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Analysis of Powertrain Acoustic Properties
Ambróz, Richard ; Novotný, Pavel (referee) ; Dundálek, Radim (referee) ; Píštěk, Václav (advisor)
Dizertačná práca rieši problematiku analýzy akustických vlastností pohonných jednotiek. V úvodnej časti je teoretický rozbor fyzikálnych princípov vibrácií a hluku a prehľad súčasného stavu riešenia problematiky v oblasti návrhu pohonných jednotiek. Vlastná časť práce popisuje konštrukčný návrh elektrodynamického budiča vibrácií, návrh hodnotenia výsledkov merania a taktiež spôsob spracovania výsledkov. Akustické vlastnosti sú hodnotené pomocou normálových rýchlostí kmitania povrchu. V závere práce sú prezentované ukážky využitia metódy v praktických príkladoch spojených s návrhom pohonnej jednotky. Celé riešenie predstavuje ucelený spôsob analýzy vhodný pre rýchle hodnotenie vplyvu konštrukčných úprav na akustické vlastnosti.
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Printed Circuit Board Modal Analysis Results Comparison from Experimental and Computational Modeling
Oplt, Tomáš ; Vosynek, Petr (referee) ; Tošovský, Jiří (advisor)
Modal analysis of printed circuit board results, gained from computional and experimental modeling, have been compared. Anylyses have been performed on dummy boards (models without electronic components), created as one-layered at first, then as three-layered PCB. Board is usually clamped by its longer edges with wedgelock. In order to enable the realization of boundary conditions in computional and experimental modeling, real clamping has been simplified to simply supported. Computional models have used FEM elements, which are comomnly used in this type of problem. Determined results have been evaluated by comparing the experimental modeling results. Models‘ sensitivity on modification of element length and number of elements through thickness have been performed.
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Creation of Modal Parameter Estimation Application for Experimental Modal Analysis
Ondra, Václav ; Žatko, Miroslav (referee) ; Lošák, Petr (advisor)
The aim of this diploma thesis is a creation of modal parameter estimation application. Modal properties (natural frequencies, damping factors and mode shapes) are used in many dynamics analysis and their accurate determination is very important therefore the modal parameter estimation is one of the most significant part of the experimental modal analysis. Many methods have been developed for modal parameter estimation, each of them with different assumptions and with different accuracy. In the beginning of this thesis, a theory connected with modal analysis and a theory which is necessary for understanding to presented modal parameter methods are given. Then four different modal parameter estimation methods are presented - Peak Picking, Circle Fit, Least Square method and Eigensystem Realization Algorithm. The application for the modal parameter estimation is the output of this diploma thesis. In addition, the application allows performing all experimental modal analysis such as estimation of frequency response functions, animation of the found mode shapes, different kinds of comparison etc. In the conclusion, three structures are shown on which the application and modal parameter estimation methods were tested.
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Modal Analysis of the Swirl Turbine Rotor Blades
Pekar, Marek ; Chromek, Lukáš (referee) ; Lošák, Petr (advisor)
The aim of this diploma thesis is to determine and compare modal properties of four swirl turbine wheels, each with a different geometry. Natural frequencies and mode shapes were obtained based on computer modelling using Ansys software and they were compared with experimental modal analysis' results. The computer modelling and the experimental modal analysis were carried out for different boundary conditions and in different environments. The beginning of the thesis is dedicated to a brief overview of literature with similar issues. Then a brief introduction of a dynamics theory is mentioned in which equations of motion for a damped and an undamped single degree of freedom system are derived. The creation of a geometry model which is obtained by a reverse engineering is shown in the second part of the thesis. The geometry model was subsequently used for the computer based modelling of the modal parameters. In the third part an experimental equipment, setting, measurement and processing of data are described. The conclusion of the thesis is dedicated to the comparison of the results obtained by the experimental modal analysis and the computing modelling is presented. Moreover, influence of boundary conditions and influence of the environment on the natural frequencies are evaluated.
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Modal analysis of turbine wheel for aircraft engine
Drahý, Jan ; Nehybka, Jindřich (referee) ; Malenovský, Eduard (advisor)
The master thesis deals with modal analysis of turbine wheel of aircraft engine. The first part is concerned with the modal analysis of the computational model of turbine wheel and separated turbine blade using the cyclic symmetry of the ANSYS software. This part of the thesis set the task of determining the natural frequency depending on the operating parameters of the motor. The second part of the thesis occupies with the experimental simulation of the task. The results of experimental simulation are verified and compared with the results from the computational modal analysis. The goal is to create a Campbell diagram and to determine the intervals of the critical revolution of the turbine wheel.
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Computational and experimental analysis the state of stress of turbine blade
Damborský, Petr ; Jaroslav, Kovařík (referee) ; Malenovský, Eduard (advisor)
This diploma thesis deals with dynamic analysis of the steam turbine blade. This blade is part of the last row of low pressure level of steam turbine. Computational analysis has been performed in first part using FEM and software ANSYS. A Transient analysis has been used to solve forced vibrations. Main goal is to obtain a behavior of main stresses and its directions as a function of loading of the blade in the crack initiation area. Second part deals contain a an experiment. Experiment has been set up to perform a modal analysis which is necessary to obtain a fundamental numbers. Then the vibration of the blade has been performed. To perform this experiment same edge conditions as which has been used during the computational analysis. Goal is the same as in the first part – obtain a behavior of main stresses and its directions as a function of loading of the blade in the crack initiation area. The comparison of results obtained during experimental analysis and computational analysis has been performed in the last part of the thesis. Also the question if any geometrical nonlinearities appeared during analyses is answered.
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Measurement and Evaluation Methods of Powertrain Vibrations
Vítek, Michal ; Janoušek, Michal (referee) ; Prokop, Aleš (advisor)
This bachelor´s thesis deals with the methods of measurement and evaluation of powertrain vibrations. Introduction of this work is defining the basic parameters of vibration. It also shows the experimental modal analysis, vibration excitation methods and measuring responses to a given excitation. The last part is operational modal analysis and its comparison with experimental modal analysis.
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Tram wheel modelling for dynamic analysis
Pešek, Luděk ; Veselý, Jan ; Podruh, J.
The wheels as vibration transformation elements and noise emitters substantially contribute to the tottal noise level of riding vehicle. Therefore rubber like material is also utilized for construction of the silent wheel. We aimed at investigation of dynamic behavior of raiway tram wheel with a special construction. The dynamic parameters of the wheel are studied. The numerical modelling, computation and analysis were performed in ANSYS Release 6 environment.
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