|
|
Comparison of characteristics of pre-impregnated and conventional carbon fibre epoxy laminates
Jones, Phillip ; Juračka, Jaroslav (referee) ; Katrňák, Tomáš (advisor)
The focus of this thesis is a comparison of pre-impregnated and conventional carbon fibre laminates. The first part focuses on the production process of carbon fibre composites from the process of converting PAN to carbon fibres to the lay-up and curing process of completed parts. The second section includes numerical comparisons of different types of carbon fibre. The data is set up in a fashion to demonstrate the improvements in carbon fibre mechanical properties by comparing outdated carbon fibre to the newest fibre on the market. The included tables aid in the process of choosing the right type of carbon fibre for each specific application.
|
|
|
Use of FRP Composites as Reinforcing Material for Concrete
Kratochvílová, Denisa ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
Because FRP composites have high fiber strength and good durability, they are increasingly used for repairs, modernisation and reconstruction of concrete structures. In practice, however there is a risk of premature separation of FRP reinforcement from concrete. This can be avoided by appropriate selecting the fibers and the matrix and the appropriate shape of the reinforcement. The actual materials and consistency of FRP reinforcement with concrete are also covered by this diploma thesis.
|
|
|
Measurement and analysis of deposition of fibers from mineral wool in respiratory system
Hájek, Ondřej ; Elcner, Jakub (referee) ; Lízal, František (advisor)
This master thesis deals with inhalation of fine particles and fibres into human lungs. This is a scientific field where computer modelling is used to describe the movement of fibres and their deposition in the lungs. However, the results of these simulations must be verified experimentally. The prediction of fibres behaviour is important from a toxicology point of view where it is important to know deposition hot-spots and places where fibres could possibly cause problems. The review of the state-of-the-art is focused on the deposition of particles in human lungs followed with a chapter on fibre as a type of particle, and occupational exposure limits set by different world associations. The last theoretical chapter describes human lungs and its diseases which can evolve when limits for occupational exposure are not met. The experimental chapter consists of a description of the used experimental setup and results from an experiment together with a comparison of results with other similar experiments.
|
|
|
Reactive powder composites and cement composites without macropores
Panenková, Monika ; Hela,, Vlastimil (referee) ; Hela, Rudolf (advisor)
This diploma thesis deals with the design principles and manifacture of ultra performance concrete (UHPC), reactive powder composites (RPC) and other fine-grained materials, such as Macro defect free (MDF) or Densified systems with small particles (DSP). Theoretical part of this work is focused on the requirements of properties and composition UHPC and RPC and methodology of their design principles. Experimental part describes design principles RPC, manufacture of test specimens, testing of certain physical and mechanical properties, such as tensile strenght, bending strenght and compressive strenght and determination chemical character X-ray and thermal analysis.
|
|
|
Electrospinning of polyvinylidenfluoride based fibers
Hošek, František ; Šťastný, Přemysl (referee) ; Částková, Klára (advisor)
Electrospinning is one of the rapidly developing methods for obtaining fibers of very small thickness. There is a wide-scale use of nanofibers, and it has a great potential in many fields, such as in medicine, biology, chemistry, electronics, environmental protection, energy-harvesting, and other. Polyvinylidene fluoride (PVDF) appears to be a promising material for fiber production for its excellent mechanical and chemical properties. It is a chemically inert substance, very resistant to thermal stress. The aim of this bachelor thesis is the preparation of PVDF fibers by electrospinning and the study of the influence of three different surfactants on the spinnability of PVDF, on the arrangement and the shape of fibers which are formed during electrospinning. The effect of surfactant concentration (1 wt%; 0.5 wt%; 0.25 wt%) on the spinning process at electrical voltages of 25 kV and 50 kV was studied. The theoretical part describes the properties and the division of polymers and looks at polyvinylidene fluoride (PVDF) as a source material in more detail. Furthermore, the electrospinning method is described, including process conditions and external parameters influencing the process of obtaining fibers. The experimental part describes the preparation of samples by electrospinning and their characterization. Fiber thickness, its appearance, arrangement, and the occurrence of defects when using individual surfactants were evaluated. It was found that the used ionic surfactants affect the thickness of the fibers and their morphology. Homogeneous fibers with a predominant arrangement in one direction, without defects, were obtained.
|
|
|
Cutting forces when drilling fibre reinforced composites
Režný, Tomáš ; Sedlák, Josef (referee) ; Humár, Anton (advisor)
This master´s thesis is focused on fibre–filled composite materials, their distribution, labeling, usage, development and production. The aim of this work is complex processing of acquired technical knowledge, and evaluation of technological rehearsals of drilling composite materials which are reinforced by glas fiber and prepreg in terms of the impact of the machined material, wor-king conditions and the tool, and its wear to the feed force value and torque.
|
|
|
Cutting forces when milling fibre reinforced composites
Martének, Libor ; Forejt, Miloslav (referee) ; Humár, Anton (advisor)
The thesis is focused on composite materials with a view to their classifi-cation, identification, usage, current trends in production and development and possibilities of effective machining. As a part of this thesis, there is an evaluation of experimentally measured values during technological testing of milling of a fibre reinforced composite with a polyester matrix reinforced by fiberglass. The technological testing was performed with a view to measure certain values, i.e. impact on machined material, working conditions for a tool and its abrasion equal to the values of components of cutting force. From the values obtained from the testing, a general analysis of cutting force when milling was created containing overall technical and economical evaluation.
|
|
| |
|
|
Experimental Investigation of the Influence of the Type of Fibres on the Behaviour of Fibre Concrete
Hanuš, Petr ; Vymazal, Tomáš (referee) ; Kocáb, Dalibor (advisor)
This diploma thesis deals with the comparison of different properties of fibre-reinforced concrete according to the type of fibres. The main monitored property is flexural strength, tested on prisms with a cross section of 150x150 mm and a length of 600 mm. Four concretes of natural aggregate and four concrete of lightweight aggregate were prepared for the experiment. There were 2 reference concrete and 6 fibre-reinforced concrete. Three types of fibres were used: steel, polypropylene and glass. More than 2500 kg of concrete was produced. The aim of the thesis is to assess the influence of fibres on the flexural strength and other characteristics of fibre-reinforced concrete.
|
|
|
Transparent fibre reinforced ceramics
Lövy, Vít ; Drdlík, Daniel (referee) ; Chlup, Zdeněk (advisor)
This bachelor thesis summarizes possibilities of toughening of ceramic materials with various types of fibres and describes the basic principles for preparation of transparent fibre-reinforced composite materials. The role of fibre-matrix interface and the measurement methods enabling estimation of the interfacial strength and other characteristics are explained. The single fibre push-out test using a standard indentation technique was chosen for interfacial parameters determination of the composite consisting from a borosilicate matrix reinforced by SiC fibres in the practical part of this work.
|
guest ::
