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Dissertation/Thèse

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2024
Thèses
1
  • KEVIN TENORIO LOBO MARTINS DE SOUZA
  • Application of the FVDAM technique in reinforced masonry

  • Leader : FRANCISCO PATRICK ARAUJO ALMEIDA
  • MEMBRES DE LA BANQUE :
  • FRANCISCO PATRICK ARAUJO ALMEIDA
  • RODRIGO RIBEIRO PACCOLA
  • ROMILDO DOS SANTOS ESCARPINI FILHO
  • SEVERINO PEREIRA CAVALCANTI MARQUES
  • Data: 5 janv. 2024


  • Afficher le Résumé
  • Masonry is one of the oldest construction techniques in humanity. Despite millenia of study and improvement, there are still gaps in scientific knowledge and disadvantages to overcome. This is partially due to the difficulty in modelling and characterizing the material, that presents heterogeneous and periodic characteristics. One way to improve masonry about some of its weaknesses is fiber reinforcement. Fiber-reinforced Cementitious Matrix (FRCM) is a kind of reinforcement that has been well studied in this context. Consists of the coating of one or both faces of a masonry wall with a mesh of fibers embedded in cementitious matrix. Several materials can be used as fibers, the most common being steel, carbon, glass and aramid. The use of natural fibers (NFRCM) presents potential advantages in the scope of sustainability, but it is still little explored. Among the natural fibers, sisal fiber stands out, which is used in the form of ropes and presents abundant production in Brazil. However, FRCM presents an even greater challenge of modelling, since it increases the complexity and number of phases of masonry. The Finite-Volume Direct Averaging Micromechanics (FVDAM) technique is a promising option and still without application in the context of natural fibers. It consists of a homogenization technique that uses the Finite-Volume Theory (FVT) to calculate the effective properties of a heterogeneous material. Thus, the objective of this work is to investigate the effectiveness of FVDAM in the modelling and homogenization of masonry reinforced by NFRCM, comparing the results with other modelling techniques and physical tests.

2
  • OTAVIO BRUNO DE ARAUJO RODRIGUES
  • Numerical Modeling of Tubing Strings in Oil and Gas Wells to Quantify Friction and Axial Forces

  • Leader : WILLIAM WAGNER MATOS LIRA
  • MEMBRES DE LA BANQUE :
  • JOSÉ RENATO MENDES DE SOUSA
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • JOAO PAULO LIMA SANTOS
  • WILLIAM WAGNER MATOS LIRA
  • Data: 26 janv. 2024


  • Afficher le Résumé
  • This work proposes the numerical modeling of tubing strings in oil and gas wells to quantify friction and axial forces. From a one-dimensional numerical model of buckling with friction, the other effects involved in the problem under study are incorporated and modeled for an accurate prediction of the efforts acting in tubing. During the life of a well it is important that the tubing supports this type of effort. Thus, the need for workover is avoided and one of the first elements of the well barrier system remains intact. The buckling of tubing forms contact regions between the column and the casing, as well as frictional forces that impact axial efforts. Due to the variety of loadings, a general solution to the buckling friction problem requires numerical solutions. In directional wells, the weight and trajectory of the tubing naturally generate frictional forces along the casing. In the literature, there are models that evaluate these forms of friction in isolation, while others even propose a joint analysis, but only for specific cases and without evaluating the loading history. In this direction, a model with all these criteria allows a more realistic analysis of the phenomenon. To achieve the proposed objective, the adopted methodology is divided into four macro-steps: i) study of friction models and aspects of column buckling; ii) computational modeling of friction buckling for tubing; iii) incorporation of new effects into frictional buckling modeling; iv) carrying out case studies on directional wells. At the end of the work, it is expected to quantify the friction in the axial forces, as well as to compare it with the other effects in scenarios of directional wells with production and injection strings under different forms of restriction. The main contributions of this work are the adaptation of a numerical model of buckling with friction to evaluate other forms of friction, buckling criteria update for directional wells and development of a strategy for evaluating the piston effect of the string in the numerical model.

3
  • AYSLAN DAVIDSON AGUIAR DOS SANTOS
  • ELABORATION OF MODELS FOR THE OPERATIONAL SEQUENCE HISTORICAL DATA BASED  OFFSHORE WELL STRUCTURES

     
  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • JOAO PAULO LIMA SANTOS
  • ROBERTO BARBOSA DOS SANTOS
  • Data: 9 févr. 2024


  • Afficher le Résumé
  • In offshore oil exploration, the construction of a well requires long and complex operations,
    which results in high costs, mainly related to the rental of drilling rigs. it is essential to
    analyze the sequence of operations required for its construction, particularly concerning its
    structure, given its importance throughout the well's lifecycle, in order to seek a reduction in
    errors and execution time. A promising analytical approach is to use historical data in the
    planning of new offshore operations, aiming to bring more predictability to the assessment
    and design process of new wells. To do so, operational sequence models of the well structure
    were developed based on actual drilling schedules to establish parameters for duration and
    anomalies for production, injection, and special wells. The analyses were conducted using a
    database of drilling schedules carried out by an oil company. The schedules were imported
    into spreadsheets, where they are grouped according to well type, and specific well structure
    activities are separated from others to establish the operational sequence and its parameters.
    The developed models can be used for both the design of new wells and the evaluation of previously executed schedules, aiming to reduce errors, downtime of equipment and personnel, and, consequently, cost reduction.

     
4
  • ANTONIO PAULO AMANCIO FERRO
  • Predictive models for ROP as support for real-time optimization of operational drilling parameters in oil well drilling

     
     
     
  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • CHARLTON OKAMA DE SOUZA
  • EDUARDO NOBRE LAGES
  • Data: 21 mars 2024


  • Afficher le Résumé
  • The Rate of Penetration (ROP) is a parameter of great interest in real-time drilling optimization. A
    higher ROP reduces drilling time and can lead to significant cost reductions in well construction.
    Predictive models for ROP are applied to predict ROP based on measured data while drilling,
    enabling the determination of optimal operational parameters such as RPM, WOB, and fluid
    flow when combined with optimization techniques. Obtaining more accurate ROP models is a
    challenging task due to the large number of factors interacting nonlinearly. This study involves the
    examination of different ROP models, including traditional ones, like Bourgoyne & Young and
    Specific Mechanical Energy, and their adaptations, compared with machine learning models such
    as Artificial Neural Networks (ANN) and Random Forests (RF). Public data from 7 wells were
    structured into a dataset with relevant information for evaluating the performance of different
    models in estimating ROP, including operational parameters, drill-bit data, lithology, geophysical
    logging data, pore pressure gradient, and unconfined compressive strength. In comparative
    analyses, error metrics such as Mean Absolute Error (MAE) and Root Mean Square Error
    (RMSE) are compared among the different models for each of the 7 wells. Statistical significance
    analysis is performed with the Bourgoyne & Young model to understand more significant effects
    on ROP. The interpretability of traditional models, along with hyperparameter tuning, is adopted
    to employ machine learning models with more meaningful inputs and greater predictive capacity.
    Next, two strategies found in the literature for using predictive models for ROP in real-time
    optimization are compared: models trained with offset well data or with the well’s own data,
    simulating a gradual data acquisition process (continuous learning). The results indicate better
    performance of machine learning models compared to traditional models. The RF model shows
    overall better performance in comparative analyses, with smaller errors and lower computational
    cost. The relevance of torque and the inclusion of formation data (Delta-T compressional) in
    machine learning models is identified. Also, continuous learning strategy can achieve lower
    errors, although both strategies are capable of generating appropriate predictions.

