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Design and verification of station for calibration of AE sensors for bearing testing
Bančák, Matej ; Mazůrek, Ivan (referee) ; Mazal, Pavel (advisor)
The diploma thesis deals with calibration of AE sensors used in diagnostics of bearings. Two different conceptual solutions similar to those used in the diagnostics of bearings were designed in the design. Subsequently, the experimental device was designed for relative calibration using the rotation of bearings as a continuous AE source. The experimental part is oriented to the observation of the RMS parameter, which serves as a sensor sensitivity evaluation parameter. As sources of AE, bearings with a certain type of damage were used, which allowed for the formation of sensitivity characteristics according to the type of damage. Sensitivity characteristics of selected AE sensors have been developed to determine the effectiveness in relative calibration. The exponential sensitivity sensitivity of the MDK-13 sensors was observed on the software amplification of the AE analyzer. A proposal for the calibration method for MDK-13 type sensors was developed on the principle of comparison with the reference sensor.
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Base frame´s oil system under the steam turbine and generator
Petržela, Zdeněk ; Vlašic, František (referee) ; Mazal, Pavel (advisor)
This bachelor thesis describes problematics of the lube system of steam turbines as an important part for its operation. The beginning of the thesis offers an overview of steam engine and steam turbine development both at home and abroad and its working cycle. The main part of the thesis discusses lube system functions and components. Next section contains a summary of required turbine oil properties and effects that affect the oil during working cycle. The conclusion of the thesis is focused on lube system operating problems, their causes, consequences and recommendations for their preventing.
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Methods of mounting of acoustic emission sensors on the surface of tested structures
Ščasný, Jakub ; Zemanová, Lucie (referee) ; Mazal, Pavel (advisor)
This bachelor thesis is focused on the issue of mounting acoustic emission sensor to cylindrical and sferical surface of tested tube segments which are made of non-ferromagnetic material. This work includes overview of current state of cognition in the basics of acoustic emission testing needed for understanding the issue. The folowing part includes the overview of commonly used practices for installing transducers. In the part of mechanical design drafts of mounting fixtures are discussed along with testing and comparision of their characteristics.
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Construction of the station for the diagnosis of damage and leaks from pneumatic systems
Kojš, Denis ; Mazůrek, Ivan (referee) ; Mazal, Pavel (advisor)
Thesis deals with the design, implementation and verification of functionality of station designed for measuring of acoustic emissions from pneumatic cylinders for the purpose of fault diagnosis. The first part of this thesis includes an overview of previous work dealing with the diagnosis of pneumatic systems, also works dealing with the diagnosis of various machine parts using acoustic emission. Further work contains a description of the proposed conceptual design and final draft is described in detail, including occurred complications and their solutions. The last part describes the results of measurements of acoustic emissions from damaged and undamaged cylinders. Functionality of the station is verified by comparing the frequency spectra and envelopes of measured acoustic emission signal.
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Mechanical design the rotary joint of satellite antenna
Šreibr, Vít ; Mazal, Pavel (referee) ; Paloušek, David (advisor)
The aim of this bachelor thesis is a mechanical design of the rotary joint of the satellite antenna. It is a partial solution of the project which is dealing with a development of new product for a commercial subject. The device enables horizontal and vertical movement of the satellite. The established aims are solved in the whole range. The basic structure is conceived as a weldment. The other parts are connected with the body by demountable joints. The choice of key points is supported by calculations and the design is documented by technical drawings. This thesis is suitable for readers with an intermediate technical knowledge.
