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Study of Influence of Strain Rate and Temperature on Formability of Titanium Alloys
Šlais, Miroslav ; Spišák, Emil (referee) ; prof. Ing. Milan Turňa, Ph.D., EWE, IWE (referee) ; Forejt, Milan (advisor)
The PhD thesis deals with the influence of temperature and strain rate on the mechanical behaviour of the Ti-6Al-4V titanium alloy. After verification tests under static loading conditions, the samples were deformed at high strain rates and elevated temperatures, using device for Hopkinson pressure bar test. The result is dependence of stress and strain rate on strain in the temperature range of 20 to 500°C. The deformed shape of specimen from the Taylor anvil test is compared with the results of the simulation in the Ansys – LS Dyna software. The parameters of Johnson-Cook equation were determined from these experiments. Also, the influence of loading conditions on the microstructure was studied. Both optical and scanning electron microscopes were used for the observations. During the research, some adjustments to the experimental devices were made in order to suppress the high-frequency components and noise in the recorded pulses. A functional tensile test adapter for the Hopkinson test was developed; it is registered under No. 2007/008 at the Technology Transfer Office of BUT.
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Tube Flaring Technology under Dynamic Conditions
Macháček, David ; Forejt, Milan (referee) ; Peterková, Eva (advisor)
This master thesis is divided into three main parts. In first part is more closely described the method of tube flaring. Tube flaring was chosen for analysis of biaxial stress, in this thesis particularly in the presence of high strain rate. In the second part is more closely described influence of high strain rate on the forming process. There is described influence of high strain rate on behavior of the material, hardening, change of quasi-static yield strength to the dynamic yield strength, influence of high strain rate on the microstructure and more. During the description of these processes there is effort to describe the cause of these changes as well. For this task was used domestic and foreign literature, as well as peer review papers whose authors study intensively this problematic. Besides all of the above there is also derived the velocity of elastic and plastic wave. In the end is evaluated experiment, in which was done tube flaring, which is part of this master thesis. Results from the 3D optical system ARAMIS are interpreted with the help of Microsoft Excel, where the chosen results were used as the input to the equations modified for the dynamic loading.
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Dynamic Tensile Test – Material Parameters Determination
Sismilich, Vladimír ; Hadraba, Hynek (referee) ; Severa, Martin (advisor)
The purpose of the work is to summarise todays existing methods of testing materials at high strain rates and techniques of evaluation acquired experimental data. There are shown the most important dynamic materials characteristics, by which is able to describe material behaviour at high strain rates. Dynamic tensile test on Eurofer’97 steel at loading rate 1m/s was conducted experimental data were analysed and evaluated. In the evaluation The most important strain and stress properties of this steel were determined.
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Tube Flaring Technology under Dynamic Conditions
Macháček, David ; Forejt, Milan (referee) ; Peterková, Eva (advisor)
This master thesis is divided into three main parts. In first part is more closely described the method of tube flaring. Tube flaring was chosen for analysis of biaxial stress, in this thesis particularly in the presence of high strain rate. In the second part is more closely described influence of high strain rate on the forming process. There is described influence of high strain rate on behavior of the material, hardening, change of quasi-static yield strength to the dynamic yield strength, influence of high strain rate on the microstructure and more. During the description of these processes there is effort to describe the cause of these changes as well. For this task was used domestic and foreign literature, as well as peer review papers whose authors study intensively this problematic. Besides all of the above there is also derived the velocity of elastic and plastic wave. In the end is evaluated experiment, in which was done tube flaring, which is part of this master thesis. Results from the 3D optical system ARAMIS are interpreted with the help of Microsoft Excel, where the chosen results were used as the input to the equations modified for the dynamic loading.
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Evaluation of deformation speed influence on adhesive bond strength
Ureš, Dan ; Müller, Miroslav (advisor) ; Hrabě, Petr (referee)
This thesis deals with the issue of bonded joints and their deformation by commonly used epoxy adhesives. It is divided into two main parts. The first part has character of searching for informations which describes various adhesives, their characteristics and applications. It also describes adhesives technology and deformation rate of the bond. The second part analyzes the results of the rate of deformation of the individual adhesives, which are assessed in terms of usability for the glued joints. The objective was to verify the properties of adhesives at different rates of deformation.
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Study of Influence of Strain Rate and Temperature on Formability of Titanium Alloys
Šlais, Miroslav ; Spišák, Emil (referee) ; prof. Ing. Milan Turňa, Ph.D., EWE, IWE (referee) ; Forejt, Milan (advisor)
The PhD thesis deals with the influence of temperature and strain rate on the mechanical behaviour of the Ti-6Al-4V titanium alloy. After verification tests under static loading conditions, the samples were deformed at high strain rates and elevated temperatures, using device for Hopkinson pressure bar test. The result is dependence of stress and strain rate on strain in the temperature range of 20 to 500°C. The deformed shape of specimen from the Taylor anvil test is compared with the results of the simulation in the Ansys – LS Dyna software. The parameters of Johnson-Cook equation were determined from these experiments. Also, the influence of loading conditions on the microstructure was studied. Both optical and scanning electron microscopes were used for the observations. During the research, some adjustments to the experimental devices were made in order to suppress the high-frequency components and noise in the recorded pulses. A functional tensile test adapter for the Hopkinson test was developed; it is registered under No. 2007/008 at the Technology Transfer Office of BUT.
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|
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Dynamic Tensile Test – Material Parameters Determination
Sismilich, Vladimír ; Hadraba, Hynek (referee) ; Severa, Martin (advisor)
The purpose of the work is to summarise todays existing methods of testing materials at high strain rates and techniques of evaluation acquired experimental data. There are shown the most important dynamic materials characteristics, by which is able to describe material behaviour at high strain rates. Dynamic tensile test on Eurofer’97 steel at loading rate 1m/s was conducted experimental data were analysed and evaluated. In the evaluation The most important strain and stress properties of this steel were determined.
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