     
5
  • HUGO AGUIAR VITORIO MENDONCA
  • Comparative analysis of damage identification methods in steel beams

  • Leader : WAYNE SANTOS DE ASSIS
  • MEMBRES DE LA BANQUE :
  • FLAVIO BARBOZA DE LIMA
  • HIGOR SÉRGIO DANTAS DE ARGÔLO
  • WAYNE SANTOS DE ASSIS
  • Data: 25 mars 2024


  • Afficher le Résumé
  • This research aimed to perform a comparative analysis between damage identification methods based on modal analysis, to cooperate with the Structural Health Monitoring (SHM) process in steel beams. To achieve that, steel beam models were be generated via commercial finite elements software Abaqus with differences in parameters such as damage level, damage location and boundary conditions. After obtaining results for mode shape displacement, two more parameters are added: noise level and the use or not of a curve fit to smooth data. As there are four methods of damage identification compared: DCM, DCMM, MSDBI and MSDBIM, it was issued a full factorial Design of Experiments (DOE) to analyze and to check the effectiveness of each method in detecting and possibly localizing damage, in addition to observe the ability to distinguish different levels of damage to each model through statistical analysis that was extended to study the influence of factors in the problem response of each damage identification methods. The results obtained show that the methods have high effectiveness to locate damage in noiseless conditions, however the presence of noise decreases the correct identification of damage, even with regression fit to smooth modal data. The modified methods performed better when compared to the originals, and the methods DCM and DCMM located the damage more easily than MSDBI and MSDBIM.

Thèses
1
  • SALVATORE VERDE
  • NON-SORTED GENETIC ALGORITHM OPTIMIZATION OF COST-EFFICIENT SYNTHETIC MOORING SYSTEMS UTILIZING POLYMER SPRINGS FOR 15 MW FLOATING WIND TURBINES IN RELATIVELY SHALLOW WATERS

     
     
     
     
  • Leader : EDUARDO NOBRE LAGES
  • MEMBRES DE LA BANQUE :
  • ADEILDO SOARES RAMOS JUNIOR
  • EDUARDO NOBRE LAGES
  • FÁBIO MARTINS GONÇALVES FERREIRA
  • GUILHERME ROSA FRANZINI
  • THIAGO PONTIN TANCREDI
  • Data: 26 mars 2024


  • Afficher le Résumé
  • The imperative transition to renewable energy sources, driven by the need to address energy security and climate change challenges, underscores the pivotal role of offshore wind energy. This study delves into the multifaceted aspects of wind energy, examining both the potential in shallow water installations and the ongoing paradigm shift towards larger turbine sizes. In the exploration of shallow water regions, economically viable locations for wind farms emerge between 50 and 70 meters in depth, employing shared anchor concepts and mooring line systems. The selection of an optimal system type is critical, and past research highlights the efficiency of synthetic fiber ropes over traditional chain catenary configurations. This paper presents dynamic analyses applied to a 15 MW turbine and the VolturnUS-S reference platform in the Celtic Sea. A comprehensive comparative assessment of planar displacements, rotations, and loads on a shared anchor is conducted using nylon and polyester ropes. Results show a notable 44% reduction in peak resolved anchor load with nylon compared to polyester, albeit with larger displacements and rotations, suggesting potential improvements in mooring design. With nylon being 10% more cost-effective than polyester and ongoing investigations into efficient anchor concepts, this study encourages further exploration of nylon applications in shallow-water wind farms. Simultaneously, the wind energy sector grapples with the challenge of escalating turbine sizes to reduce the levelized cost of energy. This necessitates smaller platform and mooring systems, especially in the context of shallow-water installations. Building upon prior research, which employed a multi-objective optimization (MO) framework for designing platforms and mooring systems with synthetic lines, this study extends the existing framework by incorporating computational efficiency strategies. The utilization of a static methodology and a running metric as a termination criteria for the MO contributes to computational efficiency. Additionally, the study explores the optimization of an alternative mooring system using spring polymer, revealing the potential for a substantial reduction in mooring system costs for smaller radii. This holistic approach addresses the dual challenge of enhancing turbine efficiency in larger sizes while adapting to the constraints posed by shallow-water installations. The fusion of insights from both aspects contributes to a more comprehensive understanding of the evolving landscape of offshore wind energy.

     
     
     
     
2023
Thèses
1
  • JORGE LUIS OLIVEIRA SILVA
  • STRUCTURAL PERFORMANCE OF CONCRETES PRODUCED WITH CONCRETE RECYCLED AGGREGATES

  • Leader : KAROLINE ALVES DE MELO MORAES
  • MEMBRES DE LA BANQUE :
  • KAROLINE ALVES DE MELO MORAES
  • PAULO CESAR CORREIA GOMES
  • CASSIA VANESSA ALBUQUERQUE DE MELO
  • Data: 28 mars 2023


  • Afficher le Résumé
  • Currently, more sustainable alternatives have been sought within the civil construction sector, as a way of reducing harmful interference to the environment. Among these alternatives, the use of recycled concrete aggregates stands out for the production of mortars and concrete, with or without a structural function. However, the use of these aggregates is a subject that still needs to be studied, in the sense of seeking alternatives that aim to understand the porosity present in recycled aggregates, considered as the main obstacle to its use for structural purposes. Thus, the main objective of this study is to evaluate the contribution of recycled concrete aggregate (ARC) dosages on the properties of structural concrete in fresh and hardened states. Concretes with different dosages were produced, using the method proposed by ABCP, varying the percentage of replacement of natural aggregate by recycled in 25%, 50%, 75% and 100%, as well as varying the size of the ARCO (fine and coarse). Fresh state performance was evaluated using the slump test. The evaluation of properties in the hardened state was carried out using the compressive strength test, modulus of elasticity and physical indices of concrete, such as water absorption, voids index and actual specific mass. From the results of the consistency test, voids index, and absorption, all mixtures showed high values. With regard to the compressive strength results at 28 days, the mixes produced with 100% ARCO replacing only the fine aggregate, showed a result of 21.21 MPa; for the mixtures replacing only the coarse recycled aggregate, up to 75% replacement, satisfactory results were found in terms of compressive strength, with a value of 20.98 MPa being obtained for the referred percentage. For replacements of both (fine and coarse), the replacement limit was between 50% and 75%, with values of 25.60 MPa and 19.74 MPa, respectively. In this way, the interference of the size of the aggregate in the properties of concrete is evident, both in the fresh state and in the hardened state. This can be justified by the granulometry of the aggregate, which interferes with the filling of voids in the concrete, favoring greater compaction and locking of the particles; in addition to the effect of the porosity of the recycled aggregate, which is more evident in the coarse aggregate, due to the particle size. This higher porosity of the coarse recycled aggregate also influenced the results of modulus of elasticity, since this property determines the stiffness of the aggregate which, in turn, controls the ability of the aggregate to restrict matrix deformation. Complementarily, the results demonstrated the potential use of ARCO, with the possibility of replacing the natural aggregate in large part, as opposed to the current standard, which limits the percentage of replacement to up to 20% in applications for structural purposes (resistance class of C20), without bringing a clear indication if this replacement refers to fine aggregate, coarse aggregate or both.

