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Modelling of damping devices in interaction with a structure
Kalina, Martin ; Lehký, David (referee) ; Frantík, Petr (advisor)
The aim of my master’s thesis was to create models of the damping device and observing their behavior in interaction with the structure. First was the construction separately modeled with Java application named FyDiK2D like a model with one degree of freedom. Model of construction takes form like a high, thin rod with full circular cross section. The lower part was restrained into the subsoil. The design was to verify the correct functionality of the model by comparing the analytical and numerical solutions. For capturing the precise behavior of the structure was converted to a multi-stage model. Then the pendulum damper was applied on this construction and found amplitude lies in highest point of multi-stage model. He was then replaced by tuned mass damper. By comparing these amplitudes from both dampers was found which kind of damper is efficient for multi-stage model.
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Active Damping of Electric Machines Platform
Vaške, František ; Houfek, Martin (referee) ; Vlach, Radek (advisor)
This thesis deals with a design of an experimental model of active damping of eletric machinery platform, its mathematical description and control through the use of a computer. It compares various ways of construction, their physical principles and feasibility. The thesis also contains a description of the model made and of the way it is controlled.
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Analysis of the effect of damping on the magnitude of the response during dynamic headlamp excitation
Lukáš, Jan ; Biskup, Martin (referee) ; Vosynek, Petr (advisor)
The aim of the submitted diploma thesis is the magnitude determination of the headlamp response to the dynamic excitation. Currently it is necessary to measure this response, because it is one of the assessed criteria of quality of the headlamp. When comparing results of the experimental measurement and the computational modelling, a good consensus of resonant frequencies is observed, but there are significant differences in acceleration amplitudes. The cause of this is the variable damping value. The theoretical part of the thesis deals with polymeric materials, basics of oscillation and damping. It serves to understand the mechanisms, which influence the results of the experimental measurement. The practical part is dedicated to the procedure of the computational modelling and the experimental measurement implementation. The analysis of the experimental measurement results leads to an ascertainment of nonlinearities, which influence the headlamp behaviour. The results of a sensitivity analysis of the computational modelling are used to create curves, on the basis of which the damping is estimated. The inclusion of the estimated damping into computational modelling leads to reduction of the compared differences of the acceleration amplitudes. The conclusion of the thesis contains the recommendation for the damping determination during the computational modelling of the headlamp.
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Computational modeling of radial hydrodynamic bearings for water machines
Pokorný, Jan ; Šimek,, Jiří (referee) ; Návrat, Tomáš (advisor)
The aim of this thesis is to calculate the stiffness and damping coefficients for radial hydrodynamic bearings. Cylindrical and lemon hydrodynamic bearings are considered. The solution to this problem mainly depends on the hydrodynamic pressure in the bearing. The numerical solution of the Reynolds equation is used to calculate the pressure. The effect of variable viscosity and density of the lubricant due to temperature changes is considered. The static equilibrium position of the journal centre is also solved. The stiffness and damping coefficients are determined using small amplitude journal motions about the equilibrium position. Three methods for determining these coefficients are presented. The outcome of this thesis is an algorithm for the calculation of stiffness and damping coefficients for cylindrical and lemon bearings. Results for lemon bearings are presented and comparison with the commercial software DynRot BR is made. The benefit of this thesis is the creation of an algorithm for the calculation of journal centre equilibrium position, a new way of incorporating the temperature changes in the viscosity and the density of the lubricant, and the modification of a method for calculating stiffness and damping coefficients based on experimental analogy.
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Simulation modeling of a vibration absorber
Kukačka, Radek ; Vetiška, Jan (referee) ; Březina, Lukáš (advisor)
The bachelor thesis gives an overview of different design solutions to car shock absorbers. The rest of the thesis describes a simplified model of passive shock absorber and its optimization. The survey contains shock absorbers used in the present. There are various passive telescopic dampers and modern semi active and active electronically controlled damping systems. The second part includes several simplified models of passive dampers. There is described an optimization of the damper parameters with respect to the displacement of the primary mass for each of the models.
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Damping of Pressure Pulsations in Elastic Pipes
Panko, Martin ; Pochylý, František (referee) ; Habán, Vladimír (advisor)
This diploma thesis deals with numerical simulation of pressure pulsations in elastic pipes. Continuity relation of fluid in elastic pipes, when calculating some damping in pipe material, is derived into practice. Rheological model of such a pipe corresponds to Voigt (Kelvin) model. For analysing dynamic effects in time periods are used numerical methods that deal with flow of compressible fluid: FTCS, Lax-Friedrichs and Lax-Wendroff method. The numerical results are confronted with the experiment. During the experiment simulation the method considers speed of sound in liquid like a function of pressure. This diploma thesis lays partial principles for finding elastic constants for describing dynamic characteristics of elastic pipes by measuring the pressure pulsations.
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Simulation Assessment of X Axis Damping Possibilities of Heavy Machine Tool
Štetina, Jakub ; Marek, Jiří (referee) ; Březina, Tomáš (advisor)
This master's thesis deals with the simulation assessment of axis X damping possibilities of Heavy Machine Tools. CAD model has been provided by company TOSHULIN a.s. In the thesis, there is described modelling of axis X as multi body system consisting of rigid and flexible bodies. The main goal is to create simplified model and get the information for strategic decision of manufacturer about damping possibilities of axis X. For the solution has been used several software products: SolidWorks 2013 - for simplifying the CAD models, Ansys 14.5. for modelling od flexible bodies, MSC.Adams for modelling multi body systems and Matlab 2012 for data processing and optimization.
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Development And Verification Of A New Method For Measuring The Stiffness And Damping Properties Of Joints In Parallel Kinematic Structures
Kolouch, Martin ; Tomáš, Jiří (referee) ; Knoflíček, Radek (advisor)
In this dissertation is presented the development of a new measurement method for the stiffness and damping characteristics of a joint in a parallel kinematic machine tool. The main contribution of this method is specially for applications, that demand accurate information about stiffness and damping parameters from assembled parts of machines tool. Methods for compensation of deformations in machines tool, that are carried out by control, belong to these applications. Another contribution of this work is the technical implementation of the proposed principle of the new method. At this point the focus of the work was devoted to signal processing, that differs in a certain degree from other types of signal processing methods, that are used in other dynamic measurements, e.g. modal analysis. One of the main requirements was the possibility to consider the nonlinear behavior of the measured structure. In another chapter the modified signal processing method was used for measuring a joint in a test rig. The results were compared with results from other measurement methods. On account of this comparison the statement was made that the new method can be used for measuring the stiffness and damping parameters of machine parts. Finally the new method was applied to measure the properties of a joint, which was built in a machine tool. Moreover, the problems, that appeared during the measurement, were also described.
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