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Using generalized functions in continuum mechanics
Procházka, Petr ; Netuka, Horymír (referee) ; Pochylý, František (advisor)
Tato práce se zabývá využitím distribucí neboli zobecněných funkcí k řešení nestacionárních okrajových problémů v mechanice kontinua. Nejprve je zavedena teorie distribucí a jejich definice jako spojitých lineárních funkcionálů na prostoru testovacích funkcí. Druhá část teoretické kapitoly představuje Laplaceovu integrální transformaci. Následující kapitola se věnuje řešení průhybu nosníků pod vlivem nespojitého časově proměnlivého zatížení. Jejím výsledkem je vytvoření obecného modelu řešení průhybových čar nosníků vužitím distribucí. Poslední kapitola se zabývá řešením nestacionárního proudění v trubicích spojených hydraulickými prvky.
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The impact of HVAC systems on the acoustic microclimate of clean rooms
Jelínek, Ondřej ; Mathauserová, Zuzana (referee) ; Papež,, Karel (referee) ; Rubina, Aleš (advisor)
The work description is to create a system of measures to prevent the spread and the consequent attenuation of sound in air handling systems serving the cleanrooms. The thesis presents a solution to noise attenuation in the investigated area, and in HVAC duct, which uses a commercially available material in the form of sound insulation hoses. In the systém solution is part of the work focuses on the optimal design of terminal elements to distribute air in a clean room. Processing methods utilize theoretical and experimental approach. The experiment comprises a unique analysis of the sound insulation properties of selected products under specific conditions. The data obtained are analyzed and incorporated into the framework of this work created program module for determining the attenuation and noise propagation in an enclosed space. Math and physical dependence are programmed into their own DLL by programming language DELPHI.
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Formulation the Methodology for Analysis the Seismic Response of the Piping Systems with Viscose Dampers
Chlud, Michal ; Salajka, Vlastislav (referee) ; Kanický, Viktor (referee) ; Malenovský, Eduard (advisor)
Viscous dampers are widely used to ensure seismic resistance of pipelines and equipment in nuclear power plants. Damping characteristics of these dampers are nonlinearly frequency dependent and thus causing complications in computational modelling of seismic response. Engineers commonly use two ways to deal with this nonlinearity: The first option is to consider damper by means of “snubber”. This is essentially linear spring element that is active for dynamic load and does not resist static loads. Snubber behaviour during seismic event is described by a equivalent stiffness (sometimes called pseudostiffness). The equivalent stiffness could be defined by the iterative calculations of piping natural frequencies and mode shapes taking into account seismic excitation. However, in complicated structures such as the main circulation loop of nuclear power plant the iterative calculation is difficult and could bring significant inaccuracies. On the other hand, the benefit of such modelling is a possibility to apply the commonly used linear response spectrum method for a solution. The second option is to describe damping characteristics using suitable rheological model. The seismic response is than determined by direct integration of the equations of motion. The behaviour of dampers is described exactly enough but the calculation and post-processing, especially nodal stresses time-histories, are time consuming. The goal of this work was to find a methodology for determining the seismic response of complex pipe systems with viscous dampers. Methodology allows a sufficiently accurate determination of the seismic response of piping systems and also allows obtaining of the results in effective time. The procedure is as follows. Firstly, specialized piping program (AutoPIPE) is used for the development of computational model. Next step is to determine a static response of structure and its verification with experimental measurements, if possible. Using script in Python language a computational model is converted from AutoPIPE into general finite element model in ANSYS system. Four-parameter Maxwell rheological model is used to describe behaviour of viscous dampers. Seismic load is represented by synthetic accelerograms. Newmark algorithm of direct integration of the equation of motion is used to obtain seismic response (only reactions and displacements in nodes of interest are necessary). Than is the equivalent stiffness is than gained from displacements and reactions as median value of their ratios. Received stiffness are subsequently transferred to AutoPIPE program where the seismic solution is performed using response spectra method. Finally, the dynamic response is combined with the static response and stress assessment according standards is done. The created methodology was applied in the seismic resistance calculation of the main circulation piping and piping of pressurizer in nuclear power plants type VVER 440 and type VVER 1000.
