding of the wire vibrations in such a system is one of the main goals of this work. More specifically, the development of a suitable vibration measurement system and the construction of dynamic models of the system are the two goals aimed. For the new scanner design this work intend to propose, the conceptual design, the optimization of the most critical parts and the operation procedure that will allow the new device to reach the required performances imposed by the forthcoming LHC conditions.La producción de partículas de un acelerador se caracteriza por las especies de partículas aceleradas, por su número y energía. La tasa de partículas se determina a partir de la sección transversal de producción, una constante natural, y de un parámetro que depende del acelerador, la luminosidad. La luminosidad es proporcional al número de partículas por haz e inversamente proporcional a la dimensión transversal de los haces. La luminosidad aumenta con la densidad de partículas y por lo tanto también aumenta la probabilidad de interacciones entre los haces. Para optimizar la sección trasversal del haz, se utilizan monitores de perfil de haz. Diversos tipos de monitores pueden proporcionar mediciones del perfil transversal del haz (Escáneres de hilo, Monitores de luz de sincrotrón, Monitores de análisis de gas residual), sin embargo el escáner de hilo está considerado como el más preciso de todos ellos. Los escáneres de hilo miden el perfil del haz atravesándolo con un hilo muy delgado de manera intermitente. En los próximos años la luminosidad del Gran Colisionador de Hadrones (LHC) se incrementará de manera significativa, por lo que serán necesarios sistemas de medida de perfil de haz más precisos que lo actuales. Las nuevas características, requerirán velocidad de desplazamiento del hilo de hasta 20 ms-1 y una precisión en la medida de posición del hilo de tan solo unas micras. Los escáneres actuales no pueden alcanzar estos requerimientos ya que su precisión está limitada por el sistema de motorización, por el medidor angular de posición que está situado fuera del tanque de vacío y por las vibraciones del hilo, la cuales han sido identificadas como una de las mayores fuentes de error a la hora de conocer la posición real del hilo. Por todo esto, el desarrollo de un nuevo dispositivo cuyas características cumplan los nuevos requerimientos era necesario. Este trabajo de tesis tiene como objetivo proporcionar criterios adecuados para el diseño y operación de un nuevo escáner, con el fin de minimizar las incertidumbres en la posición del hilo. Para lograr estos objetivos, el entender las vibraciones del hilo en un sistema de este tipo es un objetivo primordial. De manera más específica el desarrollo de sistemas de medida de vibración adecuados y la construcción de modelos dinámicos del sistema son los dos objetivos concretos perseguidos por este trabajo. De cara al nuevo diseño, este trabajo pretende proponer un diseño conceptual así como definir los criterios para la optimización de las partes más críticas y establecer un procedimiento de operación que permita al nuevo dispositivo alcanzar los requerimientos impuestos por las futuras condiciones del LHC.
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Forsling, Ekblom Albin, and Rickard Ohlén. "Balkböjning och signalbehandling." Thesis, KTH, Hållbar produktionsutveckling (ML), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299794.
