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81	Příprava experimentálního měření aerodynamických charakteristik na zmenšeném modelu automobilu v aerodynamickém tunelu / Wind tunnel experiment of scaled car model preparation Zedník, Roman January 2020 (has links) This master thesis focuses on designing of an external six-component balance. This universal concept would provide access of results from different models of wings, aircraft and automobiles with relatively small scales. This work also includes theoretical background needed in aerodynamic testing, analysis of 1D beam element model of scale and explanation of components used in scale. Lastly methods of calibration and measurement in aerodynamic tunnel are described, which can be adopted for this design to achieve the adequate level of accuracy.
82	Zesilovač pro tenzometry / Strain Gage amplifier Kneblík, Adam January 2008 (has links) The thesis deals about method of gain signals from strain gauge bridges. There are mentioned some signal conditioning methods for bridges amplifiers and charactered their properties. In the next part of this thesis are calculated the amplifier errors for various temperature. There are projected individual variants of strain gage amplifiers (instrumentation amplifier AD524, isolation amplifier, switched capacitor based instrumentation amplifier), their properties are compared with strain gage amplifier Vishay P-3500.
83	Vliv přísad redukujících smrštění na reologické vlastnosti vysokopevnostního betonu / The effect of the shrinkage reducing additives on rheological properties of high-strength concrete Červenka, Jiří January 2013 (has links) Master’s thesis examines the effect of the shrinkage reducing additives on rheological properties of high-strength concrete. The first part is focused on high-strength concrete in terms of their composition and properties. The second part contains a detailed analysis of the cementitious composites shrinkage problems. Total shrinkage is divided into individual elementary shrinkages. For each of them there is a detailed description of causes and factors that affect their sizes. The next part describes the basic additives used to reduce the shrinkage of cementitious composites. The experimental part is focused on verifying the effectiveness of the shrinkage reducing additives during preparation of high-strength concrete. Usage of shrinkage drains for relative strain measurement enables to determine the process of shrinkage immediately after placing the concrete in the form and to obtain the overall curve of the hight-strength concrete volume changes during its setting and hardening. At the end of the thesis, there are overall analysis and summary of the results of the performed experiments.
84	Stanovení zbytkové napjatosti metodou vrtání otvoru s využitím MKP / Assesment of residual stress with drilling hole method using FEM Civín, Adam January 2008 (has links) Residual state of stress in structural materials affect positively or negatively behaviour of component parts. The goal of this scope is not to deal with possible process of creating residual stresses neither about elimination of residual stress, but is focused how to determine magnitude of residual stress by hole-drilling method. We need to know magnitude and direction (angular orientation) of principal stresses to determine how residual state of stress affects behaviour of specimen. The most widely used modern technique for measuring residual stresses is hole-drilling strain-gage method. Hole-drilling method is in scope of this paper and is restricted only for measuring uniform residual stresses of steel specimens with finite dimensions. Structural, linear, elastic and isotropic material model is used with material properties =0,3 and E=2,1[10]^5 MPa. For correct application of this method we need to determine calibration coefficients “a“ and “b“ first. These coefficients are used to determine magnitude and direction of residual stresses in specific depth and diameter of drilled hole for materials with finite dimensions. Geometry and shape of model is simply represented by block with planar faces. Note that numerical determination of calibration coefficients is useful only for one type of strain gauge rosette RY 61 S. Main goals of this thesis are motivation and request to clearly report effectiveness, accuracy and applicability of calibration coefficients in relation to thickness of specimen, dimensions of drilled hole, condition of “through” or “blind” hole and number of drilled increments. High quality and accuracy of created numerical model is necessary too. Numerical simulation of residual stresses by MKP needs to be done to obtain requested results. All results are presented by 3D, 2D graphs and tables and compared with analytical results or results from other authors. Although is this publication focused on numerical modeling using FEM, hole-drilling method has many significant restrictions. The most substantial of them is influence of eccentricity of drilled hole, creation of stress concentration near drilled area and subsequent plastification, influence of geometrical inaccuracy of hole, etc. All these aspects have significant influence of determining calibration coefficients and can not be included into numerical simulation. These problems are closely discussed in background research. All obtained results should be helpful for practical use of calculated calibration coefficients to determine uniform residual stresses of specimens with various thickness and drilled hole. All these results are also applicable only for one type of strain gauge rosette, which is RY 61 S.