2
  • JOAO PAULO NOGUEIRA DE ARAUJO
  • CONTRIBUTION TO USING RELIABILITY ON WELL CASING DESIGN

  • Leader : EDUARDO TOLEDO DE LIMA JUNIOR
  • MEMBRES DE LA BANQUE :
  • CHARLTON OKAMA DE SOUZA
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • JOAO PAULO LIMA SANTOS
  • Data: 14 avr. 2023


  • Afficher le Résumé
  • The casing system is essential to guarantee integrity on oil wells. To ensure a correct casing design, equations and methodologies are suggested by international standards for resistances and loads that should be verified if the casing system designed is adequate to the well throughout its life. One example of such standard is API/TR 5C3, which on its 2008 revision added suggestions for equations and methodologies to use reliability techniques on casing design, going even as far as supplying statistic characterization of various casing tubulars using a database made of different manufacturers from along a few decades. Even so, the use of these reliability techniques and tools are still restricted to specific analyses and are not used as a routine by casing designers. With that in mind, this work aims to study various load cases on a number of casings generally used on oil wells, comparing the results obtained using the standard techniques (Safety Factors - SF) and reliability (Failure Probability - FP). The loads will be equal to the casing resistance considering the Serviceability Limit State (SLS), which is still the most used by casing designers, and would lead to a failure limit (SF = 1.0), with the objective of making a comparison between the results of the techniques. At the end of this work, it is expected to have a better understanding of how much of a risk an FP number actually means, making it easier to add the reliability analysis on regular casing design.

3
  • GILBERTO LUCAS LEANDRO DOS SANTOS
  • Mitigation Methods for Annular Pressure Build-up in Oil Wells

  • Leader : WILLIAM WAGNER MATOS LIRA
  • MEMBRES DE LA BANQUE :
  • WILLIAM WAGNER MATOS LIRA
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • JOAO PAULO LIMA SANTOS
  • CHARLTON OKAMA DE SOUZA
  • Data: 29 sept. 2023


  • Afficher le Résumé
  • This work aims to study some methods for mitigating the increase in pressure in confined annuli (APB - Annular Pressure Build-up) of oil wells. Throughout the life of the well, various operations provoke temperature variations, leading to pressure increases and decrease in the annular spaces. In some cases, the pressure variations can result in casing failures. Ultradeep waters wells present even more extreme temperature and pressure conditions, consequently raising the APB levels observed. In this context, mitigation techniques appear as alternatives to ensure the integrity of the well, keeping APB levels within the allowed limits. The methodology adopted to achieve the objective of this work is divided into four macro steps: i) study on the APB, identifying the theoretical aspects. At this stage, the study of the APB simulator, developed by Vasconcelos (2019), is also carried out, which is used in this work to model the phenomenon. Including comparing the results, for a reference scenario, with those achieved through the software StrinGnosis®, widely used by the oil and gas industry; ii) study of the methods for mitigating APB, understanding the functioning of each technique. At this stage, the open shoe or cement shortfall, rupture disks, and compressible foam methods are selected for more advanced studies based on their advantages; iii) implementation of computational routines in the simulator to reproduce the behavior of APB with the presence of each of the three previously selected techniques; and iv) final evaluation of the methods’ ability to mitigate the issues related to APB. Based on the results, the APB simulator presents a maximum difference of 3.66% compared to StrinGnosis®. Regarding the studied mitigation methods, in the scenario considering fluid drainage to the formation, different rock permeabilities cause variations of up to 1000 psi in the studied model. Furthermore, increasing the drainage section is not effective beyond a certain depth. With the use of rupture disks, less resistant casings associated with the installation of disks can be economically advantageous, maintaining the integrity of the well. With the use of synthetic foams, it is possible to evaluate their length and positioning in the annuli to keep the APB within the allowed limits. In this context, the present work contributes to studies on annular pressure build-up (APB) in oil wells and APB mitigation techniques. Additionally, it assesses, in a simplified manner, the integrity of well casings subjected to APB loads.

Thèses
1
  • LUCAS PEREIRA DE GOUVEIA
  • Residual Collapse Strength of Worn and Corroded Tubes: A Data-Driven and Numerical Modeling based Approach

  • Leader : EDUARDO TOLEDO DE LIMA JUNIOR
  • MEMBRES DE LA BANQUE :
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • JOAO PAULO LIMA SANTOS
  • WILLIAM WAGNER MATOS LIRA
  • CHARLTON OKAMA DE SOUZA
  • THEODORO ANTOUN NETTO
  • Data: 20 oct. 2023


  • Afficher le Résumé
  • This work proposes a methodology for estimating the residual strength of tubes damaged by wear and/or corrosion in oil wells, involving geometric inspection of the elements and their numerical modeling in a probabilistic approach. The objective is to provide a robust assessment of the structural integrity of tubular components in a high-complexity and high-risk environment, such as the Brazilian pre-salt region. Casing and production/injection columns are importante safety barrier elements, playing crucial structural roles and isolating the well and formation to prevent unexpected fluid flow.Wear and corrosion in these tubular components occur during diferente operations throughout their lifecycle, and they are conservatively considered in the design phase to avoid integrity loss situations. However, there is a lot of uncertainty in these predictions. Modern inspection equipment available in the market, such as ultrasonic and electromagnetic logging tools, have allowed for the assessment of the actual state of in-service tubes. Tube radius, thickness, and mass loss are the parameters measured along the well columns. Proper interpretation of this data allows for the identification of tube damage and quantification of the corresponding severities. A methodology is proposed for characterizing the cross-sectional geometry of tubes based on inspection data, in the presence of measurement uncertainties. Bidimensional nonlinear Finite Element Method models are used to estimate the residual colapse strength of the tubes. Additionally, a probabilistic analysis of the residual geometry of damaged tubes is presented, considering random variables related to damage configuration parameters such as maximum depth and position. The results obtained lead to the conclusion that the initial geometric configuration of the damaged tube can result in significant variations in residual strengths for different damage parameters, including depth, radius, position, and distribution. It is worth noting that the analytical models found in the literature only partially consider these factors, not in their entirety. A case study is developed using real ultrasound inspection data to demonstrate the application of the proposed methodology, comparing the results with reference values.