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I laborationssalarna på KTH i Södertälje, som i huvudsak används till elektrorelaterade ämnen, har det funnits ett antal balkmodeller med monterade töjningsgivare. Dessa har inte använts på många år och det saknas vidare uppgifter om modellerna. Uppdraget bestod av att utarbeta en laboration till KTH:s undervisning. Laborationen skulle handla om balkböjning och signalbehandling, med tonvikt på̊ det senare. Som hjälpmedel skulle vi använda oss av balkmodellerna. I uppdraget ingick det också att undersöka balkmodellernas elektriska och mekaniska egenskaper. Med teknisk balkteori skulle en möjlig relation mellan nedböjning och töjning tas fram. Med balkmodellen i en bryggkoppling kunde dess signal via ett DAQ-kort överföras till en PC och LabVIEW för vidare behandling. I LabVIEW kan ett anpassat gränssnitt tas fram och för visning av valda parametrar. Bryggkopplingen balanseras med hjälp av en potentiometer. I gränssnittet kan spänningsförändringen i bryggan observeras när balken påverkas av nedböjning. Efter kalibrering av systemet kan töjning och nedböjning presenteras efter beräkningar i LabVIEW. För att erhålla en så stabil och brusfri signal som möjligt har gruppen använt sig avbåde ett hårdvarufilter av lågpass-typ och ett mjukvarufilter i LabVIEW. Signalen förstärks med hjälp av en OP-förstärkare innan den matas in i DAQ-kortet. Trots sin ålder kunde balkmodellerna fortfarande användas och ge stabila signaler för vidarebehandling. Modellerna kan med fördel användas i en laboration för studenter och färdigt underlag finns för detta. Laborationen bör öka förståelsen för hur en signal från en givare kan förstärkas, filtreras och behandlas vidare i detta fall för grundläggande hållfasthetsberäkningar.In the laboratory at KTH in Södertälje, which are mainly used for electro-related subjects, there are a number of beam models with mounted strain gauges. These have not been used for many years and there is no further information about the models. The assignment consisted of preparing a laboratory task for KTH's teaching. The laboratory would consist of beam bending and signal processing, with emphasis on the latter. As an aid, the beam models will be used, these consisted of a fixed aluminum beam with mounted strain gauges. The assignment also includes examining the electrical and mechanical properties of the beam models. With technical beam theory, a possible relationship between deflection and strain would be developed. With the beam model connected in a bridge connection, its signal could be transferred via a DAQ card to a PC and LabVIEW for further processing. In LabVIEW, a custom interface can be created and for displaying selected parameters. The bridge coupling is balanced with the help of a potentiometer. In the interface, the voltage change in the bridge can be observed when the beam is affected by deflection. After calibration of the system in the interface, strain and deflection can be presented according to calculations in LabVIEW. To obtain as stable and noise-free a signal as possible, the group has used both a low-pass hardware filter and a LabVIEW software filter. The signal is amplified by an OP amplifier before being fed into the DAQ card. Despite their age, the beam models could still be used and give stable signals for further treatment. The models can be used to advantage in a laboratory for students and there is a ready basis for this. The laboratory should increase the understanding of how a signal from a sensor can be amplified, filtered and further processed in this case for basic strength calculations.
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Bianco, Vinicius Cappo. "Influência das desadaptações angulares unilaterais na distribuição de tensões da região peri-implantar de elementos unitários tipo UCLA submetidos a pré-carga e carga axial: estudo in vitro." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/25/25146/tde-11112013-162603/.
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Atualmente, os implantes são utilizados em diversos tipos de tratamento na reabilitação oral. Para manutenção da osseointegração, é essencial que o conjunto prótese/implante/osso seja submetido a forças às quais estejam aptos a suportar. Os diferentes tipos de desadaptações das infraestruturas das próteses sobre implantes são fatores que podem contribuir para o aumento das tensões na região peri-implantar. Este estudo teve como objetivo avaliar a influência das desadaptações angulares unilaterais na distribuição de tensões na região periimplantar de pilares tipo UCLA, no momento da pré-carga e carga axial. Infraestruturas de CoCr, confeccionadas utilizando-se pilares tipo UCLA, foram divididas em quatro grupos: Grupo A (adaptado), Grupo B, Grupo C e Grupo D (50, 100 e 200 μm de desadaptação unilateral angular por vestibular, respectivamente). Cada grupo foi representado por quatro infraestruturas (n=4). Quatro implantes (4.1mm/15mm) foram posicionados em uma matriz metálica, onde posteriormente foi vazado o poliuretano (PU), com função de simular o tecido ósseo. Quatro extensômetros (strain gauges) foram posicionados na região vestibular, distal, lingual e mesial de cada implante, para aferir a quantidade de deformação; cada grupo foi posicionado em seu respectivo implante. Foram realizados dois testes: o teste de pré-carga com um torque de 32Ncm e o teste de carga com uma força axial estática de 300N. Cada infraestrutura foi sujeita aos dois testes, por cinco vezes. Para análise estatística