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Defects of the bridge expansion joints - durability and expected lifetime
Daňa, Jan ; Ing.Ladislav Šašek, CSc. (referee) ; Pošvářová, Miloslava (advisor)
This thesis discusses the types of bridge expansion joints certified for use in the Czech Republic and their disorders. The first part was a theoretical evaluation of expansion joint failures. The second part focused on clarifying the failure of anchor bolts at the cantilever expansion joint. On the basis of determining the cause was then designed a method for determining the durability of expansion joints. Prognosis life cycles corresponds records according to administrator- repair works.
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Design of experimental device for visualization of axial forces in bolted connections
Ptáček, Tomáš ; Galas, Radovan (referee) ; Svoboda, Petr (advisor)
In the bachelor's thesis is created design experimental device that will be able to measure preload in bolted joints. The first part of thesis deals with research study of the current state of knowledge of bolted joints, depending on the use of different types of lubricants. According to informations, 3 different variants are introduced. The selected variant is described in detail with their advatnages and disadvantages. The final design is developed into technical drawing and electronic 3D models.
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Analysis of the rotor packet prestress on the rotor critical speed
Lekeš, Filip ; Huzlík, Rostislav (referee) ; Lošák, Petr (advisor)
The presented diploma thesis deals with the modeling of the rotor packet in dynamic calculations and analysis of the influence of the packing pressing force on the critical speed of the electric motor. The thesis can be divided into three main parts. The first part discusses the current level of rotor packet modeling in dynamic calculations and also deals with analytical theories for subsequent experimental tests. The second part describes the implementation of two experiments to determine the equivalent modulus of elasticity. The first experiment is a four-point bending test and the second is an experimental modal analysis. The third part is used for comparing the results obtained from experimental tests and describes the calculation of the critical speed of the rotor package pressed on the shaft by the finite element method.
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Strengthening of the road bridge
Neděla, Lukáš ; Pinkas, Karel (referee) ; Klusáček, Ladislav (advisor)
This thesis deals with the reconstruction of a road bridge with two simple fields over the river Olše in Třinec. The reconstruction of the bridge structure is designed in two versions, for which there is an executed design and assessment of a supporting structure according to applicable standards. The calculation of internal strenght is carried out by using the Scia Engineer 2016 program. This work contains a static calculation, a drawing documentation , an economical comparison of variants and visualization.
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Design of an apparatus for axial forces determination in screw connections
Lečbych, Jiří ; Frýza, Josef (referee) ; Svoboda, Petr (advisor)
This bachelor thesis deals with the design of the device for measuring axial forces in bolted joints. The first part of the thesis is focused on the research of the current state of knowledge of screw connections, force transducers and methods for deriving prestress including their control. Then, three conceptual solutions that fulfilled the assignment of the thesis were created based on the research. The final design that most closely corresponds to reality is described in detail including its advantages and possible measurement inaccuracies. The final 3D design was made into a drawing documentation.
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Prefabricated hall for gym
Pavličko, Jakub ; Hrubý, Tomáš (referee) ; Požár, Michal (advisor)
The aim of the diploma thesis is to design particular vertical and horizontal elements of the prefabricated gym hall. The supporting structure of the gym is formed by means of the column system with the use of the roof preloaded trusses. The entrance part of the building is designed as a column system using load-bearing beams and prefabricated ceiling sections. Overall, the structure of the building consists of columns, footings, foundation beams, reinforcing beams, prefabricated components which function as a ceiling structure, components functioning as a grandstand, a load - bearing beams a preloaded roof trusses V1. The diploma thesis designs particular supporting elements of the construction together with the construction of a grandstand.
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Active Preload Control of Machine Tool Head
Cyprian, Rudolf ; Marek, Jiří (referee) ; Březina, Tomáš (advisor)
This Master’s Thesis introducing active preload control of machine tool head supported by a company TOSHULIN, a.s. It presents a way of creating models from rigid body models to flexible bodies and finally to multi-body systems with control loop. The goal of this thesis is create active preload control using a piezo-stack system for simplified linear model of ma-chine tool head.
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Engineering optimization of a bolted joint under cyclic load
Pavlíček, Tomáš ; Kubík, Petr (referee) ; Vosynek, Petr (advisor)
This bachelor’s thesis deals with improving the service life of a cyclically stressed screw connection. In order to correctly determine the tension amplitude in the screw, it is necessary to know exactly the stiffness constant of the connection C. In this work, a comparison of analytical approaches for its calculation was made for a connection with a screw-in head screw. Based on a comparison with the numerical solution, it was evaluated as the most accurate approach according to the VDI 2230 standard. Furthermore, the influence of the size of the preload value on the life of the screw was assessed. It was found that the optimal value of the preload corresponds to the state when the clamping of the connected parts is lost. The last part of this work was focused on structural modifications that will improve the service life of the joint. The following design modifications were assessed: flexible screw, large area and spacer washer. The most significant increase in service life was achieved using a spacer washer.
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