2022
Thèses
1
  • SAMARA THAÍS LIMA RAMOS
  • Comparative analysis of loading verification methods in SWA for the issue of special transit authorization

  • Leader : WAYNE SANTOS DE ASSIS
  • MEMBRES DE LA BANQUE :
  • HUDSON CHAGAS DOS SANTOS
  • FLAVIO BARBOZA DE LIMA
  • WAYNE SANTOS DE ASSIS
  • Data: 3 mars 2022


  • Afficher le Résumé
  • Aiming to develop a comparative evaluation of the principles for load analysis in bridges, this work proposes to perform the structural verification of a special work of art - OAE, through the study of the mobile loads adopted by the Brazilian (NBR 7188:2013), American (AASHTO: 2002 and 2020) and European (Eurocode 1: 2003) standards. The verification of the loads, generated by means of the mobile loads described in the respective standards, was performed on the Croatá river bridge, located on BR-423/AL, in the municipality of Canapi/AL, observing the limits of weight and dimensions, related to cargo vehicles on Brazilian highways, established by the resolutions of the National Traffic Council - CONTRAN. The bridge design information was made available by DNIT/AL, enabling the evaluation of the applied loads generated by the design loads described in the referred standards and by a special freight train. Numerical modeling was employed, through the finite element method (FEM), to analyze the effects of the passage of the standard trains, determining the maximum loads generated in the superstructure with the passage of the standard trains, comparing them and applying the determinations established in the standards. Using the internal forces from the numerical analysis, the methodology established by DNIT was applied to the results obtained in order to elaborate the Special Transit Authorizations - STA, which establishes the criteria for verifying structural safety in highway bridges. Through this study, it was concluded that the OAE under discussion is in adequate structural conditions for the passage of special loads and loads from international standards, whose safety factors presented in the verifications are higher than the unit. It was also concluded that the Brazilian standards, in contrast with the international standards, presented in the case analyzed higher safety factor values during the structural verification.

2
  • ISAQUE SOARES FIGUEIREDO
  • Finite element analysis for wellbore stability in direction drilling

  • Leader : JOAO PAULO LIMA SANTOS
  • MEMBRES DE LA BANQUE :
  • BEATRIZ RAMOS BARBOZA
  • FRANCISCO PATRICK ARAUJO ALMEIDA
  • JOAO PAULO LIMA SANTOS
  • WILLIAM WAGNER MATOS LIRA
  • Data: 26 mai 2022


  • Afficher le Résumé
  • Directional drilling techniques are applicable in fields, such as petroleum, buildings and the mineral extraction industry. Compared to vertical drilling, directional drilling is much more complex. The curvature of the well axis passing through the stratified rock mass causes the conditions around its cross section to be strongly anisotropic. Not infrequently, the same rock material in each layer exhibits anisotropic properties. Proper determination of the stress, strain, and displacement states around the borehole is critical in the design of directional boreholes. Numerical analysis tools that take into account the rock mass structure and rock mechanical properties along the well path are used for this purpose. This paper aims to numerically evaluate the structural stability of rock masses around a directional well using the Finite Element Method. The calculations are conducted with linear elastic and viscoelastic constitutive models, used in the rock strata models. Based on the results, the influence of rock behavior on the stability of the directional well is discussed.

3
  • BRUNO CORREIA DE ARAUJO MOURA
  • On the influence of axial loads in well casing integrity

  • Leader : WILLIAM WAGNER MATOS LIRA
  • MEMBRES DE LA BANQUE :
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • EMÍLIO CÉSAR CAVALCANTE MELO DA SILVA
  • JOAO PAULO LIMA SANTOS
  • WILLIAM WAGNER MATOS LIRA
  • Data: 8 juil. 2022


  • Afficher le Résumé
  • The objective of this work is to evaluate the influence of the action of effects that cause axial stresses on the integrity verification calculations of casing tubulars. This assessment is relevant because, in well projects, some scenarios subjected to combined loads are capable of penalizing the resistance to collapse, which may cause an unexpected failure in the casing. Due to the complexity of the problem, numerical simulations supported by the finite element method are used to reproduce the evaluated scenarios. To achieve the proposed objective, the development methodology of this work is based on four main steps: i) study and determination of the scenarios that the casing tubes must be submitted; ii) determination of loads, including studies of effects and phenomena that act on the casing; iii) identification of the most appropriate numerical modeling for the reproduction of scenarios considering the integrally modeled casing tubes and the various possibilities of combined loads that act in these tubes; and iv) performing numerical analyzes contemplating the various scenarios considered and evaluating critical situations that may produce failure in the integrity of the casing. At the end of the work, the coating structure has been fully analyzed from the axial stress fields and resulting pressure forces obtained in the numerical simulations, finding the most critical sections in relation to loading and resistance and evaluating the integrity of the coating more effectively.

4
  • LEONARDO TOLEDO FERREIRA
  • NUMERICAL ESTIMATION OF IMPACT PRESSURE ON SOIL-STRUCTURE
    INTERACTIONS WITH THE MATERIAL POINT METHOD

  • Leader : ADEILDO SOARES RAMOS JUNIOR
  • MEMBRES DE LA BANQUE :
  • ADEILDO SOARES RAMOS JUNIOR
  • BEATRIZ RAMOS BARBOZA
  • DIOGO TENORIO CINTRA
  • RICARDO GARSKE BORGES
  • TIAGO PEIXOTO DA SILVA LOBO
  • Data: 29 juil. 2022


  • Afficher le Résumé
  • Many structures are under the risk of impact with natural hazards such as mudslides,
    avalanches, and submarine landslides. In the oil and gas industry, as example, the assessment
    of the positioning of pipelines must consider the risk of impact with submarine landslides, as
    an impact with such phenomena could cause leakage that would lead to severe economic
    and socioenvironmental losses. Therefore, a study of the impact of natural hazards upon
    structures is necessary. That study must begin from the resistance parameters associated
    with the impact events, among which impact pressure stands out. That parameter is difficult
    to measure in practice, however, as experimental studies with centrifuges are hard to carry
    out, and field measuring is, in most cases, impracticable. Besides, the utilization of analytical
    solutions is overly restrictive in the presence of physical and geometric nonlinearities. Thus,
    numerical simulations come as a viable alternative, as they expand from basic physics
    principles and are not limited by the same apparatus and space restrictions as the laboratory
    and field measurements. The expanding processing capabilities of modern computers is
    another argument in their favor. Among numerical methods, the material point method
    (MPM) stands out, as it has the capacity to simulate large deformation and displacement,
    which are common in impact events. To utilize the MPM, an investigation of the numerical
    procedure for the computation of the impact pressure is performed, as that procedure is not
    shared in the literature, although used by many authors. Limitations of possible solutions
    for this problem are explored in this manuscript, as well as suggestions of alternative ways
    of computing the impact pressure parameter. The analyses are performed in the context of
    classic problems, such as the study of cone penetration (T-bar), and the impact of submarine
    landslides upon subsea infrastructure via synthetic models.

