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Standardized procedure of the machine tool adjustment for change of the machined part type
Nedoma, Tomáš ; Tuna, Jaroslav (referee) ; Lošák, Petr (advisor)
The bachelor thesis at hand is dealing with standardized procedure of machine adjustment in process of machined rail type change in Bosch Diesel s.r.o. Jihlava. In the thesis, procedures of external adjustment of preparations that clamp workpieces into machining centers and overall procedure of machine adjustment are described. The elaborated standardized procedures are included in instruction manuals, which are used by workers of the company for machine adjustments. These “manuals” shall minimize occurrence of defective steps in the adjustment process and prevent their interchange. Mistakes based in incorrect procedure of the workers lead to prolongation of the time necessary for machine adjustment in process of change of machined type by up to hundreds of minutes per month. Bosch Diesel s.r.o. has adopted these instruction manuals and thanks to them shall save couple of tens of thousands euro per year.
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Simulation of Noise Emitted by a Single-stage Gearbox
Motl, Daniel ; Hadaš, Zdeněk (referee) ; Lošák, Petr (advisor)
The level of noise and vibration of gearboxes is one of the most important parameters for today´s customers. This thesis deals with mathematical acoustic behavior modelling and its contribution to the gearbox design using finite element method. The process is presented at three computations models. Two of those were validated with experimental measurement. Acoustic analysis were performed with software FFT ACTRAN.
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The use of hydraulic disc brakes for road bikes
Dvořáková, Barbora ; Lošák, Petr (referee) ; Šebek, František (advisor)
This bachelor's thesis is focused on the usage of hydraulic disc brakes on road bikes. The thesis is divided into two parts. In the first part, there is a research focused on differences in construction and properties of hydraulic disc brakes in comparison with rim brakes. The main emphasis is placed on evaluating all advantages and disad-vantages of the hydraulic disc brakes in comparison with rim brakes. Evaluation is conducted both from the functional point of view and user point of view with taking different requirements of both recreational level cyclist and professional cyclist into account. The aim of the second part is the numerical simulation of loading of the frame and fork for both types of brakes. The goal of this part is an overall assessment of suitability of hydraulic disc brakes for the road bikes.
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Analysis of the rotor packet prestress on the rotor critical speed
Lekeš, Filip ; Huzlík, Rostislav (referee) ; Lošák, Petr (advisor)
The presented diploma thesis deals with the modeling of the rotor packet in dynamic calculations and analysis of the influence of the packing pressing force on the critical speed of the electric motor. The thesis can be divided into three main parts. The first part discusses the current level of rotor packet modeling in dynamic calculations and also deals with analytical theories for subsequent experimental tests. The second part describes the implementation of two experiments to determine the equivalent modulus of elasticity. The first experiment is a four-point bending test and the second is an experimental modal analysis. The third part is used for comparing the results obtained from experimental tests and describes the calculation of the critical speed of the rotor package pressed on the shaft by the finite element method.
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Comparison of modal properties of steam turbine impeller with blades of different lengths
Havlásek, Michal ; Chromek, Lukáš (referee) ; Lošák, Petr (advisor)
The presented master's thesis deals with the safety assessment of several variants of the impeller with different blades length. The motivation for creating this thesis is to find the solution of the problem situation which is characterized by the breakdown of the steam turbine impeller with blades length of 30mm. As confirmed in this thesis, the impeller with blades length of 30mm is operated in the resonance. Likewise, according to the technical standard ČSN EN ISO 10437 its operation is not safe. As the correction action for the problem situation solving is proposed the prolongation of the impeller's blades. The safety is detected for six variants of impeller with dierent blades length. For each variant, there is executed a modal analysis and its results are drawn up into the Campbell diagram. On the basis of this diagram, the safety of individual components is evaluated. The last part of the masters thesis concerns with the examination of the influence of blades length on the modal properties of the impeller.
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Dynamic model of nonlinear oscillator with piezoelectric layer
Sosna, Petr ; Lošák, Petr (referee) ; Hadaš, Zdeněk (advisor)
Tato diplomová práce je zaměřena na analýzu chování magnetopiezoelastického kmitajícího nosníku. V teoretické části jsou odvozeny diskretizované parametry, které popisují reálnou soustavu jako model s jedním stupněm volnosti. Tento model je následně použit pro kvalitativní i kvantitativní analýzu chování tohoto harvesteru. Frekvenční odezva harmonicky buzeného systému je zkoumána v dvouparametrické nebo tříparametrické analýze v závislosti na amplitudě buzení, elektrické zátěži a vzdálenosti mezi magnety. Posledně zmíněný parametr je v práci tím hlavním, proto je vliv vzdálenosti magnetů zkoumán také s pomocí bifurkačních diagramů. Tyto diagramy byly navíc použity k vytvoření oscilační "mapy", která pro každé zatěžovací podmínky ukazuje, jakou vzdálenost magnetů je třeba nastavit, aby bylo generováno nejvíce energie. Práce je doplněna o ukázky několika jevů, které mohou značně ovlivnit chování systému, pokud se nejdená o čistě harmonické buzení.
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Design of separator
Benda, David ; Nekvasil, Richard (referee) ; Lošák, Petr (advisor)
This diploma thesis deals with design of the gas separator according to the standard ČSN EN 13445. The design is based on the specified operating parameters and the basic dimensions, including the individual positions of the connecting flanges on the device according to the relevant schema. The assignment also includes the load of the nozzles from connected pipelines to the device. The analytical calculation of the design is performed in the commercial software NextGen with the analysis of the individual components used. Furthermore, some parts of the device are inspected in detail using the finite element method in the commercial software Ansys. The thesis also included the drawing documentation of the designed gas separator.
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Interier Vibration Analysis of Moving Train
Železník, Gabriel ; Lošák, Petr (referee) ; Hadaš, Zdeněk (advisor)
In this work, a multibody system of a passing train on a railway is created. The model is focused on the vibrations, which are related to defect conditions. The subject of this work is to investigate the effect of vibrations in the interior of a rail vehicle. In the first part of the work, research of published dynamic models is performed. Various options for track and train modeling are described. Furthermore, the research presents several solution methods that can be used to simulate the moving train. Based on the research, the structure of the model and the method of solution were determined. The main areas of interest are the track, on which vibrations occur in contact with the wheel, and the car body, in which the vibrations will be further analyzed. For this reason, both parts were modeled as flexible bodies. The assembled model uses finite element discretization to describe flexible bodies. The time domain simulation is done by using generalized coordinates and modal superposition. The work describes the construction of the model in detail. The whole model is written in the Matlab and all codes are part of the appendix. The model allows change of all the parameters of the track and the car, including their geometric dimensions. The model includes 4 excitation mechanisms simulating the following defects: flat wheel, lifted sleeper, damaged sleeper and rail wear. After the model algorithm is fully described, the simulations without any defect are performed and a behavior of each system component is described. Finally, simulations of defect conditions are performed. Thanks to the combination of all defect conditions the response of the car body for the analysis of vibrations in the interior is compiled. In the last part, the compiled response in the frequency domain is used for the analysis of random vibrations in the vehicle interior in the Ansys environment. A 3D model of the train's ceiling paneling is used for the analysis, on which the effects of static and dynamic loads are compared. The area with the highest stress was determined by random vibration analysis. In the end, the modification of the part is proposed, which leads to the improvement of the strength properties of the assembly.
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