Modelagem direta de dados de eletrorresistividade 3-D

Dentre os m��todos geof��sicos, o da Eletrorresistividade �� um dos mais tradicionais, com o seu desenvolvimento ocorrido h�� mais de 80 anos. Durante esse tempo o seu uso acompanhou o avan��o no poder de processamento num��rico e mais recentemente, a modelagem e invers��o tridimensional tornou-se uma possibilidade para o geof��sico. Apresentamos, neste trabalho, a t��cnica de elementos finitos aplicada ao m��todo da eletrorresistividade 3-D, atrav��s do c��lculo do potencial secund��rio. Para o desenvolvimento da metodologia, simulamos o levantamento do m��todo da eletrorresistividade 3-D com os arranjos Dipolo-Dipolo e Schlumberger, visando medir as varia����es laterais e verticais da resistividade aparente do solo. Estes arranjos consistem na inje����o de corrente el��trica na superf��cie e de medidas de diferen��as de potencial el��trico, resultante da intera����o da corrente el��trica com o solo. Sendo que, as fontes e receptores s��o localizados de acordo com os arranjos escolhidos para o levantamento. Neste trabalho, as curvas de sondagem e as pseudo-sec����es de resistividade aparente, s��o obtidas atrav��s da modelagem de eletrorresistividade 3-D, usando malha de elementos finitos regular. Para efeito de valida����o, os resultados s��o comparados com a resposta 3-D obtida a partir dos potenciais totais.

Modelagem de eletrorresistividade 2-D a partir do potencial el��trico secund��rio

Um dos m��todos cl��ssicos da geof��sica de explora����o �� o M��todo de Eletrorresistividade, estabelecido h�� um s��culo pelos irm��os Schlumberger e desde ent��o amplamente empregado em prospec����o mineral, estudos ambientais e hidrogeologia e em pesquisa de fontes geotermais. Conceitualmente o m��todo consiste de inje����o de corrente el��trica na subsuperf��cie e de medida de diferen��a de potencial el��trico, resultante da intera����o da corrente com o meio. As localiza����es dessas fontes e receptores s��o determinadas pelo arranjo escolhido para o levantamento. Ap��s o processamento, obt��m-se pseudo-se����es de resistividade aparente que indicam a distribui����o de condutividade em subsuperf��cie. Devido �� simplicidade dos fundamentos f��sicos de sua formula����o, o m��todo apresenta f��cil implementa����o computacional quando comparado aos m��todos eletromagn��ticos de fonte controlada. Na literatura h�� in��meros trabalhos de modelagem computacional, onde se calcula a resposta para problemas 2-D e 3-D. Nestes trabalhos, as pseudo-se����es s��o obtidas a partir do c��lculo do potencial el��trico total. Neste trabalho, apresentaremos a resposta da modelagem de eletroresistividade 2-D com o arranjo dipolo-dipolo, obtida a partir do potencial el��trico secund��rio. A solu����o �� calculada atrav��s do m��todo de elementos finitos usando malhas n��o estruturadas. Para efeito de valida����o, os resultados s��o comparados com a resposta 2-D obtida a partir dos potencias totais.

Modelagem e filtragem de distor����es est��ticas em levantamentos de dipolos cont��nuos

As distor����es est��ticas s��o um grave problema que afeta o m��todo magnetotel��rico e muitas tentativas t��m sido feitas para eliminar ou minimizar os seus efeitos. Este trabalho trata de uma t��cnica nova que trata deste problema, o m��todo EMAP, que �� uma adapta����o do m��todo magnetotel��rico na qual as medidas de campo el��trico s��o feitas em uma linha cont��nua de dipolos conectados entre si, e os dados coletados desta maneira s��o tratados com um filtro espacial passa-baixa dependente da frequ��ncia. Este trabalho �� composto de duas partes principais, a simula����o num��rica dos dados contaminados com as distor����es est��ticas e a filtragem destes dados com o filtro espacial passa-baixa. Na primeira parte, aplicamos o m��todo dos elementos finitos para simular a resposta dos dipolos el��tricos, os quais fazem as medidas do campo el��trico. Na segunda parte aplicamos a janela de Hanning como filtro passa-baixa apropriado para tratar os dados.

Pesagem em movimento e caracteriza����o do tr��fego ferrovi��rio com uso da t��cnica B-WIM

