Ces travaux s’inscrivent dans le cadre du projet GENOME (GEstioN OptiMisée de l’Energie). Ce projet s’intéresse aux solutions de packaging haute-température pour des modules de puissance 40 kW embarqués en aéronautique. Ils s’intègrent dans l’étude de fiabilité des modules de puissance, notamment, les solutions alternatives aux alliages de brasure. De par leurs propriétés physiques, l’argent et l’or-étain ont été sélectionnés comme techniques d’assemblage afin d’étudier et d’évaluer leur fiabilité. Pour ce faire, une méthodologie d’étude de fiabilité des modules de puissance a été définie dans le but de garantir l’exploitabilité des résultats. Ensuite, des analyses destructives et non-destructives ont été réalisées sur des véhicules de tests. Ceux-ci ont été vieillis en cyclages thermiques suivant différents profils afin de comparer leurs influences sur la fiabilité des VTs. L’étude du comportement thermomécanique des assemblages de puissance a été réalisée à l’aide de modélisations par éléments finis. Une méthodologie d’évaluation de la fiabilité des assemblages, basée sur l’étude de la contrainte thermomécanique accumulée dans les couches de joints métalliques, au cours de vieillissements accélérés, est développée. Un deuxième axe devrait permettre de comprendre les modes de défaillance, afin de mettre en lumière les limitations des vieillissements accélérés sévères. / This work is part of “GENOME” project which focuses on high-temperature packaging solutions for electronic power modules. Its mission is to study the reliability of power modules, in particular, the die attach layer. Due to the physical properties of silver and gold-tin, they were selected as die bonds to assess the evolution of their reliability during ageing. In order to achieve this, an appropriate methodology of the power modules reliability has been defined in order to guarantee the results exploitability. Destructive and non-destructive analyzes were carried out on samples aged by different profiles of thermal cycling. These analyzes allowed us to compare the influence of each cycling profile on the reliability of samples. A study of the thermomechanical behavior of power assemblies was carried out using finite element modeling (FEM). A methodology for evaluating the reliability of assemblies during accelerated ageing is developed. A second axis allows us a better understanding of the failure modes and their effects. It also highlights the limitations of severe accelerated ageing. Consequently, the choice of temperature profile is questioned and a limitation of the temperature profile severity must be considered, in order to avoid producing degradations that are not actually found in mission profile.

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-06-21T11:44:49Z No. of bitstreams: 1 aldemonlagebonifacio.pdf: 14222882 bytes, checksum: a77833e828dc4a72cf27e6608d6e0c5d (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-07T19:04:13Z (GMT) No. of bitstreams: 1 aldemonlagebonifacio.pdf: 14222882 bytes, checksum: a77833e828dc4a72cf27e6608d6e0c5d (MD5) / Made available in DSpace on 2017-08-07T19:04:13Z (GMT). No. of bitstreams: 1 aldemonlagebonifacio.pdf: 14222882 bytes, checksum: a77833e828dc4a72cf27e6608d6e0c5d (MD5) Previous issue date: 2017-03-16 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O concreto feito com agregados leves, ou concreto leve estrutural, é considerado um material de construção versátil, bastante usado em todo o mundo, em diversas áreas da construção civil, tais como, edificações pré-fabricadas, plataformas marítimas, pontes, entre outros. Porém, a modelagem das propriedades mecânicas deste tipo de concreto, tais como o módulo de elasticidade e a resistência a compressão, é complexa devido, principalmente, à heterogeneidade intrínseca aos componentes do material. Um modelo de predição das propriedades mecânicas do concreto de agregado leve pode ajudar a diminuir o tempo e o custo de projetos ao prover dados essenciais para os cálculos estruturais. Para esse fim, este trabalho visa desenvolver uma estratégia computacional para a avaliação de propriedades mecânicas do concreto de agregado leve, por meio da combinação da modelagem computacional do concreto via MEF (Método de Elementos Finitos), do método de inteligência computacional via SVR (Máquina de vetores suporte com regressão, do inglês Support Vector Regression) e via RNA (Redes Neurais Artificiais). Além disso, com base na abordagem de workflow científico e many-task computing, uma ferramenta computacional foi desenvolvida com o propósito de facilitar e automatizar a execução dos experimentos científicos numéricos de predição das propriedades mecânicas. / Concrete made from lightweight aggregates, or lightweight structural concrete, is considered a versatile construction material, widely used throughout the world, in many areas of civil construction, such as prefabricated buildings, offshore platforms, bridges, among others. However, the modeling of the mechanical properties of this type of concrete, such as the modulus of elasticity and the compressive strength, is complex due mainly to the intrinsic heterogeneity of the components of the material. A predictive model of the mechanical properties of lightweight aggregate concrete can help reduce project time and cost by providing essential data for structural calculations. To this end, this work aims to develop a computational strategy for the evaluation of mechanical properties of lightweight concrete by combining the concrete computational modeling via Finite Element Method, the computational intelligence method via Support Vector Regression, and via Artificial Neural Networks. In addition, based on the approachs scientific workflow and many-task computing, a computational tool will be developed with the purpose of facilitating and automating the execution of the numerical scientific experiments of prediction of the mechanical properties.