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Mechanical design of the supporting frame for a satellite antenna system
Hrdonka, Štěpán ; Mazal, Pavel (referee) ; Paloušek, David (advisor)
The aim of the Bachelor thesis is to create a structural drawing of a satellite dish supporting frame. The supporting frame will allow the dish to be mounted on a car. A part of the project is also to create a drawing of a rotating mount that will allow the satellite parabole to rotate around its vertical axis. Construction of the frame is designed to withstand required wind load and to prevent its sag from fundamentally influencing the signal quality. The stress-strain analysis has been carried out by using the Finite Element Method (FEM). Under the influence of the moment of 440 N.m around the –x axis and of gravitational force of 442 N the final maximal sag was 1.6 mm. The rotating mount is constructed in a way that requires only minimal maintenance and is able to withstand adverse weather conditions. That was accomplished by a suitible selection of materials. As the thesis is a part of mobile satellite prototype development, the project is designed in a way considering the final price and easy installation. Another part of the thesis is to create drawing documentation.
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Mechanical design of rotary satellite antenna polarization system
Vítek, Petr ; Mazal, Pavel (referee) ; Paloušek, David (advisor)
The aim of this bachelor thesis is mechanical design of rotary satellite antenna polarization system. It is a part of a mobile satellite antenna positioned on the roof rack of a passenger car. Device must be designed to achieve precise positioning and smooth running. It must also resist moisture and temperature fluctuations. For this application, there has been selected and developed solution with toothed belt. The thesis includes a selection algorithm of drive, belt and bearings. The achieved polarization angle is 180 °. The results of this paper can be used to produce a functional mobile satellite antenna polarization.
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Identification of fatigue damage Al alloy treated with SLM technology using acoustic emission method
Zemanová, Lucie ; Mazůrek, Ivan (referee) ; Mazal, Pavel (advisor)
The aim of the diploma thesis is to study fatigue properties of EN AW-2618A aluminium alloy produced by selective laser melting (SLM). S-N diagrams of reference alloy and SLM material depending on manufacturing conditions were constructed. Reference alloy had the same chemical composition as the SLM material, but it was made by traditional technology (by extruding). While testing, acoustic emission (AE) and resonant frequency of loading was monitored. Fractographic analyses of fracture surfaces were performed. It was found, that SLM material has significantly worse fatigue performance. Fatigue properties are strongly dependent on SLM process parameters settings and precise observance of procedure. The most significant differences in cyclic degradation were found in the length of the stages of fatigue. The more homogeneous the material is, the longer the nucleation stage compared to the total lifetime is. The main source of AE in case of the reference material is plastic deformation on the tip of the crack. For SLM testing, stronger acoustic activity was recorded, because brittle fracture of the material between discontinuities, which is stronger AE source, is more frequent.
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Correlation of AE Signal Changes to Rolling Contact Damage Propagation
Nohál, Libor ; Čermák, Jan (referee) ; Hájek, Karel (referee) ; Hutař, Pavel (referee) ; Mazal, Pavel (advisor)
This PhD thesis deals with the experimental study of more precise rolling contact fatigue damage detection using acoustic emission method. A series of experiments was carried out on two representatives bearing steels and the analysis of sensitivity for the presence of contact damage was performed on selected parameters of acoustic emission. The extent of damage was classified into four classes and signal parameters the most characterizing the development of damage were correlated with the extent of damage. It was also verified the influence of lubricants on acoustic emission signals. The results have an impact on the implementation of more precise rolling contact fatigue tests and evaluation of parameters of acoustic emission signal. On the basis of experiments was established methodology for more precise RCF testing method using acoustic emission on test-rig AXMAT II.
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Development of a New Generation of Devices with Advanced Diagnostics for Determining Contact Degradation
Dvořáček, Jiří ; Hájek, Karel (referee) ; Náhlík, Luboš (referee) ; Pazdera, Luboš (referee) ; Mazal, Pavel (advisor)
The thesis proposes a methodology for damage identification of thrust bearings using acoustic emission method. The work is the way of the hydraulic loading of specimens and thrust bearings with programmable settings severity and duration of load cycles during contact fatigue tests at stations Axmat. They are designed structural adjustment elements (waveguides) to capture the acoustic emission signal selected apparatus, including the modification of software to capture the data. At the described experiments is verified functionality of the circular test specimens and axial bearings . Part of this work is to propose a new methodology for identifying early stages of contact fatigue using a combination of diagnostic methods.
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