dos dados, foram utilizados ANOVA (dois critérios) e o teste de Tukey (p<0,05). Os resultados mostraram que os grupos A e B tiveram menos deformação da região peri-implantar em ambos os testes, quando comparados aos grupos C e D. A estatística também mostrou que o Grupo A apresentou melhor distribuição de tensões em sua região, peri-implantar quando comparado aos outros três grupos (p<0,05). Como conclusões, este estudo mostrou que as desadaptações influem na distribuição das tensões da região peri-implantar e que quanto maior o nível de desadaptação, mais altas são as tensões geradas.Nowadays implants are used in several kinds of oral rehabilitation treatments. For the osseointegration maintenance it is important that crow/implant/bone are subjected to forces which are able to withstand. Different kinds of misfit on the crown frameworks are factors that could lead to an increase of strain around the implanted bone. This study aimed to evaluate the influence of the unilateral angular misfit in frameworks made of UCLA on the peri-implant strain distribution, subjected to preload and axial load. Frameworks made of chrome-cobalt were fabricated on UCLA abutments and divided in 4 groups: Group A (no misfit), Group B, Group C, Group D (50, 100, and 200 of unilateral angular misfit by buccal side, respectively). Each group was represented for 4 frameworks (n=4). Four implants (4.1mm/15mm) were positioned in a metallic matrix which was subsequently poured the polyurethane (PU) to simulate the bone. Four strain gauges were positioned on the buccal, distal, lingual and mesial sides of each implant to assess the amount of strain, each group was connected on its respectively implant. It was performed 2 tests: the preload test with a 32Ncm torque and the load test by applying an axial force of 300N. Each framework was subjected to the both test five times. To the statistics analysis ANOVA (2 ways) and Turkeys test were performed. The results showed that the Groups A and B presented less deformation when compared to Groups C and D. The statistics also showed that the Group A presented better distribution of strain on its peri-implant bone when compared to the other three groups (p<0,05). In conclusion this study showed that misfit had influence on the strain distribution on the peri-implant bone and that strain increased on the Groups C and D which presented higher levels of misfit.
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Gonzales, Manny. "The mechanochemistry in heterogeneous reactive powder mixtures under high-strain-rate loading and shock compression." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54393.
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This work presents a systematic study of the mechanochemical processes leading to chemical reactions occurring due to effects of high-strain-rate deformation associated with uniaxial strain and uniaxial stress impact loading in highly heterogeneous metal powder-based reactive materials, specifically compacted mixtures of Ti/Al/B powders. This system was selected because of the large exothermic heat of reaction in the Ti+2B reaction, which can support the subsequent Al-combustion reaction. The unique deformation state achievable by such high-pressure loading methods can drive chemical reactions, mediated by microstructure-dependent meso-scale phenomena. Design of the next generation of multifunctional energetic structural materials (MESMs) consisting of metal-metal mixtures requires an understanding of the mechanochemical processes leading to chemical reactions under dynamic loading to properly engineer the materials. The highly heterogeneous and hierarchical microstructures inherent in compacted powder mixtures further complicate understanding of the mechanochemical origins of shock-induced reaction events due to the disparate length and time scales involved.
A two-pronged approach is taken where impact experiments in both the uniaxial stress (rod-on-anvil Taylor impact experiments) and uniaxial strain (instrumented parallel-plate gas-gun experiments) load configurations are performed in conjunction with highly-resolved microstructure-based simulations replicating the experimental setup. The simulations capture the bulk response of the powder to the loading, and provide a look at the meso-scale deformation features observed under conditions of uniaxial stress or strain. Experiments under uniaxial stress loading reveal an optimal stoichiometry for Ti+2B mixtures containing up to 50% Al by volume, based on a reduced impact velocity threshold required for impact-induced reaction initiation as evidenced by observation of light emission. Uniaxial strain experiments on the Ti+2B binary mixture show possible expanded states in the powder at pressures greater than 6 GPa, consistent with the Ballotechnic hypothesis for shock-induced chemical reactions. Rise-time dispersive signatures are consistently observed under uniaxial strain loading, indicating complex compaction phenomena, which are reproducible by the meso-scale simulations. The simulations show the prevalence of shear banding and particle agglomeration in the uniaxial stress case, providing a possible rationale for the lower observed reaction threshold. Bulk shock response is captured by the uniaxial strain meso-scale simulations and is compared with PVDF stress gauge and VISAR traces to validate the simulation scheme. The simulations also reveal the meso-mechanical origins of the wave dispersion experimentally recorded by PVDF stress gauges.
