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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Force Measurements of Single Cylinder with Momentum Injection in Cross Flow.

Shao, Chia-chi 30 August 2004 (has links)
This research shows an experimental set-up of measuring forces acting on single cylinder in cross flow provided by a water tunnel. Water was also released at various directions from the cylinder surface to study the effect of momentum injection on cylinder forces. The fluid forces on the cylinder was measured by a strain gauge bonded on long-thin plat which is connected to the cylinder. The drag and lift coefficients of the cylinder were measured with momentum injection of various direction and magnitude. Experimental results show that the drag coefficient is effectively reduced with momentum injection at streamwise direction. Negative drag coefficient (propulsion) can be obtained if the magnitude of momentum inject is large enough. When the momentum injection has cross-stream component, lift force is obtained with its value depending on the magnitude of momentum injection. For higher Reynolds number, the magnitude of momentum injection has to be increased to maintain the effectiveness of momentum injection.
2

APPLICATION OF STRUCTURAL MONITORING IN MANAGEMENT DECISIONS FOR LARGE INFRASTRUCTURE

Levy, Joshua 18 November 2011 (has links)
The traditional bridge evaluation process contains uncertainty that affects management decisions. Numerical models require assumptions regarding structural response, and code load models are inherently conservative to ensure uniform applicability. This research investigated how structural monitoring could reduce uncertainty in the evaluation and management process. Targeted instrumentation was implemented on the MacKay Bridge. Controlled load testing was conducted to refine an existing numerical model. Long-term monitoring was completed to compare extreme in-situ traffic effects with the Canadian Highway Bridge Design Code. Throughout the project, accuracy of information collected was a priority; deviation from code recommendations requires absolute confidence in the data. Outputs from controlled testing indicated that the existing numerical model for load distribution and structural response required minimal tuning. Long-term testing indicated that actual load effects are less than code requirements. Results from this thesis show that structural monitoring can reduce uncertainty in structural evaluation and management decisions for infrastructure.
3

Semi-Trailer Structural Failure Analysis Using Finite Element Method

Baadkar, Chetan Chandrakant January 2010 (has links)
This project is centred on an ongoing trailer component failure problem at the STEELBRO New Zealand Ltd due to cracks. In this research the problem has been systematically approached using ANSYS finite element analysis software. The approach involves investigation of the problem and structural analysis of the trailer subjected to two types of service conditions. The service conditions are simulated in ANSYS which involved CAD and finite element modelling of the trailer, and then the finite element model is validated experimentally by strain gauges and geometrically by ANSYS element shape checking capability. The finite element model subjected to static structural analysis confirmed the crack locations and indicated the cause of the failure. Further fatigue analysis on one of the loading condition revealed it’s potential to cause failure at the crack locations. Finally, this research concludes with a proposal of revised component design to overcome the failure at the crack locations and recommendations for further analysis on the trailer.
4

Temperament in beef cattle : methods of measurement, consistency and relationship to production

Sebastian, Thomas 14 December 2007
Two behavioural studies were conducted at the University of Saskatchewan beef feedlot. In the first study, the temperament of 400 steers was determined using both objective and subjective measures. The consistency of temperament, over repeated tests and between different measures, was also tested. The objective behavioural tests were conducted during the individual restraint of the steers using strain gauges and an MMD (movement-measuring-device). The time required for the steers to exit the area was also recorded. Subjective assessment of animals responsiveness during restraint was recorded on a scale of 1-5 (calm to wild). The consistency of individual differences in a steers response within the evaluation series and across repetitions, shows that this trait may represent a stable personality of the animal. The significant relationship between objective and subjective measures demonstrates that objective measures of temperament can be used to replace the traditional subjective scale as it has the added advantage of reducing inter- and intra-observer variability. The positive relationship of subjective scores and MMD values with the steers performance (average daily weight gain) shows not only that a calm temperament is conducive to productivity, but also that objective measures can replace subjective techniques for assessing temperament for performance evaluation. In the second study the reactivity of a subset of the original 400 steers (262 animals from 8 pens) to a novel stimulus was assessed. The purpose of this experiment was to determine if a steers behavioural response in the novel test was correlated to its temperament assessment determined in the first study. A remote controlled ball was dropped from the ceiling of a salt feeder while a steer licked the salt. Two overhead cameras connected to a monitor through a VCR and time lapse recorder permitted us to observe and document the response. A lack of correlation between measures of handling and novelty measures show that reactivity of animals in the handling chute and their responsiveness to the novel stimulus do not represent one and the same trait.
5