This diploma thesis focuses on strength design of steam condenser. The goal of the thesis is to make strength calculations for the specific operation conditions, introduce possible solutions, provide recommendations and refer to weak points of such calculation procedures. First, thermal-hydraulic design in HTRI software is performed. Strength calculations respect ČSN EN 13445 standard. Strength calculation with imported temperature field is performed in ANSYS Workbench software. In the next step, another strength calculation is realized in Sant´ Ambrogio software. Results are evaluated in conclusion chapter, including recommendations for the possible following work.

The diploma thesis deals with the problem of application of turboprop engine to a small 2-seater airplane. In the first part, reasons why the application is in considered are stated. Then, the air-plane is characterised, the choice of the most suitable engine, propeller and the weight analysis is made and the centres of gravity are calculated. For chosen engine and propeller, in chapter 6, the flight performance is calculated. In chapter 7 follows calculations of flight envelopes and the lim-it positive and negative load factor is stated. Flight envelopes calculations are followed by the calculation of engine mount loads of flight and ground cases. In chapter 9, the design of engine mount, inlet and outlet system and positioning of important elements are solved. The design part is followed by strength analysis of engine mount and its attachment into engine partition.

This diploma thesis deals with FEM analysis and optimization of carriage for top drive system of drilling rig Bentec 350 AC and it is defined as a development contract for company MND Drilling & Services a.s. Intensive drilling leads to damages and repeated occurrence of fatigue cracks on carriage especially along edges of welded ribs in their heat-affected zone. The aim of this thesis is to draft construction improvements of carriage which leads to elimination of damages. Realization of this modifications depends on correct definition of boundary conditions, analysis of damage occurrence as well as verification of carriage drafts with finite element method.

This thesis deals with configuration of radial five-cylinder engine with attention to crank mechanism. Covered topics are motion of crank mechanism with articulated connecting rod, force analysis and balancing of inertial forces. The second part discusses FEM analysis and calculation of safety factor of selected component.

This diploma thesis describes mechanical design of mobile construction crane, specified for moving Silka bricks of weight 200 kg. Thesis contains constructing solution of steel frame - boom, column and chassis. Standard purchased components are also defined in this thesis - hydraulic circuits, el. pulley assembly and wheels. Last part of thesis verifies sufficient safety of designed frame using Finite element method. Output of this thesis are mechanical drawings of welded parts of steel frame and assembly drawing of entire crane.

The thesis deals with the design and construction of headstocks of a turning centre. The aim is to design a spindle with an output of 20 kW and a maximum speed of 5000 1/min. The research part of the thesis is focused on the description of the basic parameters of the headstock and turning centres needed for the construction of the headstock and contains an analysis of the available spindles on the market. The next part of the thesis deals with the selection and calculation of cutting conditions and the necessary parameters. Analytical calculations are then verified using FEM analysis. At the end of the thesis, a 3D model was developed and headstock drawing documentation.

This diploma thesis is focused on solve of design solutions for piston for turbocharged version of Honda K20A engine, especially on reduce of side force acting on piston. There are mentioned methods and on their basis also design solutions for piston to reduce this force. There is also included kinematic and dynamic analysis for each solution and as well their FEM analysis for testing the suitability of these solutions.

Diploma thesis deals with the design and stress analysis of the rocker suspension for an autocross car. The research describes some real cases of using suspension with pushrod and rocker in motorsport. Subsequently, the work deals with the design of the wheel bump/rebound limiting stops and bump/rebound measuring. The challenge is to design a component shape, size and select fit of a rocker with an emphasis on low weight whilst maintaining sufficient strength and rigidity. The design study include stress analysis which leads to optimize the final shape.