|
|
Probabilistic model for textile concrete reinforcement and comparison with experiments
Lomič, Jiří ; Rypl, Rostislav (referee) ; Vořechovský, Miroslav (advisor)
The scope of the presented bachelor’s thesis was the establishment of a probabilistic model for material strength of textile reinforcement used for textile reinforced concrete. This reinforcement is composed of AR-glass multi-filament yarns. The goal of this thesis was to determine the potential weak spot of the textile yarn and evaluate its strength in overall. The weak spot could have been a lateral cross-connection, which narrowed the textile yarn at several locations. Another thing of interest was the observation of statistical size effect with the increasing length of textile yarn. In order to properly fit the numerical model to real behavior of multi-filament yarns, five series of experimental tensile testing has been executed in laboratory. Each series consisted of 8-10 specimens and had a different yarn length. Maximum tensile force and maximum deformation have been measured to obtain L-D diagrams for each specimen. Measured data were statistically analyzed and gave the information necessary for the identification of probabilistic model parameters. This parameter estimation has been carried out with the help of numerical and optimization methods included in Python programming algorithms. The problem statement resulted in a combination of model parameters describing the textile yarn behavior. The statistical size effect was observed corresponding to the Weibull theory. The performed study showed that the failure of the textile yarn depends on material strength of its filaments. There are no load concentrators at the location of lateral cross-connections affecting the yarn failure.
|
|
|
Preparation of glass fiber/polyester composites
Horská, Pavlína ; Richtera, Lukáš (referee) ; Čech, Vladimír (advisor)
The bachelor thesis is aimed at an influence of surface modifications of fibrous reinforcements on mechanical properties at the fiber-matrix interface in fiber reinforced composites. Glass fibers were used as reinforcements and polyester resin was the matrix. The sample of composite consisted of polymer matrix in a form of cylindrical body placed on a bundle of glass fibers. The tensile test using a materials testing machine (Zwick) was employed to evaluate adhesion at the fiber-matrix interface. Untreated glass fibers and fibers with commercial sizing were used for fabrication of composite samples.
|
|
| |
|
|
Simulation of load tensile tests tractors.
HOLÝ, Miroslav
Work is dealing with issues of tensile testing of tractors and their methods. Teoretic part is consists of today's methods of service tensile testing overview and problems of tractors movements during driving on a contour. Practical part is dealing with proposal of mechanism for weight simulation, based on stopping winch and review of appropriateness this method.
|
|
|
Simulation of tensile load testing tractors.
KAHOUN, Petr
The paper deals with tensile testing of tractors and their methods. The theoretical part contains an overview of current methods of performing tensile tests, heorists transfer power to the caster and the issue of movement of the tractor whiledriving on sloping land. The practical part deals with design of equipment to simulate load based on a brakedwinch and the evaluation of this method.
|
|
|
Fracture behaviour of ceramic cellular solids under tensile loading
Řehořek, Lukáš ; Dlouhý, Ivo ; Chlup, Zdeněk
Cellular structures are promising type of architecture for a lot of materials whether made of metals, plastic or ceramic aimed at applications where lightweight, damping and and/or stiff properties are required. For trouble-free use of this materials all types of mechanical behaviour have to be known. The tensile tests of open cell ceramic foam material based on alumina are presented in this paper and complemented of acoustic emission data and digital image correlation for measuring deformations. From the results follows that ceramic foams under tensile loading behave significantly different from widely used compressive or bending tests.
|
|
|
Prediction of Fracture Toughness Temperature Diagram from Tensile Test Parmaeters
Dlouhý, Ivo ; Hadraba, Hynek ; Šmida, T. ; Babjak, J.
Reference temperature of fracture toughness temperature diagram has been predicted based on tensile test data. Neuron analysis was applied to solve these properties correlation. For fracture toughness determination three-point bend specimens have been applied, the reference temperature being calculated applying multi-temperature method. Different strength and deformation properties have been evaluated from standard tensile specimens focusing on data from localised deformation during specimen necking. Totally 29 data sets from low alloy steels have been generated for the analysis. Good correlation of predicted and experimentally determined values has been found. Further analysis with higher number of data sets is needed to increase the accuracy of predicted values and decrease the number of input data.
|
|
|
Tahová pevnost keramických pěnových materiálů
Řehořek, Lukáš
Full understanding of mechanical properties of highly porous (cellular) ceramic foams is important due to their applications in many ranges of industrial, medical and other applications. There is described technique of mechanical testing in tension of ceramic foam material in this paper. Tested material was based on alumina ceramic and it was manufactured by slurry coating of polyurethane foam. Testing procedure consist from fixation of ceramic foam into aluminum pots by resin. Results and statistical analysis of more than 60 ceramic foam specimens loaded by tension were also described.
|
|
|
Vliv tepelného zpracování na mechanické vlastnosti slitiny FeNiB
Zábranský, Karel ; Jirásková, Yvonna
An influence of thermal treatment in the temperature range 150 - 350 °C on the structural and mechanical properties of an amorphous FeNiB alloy is investigated. The high tensile strength of 2200 MPa in the as-prepared amorphous state slightly decreases with increasing annealing temperature up to approximately 200 °C in opposite to microhardness where an increase is observed. Above 200 °C a pronounced deterioration of both characteristics is observed which reflects the embrittlement of amorphous structure without any indication of crystallization.
|
|
| |
guest ::
