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Influence of underground installation conditions on crack propagation in polypropylene pipes
Tesař, Jakub ; Gratza, Roman (referee) ; Hutař, Pavel (advisor)
The thesis addresses the issue of buried polymer pipes and the impact of installation conditions on their lifetime. Based on data obtained from standards, the values of external loads acting on the polymer pipe are determined. To apply these values in numerical calculations, the conversion of individual load components is also provided. Various stress values, simulating different burial installation conditions, are applied to a 2D model. The numerical calculation of the 2D model includes the progression of tangential stresses and their comparison with the standard. Furthermore, the influence of installation conditions on the burial depth of the pipe is analyzed. The comparison of models is conducted for both 2D and 3D models against the standard. The comparison verifies that the models are equivalent and closely correspond to the basic calculations according to the standard. The 3D model is then extended to include a crack, and the propagation through the pipe wall under the most critical load conditions is modeled. The concept of linear elastic fracture mechanics is used to estimate the lifetime of the pipe.
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Static Analysis of Steel Joints
Vojtek, Jiří ; Kytýr, Jiří (referee) ; Gratza, Roman (advisor)
Elaboration of design principles of steel joints. Creation of the finite element model in ANSYS program, the study of static behaviour near the bolt hole, deformation of the screw and the stress components of the welded joint. Comparison with the analytical formulas.
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Static Analysis of the Parts of the Textile Structures
Husáriková, Natália ; Gratza, Roman (referee) ; Kytýr, Jiří (advisor)
Bachelor thesis deals with elastic modulus determination by experimental measurements and comparison with the manufacturer's declared values. Own methodology for measuring membrane strip is proposed in this thesis. Thus determined values of elastic modulus are used in analysis models using ANSYS software. Calculated values of displacements are compared with the manually measured values of displacements during the experiment. Membrane strip with a hole is modeled in the same way.
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Static Analysis of Steel Plates with Holes
Kolláriková, Simona ; Kytýr, Jiří (referee) ; Gratza, Roman (advisor)
The bachelor thesis deals with analyzing stress concentration factor for steel plates with circular holes subjected to different types of loading. Finite element analyses of uniaxial tension, biaxial tension and bending were performed, using ANSYS software. The aim of the thesis is to compare the results of the numerical analyses with available analytical solutions and to evaluate the dependence of stress concentration factor on changes in geometry of the plates or in the computational model.
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Buckling Analysis of Thermoplastic Pipes
Procházka, Martin ; Kytýr, Jiří (referee) ; Gratza, Roman (advisor)
This thesis deals with buckling analysis of thermoplastic pipes. An experiment was conducted in which the pipes were encumbered in axis. During this experiment, the loading force was monitored and measured at the material stability loss. For these measurements, polyethylene, polypropylene and polyvinylchloride pipes were used. Afterwards, the static and buckling analysis of pipe models were made in the ANSYS programme. The models were created on the basis of the experiment results. The outcomes of the analysis were compared with figures of the theoretical calculations. In the ANSYS programme pipes were strained by external overpressure.
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Static Analysis of Textile Structures
Husáriková, Natália ; Gratza, Roman (referee) ; Kytýr, Jiří (advisor)
This work deals with the design and calculation of membrane structure for shelter placed above selected ground plan. The hyperbolic paraboloid was chosen as most optimal shape. Subsequently, three different sub-studies were conducted. In the first study, influence of mesh density on a finite element calculation model was studied. Second study deal with the effect of the geometry changes of the computational model. In the third study, deformations and tensions of membrane structure in relation to material formation calculation model was studied. For the static solution of those selected variant, structural analysis software RFEM and RF-FORM-FINDING add-on module was used. Geometric nonlinear solution was applied in the calculation.
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Analysis of Thermoplastic Pipes in a Soil Environment
Ekr, Jan ; Kuklík,, Pavel (referee) ; prof. Ing. Alois Materna, CSc., MBA (referee) ; Gratza, Roman (advisor)
The doctoral thesis deals with an analysis of thermoplastics pipes in a soil environment, in particularly, pipes performed by using trenchless technologies. In the doctoral thesis, experiments of polyethylene pipes loaded by external hydrostatic pressure were performed. The aim of the experiments was to determine a behaviour and load-bearing capacity of the polyethylene pipes loaded by external hydrostatic pressure. For the experiments, a steel pressure chamber was designed and produced which allowed loading and observing a pipe during its loss of the stability. Mechanical properties of the pipe material were determined based on the tensile and bending tests. The series of detailed numerical analyses of the pipe experiments were performed. Various material models which take into account elastic, plastic and viscous behaviour of thermoplastic materials were used. In addition, series of standardized calculations of polyethylene pipes installed using trenchless technologies were performed. The aim was to create new design diagrams for practical assessment of these pipes placed in the partially deteriorated old pipes. In the case of the deteriorated old pipe, a numerical model for determination of design coefficients was created. These design coefficients were verified with standard values. Then, the results of the numerical model were compared with the results of the more complex numerical model which better take into account pipe-soil interaction of various soil types.
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Analysis of Thermoplastic Welded Joints
Procházka, Martin ; Kytýr, Jiří (referee) ; Gratza, Roman (advisor)
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.
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Structural Analysis of Steel Members in Fire
Runštuková, Monika ; Kytýr, Jiří (referee) ; Gratza, Roman (advisor)
This thesis deals with solution of steel members under fire conditions. The goal of the thesis is to examine and compare unprotected steel members with steel members protected by different types of passive protection. Calculation is performed according to applicable design standards. ANSYS software is used for thermal and structural analysis.
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