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Transport accessibility based on the offer of public transport in the Ledeč and Zruč regions
Šulc, Petr ; Jaroš, Václav (advisor) ; Květoň, Viktor (referee)
In this bachelor thesis, the public transport accessibility in the inner peripheries of Česko in the Ledeč and Zruč regions is analyzed. The regions are located on the boundary of the Vysočina Region and the Central Bohemian Region. The main aim is to thoroughly map the transport linkage in the given are and to explain the role of the regional administrative border and it is border effect. In the first part of the work, a traffic geographical regionalization of the area of interest has been performed based on the frequency accessibility of public transport. The reginalization is subsequently followed by a comparison of supply and demand in the field of public transport. An evaluation of the regional border influence and i tis permeability has also been included in the work. The final part evaluates the public transport accessibility of municipalities. Keywords: transport accessibility, Ledeč region, Zruč region, public transport, inner peripheries
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Evaluation of the schoolbooks used in the primary school system in the Czech Republic. Creation of a qualitative evaluation grid
Šulc, Petr ; Wildová, Radka (advisor) ; Rýdl, Karel (referee) ; Boučková, Jana (referee)
TITLE: Evaluation of the schoolbooks used in the primary school system in the Czech Republic. Creation of a qualitative evaluation grid. AUTHOR:: Department: SUPERVISOR: ABSTRACT: KEYWORDS: Schoolbook, qualitative schoolbook grid, supplemental procedure, selection of schoolbooks, pupils, teachers, parents, educational triangulation.
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Experimental modal analysis of four-planet gear-box in a steady state
Pešek, Luděk ; Bula, Vítězslav ; Šulc, Petr ; Cibulka, Jan
This research report deals with a description and presentation of results of experimental modal analysis of non-rotating four-planet gear-box specific by planets placed on flexible pins designed and fabricated by Wikov Gear. The analysis deals with an evaluation of frequency domain behavior and localization of the main inner resonances of gear-box. The results of the experiment will be used for validation and tuning of developed numerical models in IT AS CR for vibrodiagnostic purposes and description of the gear-box behavior under rotation and with additional aggregates, i.e. engine, add-on bear-box and brake.\n
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Experimental analysis of torsion vibration of hard rubbers under large deformation
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsiondeformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid to evaluation of axial stresses. It could help to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion.
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Additional axial stress of rubber cylinder at torsion deformations and large strains
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid for evaluation of additional axial stresses. It helps to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion strains.
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Measurement, analysis and identification of complex modulus of elasticity of a ruber segment pressed onto a rubber-damped whell
Pešek, Luděk ; Šulc, Petr ; Bula, Vítězslav ; Cibulka, Jan
The aim of this study was to measure, analyze and identify the complex modulus of elasticity of rubber segments pressed onto the "Hong Kong" rubber-damped railway wheels in relation to the deformation nodes of wheel vibrations. The main goal was to improve the description of the frequency dependence of the material constants of the rubber segments pressed between the disk and the rim with large pre-stress (about 20%) during the production of the rubber-damped wheel. The solution consists of two parts: a) the modal analysis of the railway wheel, b) the identification of the frequency dependence of Youngś modulus and the loss factor of the wheel rubber by the finite element method. The obtained results are in good accordance with the behavior of hard synthetic rubber.
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New method of complex modulus estimation of prepressed rubber by the FE model parameter tuning – rubber-damped wheel application
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Boháč, T. ; Tašek, H.
The main goal of the study was to develop a method for estimation of the frequency dependence of material constants of the pre-pressed hard synthetic rubbers. It was motivated the need to identify material constants, i.e. Young modulus and loss factor, of rubber segments pressed between the disk and the rim of a rubber-damped railway wheel. The rubber segments are pre-pressed about 20% strain level during the production of the wheel. Hard synthetic rubber materials exhibit complex thermalfrequency behavior with nonlinear dependence on static preload. The standard experimental procedures that evaluate the frequency dependence of the material are based on the vibrations of a cantilever beam that consists of a metal and a rubber layer. The new estimation method of the complex modulus of elasticity of rubber is based on the tuning of rubber constants of an FE wheel model according to the results of natural frequencies and mode shapes of the wheel ascertained from the experiment. Numerical FE model of the wheel consisted of the cyclic model of 1/24 sector of the wheel with an angle of 15° and containing one rubber segment and was created in ANSYS 14.5. Damping model of rubber is described by a special case of proportional damping. For calculating eigenvalues of the problem, the Lanczos method was used for the wheel as an undamped system and QR damped method for the damped system. The experimental modal analysis of the rubber-damped wheel pressed on the shaft took place at room temperature in the dynamic laboratory. Modal tests were performed in configuration with an exciter acting first in the axial direction and consequently in the radial direction of the wheel. Responses to the exactions were measured in three directions at 144 points. The identification of eigenvalues and mode shapes of the wheels was made separately for excitations both in radial and in axial direction.
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Stress analysis under torsion loading hard rubber for a large deformation and hyperelastic behaviour
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Cibulka, Jan ; Košina, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to enhance the theoretical background for experimental evaluation of material behaviour of hard rubbers on our test rig. First the Mooney Rivlin model (MRM) for shear case of loading was developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. Then the tuned MRM cylindrical model was tested under torsion loading for evaluation of stress state. Besides the radial distribution of shear stress and strain the attention was paid for evaluation of axial stresses. It could help to assess the influence of the tension stresses on the tangential deformations of the test sample during large torsion.
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Study of additional parametric excitation on reduction of forced resonance vibrations
Šulc, Petr ; Pešek, Luděk
This contribution deals with active reduction of unacceptable vibrations by means of parametric excitation fulfilling certain conditions. It is studied on the case of 2DOF system with additional parametric excitation under harmonic force excitation. On the contrary to the selfexcited vibrations or parametric resonances, the parametric excitation of the forced resonance vibrations of the studied system leads to suppression of the resonance not by "damping" but "splitting" effect.
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