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Computational and experimental assessment of natural frequencies in a bladed disk system
Mekhalfia, Mohammed Lamine ; Procházka, Pavel ; Maturkanič, Dušan ; Voronova, Evgeniya ; Hodboď, Robert
This paper examines the modal characteristics of a bladed disk in rotating machinery systems using a combination of analytical and experimental modal analysis methods. The analysis involves measuring natural frequencies and mode shapes under different operational conditions. A comparative analysis is conducted to assess modal properties obtained from both analytical and experimental approaches, while also considering the influence of rotation speed. Additionally, Finite Element Method (FEM) outputs are used to accurately position the strain gauge. Integrating these techniques provides a comprehensive understanding of the bladed disk's behaviour under varying rotational speeds, enhancing result accuracy and facilitating thorough investigation within rotating machinery systems.
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Monitoring stress in the mast
Bednář, Tomáš ; Beneš, Petr (referee) ; Bejček, Ludvík (advisor)
The subject of this bachelor´s thesis is an issue of measurement and monitoring stressing in the mast – high voltage and very high voltage.The solution of query, including the producer and the users, is also presented. The aim of this thesis is to propose sensors for this measurement and making practical measurement of the concrete very high voltage mast.
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Weight sensing of beehives with long-term stability
Vozdecký, Martin ; Marcoň, Petr (referee) ; Mikulka, Jan (advisor)
The aim of the thesis is to describe the design of stable measurement of weight in beehives. Work evaluates suitable types of weight sensors and their effect on stability. The main part of the thesis is a custom design of electronic sensing the weight of the beehive and telemetry data to the user. The concept of engagement enables stable measurement of mass loading of independence on the ambient temperature.
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The effect of the shrinkage reducing additives on rheological properties of high-strength concrete
Červenka, Jiří ; Kucharczyková, Barbara (referee) ; Daněk, Petr (advisor)
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.
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Wind tunnel experiment of scaled car model preparation
Zedník, Roman ; Doupník, Petr (referee) ; Matějů, Jiří (advisor)
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.
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Verification of operation of piezoelectric composite strain sensor
Kubiš, Juraj ; Ševeček, Oldřich (referee) ; Hadaš, Zdeněk (advisor)
The bachelor thesis deals with the use of piezoelectric elements as sensing elements in engineering practice. The work can be divided into three main parts. The first part describes the actual use of these elements in practice, either as sensing elements or as a source for energy harvesting. This section contains the selection of components for a given experiment, the creation of a model using FEM and the measurement process of the experiment. The third part is the evaluation of the obtained results and subsequent comparison with the obtained values from strain gauges and other sensors.
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Strength meter
Švancara, Michal ; Kopečný, Lukáš (referee) ; Florián, Tomáš (advisor)
The aim of this project is to improve last version of strength meter, which was designed for presentation purposes. This project describes theory and principles of used elements and contains analysis of function problems and practically solves them. The practical part also describes, how to extend strength meter with external display unit and how to control it. The final part of this project contains design solution of the device.
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Research in the field of construction elements and design of concrete pavements
Grošek, Jiří ; Birnbaumová, Marie (referee) ; Vébr,, Ludvík (referee) ; Varaus, Michal (advisor)
The presented dissertation is focused on research in the field of dowels and design of concrete pavements using the finite element method. The theory part describes the history and the currently used techniques in the world and in the Czech Republic. The practice part of the dissertation contains a description of design methods, diagnostics of concrete pavements by using FWD and a description of laboratory tests on beams with inserted dowels. The results of measurements and modelling are verified on real operating conditions on testing fields. Based on the dissertation results, the amendment of the Czech standard ČSN 73 6123-1 regarding the position of dowels were proposed and approved. In addition, methodological guidelines of the Ministry of Transport regarding the measurements of the dowels and tie bars position and diagnostic by FWD was approved. The conclusion of the work summarizes and emphasizes the results of the dissertation.
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The use of nanofibres strain gauges for construction of linear sensors
Kirchner, Jan ; Kůr, Jan (referee) ; Pernikář, Jiří (advisor)
The aim of this thesis was to determine the basic characteristics of behavior of nanofiber strain gauges and on the basis of experimental measurements to confirm the suitability of the design of the length sensors. There was a product designed with a swivel arm whose rotation burdens the nanofiber strain gauge affixed to the flat side of the cut. Some measurements were carried out to find out a suitable direction of the loading pressure and to reveal the area showing the linear behavior. This linear area is approximately between 44 ÷ 92 % of the range of the nanostrain gauge (0% maximum load tensile, 100% maximum load pressure). Other measurements dealt with temporal stability of the output value at each point. The outcome of these experiments was to determine the methodology and to propose the design of sensors for further tests, the aim of which was to develop a sensor for measuring small diameters (from 1 to 5 mm). K
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