Pulse localization and Fourier analysis in the mathematical model of acoustic transient field

The numerical model of a semi-cylindrical acoustic diffuser in planar transient acoustic field is discussed. The finite element method was used for the solution of the model. From the computed waveforms the straight and the reflected pulses were automatically extracted using cross-correlation. The harmonic decomposition was performed on the obtained pulses and the results were plotted in the polar pattern

Numerical modeling and optimization of hot pressing

Tato dizertační práce se zabývá modelováním magneto-termo-elastických procesů, kterými je potřeba se zabývat při ohřevu v oboru tepelné upínací techniky. Popisuje termoelastický jev jako fyzikální proces, který je využíván ke spojování stopek nástrojů a tepelných upínačů. Dále jsou uvedeny principy, výhody a omezení dané technologie v porovnání s dalšími možnostmi upínání. Práce se zaměřuje na definici matematického modelu sdružené úlohy, která se skládá ze tří fyzikálních polí (magnetické, teplotní a pole termoelastických posuvů či deformací), mezi kterými jsou vazby vzhledem k teplotním závislostem nelineárního charakteru použitých materiálů. Možnosti daného matematického modelu jsou demonstrovány na numerickém řešení zvoleného ilustrativního příkladu rotačního indukčního ohřevu pomocí metody konečných prvků vyššího řádu přesnosti. Výsledky jsou verifikovány prostřednictvím provedených experimentálních měření. Současně jsou využity optimalizační algoritmy pro zlepšení dosažitelných parametrů tepelného upínání. Závěrem jsou stanoveny směry dalšího výzkumu a trendy pokračování práce v dané oblasti.ObhájenoThis thesis deals with the numerical modeling of magneto-thermo-elastic processes that needs to be considered during heating in the field of thermal clamping technology. Thermoelastic phenomenon is described as a physical process, which is used for connecting the tool shanks and thermal chucks. The principles, advantages and limitations of this technology are described in comparison with other clamping options. The main part of the work focuses on the definition of the mathematical model of this coupled problem, which consists of three physical fields (magnetic, thermal and thermoelastic displacement or deformation field), with mutual interactions due to temperature dependencies of the used materials exhibiting nonlinear characters. Possibilities of the mathematical model are demonstrated on the numerical solution of an illustrative example of rotation induction heating using the higher order finite element method. The results are verified by the experimental measurements. The optimization algorithms are also used to improve the parameters of thermal clamping. Finally, the directions for further research and the trends of next work in the area are established

Numerical analysis of thermoelastic friction clutch

A thermoelastic friction clutch for transferring mechanical torque is proposed and modeled in this paper. The friction force between the driving and driven parts of the system is produced by mechanical stress of thermoelastic origin. The computations of the typical illustrative example consist of three coupled fields (magnetic field, temperature field and field of thermoelastic displacements) are carried out by own code Agros based on a fully adaptive higher-order finite element method and some results are verified by professional code COMSOL Multiphysics

Corona discharge exposure of model organisms Candida albicans and Deinococcus radiodurans study

katedra řídicí technik

The shrink-fit using the rotation heating

Hard-coupled model of rotation heating of a ferromagnetic clamping head is presented. The problem is described by three coupled partial differential equations whose coefficients are temperature-dependent functions. The system is solved numerically in the monolithic formulation and results from different software are compared together. The methodology is illustrated by a concrete example which was built and measured. The results are evaluated and discussed

The influence of arrangement of pernament magnets to rotation heating of ferromagnetic shrink-fit

Several arrangements of pernament magnets forming a magnetic circuit for rotation heating are presented. The problem is solved as hard–coupled model described by three coupled partial differential equations (for the distribution of electromagnetic field, temperature field and field of thermoelastic displacements). The results from the arrangements are compared together and discussed. One of them was built and measured and it verifies the results from the numerical solution

Analysis of natural frequencies in the transformer core

This paper presents results of natural frequency analysis of the 3D numerical model of transformer. The goal is to map structural dynamics and vibrations of its selected parts with respect of the mechanical resonance. The model taking into account the real arrangement of the transformer core with winding is solved numerically by the finite element method