5
  • ERASMO AUGUSTO BEZERRA SILVA
  • DESIGN OF THE LAYOUT OF THE RIGID CORE IN HYBRID BUILDINGS STEEL/CONCRETE WITH THE USE OF GENETIC ALGORITHM
     
  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • EDUARDO NOBRE LAGES
  • LUCIANO BARBOSA DOS SANTOS
  • ALEX SANDER CLEMENTE DE SOUZA,
  • Data: 6 oct. 2022


  • Afficher le Résumé
  • Determining the structural system of a building involves defining materials and arranging
    elements in order to efficiently resist combinations of actions. In cases where steel or composite
    rigid frames become inefficient, due to the high dimensions of the profiles or the difficulty and
    cost of rigid connections; and bracings cause considerable impact to architecture due to the
    obstruction of facades or circulation areas; shear walls systems are a viable alternative lateral
    resisting system. However, in these buildings, the shear walls positioning and the layout in
    the plan is most responsible for the torsional effects. In order to design a shear walls layout that
    minimizes these effects, is compatible with the architectural plan, and satisfies the
    requirements of the economy, strength, and rigidity, the designer performs an iterative and inefficient
    process of trial and error, whose improvement of the solutions is dependent on previous projects
    experience and intuition. To evaluate the use of a genetic algorithm in the conceptual design
    of shear walls layout, a computational program was implemented that minimizes the structural
    weight as a function of the layout, with restrictions to the resistant capacity, displacement, to
    the effect of torsion, and the need for openings for the movement of people. The comparative
    analysis carried out between four optimized models and a reference model, adapted from a real
    the project resulted in a considerable reduction in the consumption of concrete, formwork, and steel
    reinforcement; evidencing the benefits of introducing the optimal design process through the
    genetic algorithm.

     
6
  • NAYRO SILVA NORONHA CAVALCANTE
  • TOPOLOGICAL OPTIMIZATION OF TWO-DIMENSIONAL TRUSSES USING THE METHOD OF PROGRESSIVE DIRECTIONAL SELECTION

     
     
  • Leader : MARCIO ANDRE ARAUJO CAVALCANTE
  • MEMBRES DE LA BANQUE :
  • EDUARDO NOBRE LAGES
  • MARCIO ANDRE ARAUJO CAVALCANTE
  • VALÉRIO DA SILVA ALMEIDA
  • Data: 20 déc. 2022


  • Afficher le Résumé
  • More and more, inspiration is sought from nature to solve complex problems in modern society. Whether observing the morphological characteristics of animals and plants or even the behavior of living beings in the environment they live. The naturalist Charles Darwin studied this behavior in depth and proposed a theory that explains how life became what it is today, the Theory of Natural Selection. This theory helped solve problems in the biological sciences, social sciences, and engineering. The theory of natural selection of the directional type inspires the topological optimization method proposed in this study. The Progressive Directional Selection method seeks to optimize a structure by selecting the parts that contribute the most to support the mechanical loads and eliminating the parts that contribute the least in different stages of removal. Numerical applications of PDS (Progressive Directional Selection) were performed in two-dimensional truss structures, starting from a ground structure type structure. The initial design domain is formed by a grid of points interconnected by two-dimensional truss elements. The matrix analysis of plane trusses and the direct stiffness method are employed to analyze the plane truss in the linear elastic regime. The selected optimal topologies are structurally stable, efficient, and similar to those obtained by other topological optimization techniques found in the literature. The results demonstrate that this method can be employed in the optimized design of two-dimensional trusses through the topological optimization of ground structure type structure.

     
     
Thèses
1
  • MARCELO VITOR OLIVEIRA ARAUJO
  • ENERGY ANALYSIS OF THE GENERALIZED FINITE-VOLUME THEORY AND APPLICATION TO TOPOLOGY OPTIMIZATION WITH COMPLIANCE MINIMIZATION

  • Leader : MARCIO ANDRE ARAUJO CAVALCANTE
  • MEMBRES DE LA BANQUE :
  • VALÉRIO DA SILVA ALMEIDA
  • DAVID LEONARDO NASCIMENTO DE FIGUEIREDO AMORIM
  • EDUARDO NOBRE LAGES
  • FRANCISCO PATRICK ARAUJO ALMEIDA
  • MARCIO ANDRE ARAUJO CAVALCANTE
  • ROMILDO DOS SANTOS ESCARPINI FILHO
  • Data: 15 août 2022


  • Afficher le Résumé
  • The finite-volume theory is an equilibrium-based approach and has been successfully employed in solid mechanics analysis due to the equilibrium equations' local satisfaction and the imposition of continuity conditions in a surface-averaged sense through the subvolume interfaces. Previous investigations include stress and displacement fields convergence and computational cost, showing the approach's efficiency, especially in heterogeneous materials and structures. However, those investigations did not include an energy analysis, which is especially important in compliance minimization problems. As the finite element method, energy-based approaches impose energy balance, which guarantees a monotonic energy convergence. The first idea of this contribution is to address a numerical investigation about the main mechanical energy aspects involving the generalized finite-volume theory for continuum elastic structures in quasi-static analyzes. The obtained results are verified with analytical and finite element-based analyzes, showing a monotonic energy convergence for the three versions of the finite-volume theory and the energy balance's satisfaction for the higher-order versions when a sufficiently refined mesh is employed. Topology optimization is a well-suited method to establish the best material distribution inside an analysis domain. It is common to observe some numerical instabilities in its gradient-based version, such as the checkerboard pattern, mesh dependence, and local minima. This research demonstrates the finite-volume theory's checkerboard-free property by performing topology optimization algorithms without filtering techniques and employing elastic and elastoplastic formulations. The formation of checkerboard regions is directly associated with discretized domains connected by nodes, usually observed in topology optimization techniques based on the finite element method. On the other hand, the finite-volume theory satisfies the continuity conditions between common faces of adjacent subvolumes, which is more likely from the continuum mechanics point of view. An incremental elastoplastic formulation of the standard finite-volume theory is performed to verify how the plastic strain could interfere with the optimized topologies and reduce their stress concentration. The topology optimization algorithms based on the finite-volume theory are also performed using a mesh independent filter that regularizes the subvolume sensitivities, providing optimized topologies that avoid the mesh dependence and length scale issues. The solid isotropic material with penalization (SIMP) approach is employed to avoid discrete optimization problems. The proposed optimization problem has shown to be efficient, avoiding numerical instabilities, such as checkerboard pattern, mesh dependence, and length scale issues.