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Polach, Pavel. "Tréningový systém pro sportovní lezce." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-220335.
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The purpose of this diploma thesis was design and realisation of measuring system, enabling measuring forces between climber´s feet and holds on the climbing wall and using this measu-red values during a training of sport climber. In this thesis there are discovered possibilities about constructing this system and determina-ted basic requirements of measuring. There are also stated principles of application the strain gauges for measuring the tension. Descriptions of developping specific sensors, hardware interface and PC application are also part of this thesis. Constructed system was used for mea-suring climbers and values were analysed by using the application.
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Gellner, Pavel. "Měření sil působících za jízdy mezi kolem a vozovkou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417508.
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The diploma thesis is focused on the measurement of forces acting between the tire and the road. There is an outline of tire and tire models problematic in the opening part. In the following part, the rear right suspension of the formula student car was mounted with strain gauges and the data logging system was described. There is also a multi-body model of the rear axle created in Adams/Car and SAMS software, that is able to calculate forces acting between the tire and the road, taking the measured forces in the suspension, rocker position, and throttle position into consideration. After a series of calibrations and verification measurements, the measurement on the test track was made, with data analysis focused on forces acting between the tire and the road.
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Kamel, Bernard. "Développement, caractérisation et optimisation d'un capteur de pression intégré sur une bougie d'allumage." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20024/document.
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Les récentes normes environnementales et les demandes de réduction des émissions et de consommation de carburants des moteurs essence exigent de nouvelles stratégies de combustion par lesquels le mélange air/essence devrait être méticuleusement commandé en temps réel par un capteur de pression. Le contrôle de la pression cylindre est une technologie principale qui permet une coordination optimisée du mélange air/carburant, et la recirculation des gaz d'échappement par la rétroaction de contrôle. A ce jour, la mesure de pression cylindre en temps réel n'est pas fournie même sur les voitures récentes. Jusqu'à présent cette mesure a été mise en application sur des moteurs spécifiques pour le développement d'applications particulières telles que le contrôle moteur. Plusieurs obstacles empêchent l'intégration des capteurs de pression sur les nouveaux moteurs; le coût de production élevé de ces dispositifs et leurs implémentations complexe sur les moteurs standards retarde leur développement.Le capteur de pression GCS™ (Gasoline Combustion Sensor) est un capteur non-intrusif de pression cylindre intégré dans une bougie d'allumage qui a un accès direct à la chambre de combustion. Il répond aux contraintes d'intégration automobile, de performance et de fiabilité, et permet la mesure de pression jusqu'à 200bar et du cliquetis. Ce type de capteur permet le suivi de combustion en temps réel exigé pour la combustion par auto-allumage par laquelle la rétroaction rapide des événements de combustion permet la gestion étincelle/carburant dans chaque cylindre. Il agit sur l'allumage aussi bien que sur l'injection pour optimiser la combustion et réduire la consommation de carburant d'environ 1.4% et les émissions de polluants d'environ 10%.La présente thèse concerne le développement d'un capteur de pression fiable et bas-cout qui sera une condition de base pour les prochaines générations de moteurs. Cette étude concerne deux types d'éléments sensibles différents. L'un est basé sur une céramique piézoélectrique, et l'autre comporte un système piézo-résistif de jauges de contraintes sérigraphiées sur l'isolant céramique de la bougie d'allumage. Durant cette analyse, des problèmes mécaniques ont été soulignés et une section a été consacrée pour résoudre le problème de transmission de pression à l'élément sensible réduisant les bruits mécaniques notamment. Différents concepts mécaniques ont été développés et regroupés sous plusieurs familles, dont deux catégories ont été retenues pour la suite du développement.Le premier chapitre décrit le projet d'un vue globalement, les caractéristiques du capteur et le principe de mesure. Le second chapitre se rapporte à l'élément sensible et la description des technologies utilisées. Le développement mécanique du corps d'épreuve du capteur basé sur un élément sensible piézoélectrique sera présenté en détail dans le troisième chapitre. Le quatrième chapitre comprend la caractérisation des deux types de capteurs piézoélectriques et piézo-résistifs. Le cinquième chapitre décrit le traitement du signal issu de l'élément sensible et le packaging du capteur. Le dernier chapitre présente une perspective d'optimisation du dispositifRecent environmentally-friendly norms and global demands for lower emissions and lower fuel consumption on gasoline engines require