85	Berechnung der Schwingbeanspruchung in Radialturbinen unter Berücksichtigung realer Bauteilgeometrien Drozdowski, Roman 25 November 2011 (has links) Der stetig anwachsende Bedarf und die innovative Weiterentwicklung im Bereich der Großdieselmotoren als Antrieb für Schiffe und Generatoranlagen erfordert ebenfalls die Weiterentwicklung der Abgasturbolader. Hohe Leistungsfähigkeit und Wirtschaftlichkeit ist nur durch moderne Fertigungsverfahren und einer optimalen Ausnutzung der eingesetzten, hochwertigen Werkstoffe zu erreichen. Dies gilt insbesondere für die integralen Radialturbinenräder in Abgasturboladern, die aufgrund der hohen Betriebsbelastungen einen zentralen Punkt bei der Auslegung darstellen. Lebensdauerbegrenzend ist die hochzyklische Ermüdung aufgrund Resonanzschwingungen an der Beschaufelung der Turbinenräder. Die vorliegende Arbeit soll die Auslegungsmethodik zur Berechnung und Beurteilung der zu erwartenden Schwingbeanspruchungen der Turbinenräder im Hinblick der realen Geometrie verbessern. Dazu wird ein einfaches Berechnungsmodell zur Identifizierung der kritischen Schaufelmoden und Bestimmung der Schwingbeanspruchungen im integralen Turbinenrad erarbeitet. Das Modell wird auf vorhandene Turbinenräder angewendet und aus den Ergebnissen werden Hinweise für eine systematische Beurteilung der Schaufelmoden, Knotendurchmesser und Schaufelgestaltung bezüglich der kritischen Schwingbeanspruchungen angegeben. Desweiteren wird der Einfluss der Verstimmung (engl. Mistuning) des Schwingverhaltens realer, integraler Turbinenräder ausführlich im Hinblick auf die Schwingbeanspruchungen untersucht. Die wesentlichen Ursachen für die Verstimmung sind die innerhalb der Fertigungstoleranzen auftretenden Geometrieabweichungen der Schaufeln. Dabei wird ein Überblick über die typischen Geometrie- und Frequenzabweichungen Radialturbinen gegeben und Auswirkungen auf das Schwingverhalten des Rades wie Lokalisierung der Schwingformen und Amplitudenüberhöhungen ermittelt und in einen systematischen Zusammenhang mit den geometrischen Ursachen, der Komplexität der Schaufelschwingformen und Knotendurchmesser gestellt. Es zeigt sich, dass unter gewissen Voraussetzungen bei Radialturbinen KD0 und KD1 Schwingformen weniger sensibel auf die Verstimmung reagieren. Hieraus können Hinweise für die Verbesserung des Auslegungsprozess abgeleitet werden. Die Kenntnis über das reale Schwingverhalten verstimmter Turbinenräder ermöglicht die korrekte Auswahl geeigneter Schaufeln zur Applikation von Dehnmessstreifen, wodurch eine sichere Beurteilung der Betriebsbeanspruchungen erst möglich wird. info:eu-repo/classification/ddc/620 ddc:620
86	Transformation of In-Flight Measured Loads to a Fatigue Test Spectrum / Omvandling av uppmätta flygprovlaster till lastspektra för utmattningsprov Dümig, Patrick January 2022 (has links) Fatigue is a well-recognized issue in lightweight and high-performance aircraft structures. As fatigue failures have led to serious accidents and caused significant economic impact in the past, design against fatigue is crucial. Fatigue testing of full-scale aircraft as well as components is an important tool for the advance identification of potential fatigue issues in both new and operational aircraft. Furthermore, coupon testing is used extensively to obtain allowables for materials and structural details to be used in the design process. To obtain accurate results from fatigue testing, not only the test object but also the used load spectrum must accurately represent reality. If the aircraft is operational, an accurate load spectrum can be obtained by measuring the loads in-flight during a sufficiently long period of normal operation of the aircraft. However, the in-flight measured loads data contains an extraordinarily large number of cycles, resulting in long and uneconomical test durations. This thesis aims to propose a method for the selection of an optimal filtering level for fatigue test spectra developed from in-flight measured loads. The thesis also discusses and recommends methods for in-flight measurement of loads, cycle counting as well as damage evaluation using a crack-growth approach. Furthermore, ways to validate the proposed method and its practical application are discussed. An example filtering study is conducted using four different specimens chosen to represent typical structural details of aircraft. The study uses real in-flight measured loads of a light aircraft and also discusses