Nesta disserta����o �� apresentado o desenvolvimento de algoritmos para aplica����o do m��todo Bridge-Weigh In Motion (B-WIM) para a pesagem em movimento de trens e para a caracteriza����o do tr��fego ferrovi��rio, permitindo-se obter informa����es sobre a velocidade de passagem dos trens, n��mero e espa��amento entre eixos. Os sistemas B-WIM a partir de uma simples instrumenta����o permitem determinar as cargas por eixo de ve��culos em movimento, eliminando o efeito din��mico. Foram implementados os algoritmos para a determina����o dos valores referentes a geometria do trem e das cargas, que foi validado a partir de um exemplo te��rico, onde se simulou a passagem de um trem de caracter��sticas conhecidas sobre a ponte e as cargas por eixos foram determinadas com 100% de exatid��o. Al��m disso, foi feito um exemplo num��rico em elementos finitos, de um viaduto em concreto armado para aplica����o do m��todo, onde foi feita a determina����o das cargas por eixo para diferentes velocidades de passagem do trem. A fim de reduzir o tempo de processamento nas an��lises do exemplo num��rico, foi desenvolvido um algoritmo para a gera����o de cargas nodais no modelo num��rico que reduziram o tempo de processamento em at�� 96% quando comparado com a an��lise de m��ltiplos passos (���Multi-Step���), que simula automaticamente a passagem do trem sobre a estrutura. Finalmente, o m��todo foi testado em um caso real a partir de monitora����es realizadas em um viaduto de concreto armado da Estrada de Ferro Caraj��s. Apesar de n��o ter sido poss��vel a determina����o das cargas por eixo da locomotiva, foi poss��vel medir precisamente o peso bruto total da locomotiva quando se utilizou o modelo constitutivo de Collins & Mitchell (1991) para o concreto.

Influ��ncia de par��metros construtivos e operacionais na vida em fadiga de uni��es aparafusadas em tra����o

P��s-gradua����o em Engenharia Mec��nica - FEG

Efeito da ciclagem mec��nica em pr��-molares restaurados com inlays confeccionados com diferentes materiais cer��micos na resist��ncia de uni��o dentina-restaura����o

Coordena����o de Aperfei��oamento de Pessoal de N��vel Superior (CAPES)

Ader��ncia a��o-concreto: simula����o num��ricadosensaios de arranchamento pull-out e APULOT usando o programa ATENA

The bond between steel and concrete is essential for the existence of reinforced concrete structures, as both materials act together to absorb structural strain. The bond phenomenon is considered to be complex regarding many factors that affect it. Several types of bond tests have been proposed over years. One is the modified proposed of pull-out test, which was elaborated by Lorrain and Barbosa [1] called APULOT test (Appropriete pull-out-test). Based on experimental results obtained by Vale Silva[2] either by conventional pull-out tests, or by modified pull-out test, APULOT, seeks to know the numeric behavior of bond steel-concrete through a numerical simulation using a calculation code ATENA which is based on the Finite Element Method (FEM). The numerical simulation provided better evaluate the stress distribution and cracking that occurs during the test, thereby becoming a valuable tool to support the experimental project that aims to validation, validation partially or not recommend the modified bond test steel-concrete - APULOT test - as quality control test of structural concrete. The numerical results showed good representation compared to experimental results.

An��lise da falha do suporte de mancal de um eixo cardan utilizado num ve��culo pesado

P��s-gradua����o em Engenharia Mec��nica - FEG

Estudo do fen��meno de instabilidade de estruturas cil��ndricas de paredes finas submetidas ao carregamento de press��o externa

Thin walled cylindrical shells are widely used in many areas of industry, including civil, mechanical, nuclear, marine, petroleum and aerospace engineering. The wide application of thin cylindrical shells and the importance of instability phenomenon are the motivation basis to this study, since these factors have a great importance in engineering projects. It is presented a detailed study about the instability of cylindrical shells based on theoretical calculation, which results are compared with finite elements method calculation. The loading and boundary conditions analyzed are based on the most common types verified in real engineering projects and refer respectively to lateral (external) pressure and cylinders with simply supported edges. The calculation based on the finite elements method was executed with ANSYS 13.0 software. The results obtained with this calculation are in good agreement with the analytical theory presented in the technical note NACA No 1341 (BATDORF, 1947) considering a wide range of applicability. On the other hand, the analytical method presented in the book Theory of Elastic Stability (TIMOSHENKO; GERE, 1936) has a very restrict applicability and has presented considerable deviations in a great sort of the analyzed cases

An��lise e redu����o de custos e peso em ve��culo rodovi��rio de carga reboque linha de eixos

Load transportation in brazilian territory is made difficult by a deficient highway network, result of low maintenance and lack of government supervision. The problem aggravates when we consider the transportation of indivisible loads, mainly because the brazilian highways are not prepared for such task and few companies in Brazil have the necessary equipment suited for this kind of transport. In this dissertation it will be shown the analysis of a specific equipment to transport overweight indivisible loads, called hydraulic modular multi axle trailer. From an existing project (RB.04LE-01), manufactured and homologated in Brazil, it has been studied how the components in this trailer work so it could have been possible to elaborate a new model (RB.04LE-02), with two main objectives: reduction of costs and weight with subsequent increase in the liquid load for roadway transportation. The trailer���s components analyses were made utilizing the theory of fatigue strength of materials and finite element method with the von Misses criteria for a more safety when realizing the calculations

