Academic literature on the topic 'Vnitřní trhliny'

This thesis deals with the relation between structure and resistance to failure by the mechanism of slow crack growth (SCG) in HDPE. In the theoretical part there are summarized previously acquired knowledge about the production of PE and about the relation between structure and resistance to failure by the SCG mechanism. In the experimental part, three samples of HDPE with the same melt index MI and the same content of copolymer 1- hexene were synthesized by using three chromium catalysts commonly used for polymerization in industry. There samples were analyzed by GPC-IR-MALS and TREF in order to determine the distribution of side chain branches. The results were discussed with respect to the time to failure FNCT.

The aim of this thesis was to perform the classification of defects of emerging in a specific type of steel castings made by company UNEX Foundry, Ltd. and then determine the conditions of their origin. This is mainly discontinuity of casting material. The next step was to propose the corrective measures eliminating creation of these defects.

Composite materials with laminated structure provide advantages which are utilised during component design. Low density, temperature and chemical stability are the profitable properties predetermining application of ceramic laminates. The main obstacle for wide spread of ceramic materials is their inherent brittleness. Therefore, in this thesis, the crack propagation in ceramics laminates has been extensively studied. Laminated structures with various volume fractions of components (alumina and zirconia) were prepared by electrophoretic deposition. Evaluation of crack propagation through the interface and determination of basic mechanical properties was conducted on the basis of extensive literature search. Crack deflection originated in both presence of internal stresses and differences in elastic modulus during the crack interface passing was monitored. A special type of specimen geometry was employed with the aim to set arbitrary angle between crack and interface. It was experimentally found that the degree of crack deflection is dependent on entering angle and volume fraction of components. Higher crack deflection was already found in the bulk of the test piece comparing to the test piece surface. The 3D fracture surface reconstruction generated using laser confocal microscopy was used in this detailed crack propagation study. Further basic elastic and strength characteristics of laminates were determined and compared to those obtained from monolithic materials. The validity of the mix rule for elastic characteristics was confirmed by comparing of elastics modulus. The most reliable method for elastic modulus determination was marked the dynamic resonance method due to low scatter and consistency in measurement. The flexural strength of all laminates tends to be close to the flexural strength of the weakest component. Therefore the mix rule is not applicable for flexural strength estimation on the contrary of elastic characteristics. The change of component volume fraction leads only to change of flexural strength scatter. Thanks to gained knowledge about crack propagation and basic characteristic determination will be possible to design ceramic laminates more efficiently for given needs of application.

The main goal of this thesis is to get an insight into a field of non-destructive testing using potential drop techniques that have nowadays become the standard not only in the fatigue and loading tests but also in the industry. These methods can serve to non-destructively and continuously measure material specimens, thickness, corrosion losses, deformations, spectroscopy and detection and analysis of crack geometry. They can help to identify materials and measure material changes over time. The second part of this thesis deals with designing the aperture for detection of cracks in steam and product piping using potential drop technique modified by Ing. Ladislav Korec, CSc. Last part deals with extensive testing, experimenting and evaluation of the aperture.

The diploma thesis deals with design and comparison of variants of cast-in-place concrete sewage tank made from reinforced concrete and pre-stressed concrete. The layout of sewage tank is rectangular. The tank is in longitudinal way divided into two chambers. The tank is not roofed and is partialy embedded in the ground. The design for ultimate limit state and for service limit state is made for both variants. There is focus on generation and development of cracks in service limit state. For calcuation of internal forces is used model made in software SCIA Engineer, based on finite element method. The reinforced concrete and pre-stressed concrete versions are compared in last part in term of volumes of materials needed. Also there are proposed possible savings.

This thesis deals with the design and assessment of all supporting parts of a cast-in-place reinforced concrete tank of sewage plant in the village Vrbice. Tha main parts of the thesis are the technical report, static analysis, drawing documentations, construction process and visualisations. Calculation of internal forces was performed by the software Scia Engineer and verified by manual calculation. The drawing documentation constists of shape and reinforcement drawings of supporting parts.

The matter of this thesis is static design and examination of prestressed storage tank to 50000 tons of sugar. Computational model of the steel roof structure is processed and its effect on the silos. Loads is provided of sugar. Optimal design is performed and assessment ultimate and serviceability limit state reinforced concrete and prestressing horizontal silo wall including local load. Next, it is performed the design of a reinforced concrete of the plane bed and column and assessment at the ultimate limit state. The thesis is also drawing documentation, technical report and visualization of construction process. The aim of this work is to the design of the main components based on the required storage capacity tank, mechanical properties of the stored material and technical amenities.

The matter of this diploma thesis is a static storage tank for petroleum substances, the study of a solution for appropriate shape of shell and its effort to dihedral for roofing, and the study of effect of the storage of inner roofs walls of the tank to the size of the internal forces. The internal walls are carried out by the method of finite elements in the engineering program Scia Engineering 2013 and on the basis of it, designing of the framing sections of the tank. There is a calculation part of the lower horizontal bias wreaths of the shell and internal supporting wall. All the components are assessed on the 1st limit state of the load-bearing capacity and the 2nd limit state of the application (emergence cracks, limiting voltage in the concrete and a prestressing steel). The existing external wall is assessed only on the marginal status load of carrying capacity. The part of diploma thesis is also drawing documentation, accompanying report and technical report. The goal of the diploma thesis was to design the tank without an occurrence of the cracks in the concrete so as the vertical wall was prestressing only in the horizontal direction and the optimal proposal roof tanks as an addition.

The master thesis is focused on design and static calculations of fiber reinforced concrete ground slab. The assessed structure is composed of 6 floors and 2 underground floors. A ground slab is based on piles and designed as a waterproof structure. The structural analysis program RFEM 5.05 has been used for calculation of internal forces.

They analyzed the various factors affecting the design or evaluation of structural glass. Within evaluation of structural glass element is checked selected concepts of linear elastic fracture mechanics. For modeling is used programme system ANSYS based finite element method. The results are compared with the analytical solution.