|
|
Mechanical properties and their determination in materials prepared by cold deposition
Hamr, Ondřej ; Judas, Jakub (referee) ; Zapletal, Josef (advisor)
The bachelor thesis focuses on conventional mechanical properties and their determination. Additionally, this work contains the methods of determination of mechanical properties using small and miniature test specimens with a focus on tensile and bending tests of miniature size and small punch test. In the conclusion of this work, experiments were carried out, where the mechanical properties of small and miniature dimensions were investigated on the AA 7075 strength alloy, which was applied by kinetic cold deposition. The focus of the experiment on the tensile and bending tests of small specimens followed by the small punch test and the subsequent correlation of the observed results.
|
|
|
Small Punch test brittle materials
Saňka, Martin ; Válka, Libor (referee) ; Zapletal, Josef (advisor)
Bachelor’s thesis is focused on description of methods for material testing of miniature samples called „Small Punch Test“. Thesis describes the basic test procedures, interpretation of their results and sample removal techniques. Recognized methods of correlating test results with parameters obtained from conventional material tests and after test sample evaluation were described in the thesis. Furthermore, the thesis deals with the evaluation of mechanical properties of brittle materials using the „Small Punch Test“, where a statistical appoach to obtaining their characteristic strength and specifying the procedure for determining the fracture toughness was described.
|
|
|
Fatigue characteristics of Metal Matrix Composites (MMC)
Judas, Jakub ; Věchet, Stanislav (referee) ; Zapletal, Josef (advisor)
This bachelor thesis is focused on analysis of fatigue characteristics of hybrid composite based on magnesium matrix QE22 reinforced with Al2O3 fibres and SiC particles. Test specimens of the composite material prepared by infiltration method were subjected to quasi-static tensile and compression test and discovered data were afterwards compared with the magnesium matrix. Cyclic response and low-cycle fatigue life were studied on the material under stress-control mode. All of the experiments were conducted at room temperature. Cyclic curves were fit with regression analysis in order to measure fatigue parameters of the hybrid composite. Cyclic and fatigue parameters were discussed and compared to similar magnesium alloy AZ91 reinforced with SiC particles.
|
|
|
Low Cycle and High Cycle Fatigue Properties of Austempered Ductile Iron
Zapletal, Josef ; Bokůvka, Otakar (referee) ; Kunz, Ludvík (referee) ; Věchet, Stanislav (advisor)
The thesis is focused on assessment of fatigue behaviour of austempered ductile iron with nodular graphite. Optimal period of transformation was determined based on the best combination of stress and strain characteristics established by tensile test. Cyclic response and low-cycle fatigue life were studied under both stress-control and longitudinal strain-control mode at room temperature. For both modes, shapes of cyclic hardening curves are dependent on stress amplitude. Cyclic deformation curves (CDC) were fitted by power regression function. Results were compared with CDC established by multiple step test in both modes with verification of the influence of cyclic creep (high stress levels, stress-control mode). Experimental data of S-N curves are in agreement with the Manson-Coffin and the Basquin law. Fatigue and cyclic parameters were compared. Fatigue life time in high-cycle fatigue region was determined. Experimental data were fitted by suitable regression functions. Regression parameters and fatigue limit were established by means of each regression function. Experimental data in low- and high-cycle fatigue regions were used to construct S-N curve and to determine relevant parameters. Discontinuity of experimental data was not observed. Low-cycle fatigue behaviour was predicted. Approximation of tolerance bands was realized in high-cycle and both high and low cycle fatigue regions.
|
|
|
Nanocomposites with a metal matrix
Chlupová, Monika ; Kohout, Jan (referee) ; Zapletal, Josef (advisor)
This baechelor thesis is focused on metal matrix nanocomposites (MMNCs), whose research has started recently. In the first part of this thesis are generally defined composite materials, the larger part is dedicated to metal matrix composites (MMCs), on which are described the strengthening mechanisms that are also applied to MMNCs. The second part of the thesis is focused specifically on MMNCs. The concept of MMNCs and their distribution is defined first, followed by a definition of the reinforcement that can be used for the production of MMNCs. There are also described the posibilities for the production of these reinforcing phases, and their influence on the structural and mechanical properties of the final MMNCs. This section is followed by a description of possible processes of MMNCs production with their advantages and limitations. The last part outlines how research and development of these materials should be carried out in order to be commercially produced and used in the future.
|
|
| |
|
| |
|
|
Fracture Toughness of Metallic Materials and its Testing
Kosek, Lukáš ; Zapletal, Josef (referee) ; Němec, Karel (advisor)
The purpose of the work is to introduce the basic of the fracture toughness of metallic materials and its measuring under the conditions of the plane strain. There are shown essential concepts of the linear elastic fracture mechanics, which is used for the description of the material behavior at fracture of the material with a crack. It defines stress intensity factor and describes the main elements influencing the fracture toughness. Furthermore, the work contains the particular testing methods, specimens and testing equipments. In the conclusion it recapitulates the availability and the application of the linear elastic fracture mechanics.
|
|
|
Toughness of Metallic Materials and its Testing
Michalisko, Jan ; Zapletal, Josef (referee) ; Němec, Karel (advisor)
This bachelor work deals with toughness as a mechanical property of metal materials. It defines the toughness and its demonstrations. It describes the transient behaviour of some metals at the static and dynamic load. Furthermore, the work describes the particular testing methods (Charpy‘s, Izod‘s, DWT, DT, DWTT). It covers the historical consequences of toughness testing.
|
|
| |
guest ::
RSS feed.