|
|
Fuselage and control system design of VUT 081 Kondor
Kalný, Jan ; Šplíchal, Jan (referee) ; Mališ, Michal (advisor)
This master’s thesis deals with VUT 081 Kondor composite fuselage design and control system layout design. Load computation and selection of critical load cases are made. Principal inner surfaces of the fuselage are designed with respect to basic ergonomic requirements of the crew. Construction materials are chosen and a layup of composite materials is performed. Fuselage FEM model is made in MSC Patran/Nastran system and the structure-strength analysis is given for chosen load cases.
|
|
|
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.
|
|
|
Monitoring the durability of FRP composite materials
Janák, Petr ; Prokeš,, Jan (referee) ; Bodnárová, Lenka (advisor)
This diploma thesis deals with evaluation of the conditions for laboratory testing of composite profiles with fiber-reinforced polymer (FRP). Theoretical part describes the main material properties of FRP profiles and method of manufacturing by pultrusion. Experimental part evaluates imposition of the test samples in alkaline environment and their subsequent changes in physical properties. Next part contains evaluation of cuts FRP profiles by electron microscopy in combination with element analysis. The outcome of this work is the method of evaluation of accelerated durability FRP profiles.
|
|
|
Filling materials for vertical and horizontal constructions using renewable raw materials
Gregor, Petr ; Vacula, Miroslav (referee) ; Bydžovský, Jiří (advisor)
This thesis deals with industrial hemp and its use in vertical and horizontal structures. The work is mainly focused on the fillers of industrial hemp and inorganic binder. In the practical part of the feasibility study for future use of industrial hemp in the construction industry as a filling materiál in vertical and horizontal structures. This area has been targeted by all test samples. They are presented here and evaluated and compared the results of tests on unconfined compressive strength, compressive strength, depending on the deformation density of fresh and hardened mixture and the termal conductivity of different types of inorganic binders and fillers such as hemp.
|
|
| |
|
|
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.
|
|
|
Mechanical and structural characteristics of magnesium alloys reinforced with ceramic fibers
Halmazňa, Jiří ; Moravčík, Igor (referee) ; Zapletal, Josef (advisor)
This bachelor thesis deals the study of the mechanical properties of the alloy QE22 reinforced with SiC particles and Saffil fibers. This composite was produced by infiltration particles shape of the preform with molten matrix under high pressure. Test specimens prepared from the composite and the matrix were subjected to a tension strength test and compression test. The test results show pronounced asymmetry behavior in tension and compression of the matrix and composite. Adding the reinforcement into base material leads to significant increase of elastic modul, breaking strength and yield strength while reducing plastic properties. At the end of work was the behavior of the composite compared with the theoretical composite models.
|
|
|
Linear elastic fracture mechanics and its application on study of composed materials
Dohnalík, Petr ; Ševeček, Oldřich (referee) ; Máša, Bohuslav (advisor)
The main objective of this bachelor thesis is the introduction to computational methods of fracture parameters of the crack, which terminates at the bi-material interface. The preface of the work deals with composites, where possible crack can grow in materials with different elastic properties. In this part advantages of composite materials are closely described and usual structure arrangements of the components are presented. The next part of this work is focused on the linear elastic fracture mechanics and available concepts for assessment of the body with presence of the crack in the homogenous material are described. These concepts are based on analytical expressions and, also, on numerical methods. This problem is furthermore extended in the next chapter by case, when the crack terminates perpendicularly to the bi-material interface. Here are given procedures, which can provide information about the further crack behaviour. In practical part all presented procedures have been used in order to evaluate the crack parameters in the homogenous material and for the crack terminating at bi-material interface. Necessary calculations were performed using the finite element method implemented in the commercial system ANSYS. Calculated results were compared and closely discussed in the conclusion.
|
|
|
Replacing of metal sheets with laminates
Ulrich, Josef ; Němec, Karel (referee) ; Molliková, Eva (advisor)
The aim of the bachelor´s thesis is composite material, specifically fiberglass. In the first part of this thesis fiberglass is described, their composition, chosen production technology and possibility of use. Mechanical properties and its advantages of fibreglass are compared with metal sheets. Fibreglass is described on example of particular component.
|
|
| |
guest ::
