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Vliv vlhkosti na konvenční pevnost v tlaku podél vláken při roztlačování čelistí ve vývrtu
Pilát, Jaroslav
This final thesis deals with determination of moisture influence on convential strength pressure with use of the prototype diagnostic tool. This device can be used for in situ measurement of inbuilt wood properties in constructions. This new approach enables to determine strength and stiffness parameters of wood parallel to grain based on measurement of force required for pushing jaws inside the predrilled hole apart. The thesis aim is to determine the mechanical properties of wood by both experimental testing of novel device and with universal testing machine. The results of experiments are mutually compared, statically evaluated and also compared with known values. The experiments are carried out according to the standards for testing of the mechanical properties of raw wood
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Analýza mechanické funkce kořenového systému
Szórádová, Andrea
This thesis deals with the analysis of the root system and is focused on its mechanic or more precisely fixation function. The point of concern is non-destructive testing which is used in practical arboriculture for assessment of tree resistance against uprooting. The thesis analyses this method using the actual testing and data processing. New pieces of knowledge are brought out in this thesis. It provides an alternative for data processing and discusses the possible usage of the information obtained during of the investigations of tree resistance against uprooting.
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Design of the system for the carbon composite conductive layers of the L-39NG aircraft testing and the optimization of the conductive material
Pham, Ngoc Nam ; Hönig,, Martin (referee) ; Háze, Jiří (advisor)
V posledních desetiletích je v leteckém průmyslu výrazně preferováno použití kompozitů. Nejnovější projekty českého leteckého průmyslu se zaměřují také na zvýšení využití kompozitů v nových letadlech. Tato práce se zaměřuje na výzkum elektrických vlastností kompozitu za účelem optimalizace výběru materiálu. Diplomová práce představuje návrh automatické měřicí stanice sloužící k měření a testování elektrických vlastností kompozitních vzorků vyráběných společností AERO Vodochody AEROSPACE as. K tomuto účelu je použito zařízení LCR bridge R&S HM8118 a řídicí program je navržen v prostředí MATLAB s použitím jazyka SCPI. Navržený systém je následně použit pro experimentální ověření elektrické vodivosti kompozitních vzorků. Výsledky měření budou základem pro vývoj kompozitů pro leteckou vodivost v nových letadlech. Tato práce také prezentuje výsledky testu úderu blesku na vybraných kompozitních vzorcích. Výsledky testu na úder blesku poskytují hlubší znalosti o schopnosti vzorků chránit před úderem blesku. V této práci je také představen vývoj nedestruktivního testovacího systému založeného na metodě elektrické impedance/odporové tomografie. Vývoj je v prvních fázích, ale očekává se, že systém bude využíván jako systém monitorování zdraví struktur.
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Use of thermographic methods for diagnostics of concrete bridges
Janků, Michal ; Hobst, Leonard (referee) ; Matula, Radek (referee) ; Cikrle, Petr (advisor)
This dissertation is focused on the research of the applicability of the thermographic method in the diagnosis of concrete bridges in the Czech Republic. The theoretical part characterizes selected defects of concrete structures and the principle of their detection. The practical part describes the measurements made in the laboratory on the test specimen and the field on the concrete bridge. Most attention is paid to infrared thermography, ground-penetrating radar and ultrasonic pulse-echo method. Based on the results of the dissertation, recommendations for the use of the thermographic test method in practice were developed.
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Design of instrument for the analysis of crack initiation and propagation
Šubrt, Stanislav ; Andrš, Ondřej (referee) ; Houška, Pavel (advisor)
The main goal of this thesis is to get an insight into a field of non-destructive testing using potential drop techniques that have nowadays become the standard not only in the fatigue and loading tests but also in the industry. These methods can serve to non-destructively and continuously measure material specimens, thickness, corrosion losses, deformations, spectroscopy and detection and analysis of crack geometry. They can help to identify materials and measure material changes over time. The second part of this thesis deals with designing the aperture for detection of cracks in steam and product piping using potential drop technique modified by Ing. Ladislav Korec, CSc. Last part deals with extensive testing, experimenting and evaluation of the aperture.
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Detection of Failures and cavities in structures using radar
Tkadleček, Petr ; Anton, Ondřej (referee) ; Cikrle, Petr (advisor)
The bachelor‘s thesis describes non-destructive testing and methods, which are used in civil engineering. It is focused on the detection of failures and cavities in concrete structures. In the first part the methods are described and compared. The second part describes experimental measurements on concrete structures, which contain failures. The results are described and interpreted. The used methods are compared. It was evaluated, which of these methods is suitable for the detection of failures and cavities in structures.