Lastcells applikation : Verktyg för montering av trådtöjningsgivare i lastcell

Stumle, Joakim January 2007 (has links)
Ett verktyg för applicering av trådtöjningsgivare har tagits fram på uppdrag av AED AB i Växjö. Verktyget skall användas för färdigställning/slutmontering av lastceller som i sin tur skall användas till att mäta vilka krafter som påverkar en skogsmaskin när denna lastas med sin givna maxlast. Verktyget skall föras in i ett 25 mm brett hål där det skall hålla fast och lägga tryck på fyra trådtöjningsgivare, en i vardera riktning, vilka bestrykts med lim. Verktyget skall hålla ett tryck på tre till fyra kiloPond medan lastcellen värms till 150° C då limmet härdar. Verktyget består av fyra ben, ett i vardera riktning. De är ledande i en änden. Andra änden på benen är avfasad och bildar en öppning. När en kula trycker mot benens avfasade ytor expanderar dem utåt och trycker därmed den limbestrukna trådtöjningsgivaren mot hålets vägg. / A tool for the application of strain gauges have been constructed by the commission of AED AB in Växjö. The tool shall be used for the assembling of loadcells which then will be used for measuring forces that affects a loggingmachinery when loaded with its maximum load. The tool shall be inserted in a 25 mm wide hole where it is supposed to hold and apply load to four strain gauges, one in each direction, which has been smeared with glue. The tool shall maintain a pressure of three to four kiloPond while the loadcell is heated to 150 C until the glue has hardened. It consists of four legs with a joint in one end and a slant surface by the other. When a ball is pushed against the slant surfaces, the legs will expand and push the glue smeared strain gauges against the wall of the hole.
6

Temperament in beef cattle : methods of measurement, consistency and relationship to production

Sebastian, Thomas 14 December 2007 (has links)
Two behavioural studies were conducted at the University of Saskatchewan beef feedlot. In the first study, the temperament of 400 steers was determined using both objective and subjective measures. The consistency of temperament, over repeated tests and between different measures, was also tested. The objective behavioural tests were conducted during the individual restraint of the steers using strain gauges and an MMD (movement-measuring-device). The time required for the steers to exit the area was also recorded. Subjective assessment of animals responsiveness during restraint was recorded on a scale of 1-5 (calm to wild). The consistency of individual differences in a steers response within the evaluation series and across repetitions, shows that this trait may represent a stable personality of the animal. The significant relationship between objective and subjective measures demonstrates that objective measures of temperament can be used to replace the traditional subjective scale as it has the added advantage of reducing inter- and intra-observer variability. The positive relationship of subjective scores and MMD values with the steers performance (average daily weight gain) shows not only that a calm temperament is conducive to productivity, but also that objective measures can replace subjective techniques for assessing temperament for performance evaluation. In the second study the reactivity of a subset of the original 400 steers (262 animals from 8 pens) to a novel stimulus was assessed. The purpose of this experiment was to determine if a steers behavioural response in the novel test was correlated to its temperament assessment determined in the first study. A remote controlled ball was dropped from the ceiling of a salt feeder while a steer licked the salt. Two overhead cameras connected to a monitor through a VCR and time lapse recorder permitted us to observe and document the response. A lack of correlation between measures of handling and novelty measures show that reactivity of animals in the handling chute and their responsiveness to the novel stimulus do not represent one and the same trait.
7

Euler-Bernoulli Implementation of Spherical Anemometers for High Wind Speed Calculations via Strain Gauges

Castillo, Davis 2011 May 1900 (has links)
New measuring methods continue to be developed in the field of wind anemometry for various environments subject to low-speed and high-speed flows, turbulent-present flows, and ideal and non-ideal flows. As a result, anemometry has taken different avenues for these environments from the traditional cup model to sonar, hot-wire, and recent developments with sphere anemometers. Several measurement methods have modeled the air drag force as a quadratic function of the corresponding wind speed. Furthermore, by incorporating non-drag fluid forces in addition to the main drag force, a dynamic set of equations of motion for the deflection and strain of a spherical anemometer's beam can be derived. By utilizing the equations of motion to develop a direct relationship to a measurable parameter, such as strain, an approximation for wind speed based on a measurement is available. These ODE's for the strain model can then be used to relate directly the fluid speed (wind) to the strain along the beam’s length. The spherical anemometer introduced by the German researcher Holling presents the opportunity to incorporate the theoretical cantilevered Euler-Bernoulli beam with a spherical mass tip to develop a deflection and wind relationship driven by cross-area of the spherical mass and constriction of the shaft or the beam's bending properties. The application of Hamilton's principle and separation of variables to the Lagrangian Mechanics of an Euler-Bernoulli beam results in the equations of motion for the deflection of the beam as a second order partial differential equation (PDE). The boundary conditions of our beam's motion are influenced by the applied fluid forces of a relative drag force and the added mass and buoyancy of the sphere. Strain gauges will provide measurements in a practical but non-intrusive method and thus the concept of a measuring strain gauge is simulated. Young's Modulus creates a relationship between deflection and strain of an Euler-Bernoulli system and thus a strain and wind relation can be modeled as an ODE. This theoretical sphere anemometer's second order ODE allows for analysis of the linear and non-linear accuracies of the motion of this dynamic system at conventional high speed conditions.
8

