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Stress and strain analysis of skull implant
Chamrad, Jakub ; Valášek, Jiří (oponent) ; Marcián, Petr (vedoucí práce)
Mechanical behavior of cranial implant is an important factor, which influences its function. It is influenced by external load from environment and by intracranial pressure. These loads can cause movement of implant and harm of living tissue. This thesis summarizes knowledges and analyses of cranial defect reconstruction. It provides comparison of different implant materials and fixators based on stress-strain analysis of the implant loaded by force and intracranial pressure.
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Analysis suggestion for vehicle scanning method
Bayer, Jan
An analytical approach is suggested that can be conveniently applied in the framework of the Vehicle scanning method (VSM). It assumes that the modal parameters of a bridge will be imported from a finite element (FE) program into MATLAB, where the structural response caused by a moving mass and a moving spring mass is solved using coupling equations and numerical integration. A mathematical formulation of the solution is presented together with a short numerical case study that compares the results to a traditional closed form solution. It is shown that when comparing both forms of analysis the suggested approach is more accurate in the case of slow velocities of the passing sprung mass. Other advantages are that the method allows for the mass of the vehicle or (tractor) towing vehicle and a damping \nto be included in the calculation. The user-friendly preprocessing in commercial FE programs can also be considered an advantage.
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Scalable thermal model of a transistor package
Klement, Matej ; Junasová, Veronika (oponent) ; Otáhal, Alexandr (vedoucí práce)
This diploma thesis describes methods for simulating the self-heating of a discrete transistor component inside it’s package. Two methods of measuring thermal resistance are described using information from JEDEC standards. Model of a transistor package is simulated using Ansys ICEPAK FEA in a configuration described as Junction to Case heating. Using transient temperature simulation with parametric sweeping a dataset of heating curves was created for every transistor configuration. The heating curves were transformed to their time-constant spectrum representation using algorithms described in JEDEC standards implemented in Python for diploma thesis’s purpose. The time constant spectrum of each heating curve was simplified into two element Foster network and converted to Cauer ladder. For each parameter sweeping, an interpolation function of the ladder element was fitted. The scalable thermal model was constructed using the interpolation functions and simulated in LTSpice. The results from LTSpice simulation were compared against the FEA simulations.
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Estimation of mechanical properties of thin films using numerical modelling of experimental tests
Tinoco Navarro, Hector Andres ; Jančo,, Roland (oponent) ; Klusák,, Jan (oponent) ; Hutař, Pavel (vedoucí práce)
Bulge testing is an experimental technique that involves the use of numerical and analytical approaches to characterize the mechanical properties of thin films. This thesis addresses some limitations found in the classical models that describe the behavior of thin films subjected to this test. This required the development of new models and numerical strategies in order to determine several mechanical properties of monolayer and bilayer thin films under different structural conditions, such as elasticity, plasticity, and fracture. By combining finite element analysis and classical analytical solutions, different methodologies for calculating the elastic properties (E and v), residual stresses, yield stress, and fracture toughness were proposed and validated. The mechanical properties of silicon nitride, aluminum, and gold films were characterized using load-deflection experimental data obtained from bulging measurements. The determined properties showed reasonable agreement with materials of known properties, which validated that the proposed methods in this work can be useful for estimating the mechanical properties of freestanding thin films.
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Finite element solution of axially loaded bars using quadratic element
Janáčik, Lukáš ; Halabuk, Dávid (oponent) ; Vaverka, Jiří (vedoucí práce)
This bachelor thesis describes an algorithm for programming finite-element model with quadratic elements for axial loaded bar. In the introduction, we define the basic concepts of mechanics of materials, which are used in this thesis and are necessary to understand problems, for which finite element method was formulated. The thesis clarifies a transition from basic differential equation to weak formulation, which is the base of finite element method. We define element matrices and describe transition to global matrices, relating to the whole body. Then describe implementation of boundary conditions and postprocessing of the results, necessary for calculation and displaying of other unknowns. In the practical part, 3 illustrative problems are presented and calculated numerically in FEM solver using Matlab, analytically and in software ANSYS Workbench. Results are then compared and evaluated. Problems have different boundary conditions (linear axial load, tempered cross section, statically indeterminate fixation). Results of displacement and normal stress for programmed solver are identical to those from Ansys (using the same settings) and analytical solution (after more elements are added, if necessary). Problem with tempered cross section was simulated in Ansys using plain stress, because the program can’t define bar with tempered cross section. This revealed sheer stress contained in parts of cross section further from centreline, which are not calculated in our FEM solver and in some cases might be significant.
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Pedálová sestava vozu Formule Student s autonomní funkcí brzd
Skalník, Adam ; Straka, Tomáš (oponent) ; Tobiáš, Martin (vedoucí práce)
Cílem této bakalářské práce je provést rešerši možných řešení autonomního brzdění pro vozidlo Formule student, stanovit požadavky teamu na tento systém a vybrat nejvhodnější z nich. Na základě rešerše je poté proveden konstrukční návrh tohoto systému společně s celou pedálovou sestavou vozidla. Při konstrukci všech komponentů je kladen důraz na spolehlivost, hmotnost a vhodnou zástavbu do prostoru vozidla.