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Monitoring and Analysis of Corrosion of Reinforcing Steel in Reinforced Concrete Elements and Structures Using the Acoustic Methods
Timčaková, Kristýna ; Semerák,, Petr (referee) ; Medveď,, Igor (referee) ; Vaněrek, Jan (referee) ; Chobola, Zdeněk (advisor)
The dissertation thesis deals with the study of non-destructive acoustic methods as instruments for monitoring and analysing corrosion of reinforcing steel in reinforced concrete elements. Four acoustic methods were selected for this task - the impact-echo method, the nonlinear acoustic spectroscopy method, the acoustic emission method, and the ultrasonic pulse velocity method. To verify the functionality of these methods, testing was carried out on three sets of reinforced concrete samples that had been exposed to the effects of sodium chloride, which corroded the embedded steel reinforcement in these samples. Suitable parameters were proposed for individual acoustic methods to monitor corrosion of the reinforcements. In addition, experiments were designed to demonstrate the ability of the selected acoustic methods to reveal the corrosion of steel reinforcement and its influence on the concrete matrix and to assess the condition of the degraded elements and structures. The analysis of the measurement results based on their comparison shows the advantages and disadvantages of the individual methods and of their practical applications. To verify the results, correlation with common methods that are currently used for the study of corrosion was carried out and included for example the electrical resistivity measurement of the reinforcement and simultaneous monitoring of the sample surface using a confocal microscope to record the development of microcracks during the degradation.
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Survey and Diagnostics of Reinforced Concrete Structure
Filipu, Martina ; Heřmánková, Věra (referee) ; Anton, Ondřej (advisor)
The master´s thesis deals with concrete properties and it introduces problematics of building survey. In each part the study deals with diagnostic methods used for building construction. Then it closely examines selected methods, which are used for recognisability of steel reinforcement in concrete. In the practical part I conducted two engineering surveys of reinforced concrete industrial buildings. The main aims were to identify the position of reinforcement in selected elements of crane runway and to evaluate the quality of used concrete. The last part of thesis is focused on static assessment of short corbel of crane runway.
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Development and use of non-destructive testing methods from the point of view of forensic engineering
Bílek, Petr ; Vala, Jiří (referee) ; Vodička, Jan (referee) ; Hobst, Leonard (advisor)
Concretes reinforced by, using distributed steel reinforcements (fibres) are known as fibre-concrete. In case of disturbances or accidents of concrete structures reinforced with wires, it is necessary to carefully examine the actual implementation of dispersed reinforcement. Fibre concretes belong to modern building materials whose possible applications have not been fully utilized so far. Have been mainly used for floor structures loaded with factory halls and warehouses. Recently, thanks to well-known physical and mechanical properties of fibre-concrete, there were numerous attempts of designers, and namely investors, to utilize this kind of materials for support structures either. Favorable properties of wire-concrete can be utilized if there is a necessity to increase the resistance of concrete to stresses exceeding its strength, cyclic stress or impact stress. Daily practice shows to prove that the applications of fibre-concrete in such structures lead to the economic success. Necessary condition for successful application of steel fiber reinforced concrete in constructions however consists in its uniform dispersion, a homogeneous distribution of the wires throughout the volume of the structure. In case of inappropriate processing and deposition of the mixture during the manufacturing process fiber-concrete structures, the fibers are often unevenly distributed. Wires itself represent unfavourably shaped mixture components and they are extremely deteriorating its workability. A grouping of wires may be encountered as well, which reduces the overall homogeneity and the quality of steel fiber-concrete structures. If the homogeneity of fibre-concrete is not kept, the material possess different properties in various parts of the structure (for example, tensile strength), which can lead to defects in the structure (generation and development of cracks). The relevant lower reliability of the structure which is caused by unequal distribution of fibres (wires) in concrete volume can lead to damage of the property as well as the safety and the human lives can be jeopardized. Hence it is necessary to secure the effective control of the fibre-concrete homogeneity in ready support fibre-concrete structures. Contemporary homogeneity control is still ongoing on fresh blends, but if the fibre-concrete hardened and is a part of the construction, no known reliable methods are currently in available to test the homogeneity of the fibre-concrete on the structure without its destruction. The methods developed to control the concentration of wires in wire-concrete structures are based mostly on magnetic or electromagnetic properties of wires. The thesis deals with the development of the magnetic method in situ using permanent magnets for monitoring the distribution of fibers in hardened steel fiber-concrete structures. The test principle is based on measurements of the changes in magnetic field strength of permanent magnets which are induced by a change in wire distribution in steel fibre-concrete structure. Test is characterized as a so called local- failure- test using a small diameter core drill. In this sense it is a semi-destructive method.
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