innovative combustion strategies, whereby air/fuel mixture should be meticulously controlled through a real time pressure feed-back sensor. In-cylinder pressure control has shown to be a key technology that enables an optimized coordination of an air/fuel mixture, and exhaust gas recirculation through closed loop control.Nowadays real time in-cylinder pressure measurement is not provided on passenger's cars. Thus far it has been implemented on specific engine for development of particular applications such as engine control. Several obstacles prevent the integration of pressure sensors on new engines such as high production cost of this device and its complex implementation on a standard engine. The Gasoline Combustion Sensor™ (GCS) is a non-intrusive in-cylinder pressure sensor integrated into a spark plug which has direct access to the combustion chamber. It answers the automotive integration constraints performance and reliability and allows in-cylinder pressure measurement up to 200bar, knock and misfiring detection.Such sensors allow for combustion follow-up in a real-time direct mode required for auto ignition combustion whereby fast feedback of combustion events enables fine tuning and individual cylinder spark/fuel management. It operates on the ignition as well as on the injection to optimize the combustion and reduce fuel consumption by an average of 1.4% under steady-state conditions, which will reduce harmful emissions by about 10%. The present thesis relates to the development of a low-cost pressure sensor which will be a basic requirement for future engine generations. It consists on two different sensing element types, one is based on piezoelectric ceramic, and the other comprises piezo-resistive strain gauge system directly embedded on the ceramic insulator. During this analysis, mechanical problems have been emphasized and a section was dedicated to resolve the problem of the pressure transmission to the sensing element reducing structure-borne noise on the sensor. Different mechanical concepts have been developed, where two categories have been selected.Chapter one describes the project in a global overview including sensor specifications and sensing principle, chapter two relates to the sensing element materialization including technology description. Proof body development based on piezoelectric sensor will be presented in detail in chapter three, while chapter four contains device characterization of both sensor types piezoelectric and piezo-resistive. Chapter five describes the signal processing and sensor packaging, and chapter six gives an optimization perspective of the device
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Dratva, Jakub. "Experimentální stanovení zatížení letounu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377527.
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The thesis is focused on experimental load definition of an aircraft. Especially is measured bending moment is measured on wing during the flight. The thesis includes theoretical basis for strain gauge measurements and procedure of statistic evaluation. For each of flight maneuvers, there are theoretical wing loads calculated and then the values are compared. The end of the thesis shows proposals for improvement of used method of flight possible repeated measurement.
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Elshesheny, Ahmed. "Dynamic soil-structure interaction of reinforced concrete buried structures under the effect of dynamic loads using soil reinforcement new technologies. Soil-structure interaction of buried rigid and flexible pipes under geogrid-reinforced soil subjected to cyclic loads." Thesis, University of Bradford, 2019. http://hdl.handle.net/10454/18312.
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Recent developments in constructions have heightened the need for protecting existing buried infrastructure. New roads and buildings may be constructed over already existing buried infrastructures e.g. buried utility pipes, leading to excessive loads threatening their stability and longevity. Additionally applied loads over water mains led to catastrophic damage, which result in severe damage to the infrastructure surrounding these mains. Therefore, providing protection to these existing buried infrastructure against increased loads due to new constructions is important and necessary.
In this research, a solution was proposed and assessed, where the protection concept would be achieved through the inclusion process of geogrid-reinforcing layers in the soil cover above the buried infrastructure. The controlling parameters for the inclusion of geogrid-reinforcing layers was assessed experimentally and numerically. Twenty-three laboratory tests were conducted on buried flexible and rigid pipes under unreinforced and geogrid-reinforced sand beds. All the investigated systems were subjected to incrementally increasing cyclic loading, where the contribution of varying the burial depth of the pipe and the number of the geogrid-reinforcing layers on the overall behaviour of the systems was investigated. To further investigate the contribution of the controlling parameters in the pipe-soil systems performance, thirty-five numerical models were performed using Abaqus software. The contribution of increasing the amplitude of the applied cyclic loading, the number of the geogrid-reinforcing layers, the burial depth of the pipe and the unit-weight of the backfill soil was investigated numerically.
