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Mechanical behaviour of Strenx steel at high strain rates
Basler, Matěj ; Forejt, Milan (referee) ; Jopek, Miroslav (advisor)
The thesis is focused on the description of the behaviour of high-strength steel Strenx under quasi-static and dynamic conditions with emphasis on the influence of anisotropy. A compression test was used as a low strain rate test with specimens formed from rolled sheet in the 0, 45 and 90 degree directions relative to the rolling direction. The behaviour of the steel at high strain rates was described using the Taylor impact test, again with specimens oriented with respect to the rolling direction. The contour of the deformed specimens from the dynamic test was measured by image analysis and the dynamic yield strength of Strenx steel was calculated. The test results were compared between the loaded directions and the anisotropic behaviour of the material was described. From the values obtained from the performed experiments, the material constants for Johnson-Cook's material model were determined and its reliability was compared with both quasi-static and dynamic test results. The calculated values using the material model achieved satisfactory accuracy and the developed material model can be considered reliable.
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Optimization of infill selection with an emphasis on maximum dynamic resistance
Konvalina, Michal ; Svoboda, Petr (referee) ; Jopek, Miroslav (advisor)
The thesis deals with the study of the effect of different wall thicknesses of 3D printed infill patterns at constant cross-sectional area on their final properties under static and dynamic loading. Based on literature study, two experimental methods are chosen. The quasi-static test and the Taylor anvil test. For the experiment, square and hexagonal grid specimens are printed using FDM technology from PLA material. Quasi-static test is used to measure the static properties such as maximum compressive strength, yield stress, modulus of elasticity and to derive material model of Johnson-Cook. The dynamic impact test TAT is used to evaluate different types of patterns at high impact velocities. In ANSYS, the specimens that resisted the highest impact velocities in TAT are simulated and strain rate sensitivity parameter is optimized for the specific velocity. The highest dynamic resistance was achieved by a square infill pattern with wall thickness of 0,4 mm at an impact velocity of 37 ms-1.
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Evaluation of materials characteristics exploiting static and dynamical tests
Riesner, Jan ; Forejt, Milan (referee) ; Samek, Radko (advisor)
The project elaborated in frame of engineering studies branch M-STG describe characteristics of plasticity of non-anneal materials E 235, E 190 and E 220. Materials characteristic was receive by static and dynamical tests. Based on the literature study it was conducted survey of the current state of experimental techniques for high-speed deformation. The materials were designed by Holomon approximation of rigid-plastic material model without hardening. It was conducted force analyses for machine Unison MG 2790 for rewind bending and bend with compressive force considering the identified material model. It was describe the impact passive and active forces to move the neutral axis.
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Method of measurement parameters in metal forming.
Knebl, Martin ; Šlais, Miroslav (referee) ; Forejt, Milan (advisor)
This master’s thesis deals with the problem of measurement for thermomechanical parameters during metal forming under higher deformation rate. The first part works up general literary studies, comprising a summary of measurement methods for required parameters. There is described a principle of their function and usage. Further assessed the current situation and recommendation of appropriate methods for the dynamic processes of forming, especially their testing. The second part is devoted to the measurement for dynamic features of the material. This is a problem specified by Split Hopkinson preassure bar test. The test is described, including the mathematical evaluation process, in the theoretical part. In the practical part, there is a detailed description of the process and evaluation of the real test with aluminum alloy AlMg4, 5Mn ,07-EN AW 5083 performed within the framework of the junior project.
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Evaluation of materials characteristics exploiting static and dynamical tests
Riesner, Jan ; Forejt, Milan (referee) ; Samek, Radko (advisor)
The project elaborated in frame of engineering studies branch M-STG describe characteristics of plasticity of non-anneal materials E 235, E 190 and E 220. Materials characteristic was receive by static and dynamical tests. Based on the literature study it was conducted survey of the current state of experimental techniques for high-speed deformation. The materials were designed by Holomon approximation of rigid-plastic material model without hardening. It was conducted force analyses for machine Unison MG 2790 for rewind bending and bend with compressive force considering the identified material model. It was describe the impact passive and active forces to move the neutral axis.
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Method of measurement parameters in metal forming.
Knebl, Martin ; Šlais, Miroslav (referee) ; Forejt, Milan (advisor)
This master’s thesis deals with the problem of measurement for thermomechanical parameters during metal forming under higher deformation rate. The first part works up general literary studies, comprising a summary of measurement methods for required parameters. There is described a principle of their function and usage. Further assessed the current situation and recommendation of appropriate methods for the dynamic processes of forming, especially their testing. The second part is devoted to the measurement for dynamic features of the material. This is a problem specified by Split Hopkinson preassure bar test. The test is described, including the mathematical evaluation process, in the theoretical part. In the practical part, there is a detailed description of the process and evaluation of the real test with aluminum alloy AlMg4, 5Mn ,07-EN AW 5083 performed within the framework of the junior project.
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