Lastcells applikation : Verktyg för montering av trådtöjningsgivare i lastcell

Stumle, Joakim January 2007 (has links)
<p>Ett verktyg för applicering av trådtöjningsgivare har tagits fram på uppdrag av AED AB i Växjö. Verktyget skall användas för färdigställning/slutmontering av lastceller som i sin tur skall användas till att mäta vilka krafter som påverkar en skogsmaskin när denna lastas med sin givna maxlast. Verktyget skall föras in i ett 25 mm brett hål där det skall hålla fast och lägga tryck på fyra trådtöjningsgivare, en i vardera riktning, vilka bestrykts med lim. Verktyget skall hålla ett tryck på tre till fyra kiloPond medan lastcellen värms till 150° C då limmet härdar. Verktyget består av fyra ben, ett i vardera riktning. De är ledande i en änden. Andra änden på benen är avfasad och bildar en öppning. När en kula trycker mot benens avfasade ytor expanderar dem utåt och trycker därmed den limbestrukna trådtöjningsgivaren mot hålets vägg.</p> / <p>A tool for the application of strain gauges have been constructed by the commission of AED AB in Växjö. The tool shall be used for the assembling of loadcells which then will be used for measuring forces that affects a loggingmachinery when loaded with its maximum load. The tool shall be inserted in a 25 mm wide hole where it is supposed to hold and apply load to four strain gauges, one in each direction, which has been smeared with glue. The tool shall maintain a pressure of three to four kiloPond while the loadcell is heated to 150 C until the glue has hardened. It consists of four legs with a joint in one end and a slant surface by the other. When a ball is pushed against the slant surfaces, the legs will expand and push the glue smeared strain gauges against the wall of the hole.</p>
9

Extensometria : avaliação de implantes de sextavado externo posicionados na configuração linear e compensada (offset), sob carregamento axial /

Kojima, Alberto Noriyuki. January 2008 (has links)
Orientador: Renato Sussumu Nishioka / Banca: Wirley Gonçalves Assunção / Banca: Alysson Noriyuki Kajishima Konno / Banca: Eduardo Shigueyuki Uemura / Banca: Osvaldo Daniel Andreatta Filho / Resumo: O objetivo deste estudo foi avaliar, por meio da extensometria, a distribuição de tensões ao redor de implantes em função dos diferentes locais para carregamento, tipo de coifa (plástica ou usinada) e configuração (linear e compensada). Para tanto, em um bloco de poliuretano, foram posicionados paralelos entre si e com uma configuração linear, implantes auto-rosqueáveis de hexágono externo, com dimensões de 3,75 X 13mm, a uma distancia de 7mm, de centro a centro. Em um outro bloco a fixação do meio foi deslocada em 2mm para gerar uma configuração compensada (offset). Pilares protéticos Micro-unit, com 3mm de cinta foram instalados sobre as fixações. Com duas matrizes em aço inoxidável foram confeccionados 10 enceramentos para cada bloco, distribuídos da seguinte forma: 5 para coifa plástica e 5 para coifas usinadas (n=5). A seguir esses padrões foram fundidos com uma liga de Co-Cr. Quatro extensômetros (strain gauges) foram colados na superfície superior de cada bloco tangenciando a plataforma de cada fixação. Um carregamento de 30kg durante 10s foi feito em cinco posições (A, B, C, D, E), sendo repetido três vezes para aquisição dos dados (em με) pela aparelho condicionador de sinais. Os dados obtidos foram submetidos a análise de variância (ANOVA) e teste de Tukey (p<0,05). Como conclusão da análise dos resultados obtidos pudemos observar que não houve diferença na utilização de coifas plásticas e usinadas, que não houve diferença entre as configurações linear e compensada; havendo diferença estatisticamente significante para os locais de carregamento / Abstract: The aim of this study was to evaluate, using strain gauge, the load distribution surround the implants according differents loading sites, coping types (plastic and machined) and configuration (linear and offset). In one polyurethane block, three cylindrical implants with external hexagon (3.75mm x 13mm) were fixed parallel with 7mm between their centers in a linear configuration. In another block the midle implant was positioned in a 2mm offset. Micro-units abutments with 3mm of metallic neck were fixed. With two metallics matrix, it was manufactured 10 wax patterns for each block, distributed in the following form: 5 for plastic copings and 5 for machined copings (n=5). After, patterns were casted in cobalt-chromium alloy. Four strain gauges were positioned on the upper surface of each polyurethane model around the implants. An axial load of 30kg within 10 seconds in five positions (A, B, C, D, E), with three repetead measurements for data aquisition (in με) by the multichanel bridge machine. The datas were submitted to ANOVA and Tukey test (p<0.05). Such as conclusion from the obtained data treatment: there was no difference between the plastic and machined copings, there was no difference between the linear and offset configuration; there was statiscal significance only with the differents loading sites. / Doutor
10

Biomechanical Applications and Modeling of Quantum Nano-Composite Strain Gauges

Remington, Taylor David 01 April 2014 (has links) (PDF)
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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