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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Bio-based wood adhesive derived from brewers spent grain

Muselíková, Vladislava January 2017 (has links)
Brewers spent grain (BSG) is an abundant waste material from the brewing process, representing approximately 85% of total by-products generated, is rich in cellulose and non-cellulosic polysaccharides and has a strong potential to be recycled. One of the main components of the BSG is protein, which has a potential to be extracted, modified and used as an adhesive for the woodworking adhesive. This work deals with the protein extraction through alkali treatment and its subsequent modification, crosslinking with glyoxal. The crosslinked adhesive was tested through ABES method to find, that ideal content of glyoxal is 20%. Subsequent adjusted standard tests for the lap shear strength and bend strength (MOE and MOR values) were used to compare its values to commercially available PVAc adhesive. The lap shear strength results were 2,7 times lower to PVAc, the bend strength values were, on the other hand, 1,5 times higher. The PVAc was partially replaced (50 and 25%) by the protein adhesive showing that the extracted adhesive could serve as a partial replacement to lower the ecological impact of the PVAc adhesive.
12

Posouzení procesu delaminace lepených materiálů

Matušinec, Luděk January 2015 (has links)
The thesis aims to explore the process of delamination on glued prism. It will be evaluated different types of wood (SM, DB) in combination with heat-treated wood (Thermowood TW). These materials will be exposed in an environment with high humidity. It will also be assessed shear strength test specimens, which will also be exposed to conditions of environment high humidity. Based on the measurement results will be evaluated different types of glue joints. They will vary in type and quantity of glue. The work is consisting of two parts. The first part deals with literature review on glueing of wood, thermal modification of wood and modern glued materials. The second part of the thesis is practical, which will be determined by the methodology of experiment and the subsequent testing. In this thesis will be displayed charts and graphs that will be evaluated at the end of work and commented for practical use in the company.
13

Lepení FDM 3D tištěných dílů z PLA / Gluing of FDM 3d printed parts from PLA

Šlimar, Filip January 2021 (has links)
The thesis deals with the theory of 3D printing, materials for printing and bonding. It focuses on FDM printing and PLA material. It also compares gluing with other methods and deals with the distribution of adhesives, the gluing procedure and tests of glued joints. The work, based on literature studies, proposes an experiment to evaluate selected adhesives. The practical part contains a description, results and evaluation of the experiment. The evaluation of adhesives is based on tensile and shear strength.
14

Povrchové úpravy skleněných vláken s využitím plazmové nanotechnologie / Surface modification of glass fibers using plasma nanotechnology

Sedlák, Filip January 2017 (has links)
Diploma thesis is aimed at deposition of thin films on glass fibers using plasma-enhanced chemical vapor deposition from tetravinylsilane as a monomer. Such surface modified glass fibers were used as reinforcements for fabrication of polymer composites with unsaturated polyester resin as a matrix. Chemical and optical properties of prepared thin films were characterized using infared spectroscopy and spectroscopic ellipsometry. An influence of deposited thin films on the shear strength of composite material was observed using short-beam shear test.
15

Analýza zesilování železobetonových desek s ohledem na mezní stav protlačení / Analysis of Strengthening Reinforced Concrete Slabs Against Punching Shear

Nováček, Jan Unknown Date (has links)
The thesis deals with the topic of the punching shear of the reinforced concrete structures with a focus on an additional strengthening. The introduction of the thesis is devoted to the research of various types of strengthening against the punching and their efficiency on an increase of load-bearing capacity. Material nonlinear models are formed for strengthening by an additional concrete head, a slab concrete overlay and a column concrete jacketing. The results from the nonlinear analysis are compared with various standards, including the new generation of Eurocodes. Detailed analysis of an additional concrete head is performed regarding governing inputs, which influence load-bearing capacity. Theoretical assumptions were applied to the design of the additional concrete head, where long-term measurement has been performed for the comparison with the analytical assumptions and the material nonlinear model. The second part of the thesis deals with the strengthening of foundation structures, which are accessible only from one surface. There is presented newly developed technology for strengthening by the additional shear reinforcement with the combination of bonding and mechanical anchorage. The assessment of proposed technology is defined for the strengthening against punching shear based on tested samples. The detailed technological procedure is described, including the procedure for the application on the structures below ground water level. Long-term measurement of the shear reinforcement was carried out for the strengthened foundation slab.
16

Počítačové modelování hranic dvojčatění ve slitinách s tvarovou pamětí / Computer modeling of twin-boundaries in shape memory alloys