2
  • RODRIGO MERO SARMENTO DA SILVA
  • COUPLING BETWEEN GEOMETRIC OPTIMIZATION MODELS OF PARTICULATE SYSTEMS AND MEDIUM FIELDS MICROMECHANICS MODELS FOR EVALUATION OF MULTIPHASE CEMENT COMPOSITES

     
  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • RODRIGO RIBEIRO PACCOLA
  • ALINE DA SILVA RAMOS BARBOZA
  • FRANCISCO PATRICK ARAUJO ALMEIDA
  • MARCIO ANDRE ARAUJO CAVALCANTE
  • SÉRGIO CIRELLI ANGULO
  • Data: 22 déc. 2022


  • Afficher le Résumé
  • The concrete in its macro scale can be considered a heterogeneous material, even being tested as such, however, when reducing its scale, it has phases inherent to each level. Modeling concrete has always been a great challenge, due to all the complexity of this cementitious material, despite that proposals constantly arise, such as homogenization by micromechanics. The mean-fields micromechanics has in its basic foundation the homogenization of two-phase composites, composed of inclusions immersed in an infinite matrix. In fact, on a macroscopic scale, concrete can be understood as being composed simply by inclusions (gravel) immersed
    in a matrix (paste), being often modeled in this macro configuration. However, it is known that there are more phases that need to be evaluated to obtain a result closer to laboratory tests, as an example can be cited in the interfacial transition zone. In addition to modeling, it can be said that the construction industry seeks to maximize the properties of concrete, being an initial idea to seek the packaging of particulate systems (inclusions) minimizing the dispersed phase (matrix). In view of this open field, the present work proposes to study the coupling of optimization models of particulate systems to composite homogenization models, aiming at maximizing the mechanical properties of concrete using multiscale modeling. As a subsidy to this problem, an object-oriented framework is built to carry out the aforementioned modeling. The results obtained with the coupling between the techniques confirm the maximization of the mechanical properties when optimizing the particulate systems.

     
2021
Thèses
1
  • WEVERTON MARQUES DA SILVA
  • MODELING AND DEVELOPMENT OF AN INTEGRATED TOOL FOR FATIGUE ANALYSIS IN SUBMARINE DUCTS IN FREE GAMES
  • Leader : ADEILDO SOARES RAMOS JUNIOR
  • MEMBRES DE LA BANQUE :
  • ADEILDO SOARES RAMOS JUNIOR
  • WILLIAM WAGNER MATOS LIRA
  • EDUARDO SETTON SAMPAIO DA SILVEIRA
  • LEANDRO MELO DE SALES
  • CYNTIA GONÇALVES DA COSTA MATT
  • Data: 12 janv. 2021


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  • Safety in the transportation of hydrocarbons and other fluids in pipelines is one of the topics of
    greater attention in the oil and gas industry. Recently, this industry has had great
    concerns about how the Vortex-Induced Vibration (VIV) phenomenon affects life
    fatigue of submarine pipelines and components, especially free-range pipelines. Worldwide,
    there are several of these structures installed that have reached the end or half of their design life,
    which makes it imperative to revisit the initial predictions and assess the need for intervention in the
    to extend their useful life, especially with regard to VIV. These and other
    analyzes are based on the correct representation of the pipeline's on-site behavior. The method of
    Finite elements are widely used in modeling this behavior. However,
    this is not a trivial task, since it depends on the use of various software for stages
    intermediate. In addition, these analyzes involve handling large amounts of
    data related to the bathymetry of the seabed and material properties, geometry
    duct, current, among others. In this way, this whole process is usually time consuming and
    prone to errors. At the same time, the oil and gas industry has undergone a transformation
    in recent years. This scenario brought opportunities for the development of
    new tools for the day-to-day of the professional responsible for these analyzes. This job
    presents the development and structure of a computational with functionalities from pre to
    post-processing of analysis data aimed at improving the flow of fatigue analysis in
    submarine pipelines subject to free spans.

2
  • JOAO PAULO LEAO LESSA
  • ANALYSIS OF GROUND-SUPPORTED CYLINDRICAL TANKS SUBMITTED TO DIRECT AND INDIRECT ACTION OF SHRINKAGE AND THERMAL GRADIENT

  • Leader : EDUARDO NOBRE LAGES
  • MEMBRES DE LA BANQUE :
  • JOSÉ NERES DA SILVA FILHO
  • EDUARDO NOBRE LAGES
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • FLAVIO BARBOZA DE LIMA
  • Data: 6 juil. 2021


  • Afficher le Résumé
  • Ground-supported cylindrical concrete tanks are largely used with many purposes, such as storing of liquids (water and wastewater, for example) and grains, or even used in projects that have bolder architectural appeal. These structures are often composed of thin walls and are commonly explored worldwide due to their versatility and structural performance. Despite many computational techniques developed on the study of reservoirs, these structures draw attention to the high number of recovery and structural reinforcement interventions that are still commonly done. In some cases, restauration processes are expensive and must be performed still early in structure’s lifespan. Not considering indirect loads is a common reason to a lower structural performance, since these neglected actions at design level may cause internal stresses-strains that have the potential to turn the structural performance impracticable. In reinforced concrete tanks, some indirect actions must be considered in order to obtain accurate structural performance, such as concrete shrinkage and thermal gradient effects, in the case of hot liquid storing. Therefore, this work aims to study the mechanical behavior of reinforced concrete reservoirs subjected to indirect actions caused by shrinkage and thermal gradient effects through classical analytical theories of axisymmetric structures. The results show that indirect loads generate stresses of great magnitudes in shell elements subjected to elastic analysis. Furthermore, variables such as humidity may increase strains caused by shrinkage, implying in loads that overcome concrete’s traction resistance, which favors the formation of cracks. The examined examples also show that stresses generated by thermal gradient effects are even higher than the other actions, leading to impractical structural performance when they are not considered in the design phase of the structure.

3
  • TEOFANES VITOR SILVA
  • INFLUENCE AND STATISTICAL ANALYSIS OF TRAJECTORY DEVIATION ON THE TORQUE & DRAG MODEL ON THE DRILLING COLUMN

  • Leader : JOAO PAULO LIMA SANTOS
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • JOAO PAULO LIMA SANTOS
  • JOÃO CARLOS RIBEIRO PLÁCIDO
  • Data: 30 juil. 2021


  • Afficher le Résumé
  • Currently, the most diverse oil deposits are discovered in increasingly challenging environments for existing technologies. Thus, the constant development of research and technologies to support the various areas of petroleum engineering is important. The well engineering, which is responsible for designing its structure and trajectory, stands out in this work. Drilling string failure is a very costly event for the oil and gas industry, as it is necessary to stop the entire operation, which results in non-productive time. Therefore, several studies are carried out in order to predict problems during drilling. Torque, tension, compression and bending can be correctly predicted for known well geometries, but unwanted changes in well geometry during the drilling process can result in errors and uncertainties in predicting the stress state. It is proposed to predict these uncertainties in the trajectory by the statistical analysis of previously executed wells and categorized according to their correlations with each other. Performing the data analysis enables the construction of the fictitious trajectory which will be used to predict the additional forces to the loads acting on the drill string induced by the trajectory deviation.

