The master’s thesis deals with computational modelling of mechanical testing of isolated cells, particularly of single-axle tensile test. The aim is to imitate the real deformed shape known from experiments. At first, the structure of each cell component is described and analyzed according to their significance for mechanical behavior. The outline of basic mechanical tests used for cell testing is discussed next. A structural computational model comprising all components significant for mechanical purposes is created for the modelling. Those components are nucleus, cytoplasm, cell membrane and cytoskeleton. Due to the problems with convergence the model was divided into two parts. The first one treats separately the shape of cytoskeleton and the second one treats the shape of communicating components (nucleus, cytoplasm and cell membrane). Both of those partial models succeed in reaching the deformations according to the experiments.

Within the master thesis a computational model of biaxial tension test of soft biological tissues was developed. The tested specimen can be attached using clamps or hooks. The number and the size of clamps and hooks have a significant impact on the distribution of stress and strain in the centre of the specimen, where deformation is measured. Using the developed computational model, a sensitivity analysis of number and size of clamps and hooks and a sensitivity analysis of placement of clamps was elaborated. The number and size of clamps and hooks were optimized in such a way that the material’s parameters obtained by the tension test correspond to the utmost to the actual parameters of the material. By analyzing the placement of clamps, the influence of selected deviations on the outcome of the tension test was determined. Finally, a plan of the next course of action has been proposed.

This diploma thesis focuses on the influence of carbon nanotubes (CNTs) on the mechanical properties of a composite material with polyurethane (PU) matrix. The material was supplied in the form of thin films with thickness from 0.2 mm to 1.2 mm. The theoretical part of this thesis describes the production technology, properties and applications of composite materials PU/CNTs, and also deals with preparation technology and properties of both components of this composite material separately. The theoretical part also describes the principle of tensile testing of polymer materials. The experimental part of the thesis was primarily focused on comparing the tensile properties of a composite material PU/CNTs with tensile properties of pure PU. At first, tensile properties of pure PU were investigated, while the influence of various factors like strain rate, specimen thickness, heat treatment and aging was examined. In adition, stress relaxation tests and tests with strain rate jumps were performed on pure PU specimens. Then composite PU/CNTs was tested in tension and the results were compared with the results of tensile tests of pure PU. Composite material PU/CNTs was prepared with various concentrations, so it was possible to determine the effect of CNTs content on the tensile properties of the composite. The last part of this thesis deals with tensile tests of PU composite material with functionalized carbon nanotubes (PU/FCNTs), where the influence of surface modification (functionalization) of CNTs on the tensile properties composites was investigated. It was shown that the effect of both CNT and FCNT on mechanical properties of the composite is not significant. This conclusion was discussed on basis of the works of other authors, which do not unambiguously proved the positive effect of CNT or FCNT on mechanical properties of composites with polymer matrix.

Diploma thesis is focused on comparison of small punch test results and tensile test results. For experiments were chosen steel P91, 10Ch2MFA, 20CrNi2MoV, 11 416 and 42 2707. These steel are used in nuclear power engineering, or they were developed for this purpose. Basic mechanical characteristics, namely ultimate tensile stress and yield stress, were evaluated from small punch test records of observed materials. This is done via convenient correlation relationships. Obtained values were compared with values obtained by conventional tensile tests. There are mentioned own suggested correlation relationships and comparison of temperature curves gained from small punch test and tensile test in the thesis. Assessment of microstructure of observed materials and analysis of fracture surfaces was provided as well. It was found out, that for assessing basic mechanical characteristics (ultimate tensile stress and yield stress) is the best to suggest own correlation relationships, instead of using universal relationships from literature. The fracture mechanism of all types of assessed steel was ductile in entire temperature range (up to -40 °C).

The goal of this thesis was to invent and perform a testing protocol, witch can detect connective tissue mechanical and structural properties simultaneously in patients with clubfoot. Based on literature findings, it was presumed that connective tissue differ between medial and lateral side of foot. Because of low availability of specimen, it was important to draw and mention crucial alterations of testing protokol, for minimization of failed measurments. For reasons above, two specimens diveded into two samples was used for experiment. Described and discused methodics may enable of reader to insigt to drawbacks of this examination. For usability of this protocol, a setting and testing of few hypotheses was performed. One axis tensial testing with SHG microscopy examination was used in combination for experiment. One of the main result was finding, that structural differencies witch were expected, were not distinctive in samples in untensioned state. But, distingtive differencies may be drawed in tensioned samples. This differences for low number of specimen, cannot show any tendence. Results of tensial testing showed, that samples from medial side of foot can have higher toughness and higher fragility. For future acquisition of tendencies in specimen differencies, it is important to set particular...

