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Lightweight composite materials for automotive applications
Sousedík, Jan ; Poláček, Petr (referee) ; Přikryl, Radek (advisor)
This bachelor thesis investigated the influence of lightening filler in the form of hollow glass microbeads on the mechanical properties of composite material. The method chosen for the preparation of composite material was pultrusion. Two types of composite material were prepared as part of the bachelor thesis, specifically epoxy-vinyl ester resin-based composites and unsaturated polyester resin-based composites. Special bulked glass fibres were used as reinforcement. The final composite material was subjected to a three-point flexural test where mechanical properties were monitored. In addition, control of the distribution and adhesion of the filler was performed by using light microscopy and scanning electron microscopy (SEM).
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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.
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3D print of composite materials
Kašpárková, Kristýna ; Zemčík, Oskar (referee) ; Zouhar, Jan (advisor)
The submitted thesis deals with a study of composite materials and processing them using 3D printing technology. The experimental part of this thesis is focused on the production of test samples with the use of additive technology Fused Deposition Modeling and Continuous Filament Fabrication. The composite samples made of common onyx material, individually reinforced with continuous carbon fiber filaments, kevlar, or fiberglass, were made with Marforged Mark Two 3D printer. The other samples made of PETG PM and PETG CFjet materials were made with Original Prusa i3 MK2S 3D printer. For technological evaluation, a tensile test was performed on samples, following the norm EN ISO 527-2:2012. Based on results obtained from tensile testing, the properties of materials strength and usability are verified and compared. In this work, the production process is proposed, and technical-economic evaluation is made. In conclusion, achieved results and overall benefits of this work are summarised.
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Properties of pultruded composites based on epoxy matrix
Huljak, Pavel ; Bálková, Radka (referee) ; Přikryl, Radek (advisor)
The theoretical part of this bachelor thesis deals with research of composite materials, especially based on polymer epoxy and polyester resins, using as reinforcement a glass fiber bundles. The practical section includes the production of composite materials and their components along with the most important testing methods. The main goal of the experimental part is to characterize the optimal conditions pultrusion production of epoxy composite material. Another point is characterization of mechanical and chemical properties of the produced composite at a number of test methods. Finally the optimized epoxy composite materials are compared with composites based on polyester resins.
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Structural design and stress analysis of ski landing gear for airplane with short take-off and landing
Hostinský, Vladimír ; Vaněk, František (referee) ; Katrňák, Tomáš (advisor)
The aim of this thesis is a design of a ski landing gear for the STOL Cruiser airplane and strength analysis of its parts with consideration of UL-2 and CS-LSA regulation requirements. First part follows the design process from a concept to detailed design. Decisions taken during the process and reasons behind them are discussed. In second part requirements of regulations for said aircraft’s landing gear are summarized and forces acting on the landing gear are calculated. This calculation is followed by a strength analysis of critical parts. Analysis of composite body of the ski carried out with a use of FEA and optimalization of its composite material layout is presented in a more detailed way.
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The use of Electrical Properties of Composites with Modified Cement Matrix
Macháň, Ladislav ; Husák, Miroslav (referee) ; Sýkora, Jiří (referee) ; Šteffan, Pavel (advisor)
The dissertation thesis is focused on practical use of composite material with modified cement matrix. Especially the area of electrical behavior of composite materials in use has been examined, for strain sensing material. The experimental part solves the problematics of corrosion of carbon and metallic materials in alkaline environment of the cement matrix. The physical design of the sensor and its fabrication using functional composite cement material have been described here. The thesis has also discussed defining the influence of temperature change and humidity change on the change of electrical parameters of integrated sensors. An important part of the thesis is the area of evaluating a series of measurements of electrical parameters under dynamic loading. The thesis analyzes designed measurement method in detail, being suitable to determine electrical properties of cement composite materials including the construction of a monitoring system that enables practical application of sensors in complex structures.
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Computational modelling of mechanical tests of composites "rubber - steel fibre"
Jarý, Milan ; Profant, Tomáš (referee) ; Burša, Jiří (advisor)
This diploma thesis focuses on realization of a computational model of fibre composite with elastomer matrix and on homogenization of properties of this composite. The work deals with computational modelling of strain-stress states which arise in mechanical tests of composites. The composites investigated by mechanical tests comprise of hyperelastic rubber matrix and steel reinforcing fibres. Computational modelling is carried out at two levels of the model. First, with three-dimensional modelling of fibres and matrix as two different materials and, second, using a homogenized model of composite; this constitutive model describes the composite as a homogeneous anisotropic material. It means that properties of fibres are encompassed into strain energy density by the mathematical formulation of the constitutive model. Further, the work deals with computational modelling of mechanical tests of hyperelastic isotropic materials used for identification of their material parameters and for verification of the selected constitutive model of material. For particular hyperelastic material, simulations of tests were carried out, namely of uniaxial tension, biaxial tension, uniaxial compression, biaxial compression, pure shear and uniaxial tension with constrained transversal strain (planar tension). Parameters of the constitutive model were determined of experimental input data. Verification of the constitutive model was carried out by comparison of the data acquired by experiments with the results of simulations of mechanical tests in FE program system Ansys. Then the authentic constitutive model of material was used for description of matrix behaviour in models of mechanical tests of composite material and results were compared with experimental data. Principal objectives which I want to attain are following: • to acquaint with the constitutive models of hyperelastic isotropic and anisotropic materials and identification of their perameters on base of mechanical tests. • to create computational models of testing specimens of composite “ rubber – steel fibre“ for different fibre arrangements and to use the created computational models in simulations of chosen tests. • to test the possibilities of computational modelling of composites with application of homogenized properties and to compare the results of both approaches. Results which were attained: • the computational models were created with the fibres modelled; the strain – stress characteristics are qualitatively corresponding to experiments, and quantitative difference is 20% - 40% (see (4.3)). • the computational models based on homogenization of properties were tested and gave results corresponding to the models with modelled fibres (see (4.4)) with a good accuracy.
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Technological analysis of the usability of new thermosetting materials for the construction of headlamps
Rašner, Martin ; Kolář, Michal (referee) ; Píška, Miroslav (advisor)
The diploma thesis presents the usability of a new thermosetting material BMC for the construction of a car headlight. In the theoretical part there are described headlights, basic characteristics and properties of plastics focussing on polymer composite materials and material testing. The practical part deals with the processing of test samples for mechanical testing by compression moulding and also with the production of real samples of reflectors and carrier frames by injection moulding. The evaluation is based on comparison of the results of the performed tests of alternative material and the currently used BMC TETRADUR TD 492/2 in HELLA Autotechnik Nova s.r.o. Basic physical-mechanical properties such as strength, stiffness, toughness and hardness are tested and monitored. The reflectors and carrier frames are assembled into the headlight and then tested according to legal and customers´ requirements for climate and vibration resistance and photometry.
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Technology of manufacturing of carbon fibre composites by hot forming
Přikryl, Pavel ; Slaný, Martin (referee) ; Zouhar, Jan (advisor)
This master’s thesis deals with the composite materials and especially aims on the carbon and glass fiber composites. It points out different composition types and manufacturing methods which reflect in the different mechanical properties, final quality of the manufactured part and also in the manufacturing time. The practical part includes two particular manufacturing methods using prepregs, one cured in an autoclave and one by hot compression moulding.
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