temperature compensation of the loads data. The effect of filtering on fatigue damage is evaluated using crack-growth simulations conducted at a range of filtering and stress levels. The results show that a remarkable reduction of testing time is possible and as many as 99 % of all cycles in the studied flight load history can be discarded without significantly reducing fatigue damage. The allowable filtering level is shown to differ between the specimens and the different stages of fatigue crack growth. In addition, the applied stress level is found to have a consistent effect on the allowable filtering level. Aerospace engineering Aircraft load spectra ASIP Crack growth Fatigue testing Flight loads Flight test Fracture mechanics FSFT In-flight measurements Load spectrum reduction Racetrack filtering Strain gauge measurements Aerospace Engineering Rymd- och flygteknik
87	Komplexní teoretická analýza metody sloupku pro zjišťování zbytkových napětí / Comprehesive Theoeretical Analysis of Ring-Core Method for Residual Stress Determination Civín, Adam January 2012 (has links) Comprehensive analysis of the ringcore method used for the determination of the residual stresses in mechanical components is presented in this thesis. Principles, advantages, disadvantages and applicability of this semidestructive experimental method are discussed too. At the same time the ringcore method is compared with the hole drilling method, which is used more frequently. All aspects of the ringcore method are analyzed by the finite element method. FE simulations, performed on the universal numerical model, verified principles of the integral method and the incremental strain method. FE simulations also provided basic information for the uncertainty analysis, which significantly affects the accuracy of the residual stress measurement. The main goal, which the present work deals with, is to create a global overview of all ringcore methods´ aspects elaborated in a clear and complex form.
88	Design and Development of a Data Acquisition and Communication System for Point Absorber Tracking Kannan, Balakrishnan January 2021 (has links) The recent trend in generating energy from the waves has led to several advancements in the methods and the various research is conducted across the world, to study the behaviour of point absorbers on the waves. The point absorbers such as wave buoys are designed to move according to the waves and the generator that is mechanically coupled with the buoys, generate electricity. But these buoys can also be used for measuring important parameters like the force acting on it due to the incident waves and their movement can be tracked to study the effects on the buoy due to the incident waves. This project, as an extension of a previous work titled ‘Design and Development of a Measurement System to Track the Motion of a Point Absorber’ by Juliana Lüer, focuses on modifying and replacing the controller data acquisition and the communication system. The main aim is to increase the stability of the system and increasing the size of data storage and range of the data transmission. This is done in 3 steps that are as follows: - The Arduino based controller is replaced with an advanced Raspberry Pi based computer called RevPi Compact. - The Secure Digital (SD) card storage is replaced with a solid-state (Universal Serial Bus) USB memory stick with a large capacity. - The Radio Frequency (RF) based data transmission is replaced with a 4G (fourth generation) internet modem. The 60 W solar panels are retained from the previous project. But the Lead-Acid battery is replaced with two Lithium Polymer (Li-Po) batteries of 768 Wh capacity each. This increases the stability of the power source and enables the buoy to stay active for a longer time even when there is no useful solar irradiance for many days. There are two force transducers (strain gauge) to measure the line force and the angular force acting on the buoy. The Ellipse2-D Inertial Measurement Unit (IMU) from SBG systems is retained from the previous experiment. This sensor can track the Altitude and Heading Reference (AHRS) data along with the Global Positioning System (GPS) data with high levels of accuracy. All the data collected are can be tracked instantaneously due to the 4G internet communication protocol and this is enabled by TelenorTM connection and HuaweiTM 4G modem. A copy of these data is also stored in a SanDisk USB memory of 500 GB capacity. The tests are carried out under the laboratory conditions and the outputs are as expected. The whole setup is to be installed in a metallic buoy and to be tested in the Lysekil test site in the future. Data Acquisition System Raspberry Pi Controller Processor Wave buoy Lysekil wave energy measurements IMU GPS Strain gauge force Solar energy Battery communication 4G internet Remote tracking Shell Python Energy Engineering Energiteknik Marine Engineering Marin teknik Annan elektroteknik och elektronik Elektroteknik och elektronik
