|
|
Effect of radiation cross-linking of PA on its thermomechanical properties
Mikel, David ; Tocháček, Jiří (referee) ; Jančář, Josef (advisor)
The influence of ionizing radiation on thermomechanical properties of polyamide reinforced by glass fibers was studied in this bachelor thesis. Ionizing radiation caused reduction of crystallinity, melting and crystallization temperature of polyamide. Tensile strength and tensile modulus increased due to irradiation, meanwhile elongation at break decreased. Notched and unnotched impact strength at laboratory and lower temperature increased with dose of radiation and after reaching the maximum it decreased for higher doses of radiation. Heat deflection temperature increased significantly with dose of radiation and after reaching the maximum it decreased for higher doses of radiation, too. Based on measured properties of investigated material was chosen optimal dose of radiation. Radiation rosslinking is an appropriate technology for increasing dimensional stability at elevated temperatures of polyamide reinforced by glass fibers.
|
|
|
Mechanical properties of polymers produced by 3D printing technology
Král, Filip ; Moravčík, Igor (referee) ; Válka, Libor (advisor)
The thesis deals with the dependence of mechanical characteristics on the anisotropy of polymers Nylon 12 and Ultem 9085 made by a 3D printing technology Fused Deposition Modeling (FDM). The evaluation of the material characteristics was performed on the basis of tensile and non-instrumental impact tests. It was proven that the material characteristics are strongly dependent on anisotropy, i.e. on layer thickness and raster angle for both types of polymers.
|
|
|
Mechanical properties of materials for 3D printing
MIKUDA, Martin
This bachelor's thesis deals with the comparison of the mechanical properties of PLA 3D printing materials produced in the Czech Republic. Materials from the manufacturers Prusa, Filament PM and Aurapol were selected for comparison. Materials were compared using ovality measurements and standardized mechanical tests. During the measurement, it was found that the most accurate filament is supplied by the Prusa manufacturer. For this manufacturer, the ovality was 0.21 +- 0.02%. From the results of the tensile test, the material with the highest tensile strength values was determined. It is a Filament PM material that reached values of 48.6 +- 0.8 MPa for printing using perimeters and 33 +- 2 MPa for printing using two perimeters and 100% filling. In the impact resistance test, it was found that depending on the orientation of the printing layer, we can achieve double the impact resistance. From the results of the tests, it was determined that for printing where mechanical resistance is required for the product, it is most appropriate to choose the material from the manufacturer of Filament PM. For other prints, it is possible to choose the cheapest material from Aurapol. The difference in mechanical properties is not significant for the most expensive Prusa material and the cheapest material Aurapol. For some properties, Aurapol material achieved better results than Prusa.
|
|
|
Hodnocení kvality pomocí nedestruktivních technologií
Šarocký, Robert
This diploma thesis is focused on evaluating quality of materials which are manufactured by additive method of production. The thesis describes methods of additive production and their materials. Furthermore, the thesis deals with the methodology of investigation of mechanical properties of products of additive production. The following part of the thesis describes production of samples from two different types of material. Subsequently, these samples were tested by acoustic emission in the impact bending test and the tensile strength test.
|
|
|
Mechanické vlastnosti dřeva smrku ztepilého napadeného lýkožroutem smrkovým v různých stádiích poškození
Brüstl, Pavel
This thesis deals with the determination of mechanical properties of Norway spruce wood attacked by spruce bark beetle at various stages of damage by means of bending tested samples and impact strenght according to European standards. Due to the current occurrence of bark beetle calamities is only wood from these logs largely marketed. The main objective was to find out whether the wood affected by spruce bark beetle has comparable mechanical properties with undemaged wood and its subsequent use in construction as a construction timber. We did not notice any significant changes in the bending test where the modulus of rupture and modulus of elasticity of the wood affected by spruce bark beetle were comparable to those of the undamaged. On the contrary the impact strength test showed a decrease in the values for the maximum strength and toughness of the damaged wood compared to the undamaged. This shows us that wood affected by spruce bark beetle is becoming more fragile than undamaged trees. By done research we have found out that the bending strength of the wood affected by spruce bark beetle is not significantly different compared with undamaged trees. The theoretical part includes issues related to the testing of wood and its strength characteristics. Afterwards, there are listed the results of a statistical evaluation.
