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Laboratory demonstrator for vibrodiagnostics
Blecha, Martin ; Krejčí, Jakub (referee) ; Klusáček, Stanislav (advisor)
This thesis deals with a vibration diagnostics of objects, structures and machines. The theoretical part is divided into three chapters according to type of the measurement. The first part called Modal Analysis discusses the basis of vibration, methods of measurement, relevant technical equipment and principle of experimental modal analysis. The second and third chapters of the thesis are focused on the diagnosis of defects. Each chapter mentioned above describes diagnosed defects, used methods and procedure for the diagnosis. Another part of the thesis summarizes practical issues and results gained in the laboratory experiments. It begins with discovering parameters of the measured object using technical diagnostics – experimental modal analysis. In the next step the hardware concept design was created, including custom measuring application programmed in LabVIEW. One part of the design is the laboratory model which includes a structure for free mounting and a possibility of excitation by an electrodynamic exciter. The application is also modified to enable measurements with shaker excitation. Finally, applications cooperating with professional software ModalVIEW and BK Connect were developed in order to simplify the operation and increase the comfort.
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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 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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