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Design and Optimization of High-Torque Ferrite Assisted Synchronous Reluctance Motor
Knebl, Ladislav ; Rafajdus,, Pavol (oponent) ; DUŠEK,, Jiří (oponent) ; Vítek, Ondřej (vedoucí práce)
The high-torque assisted synchronous reluctance machine could be still considered, based on the relatively low amount of publications, as a rather unknown area of research. This and other main advantages, such as low manufacturing cost and a higher torque density of this machine type are driving researchers interest. Even though this machine type has become more interesting in the conventional or high-speed applications, the area of traction applications is slowly getting forward as the machine capabilities are discovered. This thesis is serving just this purpose of developing the ship propulsion driving motor, that is capable of sustaining the high-torque at low-speed. The application is defined by the 55 kW at 150 rpm using the low- cost ferrite magnets aiming to lower the cost. The design will be closely tied with optimization algorithms to deliver the best possible performance in the given volume. However the design challenge being difficult task on its own, the thesis is declaring other goals within, that are still very interesting and important. Since the optimization is included in the design process, the first goal, concluding from the given topic is to compare various optimization methods. Not only the two different optimization algorithms, self-organizing migrating algorithm and genetic algorithm, will be compared in the thesis, but even two multi-objective optimization approaches will be compared as well. The preference based vector and ideal multi-objective optimization techniques comparison will be demonstrated in one optimization scenario with a higher amount of optimized parameters. Other demonstrated goal within the thesis is the comparison of ideal multi-objective optimization with a lower number of parameters. The last goal will be the measurement of the designed and optimized machine, that introduced variety of challenges itself and all of them will be discussed within the last chapter.
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Miniinvazivní stabilizace poranění zadního pánevního segmentu transiliakálním vnitřním fixátorem a dvěma iliosakrálními šrouby: srovnání funkčních výsledků a biomechaniky
Salášek, Martin ; Pavelka, Tomáš (vedoucí práce) ; Džupa, Valér (oponent) ; Plánka, Ladislav (oponent)
Úvod: Vertikálně nestabilní transforaminální zlomeniny kosti křížové mohou být stabilizovány jak transiliakálním vnitřním fixátorem (TIFI), tak iliosakrálními šrouby. Cíle: 1. Srovnání radiologických a klinických výsledků mezi stabilizací zadního pánevního segmentu TIFI, resp. IS, 2. Vyhodnocení a srovnání biomechanických vlastností TIFI a IS konstrukce. Metodika klinické studie: Prospektivní studie, jak ve skupině TIFI, tak IS bylo 32 pacientů, většina poranění byla typu C1.3, zařazeni byli jen pacienti s vysokoenergetickým mechanizmem poranění. Radiologické výsledky byly vyhodnoceny podle Matty, klinické podle Pelvic Outcome Score a Majeedova skóre. Kategoriální data byla hodnocena pomocí oboustranného Fisherova exaktního testu nebo Pearsonovým χ2 testem, souvislá data Studentovým t-testem. Výsledek testu s p <0,05 byl považován za statisticky významný. Metodika biomechanické studie: S využitím CT skenů byl vytvořen konečnoprvkový model pánve. Byla simulována zlomenina typu Pohlemann II a fixována buď TIFI, nebo 2 IS. Na bázi kosti křížové byla aplikována vertikální zátěž (250-500 N), byly vypočteny velikosti dislokace na mediální a laterální ploše zlomeniny a maximální napětí v kosti. Neporaněná pánev byla použita jako srovnávací. Tuhost byla určena pomocí lineární regrese zátěže a dislokace,...
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Preference Based And Ideal Multi-Objective Optimization Applied On Hightorque Ferrite Assisted Synchronous Reluctance Machine
Knebl, Ladislav
This paper introduces comparison of optimization algorithms applied on high-torqueferrite-assisted synchronous reluctance machine. The comparison is focused not solely on two algorithmswithin the same multi-objective optimization approach - preference based or ideal, but also oncomparison of these two approaches. The genetic algorithm and self-organizing migrating algorithmin both approaches are used to find optimal solution. The optimization goal is an optimal parametercombination to achieve the highest torque and power factor, while developing the lowest torque ripple.The optimized design will be evaluated by the 2D finite element analysis in steady-state analysis.
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Workshop mobile handling table
Macejka, Andrej ; Špička, Jiří (oponent) ; Škopán, Miroslav (vedoucí práce)
This diploma thesis is concerned with the design of lift table with hydraulic actuator system. Lift table is supposed to perform vertical motion and tilting the upper desk in horizontal axis. In background research are explored various suitable movement mechanisms and types of actuating systems. After choosing the right mechanism type for lifting and tilting, actuating system and various design components the force and strength calculations are performed analytically and by finite element analysis. The hydraulic schema, 3D model of assembly and drawings are made.
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