Heczko, Martin January 2020 (has links)
This Master‘s thesis is focused on theoretical study of twinning in magnetic shape memory alloys based on Ni2MnGa using ab initio calculations of electronic structure within the projector augmented wave method. In particular, the effect of increasing concentration of manganese at the expense of gallium was studied on total energy and stress profiles along different deformation paths in the (10-1)[101] shear system of non-modulated martensite. Further, this work deals with the effect of the concentration of manganese on the energy of planar fault caused by presence of partial dislocation due to motion of twin boundary. The results show that the shear modulus in studied shear system increases with the increasing concentration of manganese as well as energy barrier and deformation characteristics along shear deformation paths increases, which makes the shear more difficult in Mn-rich alloys. Increasing concentration of manganese also leads to rising the planar fault energy. All these effects can be responsible for lower mobility of twin boundaries in alloys with higher concentration of manganese.
17

Vliv složení mezivrstvy na pevnost adhezního spoje mezi vláknovým a částicovým kompozitem / Effect of Interlayer Composition on Bond Strength between FRC Framework and Composite Veneer

Ibarra, Jonatanh José January 2010 (has links)
Hlavním cílem této práce je studium aktuálního problému adheze mezi kompozitními materiály, a určení vlivu složení mezivrstvy v pevnosti adhezivního spoje mezi vláknové (FRC) a částicové (PFC) kompozity, používané ve stomatologii. FRC tyčinky byly vytvořené na bázi komerční dimetakrylatové pryskyřice a skleněných S vláken. PFC byl vytvořen ze směsi pryskyřic (bis-GMA a PEGDMA), plněných drceným barnatým sklem. Celkově bylo připraveno a vyzkoušeno 84 vzorků. Vzorky byly rozdělené do pěti hlavních skupin. První skupina byla vytvořena ze série vzorků bez mezivrstvy. Zbylé čtyři skupiny byly rozděleny dle složení mezivrstvy (tloušťky a druhu pryskyřic). Částicové kompozity vzorků se lišily obsahem plniva (0, 10, 40 hm %). FRC tyčinky byly stejné pro všechny vzorky. Univerzální testovací přístroj ZWICK Z010 byl použit k zjištění smykové pevnosti adhezivního spoje všech vzorků. Rastrovací elektronový mikroskop byl použít k pozorování místa porušení. Ze získaných výsledků vyplívá, že s přidáváním mezivrstvy mezi vláknovým a částicovým narůstá smyková pevnost spoje. Důležitost těchto výsledků je způsobená tím, že v posledních letech použití těchto materiálů ve stomatologii narůstá a adheze zůstává jeden z hlavních problémů při klinické praxi.
18

Hodnocení napjatostního chování lepeného konstrukčního dřeva pomocí DIC analýzy. / Evaluation of load-deformation characteristics of glued timber using DIC analysis

Šot, Michal January 2015 (has links)
The work deals with issues of evaluation of the shear properties of timber structural materials, particularly CLT elements. The work contains an overview of extensive research so far presented scientific studies dealing with the characteristic shear properties of wood. In the practical part was carried out the experiment dealing with the failure mode of transverse lamellae of CLT elements that were exposed to shear stress. There were observed individual effects that this may affect the material properties. In the first part of the experiment were performed numerical models using FEM. In the second part, the test specimens were tested in three point bending. Here, attention was paid to the influence of macroscopic properties of wood on the distribution of stress cracks and shear strength, the tests were recorded using DIC system.
19

Čerpaní kalu v technologii ČOV / Sludge Pumping on WWTP

Fadrný, Tomáš January 2011 (has links)
This diploma thesis deals with the best solution design for a sludge fitting, especially focusing on the right choice of pumps for the waste water treatment plant in Prostějov. The pumps were selected for a circulation pipeline, which heats up the sludge. Several measurements were carried out in order to determine the statistical evaluation of the properties of the pumped medium. The figures gained were used to calculate pressure losses.The diploma thesis is divided into two parts. The first part provides a theoretical analysis of the problem and the second part presents the results and subsequently the reasoning for the new selection of pumps in order to change the WWTP technology from the mesophilic to the thermophilic sludge digestion. The test records describing the testing of the individual samples of the pumped sludge are attached.
20

Polymerní kompozity s vyššími užitnými vlastnostmi / High Performance Polymer Composites

Bábík, Adam January 2013 (has links)
High performance polymer composites are materials with emphasis on specific chemical and mechanical properties due to their broad scope of applications. The main advantages are high strenght and toughness in comparison with their low weight and density. An increased adhesion at composite interfaces is important to ensure excellent composite properties. Bundles of glass fibers were coated by plasma-polymerised interlayers of tetravinylsilane (pp-TVS) of different thicknesses and at different effective powers. The prepared interlayers of pp-TVS were analyzed to evaluate chemical composition (RBS, FTIR, XPS) and mechanical properties (NI-AFM). Microindentation test and fiber-bundle pull-out test were used to determine the interfacial shear strenght.

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