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Using generalized functions in continuum mechanics
Procházka, Petr ; Netuka, Horymír (referee) ; Pochylý, František (advisor)
Tato práce se zabývá využitím distribucí neboli zobecněných funkcí k řešení nestacionárních okrajových problémů v mechanice kontinua. Nejprve je zavedena teorie distribucí a jejich definice jako spojitých lineárních funkcionálů na prostoru testovacích funkcí. Druhá část teoretické kapitoly představuje Laplaceovu integrální transformaci. Následující kapitola se věnuje řešení průhybu nosníků pod vlivem nespojitého časově proměnlivého zatížení. Jejím výsledkem je vytvoření obecného modelu řešení průhybových čar nosníků vužitím distribucí. Poslední kapitola se zabývá řešením nestacionárního proudění v trubicích spojených hydraulickými prvky.
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The impact of HVAC systems on the acoustic microclimate of clean rooms
Jelínek, Ondřej ; Mathauserová, Zuzana (referee) ; Papež,, Karel (referee) ; Rubina, Aleš (advisor)
The work description is to create a system of measures to prevent the spread and the consequent attenuation of sound in air handling systems serving the cleanrooms. The thesis presents a solution to noise attenuation in the investigated area, and in HVAC duct, which uses a commercially available material in the form of sound insulation hoses. In the systém solution is part of the work focuses on the optimal design of terminal elements to distribute air in a clean room. Processing methods utilize theoretical and experimental approach. The experiment comprises a unique analysis of the sound insulation properties of selected products under specific conditions. The data obtained are analyzed and incorporated into the framework of this work created program module for determining the attenuation and noise propagation in an enclosed space. Math and physical dependence are programmed into their own DLL by programming language DELPHI.
|
|
|
Formulation the Methodology for Analysis the Seismic Response of the Piping Systems with Viscose Dampers
Chlud, Michal ; Salajka, Vlastislav (referee) ; Kanický, Viktor (referee) ; Malenovský, Eduard (advisor)
Viscous dampers are widely used to ensure seismic resistance of pipelines and equipment in nuclear power plants. Damping characteristics of these dampers are nonlinearly frequency dependent and thus causing complications in computational modelling of seismic response. Engineers commonly use two ways to deal with this nonlinearity: The first option is to consider damper by means of “snubber”. This is essentially linear spring element that is active for dynamic load and does not resist static loads. Snubber behaviour during seismic event is described by a equivalent stiffness (sometimes called pseudostiffness). The equivalent stiffness could be defined by the iterative calculations of piping natural frequencies and mode shapes taking into account seismic excitation. However, in complicated structures such as the main circulation loop of nuclear power plant the iterative calculation is difficult and could bring significant inaccuracies. On the other hand, the benefit of such modelling is a possibility to apply the commonly used linear response spectrum method for a solution. The second option is to describe damping characteristics using suitable rheological model. The seismic response is than determined by direct integration of the equations of motion. The behaviour of dampers is described exactly enough but the calculation and post-processing, especially nodal stresses time-histories, are time consuming. The goal of this work was to find a methodology for determining the seismic response of complex pipe systems with viscous dampers. Methodology allows a sufficiently accurate determination of the seismic response of piping systems and also allows obtaining of the results in effective time. The procedure is as follows. Firstly, specialized piping program (AutoPIPE) is used for the development of computational model. Next step is to determine a static response of structure and its verification with experimental measurements, if possible. Using script in Python language a computational model is converted from AutoPIPE into general finite element model in ANSYS system. Four-parameter Maxwell rheological model is used to describe behaviour of viscous dampers. Seismic load is represented by synthetic accelerograms. Newmark algorithm of direct integration of the equation of motion is used to obtain seismic response (only reactions and displacements in nodes of interest are necessary). Than is the equivalent stiffness is than gained from displacements and reactions as median value of their ratios. Received stiffness are subsequently transferred to AutoPIPE program where the seismic solution is performed using response spectra method. Finally, the dynamic response is combined with the static response and stress assessment according standards is done. The created methodology was applied in the seismic resistance calculation of the main circulation piping and piping of pressurizer in nuclear power plants type VVER 440 and type VVER 1000.
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