An��lise cr��tica de um vaso de press��o do setor sucroalcooleiro

This study aims to evaluate structurally a heat exchanger that has been in operation since the mid-60's and was built COSAN for operation in one of its sugar production plants in S��o Paulo, this equipment as well as many similar devices are operation in plants throughout Brazil, and thus to be acquired by large corporations as in the case of COSAN, pass the scrutiny of inspection work, and work such as recalculations in the latter case in structural evaluations to verify the possible need for adjustments to project or operation and thus ensure the structural integrity of the equipment. To this were first done field survey using techniques of NDT and NDT's for determining the thickness of the main parts of the equipment, made the revaluation dimensional and existing project and considering the loads operating performing the characterization of the equipment as specified in the standard regulatory number 13 - NR13 and the other for this type of equipment and finally an analysis using a static approach, as an analysis tool using the finite element method

Projeto de conjunto redutor de velocidade utilizando engrenagem sem-fim

This work is initially based in give a solution to a problem consisting of lifting a load in a warehouse focusing specifically on the solution��s project and comparison of the results obtained following the sequence of the book and comparing these results with the finite elements simulation based on the 3D components modeling. Starting from that was realized the project of the worm gear reducer to solve the problem and makes the work easier. The project consisted basically of the study, project itself and simulation by software of a worm gear reducer and projects steps, starting with the initial problem conditions (to lifting a load up to an specific height at a given time) following all the reducer project sequence, starting by the preliminary draft and electric motor selection using iterative process, material selection, worm gear dimensioning, axles, keyways, bearings and coupling. After that was performed the three dimensional modeling of the components using SolidWorks software and simulating these components using Ansys software. The results show the importance of the CAD in terms of improving project development speed and reducing costs with prototypes

Desenvolvimento de um protetor lateral em alum��nio

In view of the need to develop a device for security and lateral protection, due to the Resolution 323/09 of CONTRAN, which requires the use of such equipment for most trucks and tow trucks, the objective of this work is to develop a project for an aluminum lateral protection device, according to the ABNT NBR 14.148 regulation, that, among many specifications, stipulates that the equipment must support a load of 5 kN and suffer a maximum deflection of 30mm, but does not say what material it should be made of. The reason for choosing aluminum is because of its low density, so as not to significantly increase the curb weight of the truck, which, consequently, reduces CO2 emissions and maintenance expenses. Additionally, this material presents a good resistance/weight ratio, high resistance to corrosion, excellent surface finish and it's fully recyclable; reason why it has been gaining the attention of many industry segments. For the realization of the project, profiles were chosen to make the assembly of the set, and then a finite elements analysis was performed in the HyperWorks software, to verify if the designed device would support the loads stipulated by the regulation. One details to note is that these simulation programs could show inaccuracies, because of the size and shape of the elements that compose the mesh, and for many other reasons, so it is necessary that, even with the results coming back satisfactory, actual physical tests are conducted to validate the proper functioning of the equipment, which was not done for this study

Otimiza����o da estrutura metalica para um carro aleg��rico

Carnival is a unique opportunity for the associations demonstrate the community���s annual work and the float is a major component of this celebration, responsible for pitch the samba using allegories and carry important figures. The excess weight of the floats which are mostly manufactured from truck and bus structures requires larger amount of people to push the vehicle in addition to increased efforts on the steering systems, suspension and wheels, raising the probability of breakage and loss of one year work. The objective of this study is to use the concepts of strength of materials combined with computer simulation to obtain a structure that has the lowest possible weight without compromising the safety of transported components and that is also easy to manufacture, drive and store

Simula����o num��rica de fluxo de ��guas subterr��neas na bacia do Rio Grande (BA)

The Urucuia Aquifer System represents a strategic water source in western Bahia. Its baseflow is responsible for the flow rate of the main tributaries of S��o Francisco river left bank in the dry season, including the Rio Grande, its main tributary in Bahia state. This river has a hydrological regime heavily affected by groundwater and is located in a region with conflicts about water resources. The aquifers geology is constituted by neocretacious sandstones of Urucuia Group subdivided in Posse Formation and Serra das Araras Formation. The embasement is formed by neoproterozoic rocks of Bambu�� Group. This work focuses on an important tool application, the mathematical model, whose function is represent approximately and suitably the reality so that can assist in different scenarios simulations and make predictions. Many studies developed in this basin provided the conceptual model basis including a full free aquifer, lithological and hydraulical homogeneity in entire basin, null flux at plateau borders and aquifer base. The finite element method is the numerical method used and FEFLOW the computational algorithm. The simulated area was discretized in a single layer with 27.357,6 km�� (314.432 elements and 320.452 nodes) totaling a 4.249,89 km�� volume. Were utilized 21 observation wells from CERB to calibrate the model. The terrain topography was obtained by SRTM data and the impermeable base was generated by interpolation of descriptive profiles from wells and electric vertical drilling from previous studies. Works in this area obtained mean recharge rates varying approximately from 20% to 25% of average precipitation, thus the values of model recharge zones varying in this range. Were distributed 4 hydraulic conductivity zones: (K1) west zone with K=6x10-5 m/s; (K2) center-east zone with K=3x10-4 m/s; (K3) far east zone with K=5x10-4 m/s; e (K4) east-north zone with K=1x10-5 m/s. Thereby was incorporated to the final conceptual model...