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Contribution to modelling of bladed model disk with dry-friction contacts in tie-bosses
Pešek, Luděk ; Šnábl, Pavel ; Šulc, Petr ; Půst, Ladislav ; Bula, Vítězslav
The experimental set-up for studying dynamical behavior of the bladed wheel with pre-stressed dry-friction contacts in tie-bosses was built. The numerical solution of the turbine bladed wheel with tiebosses based on 3D finite element method with surface to surface dry friction contact model is proposed. Comparison of experimental and preliminary numerical results of dynamical behavior and damping estimation of our bladed wheel design yielded a reasonable agreement. Limitation of the non-linear solution due to dry friction contacts is HPC computations and long computation times. The contribution will deal with the achieved results.\n
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Testing of HPD model of dissipated energy of hard rubbers at torsional finite Deformations and temperatures
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Šnábl, Pavel
This paper deals with the temperature dependence of hard rubber behavior on torsional harmonic loading. This behavior was described by dissipated and deformation energy of the rubber. This knowledge was used to test the validity of the hyperelastic proportional damping (HPD) in dependence on temperature and finite deformations. From the experiments, the dissipated energy was obtained from the hysteresis loop in one period of harmonic load, depending on the temperature for the given frequency. The deformation energy was determined from the shear stress analysis on the surface of the cylinder considering hyperelasticity. The constants of these models were obtained by optimizing the stress-strain curve from the shear analysis on the cylinder surface. With this optimization, the Yeoh hyperelastic model was chosen.
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Influence of variable stiffness in toothed gears on the internal dynamics of the planetary gearbox
Šulc, Petr ; Pešek, Luděk ; Maturkanič, Dušan
This contribution is continuation of the work of above mentioned authors to whom this paper is dedicated. Their latest work dealt with numerical modelling of dynamics of planetary gearboxes with four satellites on flexible pins. They programmed the gear-box model in SIMULINK and now the model is an object of numerical investigations. This contribution describes the numerical model of the planetary gearbox. The numerical simulations are aimed to study an influence of variable stiffness in toothed gears on the internal dynamics of the planetary gearbox.
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Rozvoj malých měst ve středním Posázaví
Šulc, Petr ; Perlín, Radim (vedoucí práce) ; Vaishar, Antonín (oponent)
Diplomová práce se věnuje rozvoji tří malých měst ve středním Posázaví. Předpoklady rozvoje jsou hodnoceny na základě realizace a způsobu financování projektů a komunikace vedení města s širokou veřejností. Cílem práce je vyhodnotit, jaké projekty města realizovala za sledované časové období a zdali tyto projekty pomohly k rozvoji města. V teoretické části práce jsou definovány jednotlivé typy fungování veřejné správy a faktory rozvoje s důrazem na lidský a sociální kapitál. Dále práce diskutuje přístupy ke strategickému plánování jako hlavnímu nástroji sloužícím k úspěšnému rozvoji. Do teoretické části je také zařazena kapitola o rozpočtu se větším zřetelem na dotace. Z teoretické části vzešly dvě hypotézy, na které se snaží následně odpovědět provedené analýzy. Praktická část je postupně rozdělena na primární a sekundární analýzu. V rámci sekundární analýzy byly zhodnoceny vnitřní faktory rozvoje a realizované projekty, které byly rozčleněny na rozvojové a udržovací. Pro tuto analýzu byly využity volně dostupné zdroje. Informace pro primární analýzu byly získány z rozhovorů s klíčovými aktéry vybraných posázavských měst. Primární analýza sloužila jak k ověření výsledků analýzy sekundární, tak k získání nových poznatků důležitých k zodpovězení stanovených hypotéz. Z výsledků obou analýz je jasné,...
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Deformation energy of Yeoh hyperelastic model and constant hyperelastic proportional damping
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Košina, Jan ; Cibulka, Jan
The paper deals with a proposal of the dissipated energy of hard rubbers as a function of the deformation energy expressed by the Yeoh hyperelastic model. Then the deformation energy may be dependent only on the first invariant of deformation. Based on the experiment, a “hyperelastic proportional damping” (HPD) is proposed for hard rubbers under finite strains. It is analogical to the model of proportional damping in the elastic theory, i.e. the dissipated energy is proportional to the deformation energy multiplied by the frequency of dynamic harmonic loading. The Yeoh model is chosen since the deformation function is dependent only on the first strain invariant for a description of the simple shear of a surface cylinder. The constants are used to an enumeration of the deformation energy of the Yeoh model for the specific cases of tested rubbers. The coefficients of hyperelastic proportional damping are evaluated on the basis of experimental results,too.
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Dissipated energy of hard rubbers at dynamic torsional finite straining
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 find the dependency the dissipated energy on the deformation energy. Based on the results of an experiment, a function of dissipation energy of hard rubbers for finite strains using the theory hyperelasticity was proposed herein analogically as a prportional damping for elastic theory. Samples of hard rubber of different hardness (EPDM, Silcone) were dynamically tested on the developed torsional test-rig at different frequencies, amplitudes. First the Mooney Rivlin model (MRM) for a shear case of loading was analytically developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. These constants were used to obtain the deformation energy of the MRM models. The coefficients of hyperelastic proportional damping relating a dissipated energy to a strain energy were evaluated for tested rubbers on the basis of experimental results.
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Design of low-subsonic blade cascade model for aero-structural dynamic testing
Pešek, Luděk ; Hála, Jindřich ; Šulc, Petr ; Chládek, Štěpán ; Bula, Vítězslav ; Uruba, Václav ; Cibulka, Jan
Low-subsonic blade cascade model for aerodynamic testing was design in the Institute. The aim is to study the flow dynamics and flutter phenomenon in the cascade with moving blade profiles. The numerical calculations of two proposed cascades were performed for analysis of influence of stagger angle, incident angle of flow and inter-blade phase angles of the relative movement of blades. The results of numerical simulations of fluid dynamics of non-stationary flow both as viscid and non-viscid are presented. Futhermore the solution of the physical model of the designed cascade including excitation of profiles, measuring of the profile displacement and aerodynamic forces are described.
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Proposal of hyperelastic proportional damping as dissipated energy model of hard rubbers
Šulc, Petr ; Pešek, Luděk ; Bula, Vítězslav ; Košina, Jan ; Cibulka, Jan
The paper deals with a stress analysis of hard rubber under large torsion deformations. This study was motivated by effort to find the dependency the dissipated energy on the deformation energy. Based on the results of an experiment, a function of dissipation energy of hard rubbers for finite strains using the theory hyperelasticity was proposed herein analogically as a proportional damping for elastic theory. Samples of hard rubber of different hardness (EPDM, Silicone) were dynamically tested on the developed torsional test-rig at different frequencies, amplitudes. First the Mooney Rivlin model (MRM) for a shear case of loading was analytically developed and then MRM constants were attained by fitting of the MRM to the experimental torsion-deformation curve. These constants were used to obtain the deformation energy of the MRM models. The coefficients of hyperelastic proportional damping relating a dissipated energy to a strain energy were evaluated for tested rubbers on the basis of experimental results.
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