The inclusion of the geogrid-reinforcing layers in the investigated pipe-soil systems had a significant influence on decreasing the transferred pressure to the crown of the pipe, generated strains along its crown, invert and spring-line, and its deformation, where reinforcing-layers sustained tensile strains. Concerning rigid pipes, the inclusion of the reinforcing-layers controlled the rebound that occurred in their invert deformation. With respect to the numerical investigation, increasing the number of the reinforcing-layers, the burial depth of the pipe and the unit-weight of the backfill soil had positive effect in decreasing the generated deformations, stresses and strains in the system, until reaching an optimum value for each parameter. Increasing the amplitude of the applied loading profile resulted in remarkable increase in the deformations, stresses and strains generated in the system. Moreover, the location of the maximum tensile strain generated in the soil was varied, as well as the reinforcing-layer, which suffered the maximum tensile strain.Government of Egypt
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Dokoupil, Pavel. "Měření napjatosti ve spirále vodní turbíny pomocí tenzometrů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231230.
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The Master‘s thesis is focused on measuring of the stress in the spiral case of water turbine using the strain gauges measurement. It contains the theoretical and the practical part. The theoretical part includes a description of theoretical background (basic mechanics, measurement and evaluation, strain gauges, pressure measurement, uncertainty of measurement). One of the chapters describes Water Power Plant Lipno nad Vltavou (history of power plant, issues and the history of measurement). The practical part contains a theoretical calculation of measurement uncertainty and measuring of stress on spiral case Francis turbine at Water Power Plant Lipno I (Unit TG2). Measurement was made before and after overhaul. There are described technical data of spiral cases, description of measurement, results of measuring of strain and stress including comparison with the pressure in spiral case and calculation of uncertainties of measurement.
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Leo, Riccardo. "The axial response of offshore piles in sand from large scale tests." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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This thesis focuses on deep foundations used in offshore environment, in particular for offshore wind turbines. Piles are necessary when the bearing capacity of the shallow soil layers is not enough to ensure stability. Piles can work on both axial and lateral response. In the thesis only axially loaded piles will be considered. The analysis of the axial behavior of piles should be considered in terms of ultimate capacity as well as the load transfer mechanism between the pile and the soil.
The technical aim of this thesis concerns the understanding of the load transfer curves, their extrapolation and the exploration of load distribution along the pile during a given load. To achieve this, a thorough study of literature on current design methods is carried out and two instrumented piles will be analysed in order to understand how the load is distributed along the pile shaft and how experimental load transfer curves can be extrapolated.
The more general aim of this work is to optimize design procedures and try to reduce the cost related piles and their installation in offshore environment, since it is quite known to be higher than onshore fields, as it will be explained in the first chapter of this thesis.
A geotechnical software IGtH Pile developed by the Institute of geotechnical Engineering (IGtH), Leibniz Universität Hannover will be used in the evaluation of the ultimate capacity and the results will be compared with a Matlab code developed at the IWES research institute.
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Decorde, Nicolas. "Développement de jauges de contrainte à base de nanoparticules colloïdales : Application à la réalisation de surfaces tactiles souples." Thesis, Toulouse, INSA, 2014. http://www.theses.fr/2014ISAT0002/document.