89	Komplexní teoretická analýza metody sloupku pro zjišťování zbytkových napětí / Comprehesive Theoeretical Analysis of Ring-Core Method for Residual Stress Determination Civín, Adam January 2012 (has links) Comprehensive analysis of the ringcore method used for the determination of the residual stresses in mechanical components is presented in this thesis. Principles, advantages, disadvantages and applicability of this semidestructive experimental method are discussed too. At the same time the ringcore method is compared with the hole drilling method, which is used more frequently. All aspects of the ringcore method are analyzed by the finite element method. FE simulations, performed on the universal numerical model, verified principles of the integral method and the incremental strain method. FE simulations also provided basic information for the uncertainty analysis, which significantly affects the accuracy of the residual stress measurement. The main goal, which the present work deals with, is to create a global overview of all ringcore methods´ aspects elaborated in a clear and complex form.
90	Seismic Retrofit of Load Bearing URM Walls with Internally Placed Reinforcement and Surface-Bonded FRP Sheets Sabri, Amirreza 22 June 2020 (has links) Concrete block masonry is a common building material used worldwide, including Canada. Reinforced masonry buildings, designed according to the requirements of recent building codes, may result in seismically safe structures. However, unreinforced masonry (URM) buildings designed and constructed prior to the development of modern seismic design codes are extremely vulnerable to seismic induced damage. Replacement of older seismically deficient buildings with new and seismically designed structures is economically not feasible in most cases. Therefore, seismic retrofitting of deficient buildings remains to be a viable seismic risk mitigation strategy. Masonry load bearing walls are the most important elements of such buildings, potentially serving as lateral force resisting systems. A seismic retrofit research program is currently underway at the University of Ottawa, consisting of experimental and analytical components for developing new seismic retrofit systems for unreinforced masonry walls. The research project presented in this thesis forms part of the same overall research program. The experimental component includes design, construction, retrofit and testing of large-scale load bearing masonry walls. Two approaches were developed as retrofit methodologies, both involving reinforcing the walls for strength and deformability. The first approach involves the use of ordinary deformed steel reinforcement as internally added reinforcement to attain reinforced masonry behaviour. The second approach involves the use of internally placed post-tensioning tendons to attain prestressed masonry behaviour. The analytical component of research consists of constructing a Finite Element computer model for nonlinear analysis of walls and conducting a parametric study to assess the significance of retrofit design parameters. The results have led to the development of a conceptual retrofit design framework for the new techniques developed, while utilizing the seismic provisions of the National Building Code of Canada and the relevant CSA material standards. Masonry Seismic Retrofit Urm Wall Earthquake Frp Reinforcement Internally Placed Load Bearing Experimental Analytical Sap2000 Finite element Fem Prestressing Amir Amir sabri Saatcioglu Sika Seismic retrofit Post-tensioning Nonlinear Design Retrofit design Masonry design Frp design Polyurea Epoxy Injection Surface Treatment Seismic retrofitting Wall Test Mortar Shear Instrumentation Drift Strain Gauge Shell Shell Elements Stress Contour Concrete Steel Block Concrete block Sap Flextur Surface Bond Post tensioning Sheet Unreinforced masonry

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