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Effect of surface on bonded joint
Trhoň, Vojtěch ; Halamík, Tomáš (referee) ; Kubíček, Jaroslav (advisor)
This master’s thesis is divided into two parts. In the first part are these topics: bonding theory, treatment of bonding surface, types of adhesives, adhesives in the transportation industry and construction and stress of bonded joints. In the second part of this thesis is experimental evaluation of the effect of surface of material on strength of bonded joint.
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Badminton rackets
Kuriál, Jakub ; Doležal, Pavel (referee) ; Molliková, Eva (advisor)
The fundamental topic of this thesis is the analysis of materials used in the production of sports equipment for badminton. The thesis describes the evolution of materials used in the context of the historical development of the game system. The thesis explains the game principles and the requirements for the technical characteristics of the gaming equipment. The thesis deals primarily with material properties of individual parts of the badminton racket (frame, string bed, wrap) but it also mentions the demands on the ball or the playing surface. In the final section of the thesis the expected development in the sports industry using the acquired knowledge is described. The most likely direction seems to be the area of nanotechnology. The importance of this work lies in the complete discussion of a topic in the field of material sciences which has not been composed yet.
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Durability of Polyehtylene Ribbons from Netwrap
Huljak, Pavel ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
This diploma thesis deals with the measurement of mechanical properties and accelerated aging of monoaxially stretched polyethylene strips coming from three types of polymeric mesh, which serves to pack hay on baling machines. The strength of the strips is evaluated from two points of view. The first one is static tensile strength measured before and after accelerated aging at 23 °C and 40 °C, the second one determines the strength as the weight that causes the strip failure on a simple machine at 23, 40, 60 and 80 ° C. The results show that the smallest static strength has the least stabilized strip, which, on the other hand, revealed the highest strength in a dynamic loading. The change of supermolecular structure was evaluated by calorimetric measurements. The data shown only very little change of inner structure due to the average response of the whole crystalline phase comprising relatively wide distribution of crystallites. It is more than probable that supermolecular structure had been changed but the method is not sensitive to see the change of orientation of lamellae and macromolecular chains in them.
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Effect of Structure of FRC and Adhesive on the Bond Strength of Joint between FRC and Particulate Filled Dental Composite
Bystřický, Zdeněk ; Přikryl, Radek (referee) ; Poláček, Petr (advisor)
This bachelor’s thesis investigates how is the strength of adhesive bond between dental FRC (Fiber Reinforced Composite) and adhesive affected by the type of reinforcement of dental FRC and by the type of adhesive. The nature of the fracture was investigated also. The strength of adhesive bond of the experimentally designed samples was measured using universal tensile testing machine in the specially constructed jaws. The nature of the fracture was viewed by the confocal microscope. The obtained results suggest that the strength of adhesive bond is mostly affected by the type of reinforcement of the FRC provided that there is a good wetting on the FRC surface. In this case, interlaminar strength of FRC was the limiting factor. The strength was lower in the case of FRC with multidirectional (spliced) glass fibers. The strength was also affected in a certain manner by the creation of locations where the stress was concentrated. This effect was most notably in the case of adhesives with the high cohesive strength. The impact of aqueous environment on the stability of adhesive joint was most major in the case of the low - crosslinked resins and in the case when the molecules of water penetrates into the interface between materials in consequence of poor wetting.
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Research of effective use and activation of activ concrete additions
Mikhailova, Olesia ; Ťažký, Tomáš (referee) ; Hela, Rudolf (advisor)
The theoretical part describes the admixtures that are used in cement replacement. Here also summarizes the findings on the influence of granulomentry, grain shape and fineness of admixtures on the density of the cement matrix. The practical part is experimentally verified the influence of fineness admixtures and grain size on the mechanical properties of concrete. Also, the rheological properties of cement are compared with admixtures depending on the type and dosage and time.
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Properties of Zeolites and Their Use in Building Binders
Rousková, Jana ; Sedlmajer, Martin (referee) ; Rovnaníková, Pavla (advisor)
Zeolites, such as natural or synthetic aluminosilicates, have a wide range of applications. Their application in the construction industry tends to use zeolites as impurity type II. However, it has to prove their reactivity and affect the content of calcium hydroxide in the concrete. The aim is to determine the effect of zeolite as a partial replacement of cement in different concentrations on the mechanical properties of fine-grained concrete and consumption of calcium hydroxide.
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Evaluation of properties of lime mortars
Babíková, Barbora ; Švec, Jiří (referee) ; Opravil, Tomáš (advisor)
This bachelor thesis deals with evaluation of properties of lime mortars and their application in field of restoration and preservation of cultural heritage. The aim of this works is to compile evaluation line of different types of lime mortars based on comparison of their behavior during testing of their characteristic properties and resistance. Studied properties like setting time, compressive strength, tensile strength in bending, frost resistance, reactivity, content of free lime, loss of mass on ignition, point to applicability of given mortar in different interior or exterior conditions. The results of individual tests are further processed and evaluated.
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Tightness evaluation of gasketed tubesheet
Trubač, Daniel ; Pernica, Marek (referee) ; Létal, Tomáš (advisor)
This master thesis focuses on the issue of tightness evaluation of gasketed tubesheet in U tube exchangers, which meets strength requirements of ČSN EN 13 445-3 and ČSN EN 1591-1 standards. It deals with the forces acting on the gasket when measuring the effects acting on the entire heat exchanger. A separate part is devoted to the calculation of the heat profile in the heat exchanger and verification of the strength of the heat exchanger. The final part introduces model of a heat exchanger, on which a possible approach to solving the tightness of the tubesheet in heat exchangers is presented. In thesis temperature field evaluation was conducted, the results of which were used in stress strain analysis, in order to obtain gasket contact pressure. Extreme gasket contact pressures were used to estimate leak rate limits.
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