This thesis deals with analyses of thermoplastic welded joints. Experiments were performed, in which the not-welded specimens and specimens with cruciform welded joints were tested by tensile and three-point bending test. For these measurements, polypropylene and polyethylene specimens were used. Afterwards, the analyses of specimen models were made in the ANSYS programme. The results of the analyses were compared with figures of the analytic calculations and measurements.

Placing recrystallization annealing in a manufacturing proces is often necessary in order to restore plasticity of worked blanks right before working products to its final shape. For better understanding of processes which are taking place in a material during annealing the use of in-situ techniques is favorable. Such observations enable us to watch changes in the materiál in real time at the original spot. Observations at grain-level are ideally made with scanning electron microscope – SEM by electron back-scattered diffraction – EBSD. The technique makes watching nucleation, growth and potential coarsening of recrystallized grains possible. Special construction of a tensile stage allows us to watch changes of a sample during tensile tests which can be used in observing influence of MnS inclusions on plasticity of free-cutting steels. Materials studied in this work are commonly used free-cutting steel 11SMnPb30 and its lead-free alternative 11SMnBi30.

This paper deals with the problem of abdominal aortic aneurysms (AAA), taking into account the possibility of using mechanical tests of aortic tissues for improvement of level of their constitutive models. First part of thesis deals with the introduction into the problem, description of the structure of the wall of the healthy aorta, its main components and the degenerative changes which lead to formation of AAA. This is followed by a brief excursion into constitutive modeling, which focuses closely on the description of the models used to describe the mechanical behavior of soft tissues. The theoretical part is then supplemented by a narrower selection of constitutive models used for modeling aortic wall and intraluminal thrombus, together with published results, which are reviewed and discussed at the end of this section. The main part of this thesis is devoted to tests of mechanical properties of arterial tissues. First, the methodology is presented together with the description of the customizations of the laboratory equipments together with the test rig. In addition, attention is focused on the results of mechanical tests of intraluminal thrombus, where the results of both uniaxial tensile tests and equbiaxial testing are presented. Also the influence of distance ILT from the lumen on the mechanical properties of the thrombus is examined. Another area of interest is the investigation of the effect of elastase on the chnage of mechanical properties of pig aorta. In this case, porcine aortas are experimentally tested only by biaxial testing, and the time of elastase action to alter the mechanical properties is analyzed so that the resulting tissue has a similar stress-strain response as aneurysmal tissue. Finally, the results of experimental measurements, limitations and other possible ways of research are summarized.

The thesis presents computational simulation of compression test of a nickel foam and the 3D reconstruction of micro-CT images was utilized to generate the foam’s model of geometry. Explicit FEM is used to simulate compression test using software tool LS-DYNA and the stress–deformation curve is obtained together with deformed model’s mesh used for subsequent analysis. Sensitivity analyses were performed to configure the model and ensure best fit with values obtained during real-life experiment. The ANSYS Classic environment was then used to simulate tensile test of the foam compressed to various thicknesses. The tensile moduli in three mutually perpendicular directions of nickel foam were computed and the results were compared to experimental values as well. The results of tensile test simulation revealed considerable anisotropy of the foam’s elastic behavior. It can be said that the measured experimental data correspond very well with the elastic properties obtained from simulation up to certain level of compression. Analysis of the relationship between the element size and tensile moduli showed a significant difference between fine and coarse mesh. The optimal level of discretization and the overall model configuration ensuring high level of accuracy is proposed in this thesis.

Physical aging of commercially produced polypropylene homopolymers Mosten was studied. The work is focused on monitoring the changes in physical properties of polymer in the time period 90 days from the date of preparation of the test specimen. The aging of polymers was realized at storage temperatures of 23 and 80 °C. The changes in crystallinity, yield strength, modulus, elongation and impact strength using DSC method, tensile tests and impact tests according to Charpy were monitored. Molecular weight distribution was determined by means of GPC at each polymer. Relationships between the changes in physical properties and polymer molecular weight were sought.