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Un grand défi actuel consiste à réaliser des capteurs innovants tirant partie des propriétés singulières de nanoparticules colloïdales synthétisées par voie chimique et assemblées de manière contrôlée sur des surfaces. L’objet de cette thèse est le développement de jauges de contrainte résistives à base de nanoparticules. Ces jauges de contrainte sont constituées de lignes parallèles, de quelques micromètres de large, denses, de nanoparticules colloïdales d’or synthétisées par voie chimique et assemblées sur des substrats souples par assemblage convectif contrôlé. Le principe de ces capteurs résistifs repose sur la conduction tunnel entre les nanoparticules qui varie de manière exponentielle lorsque que l’assemblée est déformée. Des mesures électro-mécaniques couplées à des observations en microscopie électronique à balayage et à force atomique ont permis d’identifier, de quantifier et de comprendre l’impact de la taille et de la nature des ligands des nanoparticules sur la sensibilité et les phénomènes de dérive de la résistance à vide des jauges de contrainte. Ces travaux, associés à des mesures de diffusion de rayons X aux petits angles ont permis de corréler les variations macroscopiques de résistance électrique des jauges de contrainte aux déplacements relatifs des nanoparticules. Finalement, ces jauges de contrainte ultra-sensibles et miniatures, mises en matrices, ont été exploitées pour réaliser des surfaces tactiles souples multi-points et sensibles à l’intensité de l’appuiOne recent big challenge is to implement innovative sensors that take advantage of the unique properties of colloidal nanoparticles chemically synthesized and assembled on various surfaces. The goal of this work is the development of nanoparticle based resistive strain gauges. These strain gauges are constructed of few micrometers wide parallel wires of close packed colloidal gold nanoparticles, chemically synthesized, and assembled on flexible substrates by convective self assembly. The principle of these resistive sensors is based on the tunnel conduction between the adjacent nanoparticles which varies exponentially as the assembly is stretched. Electro-mechanical measurements coupled with scanning electron microscopy and atomic force microscopy observations were used to identify, quantify and understand the impact of the nanoparticle size and the nature of the protecting ligands, on the gauge sensitivity and the drift of the resistance at rest of the nanoparticle based strain gauges. Coupled with small angle x-ray scattering measurements, these studies allowed us to correlate the macroscopic changes in electrical resistance of the strain gauges to the relative displacement of the nanoparticles at the nanoscale. Finally, a matrix of these miniature ultra-sensitive gauges was used to construct flexible touch screen panels capable of measuring the intensity of several touches simultaneously
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Terçariol, Walter Luis 1975. "Contribuição ao projeto de circuitos integrados de reguladores de tensão com charge pump em tecnologia CMOS : aceleração do tempo de partida, redução do ripple, redução do efeito kick-back e técnica indireta de medida da tensão de saída." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260876.
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Orientador: José Antonio Siqueira DiasTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação
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Resumo: Este trabalho visa compilar três contribuições na melhoria dos projetos de reguladores de tensão com unidades de bombeamento de carga embutidos (células elevadoras de tensão Dickson - BC). A primeira aborda uma técnica inovadora de arranque na partida deste módulo elevador quando habilitado. Este projeto se refere à aceleração da inicialização do modulo BC, tendo como objetivo a diminuição do intervalo de tempo da rampa ascendente da tensão de saída Vo até atingir o nível alvo de regulação. A técnica consiste em gerenciar o aumento da freqüência do relógio de bombeamento entregue as unidades de bombeamento durante a fase de subida, quando a regulação estiver estabelecida o sistema se regenera voltando ao estado original de freqüência de bombeamento natural. Uma segunda proposta inovadora de projeto é referente à homogeneização e redução da aleatoriedade da ondulação da tensão de saída Vo, referente ao regulador com o modulo BC embutido, baseado em comparadores com trava, com proposta de redução do erro de comparação devido ao efeito aleatório durante o estagio de comparação comumente encontrado neste tipo de abordagem, a técnica consiste em suprimir o acoplamento capacitivo nocivo durante a fase de isolamento elétrico no processo de comparação mantendo o espelho de corrente do comparador na região de saturação. Esta técnica visa proporcionar uma redução significativa da capacitância de desacoplamento utilizada para filtragem da tensão Vo. Uma terceira e última contribuição é referente a uma inovadora técnica de medição indireta da tensão de saída Vo do regulador com módulo BC baseada em uma medida simples e precisa dos pares tensão da porta e fonte (VPS) e corrente elétrica do dreno (Idreno) de um dispositivo NMOS de alta tensão adicionado de modo que duas tensões conhecidas (preestabelecidas) são aplicadas na porta do dispositivo e as respectivas correntes de dreno são mensuradas e uma terceira desconhecida (oriunda do regulador elevador BC) desconhecida pode ser extrapolada de forma simples. Esta técnica visa ser útil para medição de reguladores de baixa potencia pois o carregamento do regulador (Vo) é quase nulo.Todas as inovações e melhorias propostas foram analisadas em veículos de teste (silício) e com as provas de conceito, feitas em simulações elétricas
