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NUMERICAL STUDY OF UNIVERSAL BEAM (I SECTION) UNDER BENDING LOAD WITH CRACK
Morán, Alvarez J. ; Seitl, Stanislav ; Miarka, Petr
The structural components often contain cracks as a results of applied load. Therefore, these cracks must be studied how they affect the structural behavior and the total service life-time of the component. Bearing beams of the bridges have usually cross-section in the shape of an I-profile. In this contribution, a numerical parametric model was made in order to study the influence of the crack length, Poisson's ratio and web thickness on the stress distribution in the structural element, for which a three-point bending specimen was applied. The model is based on the linear elastic fracture mechanics (LEFM), with focus set on the determination of the stress intensity factor, as it is one of the main parameters used in the description of the stress fields in vicinity of the crack tip.
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The influence of multiple cyclic loading on the properties of ordinary concrete
Pešek, Lukáš ; Topolář, Libor (referee) ; Kocáb, Dalibor (advisor)
The diploma thesis deals with the observation of elastic and strength properties (primary moduli of elasticity and Poisson's ratio) of ordinary concrete before and after multiple cyclic loading. Test specimens with cylinder shape and diameter of 150 mm and height of a 300 mm were cyclically loaded up to 5000 loading cycles with resistive strain gauges to measure deformations so static modulus of elasticity could be determined. Further on the test specimens were performed tests to determine the dynamic modulus of elasticity and whole testing was finished with compressive strength test. The results were processed and selected properties evaluated in tabular and graphical form to determine statistical data and formulate a conclusion.
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Stiffness anisotropy of Brno Tegel determined by continuous loading in triaxial tests
Mohyla, Tomáš ; Boháč, Jan (advisor) ; Miča, Lumír (referee)
This Thesis deals with the determination of Young's modulus and Poisson's ratio from the measurement of small strains (10-3 - 10-5 ) in triaxial tests on the overconsolidated Miocene clay from Moravia (Brno Tegel). The tests were performed in a hydraulic triaxial chamber, fitted with submersible local LVDT sensors, which were fixed directly on the sample. The tests were carried out on undisturbed samples of standard height and diameter (76x38 mm). There were three types of tests - isotropic loading probe, axial loading probe and shear test to the failure. The measured data were analyzed and the results were discussed. The research part of the Thesis briefly describes previous works on stiffness of Brno Tegel and also some works on stiffness of similar material to Brno Tegel - London Clay.
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Methodological detection solution scaffolds response to mechanical stress, depending on the degree of hydration
Mejzlíková, Kateřina ; Jelen, Karel (advisor) ; Kubový, Petr (referee)
Title: Methodological detection solution scaffolds response to mechanical stress, depending on the degree of hydration Objectives: Determining the extent of lateral deformation u scaffolds made of PVA polymer electrospinning technique. Identify the extent of differences in transverse deformation for different groups of nanofiber scaffolds made of PVA polymer electrospinning technique. Methods: Research scaffolds, we used a measuring device μ-tester, which has two jaws. For the measurement, we chose uniaxial tension test in -tester and record the fluorescence microscope was used with HD camera Olympus 320 for online video recording. Results: The results of this study showed that the ratio of the samples U: L and crosslinking time affects the degree of lateral deformation of the samples scaffolds. Samples scaffolds are compressible, some groups even reached the limits of incompressibility 0.5 Poisson's ratio. Keywords: Poisson, Poisson's ratio, scaffold, nanofiber scaffold, scaffold hydrated, electrospun scaffold, lateral deformation
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Stiffness anisotropy of Brno Tegel determined by continuous loading in triaxial tests
Mohyla, Tomáš ; Boháč, Jan (advisor) ; Miča, Lumír (referee)
This Thesis deals with the determination of Young's modulus and Poisson's ratio from the measurement of small strains (10-3 - 10-5 ) in triaxial tests on the overconsolidated Miocene clay from Moravia (Brno Tegel). The tests were performed in a hydraulic triaxial chamber, fitted with submersible local LVDT sensors, which were fixed directly on the sample. The tests were carried out on undisturbed samples of standard height and diameter (76x38 mm). There were three types of tests - isotropic loading probe, axial loading probe and shear test to the failure. The measured data were analyzed and the results were discussed. The research part of the Thesis briefly describes previous works on stiffness of Brno Tegel and also some works on stiffness of similar material to Brno Tegel - London Clay.
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