4
  • JOAO MARCOS FERREIRA DOS SANTOS
  • STUDY OF THE BEHAVIOR TO THE FLEXION OF PRODUCED ELEMENTS WITH FUNCTIONAL CRFA GRADATION
  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • ALESSANDRA LORENZETTI DE CASTRO
  • ALINE DA SILVA RAMOS BARBOZA
  • KAROLINE ALVES DE MELO MORAES
  • Data: 1 déc. 2021


  • Afficher le Résumé
  • Man's search for change linked progress to new ways of building and ways of conceiving structures, their materials, and methods. Faced with so many changes, concrete no longer presents itself as a simple mixture defined by the composition of aggregates, cement, and water, being today susceptible to the incorporation of new ones and the replacement of these basic materials by fibers, residues, and additives of various types. The incorporation of steel fibers, which resulted in the use of Steel Fiber Reinforced Concrete (SFRC) has shown great benefits to the conventional material in the world scenario, acting mainly in the post-cracking stage and mobilizing a portion of tensile strength triggered by the need of durability guarantee. In this context, the optimization of the use of short steel fibers in an element under bending, through a layered fiber grading, resulting in a functionally graded element (FGM), demonstrates its relevance. Fibers concentrated in higher percentages are located in the strip most stressed to traction and on the opposite compressed surface a null amount of these reinforcements is used. In this work, the elements have a cross-section graduated in 3 layers, for which the phase of determining the percentages of each fiber layer is highlighted, using the pre-existing results of SFRC beams in the three-point bending test (EN – 14651/2017) measured in previous works and comparing the height and area of cracks found in tests that correlate digital images and with displacement transducer measurements. It was possible to evaluate the influence of concrete casting through induction techniques and surface analysis. The results provide an effective overview of the preferential orientation of the fibers found in this configuration, 68° in relation to the oriented axis of the load application direction and 49° in relation to the plane perpendicular to the load application, confirmation of the initially desired proportion and expressive gains in post-peak crack containment, about 34.15%, when compared to beams in traditional molding, consequently, more effectively influencing the post-cracking resistance, bending and economy of steel fibers in the less tensioned regions of beams and plates molded in SFRC, like beams and slabs under bending.

5
  • GABRIEL ROCHA DOMINGOS
  • TOPOLOGY OPTIMIZATION APPLIED TO CONCEPTUAL DESIGN OF CABLE STRUCTURES SUBJECTED TO FINITE STRAIN

  • Leader : ADEILDO SOARES RAMOS JUNIOR
  • MEMBRES DE LA BANQUE :
  • ADEILDO SOARES RAMOS JUNIOR
  • EDUARDO NOBRE LAGES
  • ANDERSON PEREIRA
  • FÁBIO MARTINS GONÇALVES FERREIRA
  • Data: 16 déc. 2021


  • Afficher le Résumé
  •  The design of civil construction structures is commonly associated to three general steps:
    structural conception, sizing, and analysis and veri cation. It is an approach highly dependent
    on the experience and creativity of the designer, and is tied to an trial and error
    strategy. This work aims to formulate and to implement computational models based
    on topology optimization to assist on the de nition of initial structural conception of
    cable-based structures. The mathematical formulation proposed in this work incorporates
    multiple load cases, nodal cost and a constitutive model of cables with limit resistance.
    The results show that topology optimization tools can be used to suggest initial structural
    conception, assisted by a mathematical method, and with the potential of break the pattern
    of traditional topologies, unlocking designer's creativity. However, structural systems based
    solely on cables are rare, and therefore for the features presented in this work to have a
    direct application in industry, there is still the need to evolve the formulation presented
    here, also incorporating elements resistant to compression actions.

Thèses
1
  • MARCELO VITOR OLIVEIRA ARAUJO
  • NEW CONTRIBUTIONS FOR THE GENERALIZED FINITE-VOLUME THEORY: FROM ENERGY ANALYSIS TOWARDS TOPOLOGY OPTIMIZATION OF COMPLIANCE MINIMIZATION PROBLEMS

  • Leader : MARCIO ANDRE ARAUJO CAVALCANTE
  • MEMBRES DE LA BANQUE :
  • ADEILDO SOARES RAMOS JUNIOR
  • ANDERSON PEREIRA
  • EDUARDO NOBRE LAGES
  • EMILIO CARLOS NELLI SILVA
  • GLÁUCIO HERMOGENES PAULINO
  • MARCIO ANDRE ARAUJO CAVALCANTE
  • Data: 30 août 2021


  • Afficher le Résumé
  • The finite-volume theory is an equilibrium-based approach and has been successfully employed in solid mechanics analysis due to the equilibrium equations' local satisfaction and the imposition of continuity conditions in a surface-averaged sense through the subvolume interfaces. Previous investigations include stress and displacement fields convergence and computational cost, showing the approach's efficiency, especially in heterogeneous materials and structures. However, those investigations did not include an energy analysis, which is especially important in compliance minimization problems. As the finite element method, energy-based approaches impose energy balance, which guarantees a monotonic energy convergence. The first idea of this contribution is to address a numerical investigation about the main mechanical energy aspects involving the generalized finite-volume theory for continuum elastic structures in quasi-static analyzes. The obtained results are verified with analytical and finite element-based analyzes, showing a monotonic energy convergence for the three versions of the finite-volume theory and the energy balance's satisfaction for the higher-order versions when a sufficiently refined mesh is employed. Topology optimization is a well-suited method to establish the best material distribution inside an analysis domain. It is common to observe some numerical instabilities in its gradient-based version, such as the checkerboard pattern, mesh dependence, and local minima. This research demonstrates the generalized finite-volume theory's checkerboard-free property by performing topology optimization algorithms without filtering techniques. The formation of checkerboard regions is associated with the finite element method's displacement field assumptions, where the equilibrium and continuity conditions are satisfied through the element nodes. On the other hand, the generalized finite-volume theory satisfies the continuity conditions between common faces of adjacent subvolumes, which is more likely from the continuum mechanics point of view. The topology optimization algorithms based on the generalized finite-volume theory are performed using a mesh independent filter that regularizes the subvolume sensitivities, providing optimum topologies that avoid the mesh dependence and length scale issues. The solid isotropic material with penalization (SIMP) approach is employed to avoid discrete optimization problems. The proposed optimization problem has shown to be efficient, avoiding numerical instabilities, such as checkerboard pattern, mesh dependence, and length scale issues.

2020
Thèses
1
  • WILL JOSÉ DE LIMA JÚNIOR
  • IDENTIFICAÇÃO DE DANOS EM VIGAS VIA ANÁLISE MODAL

  • Leader : WAYNE SANTOS DE ASSIS
  • MEMBRES DE LA BANQUE :
  • WAYNE SANTOS DE ASSIS
  • ADEILDO SOARES RAMOS JUNIOR
  • HIGOR SÉRGIO DANTAS DE ARGÔLO
  • Data: 20 févr. 2020


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  • Este trabalho busca contribuir no campo de pesquisa de identificação de danos em vigas com base nas propriedades modais, propondo estudos de sensibilidade em dois modelos numéricos, que serão elaborados em software comercial de elementos finitos, a saber: uma viga biapoiada de concreto simples e uma viga biengastada de aço, para avaliar a fiabilidade de quatro métodos de identificação de dano único e dano múltiplo: (1) Diferença da Curvatura Modal, (2) Indicador Baseado em Dados dos Modos de Vibração, (3) Mudança da Energia de Deformação Modal e (4) Mudança da Energia de Deformação Modal Reformulada, propondo-se ainda a modificação dos dois primeiros métodos. Os resultados obtidos mostraram que o método Mudança da Energia de Deformação Modal, apesar da dificuldade existente quanto à aplicação prática na engenharia, identificou os danos corretamente, o método Mudança da Energia de Deformação Modal Reformulada se mostrou promissor e os métodos modificados
    propostos apresentaram melhor desempenho em relação aos originais.

