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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.
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Corrosion resistance of PA and PC components
Mikel, David ; Pospíšil, Ladislav (referee) ; Jančář, Josef (advisor)
The influence of two lubricating and cleaning agents and diesel fuel on environmental stress cracking of polyamide reinforced by glass fibers and polycarbonate was studied in this master thesis. Testing of environmental stress cracking was performed by the method of critical bending deformation. Bergen elliptical strain jig was used for testing. The test liquids caused varying levels of environmental stress cracking of amorphous polycarbonate, but they did not cause environmental stress cracking of glass fiber reinforced polyamide. The test method used allows testing the resistance of both materials against environmental stress cracking of any liquid. The results can be used to design products that are expected to be exposed to corrosive liquids. Quantification of the influence of stress free corrosion on the static and impact properties of polycarbonate and glass fiber reinforced polyamide was performed by accelerated test. Specimens were exposed to test liquid and an elevated temperature of 70 °C. The mechanical properties of the tested materials were significantly affected by elevated temperature exposure. The yield strength of the polycarbonate has increased and the toughness has decreased due to physical aging. The tensile strength of glass fiber reinforced polyamide has increased due to a decrease of the moisture content of the material.
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Možnosti zvyšování tahových vlastností traktoru
Šutera, Pavel
The diploma thesis deals with selected possibilities of increasing the efficiency of the transfer of power from the motor to the mat for achieving higher tensile properties. The theoretical part describes the issue of torque transmission, a brief overview of the most commonly used engines, transmissions, chassis, tires, belts and their influence on the tractor's characteristics. There are a number of statements that prove the practical part of the diploma thesis. In the practical part, an evaluation of the influence of load on the driving wheels on the tensile properties of the Case IH Magnum 370CVX wheeled tractor, the evaluation of tire inflation pressure measurements on the tensile properties of the John Deere 8320R and the tensile tests of the John Deere 8320RT tracked tractor. John Deere tractors are compared with each other.
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Corrosion resistance of PA and PC components
Mikel, David ; Pospíšil, Ladislav (referee) ; Jančář, Josef (advisor)
The influence of two lubricating and cleaning agents and diesel fuel on environmental stress cracking of polyamide reinforced by glass fibers and polycarbonate was studied in this master thesis. Testing of environmental stress cracking was performed by the method of critical bending deformation. Bergen elliptical strain jig was used for testing. The test liquids caused varying levels of environmental stress cracking of amorphous polycarbonate, but they did not cause environmental stress cracking of glass fiber reinforced polyamide. The test method used allows testing the resistance of both materials against environmental stress cracking of any liquid. The results can be used to design products that are expected to be exposed to corrosive liquids. Quantification of the influence of stress free corrosion on the static and impact properties of polycarbonate and glass fiber reinforced polyamide was performed by accelerated test. Specimens were exposed to test liquid and an elevated temperature of 70 °C. The mechanical properties of the tested materials were significantly affected by elevated temperature exposure. The yield strength of the polycarbonate has increased and the toughness has decreased due to physical aging. The tensile strength of glass fiber reinforced polyamide has increased due to a decrease of the moisture content of the material.
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Vliv rozložení hmotnosti traktoru na jeho tahové vlastnosti
Friedl, Pavel
This thesis deals with the nowadays tractors construction. Theoretical part is divided into three subgroups - tractor engine, powertrain and chassis. The problematics of emission limits is discussed in the first subgroup. Major part of second subgroup is devoted to hydro mechanical powertrain. Finally wheeled and tracked chassis construction, tyre construction and automatic tire inflation systems are described at the end of theoretical part of the thesis. Practical part devotes to methodology and field measurements with the aim on various weight distribution of the tractor. Measurements were realized with CASE IH Magnum 370 CVX tractor. Obtained values are processed into graphs and charts. Subsequently the dependencies of wheel slip and pull power properties on pulling force of the tractor are created. Conclusion of the thesis provides recommendations for optimal weight distribution of the tractor for pull power operations.
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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.
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Hodnocení tahových vlastností traktoru Zetor s pohonem 4K4 a 4K2
Novotný, Michal
The vast majority of currently produced tractors have a 4K4 drive. Despite this fact, when purchasing a new tractor utilized mainly for transport on paved surfaces or on the road, the question arises whether to invest less money and prefer a tractor with a 4K2 drive. Differences in price of a new tractor with front drive or only with driven axle can reach tens to hundreds of thousands of crowns, according to the selected type and model. This thesis may contribute to the correct decision when purchasing a new tractor by comparing the tensile properties of the same tractor with 4K4 or 4K2 drive and offering a direct comparison of the difference of tensile properties of the tractor, which are highly dependent on traction and slippage of the drive wheels. It is at the discretion of each user whether to invest more funds into tractors with a 4K4 drive and take advantage of the tractor's maximum tensile properties or to save and buy a tractor with a 4K2 drive for a price of lower utility values.
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