Abstract: This work aims to compile contributions in improving designs based on voltage regulators with voltage elevator with built-in charge pump CP. The first deals with an innovative technique rump-up this module when enabled. This project refers to the acceleration of startup the CP module, aiming at the reduction of the period of stabilization of the ramp output voltage Vo to the level of regulation target. The technique is to manage increasing the frequency of pumping clock during the phase of rump up and when the setting established the system regenerates back to the original state pumping frequency. A second innovative project proposal was made on the homogenization and reduction of the ripple of the output voltage Vo, referring to the regulator with the |CP module, based on latch comparators , alignment error reduction proposal because of the random effect during the stage comparison commonly found in this type of approach, the technique is to remove the harmful capacitive coupling during electrical isolation phase on the comparison keeping the comparator current mirror in saturation region. This technique aims to provide a significant reduction in the decoupling capacitance used for filtering the voltage Vo. A third and final contribution is related to an innovative technique of indirect measurement of the output voltage Vo of the regulator module CP, based on a simple and accurate measure of the gate voltage and couples the drain electric current of a high voltage NMOS device
Doutorado
Eletrônica, Microeletrônica e Optoeletrônica
Doutor em Engenharia Elétrica
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Akah, Ebiji Anthony. "Experimental and Analytical Collapse Evaluation of an Existing Building." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437620552.
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Bednarz, Tomáš. "Zjišťování složek zátěžné síly u tvarově složitých součástí vozů Škoda." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228303.
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Diploma project is aimed to load force vector decomposition to x, y and z direction for complicated Skoda car parts. The methodology of decomposition is based on measuring of car parts deformation by strain gauges and mathematical identifation of force compoments by neural network (ANN). ANN will be trained by results of FE model simulations or by calibration on real car parts.
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Huang, Jun Fei. "Stress-strain models for light-gauge carbon steels." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2586269.
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Tuncay, Orbay. "Wireless Strain Gauge System in a Multipath Environment." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1222089977.
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Welham, Christopher J. "A silicon micromachined lateral resonant strain gauge pressure sensor." Thesis, University of Warwick, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389458.
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Suslov, E., O. Nozhenko, and A. Mostovych. "Strain gauge measurement data analyzing for flat wheel detection." Thesis, Національний авіаційний університет, 2017. http://er.nau.edu.ua/handle/NAU/32947.
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Khanniche, Rachid. "Characterisation of an optical strain gauge for pantograph applications." Thesis, Swansea University, 2002. https://cronfa.swan.ac.uk/Record/cronfa42266.
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An optical strain gauge is developed and characterised for an active pantograph for high-speed electrical trains applications. The pantograph is subjected to a continuous impact forces when it makes contact with the 25 kV overhead AC line. The carbon based pantograph head is susceptible to crack damage due to these impacts An optical strain gauge based on the photo-elastic effect has been developed to monitor on line the contact force applied to the pantograph. The sensing system exploits the concept of chromatic modulation that can be produced by spectral changes induced by a controlled birefringence. Moreover the chromatic sensing technique is independent of the light intensity and provides total electrical isolation. The developed optical strain gauge was assessed to evaluate its performance and to find the range of operation. Static, hysterisis, repeatability and dynamic tests were carried out and the results compared to the theory when applicable. In the static test, it was found that the force against dominant wavelength was linear in the range of 0 to 80 N and became progressively non-linear for forces above 80 N, this is in a good agreement with the theory. These tests were carried out several times over a long period of time, and the results showed a good repeatability, although an acceptable degree of hysterisis was noted. Finally the resistance of the optical strain gauge was tested against dynamically varying loads and found that it exhibited a good resistance. These tests proved the suitability of this proposed optical strain gauge for the development of an active pantograph for high-speed electrical trains applications.
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Creasey, Christopher David. "The development of a hand-held optical diffraction strain gauge." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/27041.
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The measurement of strain is critical in many engineering design, test, and health monitoring procedures. Despite the promise of non-contacting and remote strain measurement, optical techniques have not been widely adopted by industry; the preference being the use of electrical resistance strain gauges. This is due to the perceived and real complexities of many optical techniques.