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Design and developement of control unit for material testing machine
Kališ, Miroslav ; Appel, Martin (referee) ; Krejčí, Petr (advisor)
This bachelor's thesis is focused on the creation of the software and hardware part of a small benchtop mechanical testing machine available at UMTMB and will serve as a mechanical testing demonstrator enabling material tensile testing. The goal is to create a control program in the LabVIEW environment that communicates with control and measurement components. Another goal is to verify and test the functionality of the proposed solution on real test specimens.
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Application of digital image correlation technique in studies of plastic deformation evolution in metallic materials
Pavelčík, Dalibor ; Hutařová, Simona (referee) ; Šmíd, Miroslav (advisor)
This thesis studies evolving plastic deformation of metallic materials under uniaxial tensile load. The risk of disabling or accidents due to deformation is serious because of considerable loading of engineering components during their operational period. Therefore, many non-destructive methods have been developed to investigate the material response to loading. A good example is digital image correlation (DIC), which can be used to observe plastic deformation during loading at an optional level - from examining the behavior of the entire component (light optics) to detailed observations at the submicron level (electron microscopy). Within this work, an interupted tensile test experiment of an austenitic stainless steel sample X2CrNi18-9 with simultaneous observation of the development of plastic deformation by the DIC method using a scanning electron microscope during individual test interruptions was proposed and performed. At the same time, crystallography of the deformed sample using EBSD was investigated during the deformation. The obtained crystallographic data enabled the identification of active slip systems of selected observed grains, which made it possible to obtain a comprehensive overview of the development of the localization of plastic deformation in the observed area.The obtained results showed that the distribution of plastic deformation in the structure of the studied steel is very heterogeneous, where locally it can significantly exceed the achieved macroscopic deformation of the tested sample. The proposed methodology has proven to be an effective tool for describing the relationship between microstructure and mechanical properties.
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Kompozitní materiály a jejich užití v dopravní technice
ZEMAN, Tobiáš
This bachelor thesis is divided into theoretical and practical parts. The theoretical part deals with composite materials themselves, their types, production technologies and especially their use in transport technology. In the practical part, an experimental test of tensile and flexural strength was carried out on carbon fibre samples in order to compare the resulting values. The tensile strength was found to be many times higher than the flexural strength.
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Surface quenching of ductile cast iron
Neduchal, Bronislav ; Roučka, Jaromír (referee) ; Záděra, Antonín (advisor)
This diploma thesis is focused on the surface hardening of cast irons with spheroidal graphite. The work describes a theoretical analysis of the structure and properties of cast irons and individual methods suitable for surface hardening. The practical part describes the production of cast iron castings with spheroidal graphite, on which the surface hardening is performed, tensile test, hardening of produced castings by induction and laser surface hardening, preparation of samples for measuring microhardness and metallographic analysis of metal structures.
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Welding with laser machines
Hanáková, Anna ; Osička, Karel (referee) ; Kalivoda, Milan (advisor)
This bachelor thesis is focused on the usage of laser beam and laser beam machines in engineering. It will be mainly focused on laser beam welding (LBW). History of laser, its development and principal are all described in the opening part of this bachelor theses. Types of lasers and its use are also included. Next part is focused on laser welding itself. Thus, welding methods, parameters entering the process and advantages/disadvantages of this technology are introduced. The last theoretical part includes material tests of welded joint and outputs of those tests. In the experimental part the process of laser welding itself is presented and the results of tensile test are described.
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Mechanical properties of fiber reinforced composites for automotive applications
Bayer, Adam ; Žídek, Jan (referee) ; Jančář, Josef (advisor)
Bachelor’s thesis deals with studying mechanical features of fiber composites. As a matrix was chosen PMMA and as reinforcement was chosen glass fabric. Theoretical part sums up contemporary issues of polymer composites in automotive industry such as their production techniques and methods of impregnation. In experimental part were prepared samples by block polymerization of 30 % solution PMMA in monomer with initiator by 65° Celsius warmth oath, when was fabric directly unfolded in pre-polymer solution. On these samples were executed tensile tests by testing device Zwick and these samples were compared with results of theoreticaly calculated values.
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Parameter Identification for Elastic-plastic Material Models from Experimental Data
Jeník, Ivan ; Šebek, František (referee) ; Kubík, Petr (advisor)
This master's thesis deals with the identification of the material flow curve from record of tensile test of smooth cylindrical specimen. First, necessary theory background is presented. Basic terms of incremental theory of plasticity, tensile test procedure and processing its outputs are described. Furthermore, possibilities of mathematical expression of the elastic-plastic material constitutive law, thus mathematical expression of the material flow curve itself. Mechanism of ductile damage of material is explained briefly as well. Overview of recent methods of the flow curve identification is given, focused on cases, when the stress distribution in a specimen is not uniaxial. That is either kind of analytic correction of basic formulas derived for uniaxial stress state, or application of mathematical optimization techniques combined with numerical simulation of the tensile test. Also unusual method of neural network is mentioned. For 8 given materials, the flow curve identification was performed using different methods. Namely by analytic correction, optimization, sequential identification and neural network. Algorithms of the last two methods were modified. Based on assessment of obtained results, application field and adjusting the parameters of single algorithms was recommended. It showed up, that an effective way to the accurate and credible results is the combination of different methods during flow curve identification procedure.
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