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Experimental determination of the relationship between NDT parameters and the compressive strength of concrete
Kozáček, Vojtěch ; Komárková, Tereza (referee) ; Kocáb, Dalibor (advisor)
The diploma thesis deals with non-destructive testing of concrete as well as with the relationship between determined parameters and the compressive strength of concrete. The thesis is mainly focused on the ultrasonic pulse velocity method and the rebound hammer test. The experimental part of the thesis describes non-destructive tests performed on concrete blocks. The compressive strength was tested on the drill cores taken from the concrete blocks. The aim of this thesis is to find regression models of the relationship between the compressive strength and non-destructive parameters, and the subsequent analysis of the results.
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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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Production of the material chamber to a blast furnace
Netopil, Lubomír ; Kubíček, Jaroslav (referee) ; Sigmund, Marian (advisor)
The theses deals with the production of furnace-top hopper. Mainly it is focused on the welding of abrasion-resistant materials and steel for pressure vessels using the FCAW method. These materials are described in detail in the research section, including the additional materials used, the welding methods used and NDT tests used to check the quality of the welds. The practical part then describes the technological process of production. Subsequently, the procedure of welding of the abrasion-resistant steels and steel for pressure vessels, including the developed WPS, is elaborated. The procedure of testing by non-destructive tests of selected combinations of materials with documented test reports and a plan of inspections and tests is also described. Finally, a technical and economic evaluation of production was performed.
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Primary Calibration of Acoustic Emission Sensors
Keprt, Jiří ; Mazal, Pavel (referee) ; Hájek, Karel (referee) ; Beneš, Petr (advisor)
The aim of the doctoral thesis is the problem of the primary calibration of acoustic emission sensor. In the introductory chapters, there are the results from the study of literature in field of AE and primary calibration of AE sensor summarized. The practical part of the thesis is aimed on realization of the primary calibration of AE sensors by different methods. The standardized methods of step function calibration and reciprocity calibration were practically realized as a part of the research on the same aparature. The method of reciprocity calibration with wideband excitation was practically realized too. The comparison between results from each used method was realized and the influences of the different sources of uncertainty and the different configuration of the calibration aparature on the step function calibration and the reciprocity calibration were determined. The uncertainties were determined for each realized methods. The recommendations for the calibration by the different methods on the available calibration aparature were presented. All the proceses of the reciprocity primary calibration was automated by the programmed software and the channel switcher. The UT 1000 (s.n. 169) by Physical Acoustic Corporation was used as the calibrated sensor for the comparison of the results of the calibrations.
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Non-destructive testing of gear-wheels
Krejčí, Martin ; Juliš, Martin (referee) ; Čech, Jaroslav (advisor)
This diploma thesis resolves aplication of particular non-destructive testing methods while producing castings of steel wheels and quality control of this process. There are described fundamentals of flaw detection, determination of flaw-generation cause and suggestions for optimalization of casting process and increasing of its quality.
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Automation of test line for flaw detection of railway wheels
Hubený, Marek ; Matz,, Václav (referee) ; Pásek, Jan (advisor)
This thesis describes the design and implementation of a control system for testing line using ultrasonic testing and magnetic particle testing. The test line is designed for non-destructive testing of railway wheels with detection and localization of surface and subsurface defects. The thesis describes the design and operating principles of the test line. On this basis, the design of a control system that controls various processes throughout the test line is clearly described. The proposed control system was implemented in the industrial application.
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The Influence of Moisture of Lightweight Aggregate on the Concrete Properties
Pešek, Lukáš ; Lišovský, Martin (referee) ; Kocáb, Dalibor (advisor)
The bachelor thesis deals with the influence of moisture of lightweight aggregate on the concrete properties. In the experiment, test specimens from two different lightweight aggregate, and two different input moisture states of lightweight aggregate were tested. The tests were performed to determine the basic properties of lightweight concrete after 7, 28 and 90 days of maturing. Compressive strength, tensile splitting strength and depth of penetration of water under pressure were determined on cubic specimens. On the test prisms were performed tests to determine the flexural strength and dynamic modulus of elasticity. The results were processed and evaluated in tabular and graphical form to determine statistical data and formulate a conclusion.
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Nondestructive testing in current industrial practice
Jakubcová, Eliška ; Klakurková, Lenka (referee) ; Juliš, Martin (advisor)
The bachelor thesis is focused on personnel certification of non-destructive testing according to valid standards. The theoretical part compares the Czech certification system for non-destructive testing with systems in other countries and evaluates their differences. Problems that occur during certification according to ČSN EN ISO 9712 are also discussed. In the practical part of the thesis the evaluation of the test sample is documented by means of radiographic test, magnetic particle test and leak test. At the end of the thesis the results are evaluated and discussed and also described in the form of measuring protocols.
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Preliminary survey of the historic reinforced concrete bridge
Ježíková, Pavlína ; Žítt, Petr (referee) ; Cikrle, Petr (advisor)
This bachelor thesis focuses on the preliminary survey of a bridge connecting the west and east wing of the Veveří castle. It is a structure of a very high significance because it is presumably the oldest preserved bridge made from reinforced concrete, it was completed in 1898. A visual inspection of the outside and inside parts of the bridge was performed. To examine the quality of used concrete and type reinforcement and finding out the condition of the structure, destructive and non-destructive diagnostic tests were used. Because of the historical significance of the bridge is part of the thesis devoted to the history of bridge construction and the author of the Veveří Bridge and the pioneer of reinforced concrete constructions in our country professor Josef Melan.
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