|
|
|
Vliv podmínek skladování lepených materiálů na bázi dřeva na houževnatost lepených spojů
Steindlberger, Jan
The aim of this bachelor thesis is to analyze the influence not only of climatic conditions, but also of used adhesive and, last but not least, of the material used, on the toughness of bonded joints. Impact strength is determined when using a cutting machine, the Charpy Hammer. Acacia wood and beech plywood were selected as the gluing material. Three adhesives from different polyvinyl-acetate-based adhesives were used to bond these materials. The tested samples were before the cutting exposed to three different climatic conditions; standard climatic conditions, cold climatic conditions and extreme conditions at an elevated temperature and humidity.
|
|
|
Mechanical properties of polymers produced by 3D printing technology
Král, Filip ; Moravčík, Igor (referee) ; Válka, Libor (advisor)
The thesis deals with the dependence of mechanical characteristics on the anisotropy of polymers Nylon 12 and Ultem 9085 made by a 3D printing technology Fused Deposition Modeling (FDM). The evaluation of the material characteristics was performed on the basis of tensile and non-instrumental impact tests. It was proven that the material characteristics are strongly dependent on anisotropy, i.e. on layer thickness and raster angle for both types of polymers.
|
|
|
Evaluation of Impact Strength and Bending Strength of Thermally Modified Beech Wood with the False Heartwood
Vykoukal, Jakub ; Zeidler, Aleš (advisor) ; Procházka, Jiří (referee)
This bachelor thesis examines the influence of thermal modification on beech wood, with taking into account the difference of properties of healthy samples and samples with false heartwood. Thermal modification took place in two stages (165 ° C and 210 ° C), which are together with the untreated set tried on impact strength, bending strength (static modulus of elasticity) and the dynamic modulus of elasticity. The additional measured properties were density, equilibrium moisture and change of color spectrum. The first level of treatment slightly increased the bending strength and the static modulus of elasticity, residue tests, however, showed a negative effect on the other measured properties of the heat treated samples. It has been shown also that false heartwood has a clearly negative effect on the measured mechanical properties.
|
|
|
Effect of radiation cross-linking of PA on its thermomechanical properties
Mikel, David ; Tocháček, Jiří (referee) ; Jančář, Josef (advisor)
The influence of ionizing radiation on thermomechanical properties of polyamide reinforced by glass fibers was studied in this bachelor thesis. Ionizing radiation caused reduction of crystallinity, melting and crystallization temperature of polyamide. Tensile strength and tensile modulus increased due to irradiation, meanwhile elongation at break decreased. Notched and unnotched impact strength at laboratory and lower temperature increased with dose of radiation and after reaching the maximum it decreased for higher doses of radiation. Heat deflection temperature increased significantly with dose of radiation and after reaching the maximum it decreased for higher doses of radiation, too. Based on measured properties of investigated material was chosen optimal dose of radiation. Radiation rosslinking is an appropriate technology for increasing dimensional stability at elevated temperatures of polyamide reinforced by glass fibers.
|
|
|
Návrh inovace konstrukční skladby dřevěného jádra snowboardu
Bátěk, Silvestr
This diploma thesis describes the comparison of two different kinds of structures of snowboard wooden core. One is a combination of ash and poplar (long known and reliable structure currently used by the company Hackboards Ltd.). The other is tested combination when abele is replaced by lighter balsa wood. For both types of core the same types of fibreglass, base and top sheet are used (triaxial fibreglass, sintered base, protective top sheet). The individual mouldings were cut to the required sample on which the tests were made for the determination of bending strength according to ČSN EN 310 and impact bending according to ČSN EN ISO 179-1. Then according to ČSN EN 322 and ČSN EN 323 the moisture and density of used wooden boards were set. The measured results were evaluated and presented in charts and tables in the experimental part of this work.
|
guest ::
