National Repository of Grey Literature 117 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Design of Acoustic Emission Detector
Velecký, Petr ; Křenek, Ladislav (referee) ; Rubínová, Dana (advisor)
This bachelor thesis deals with design of acoustic emission detector, a professional device for leak detection in pneumatic systems. The aim was to create an intuitive device that would have a distinct appearance and respect all ergonomic, technical and aesthetic requirements. Manipulation with the device was made easier.
Optimization of ultrasonic leak detector of pneumatic system
Macků, Ondřej ; Mazal, Pavel (referee) ; Vlašic, František (advisor)
The thesis deals with design and optimization of exchangeable modules for localization of air distributable ultrasound in concept of ultrasound probe design. Several series of these modules were manufactured using the technology of rapid prototyping and tested on artificially created source of air leak. Based on these verification experiments two types covering wide use for identification of pneumatic systems leaks were selected and modified. These two types are long range module for more accurate and expended reach of the leak detection and focusing attachment for narrowing the received range of scanning module and elimination of surrounding ultrasound. Part of the thesis is also analysis of the acoustic signal processed by modern acoustic emission analysers which allow besides standard parameters recording also continuous sampling up to 10 MHz and design solution for attachment of add-on modules to the detector. The thesis is beneficial for raising awareness of leak measurements, prototype manufacturing by using the 3D printing and designing and manufacturing of modules.
Acoustic emission sources from fast dislocation motion
Hora, Petr ; Machová, Anna ; Červ, Jan ; Uhnáková, Alena
Acoustic emission from the fast dislocations emitted from an edge crack in 3D bcc iron crystal is studied via atomistic simulations by molecular dynamics technique. Acoustic emission patterns arising from the fast dislocation motion in molecular dynamics are visualized via the local kinetic energies of individual atoms and further modeled as a moving source of the stress waves in the anisotropic continuum.
DETECTION OF DEFECTS BY ACOUSTIC EMISSIONS (AE) UNDER HIGH-TEMPERATURE CREEP CONDITIONS
Dvořák, Jiří ; Sklenička, Václav ; Král, Petr ; Kvapilová, Marie ; Svobodová, M. ; Šifner, J. ; Koula, V.
Current acoustic emission (AE) applications are preferably oriented to continuous monitoring of machine component operation. AE is a perspective non-destructive method for early prediction and identification of material defects to avoid a disaster of running equipment. The paper analyzes the measured data and analysis of signals at the level of individual emission events during the creep test of a copper based on the results of previously performed microstructural and fractographic analyses of its creep damage evolution and fracture. The aim of the model study is to contribute to the successful application of AE for real operating components of power equipments and thus to increase their operational safety.
Analysis of corrosion damage of steem pipe by acoustic emission: results for a pipe in EBO
Tichavský, Petr
We studied acoustics emission of steem pipes from measurements from EBO. We counted frequency of sudden increases of the acoustics emission, which can be used as indicator of corosion demage of the pipes.
Investigation of deformation mechanisms in Mg-Gd alloys
Szabóová, Andrea ; Mathis, Kristián (advisor) ; Drozdenko, Daria (referee)
Title: Investigation of deformation mechanisms in Mg-Gd alloys Author: Andrea Szabóová Department: Department of Physics of Materials Supervisor: doc. RNDr. Kristián Mathis, DrSc. Abstract: In the present work, the deformation behavior of magnesium-gadolinium binary alloys was investigated. Dependence on the concentration of Gd and deformation temperatures was studied. Extruded samples had relatively strong initial texture. Compression tests were done at room temperature and 200řC. Simultaneously with deformation acoustic emission was recorded. Data from acoustic emission was analyzed with advanced statistical methods. Results of the combination of these two experimental methods indicated that at the beginning of the deformation twinning is the dominant mechanism. In the following stage of plastic deformation non-basal slip systems became the governing deformation mechanism. With higher content of Gd the size of twins decreases as a result of the decreased mobility of twin boundaries caused by solute atoms. At higher temperatures twinning activity was increasing. In addition, results were confirmed by optical light and scanning electron microscopy. Keywords: magnesium alloy, deformation tests, acoustic emission, microscopy
Study of advanced high strength magnesium alloys by in situ techniques
Fekete, Klaudia ; Dobroň, Patrik (advisor) ; Lejček, Pavel (referee) ; Mayama, Tsuyoshi (referee)
The aim of the present doctoral thesis was to reveal the active deformation mechanisms in novel high strength magnesium (Mg) alloys using advanced in-situ techniques with high time and space resolutions. The deformation behavior of two extruded Mg-LPSO alloys with a different volume fraction of the long-period stacking ordered (LPSO) phase was investigated in tension and compression at room temperature and in compression at 200 řC, 300 řC, and 350 řC. In order to support the results obtained by in-situ acoustic emission and synchrotron diffraction methods, detailed microstructure investigation was provided by transmission and scanning electron microscopy, particularly the backscattered electron imaging and electron backscatter diffraction technique were used. The results indicate that both temperature and the LPSO phase content significantly influence the plasticity of the magnesium matrix, particularly they affect the activation of extension twins and non-basal slip. Moreover, both parameters have a high impact on the formation of the deformation kinks in the LPSO phase. Keywords: Mg-LPSO alloys, deformation mechanisms, acoustic emission, synchrotron diffraction, in-situ methods.
Influence of dynamic loading on the contact fatigue characteristics of bearing material
Hložek, Jiří ; Hutař, Pavel (referee) ; Mazal, Pavel (advisor)
This thesis deals with the study of sudden step changes observed in model testing of standard bearing steel 100Cr6. Methodology of experiments with step change of load is proposed and applied in measurements. Three complete series of experiments were conducted, and rating life was determined for each loading trend. Based on the experiments carried out, it was found that the selected steel is able to withstand the sudden step of load changes, despite the fact that it is not material of choise for this type of load. Part of this work was to verify functionality of the innovated test stations AXMAT with modern diagnostics and a new control system, and also of the hydraulic variant of AXMAT, which allows to remotely derive dynamic loading of the test sample.
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.
Vibration and impact measurement for collision analysis
Andruška, Martin ; Hrubý, Lukáš (referee) ; Musil, Tomáš (advisor)
This bachelor’s thesis deals with the issue of CubeSat collision and detection with microscopic particles of space debris and meteoroids. The aim of the thesis is to approach methods of detection, to describe various sensors for measurement of acoustic emission, shock and vibrations caused by collisions and by experimental comparison determine the suitability of their application. The thesis also contains description of possible methods of data analysis using amplitude and spectral analysis. Finally, there is a suggestion and realization of a possible way of processing acquired data from a sensor using an FPGA.

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