2
  • LUIS PHILIPE RIBEIRO ALMEIDA
  • Modelos Probabilísticos para Análise de Propagação de Fissuras em meios Coesivos via Método dos Elementos de Contorno

  • Leader : EDUARDO TOLEDO DE LIMA JUNIOR
  • MEMBRES DE LA BANQUE :
  • EDSON DENNER LEONEL
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • FÁBIO CARLOS DA ROCHA
  • JOAO CARLOS CORDEIRO BARBIRATO
  • Data: 27 mars 2020


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  • Apresenta-se neste trabalho o emprego de formulações do método dos elementos de contorno (MEC) em problemas de fratura e também na análise mecano-probabilística de sólidos fraturados. O MEC é um método adequado para resolução desses tipos de problemas, uma vez que a ausência de malha de domínio resulta em uma modelagem mais eficiente de regiões com alta concentração de tensões. Além disso, a redução de dimensionalidade da malha diminui fortemente os dados de entrada e também o trabalho de remeshing no processo de propagação de fissuras. Com relação a formulação não linear do MEC, será utilizada uma alternativa a formulação clássica dual, com a introdução de um campo de tensões iniciais para representação da zona coesiva e formulado a partir do conceito de dipolos. Esta formulação é particularmente interessante por conseguir representar matematicamente a presença da Zona de Processos Inelásticos (ZPI) em apenas três equações algébricas (equações relacionadas à correção de tensões) por ponto fonte situado no caminho da fissura. Em contraste, a formulação dual requer quatro equações algébricas (deslocamentos e forças) por ponto fonte. Quanto aos efeitos pertinentes ao sistema não linear, serão utilizados dois algoritmos distintos de resolução iterativa, Operador Constante (OC) e Operador Tangente (OT). No acoplamento com modelos da confiabilidade, apenas o OT será utilizado por apresentar respostas satisfatórias em um número menor de iterações. Com relação à análise probabilística, duas abordagens são consideradas, a primeira refere-se ao acoplamento direto entre o modelo numérico e um método de transformação (HLRF/FORM), já a segunda consiste no acoplamento mais simples com o emprego do Método de Monte Carlo. Os parâmetros de fraturamento são tratados como aleatórios e o Método de Confiabilidade de Primeira Ordem (FORM) é empregado para avaliação de fatores de importância bem como probabilidade de falha. Por fim, a técnica de Amostragem inteligente por Hipercubo Latino é também empregada, por apresentar melhores taxas de convergência. Exemplos são apresentados para validar o uso da formulação de dipolos na análise de propagação de fissuras, à luz da confiabilidade estrutural.

3
  • LUCAS DA MATA ROCHA MENEZES
  • Otimização de Amortecedores de Massa Sintonizados no Controle de Vibrações em Vigas e Placas

  • Leader : EDUARDO NOBRE LAGES
  • MEMBRES DE LA BANQUE :
  • EDUARDO NOBRE LAGES
  • EMERSON FIGUEIREDO DOS SANTOS
  • FÁBIO MARTINS GONÇALVES FERREIRA
  • JOSÉ GUILHERME SANTOS DA SILVA
  • Data: 30 avr. 2020


  • Afficher le Résumé
  • A possibilidade de se trabalhar com materiais mais resistentes permite conceber estruturas mais esbeltas e leves que, por sua vez, podem ser mais sensíveis à ação das cargas dinâmicas oriundas do movimento de pessoas, máquinas ou ações da natureza, como o vento. O surgimento e propagação de fissuras, acréscimos de tensão devido a deslocamentos excessivos bem como desconforto aos usuários do empreendimento devido às acelerações que surgem na estrutura são alguns dos problemas estruturais que envolvem a dinâmica. Outra adversidade está relacionada com equipamentos sensíveis instalados em pisos, em que, ao estarem submetidos à determinada (indevida) aceleração, podem sofrer danos. As abordagens mais comumente empregadas para controle dessas vibrações excessivas é o enrijecimento da estrutura, porém em muitos casos este tipo de abordagem é inviabilizada por restrições arquitetônicas, estéticas ou relativa à própria capacidade da estrutura ao sofrer o acréscimo de elementos estruturais pesados para o enrijecimento. Problemas de vibrações em lajes não são incomuns; lajes industriais, por exemplo, estão sujeitas a vários tipos de ações dinâmicas simultâneas provenientes das diversas máquinas em operação instaladas no piso da fábrica. Outro caso são as lajes de academias, salões de festas e outros ambientes com grande movimento de pessoas que geram acelerações no piso. O presente trabalho explora a adoção de sistemas mecânicos de controle de vibrações (amortecedores) acoplados às estruturas, especificamente em vigas e placas, como uma solução alternativa à resolução do problema de engenharia. Utilizam-se ainda técnicas de otimização com o objetivo de obter projetos com a melhor relação custo-benefício de amortecedores. Dessa forma, realiza-se uma modelagem numérica via implementações computacionais do problema de vibração e seu controle em vigas e placas, com os resultados são validados e comparados com exemplos da literatura. Notou-se que, com o processo de otimização, pode-se chegar com a mesma eficiência na resposta estrutural, que utiliza massa e taxa de amortecimento menores.

4
  • IVA EMANUELLY PEREIRA LIMA
  • ESTUDO DOS ASPECTOS DE DIMENSIONAMENTO DE ELEMENTOS ESTRUTURAIS DE CONCRETO REFORÇADO COM FIBRAS COM BASE NA TEORIA DE FLEXÃO EM VIGAS

  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • FLAVIO BARBOZA DE LIMA
  • GUSTAVO HENRIQUE SIQUEIRA
  • Data: 24 juil. 2020


  • Afficher le Résumé
  • Os concretos reforçados com fibras (CRF) apresentam uma menor propagação de fissuras e, consequentemente, promovem para o compósito um acréscimo de tenacidade e resistência residual. Apesar disso, o aumento dessa capacidade só acontece se o concreto for dosado e aplicado de maneira adequada e, para isso, existem códigos de referência que estabelecem aspectos de controle tecnológico e de dimensionamento para o uso do CRF. No entanto, nesses documentos, ao que refere-se a um dos aspectos de dimensionamento, a parcela de força resultante resistente das fibras é descrita para algumas aplicações específicas, onde faz-se a consideração de que a carga máxima corresponde a carga de fissuração, o que pode não se aplicar para concretos que possuam uma orientação preferencial das fibras. Diante disso, sabendo da significativa mudança que a orientação das fibras pode proporcionar, e a fim de determinar a força resultante resistente das fibras na parte tracionada de um concreto fibroso fluido, apresenta-se um estudo relacionado a proposição de um modelo de cálculo de CRF fundamentado nessa definição. O estabelecimento desse modelo foi obtido com base na teoria de flexão em vigas, a partir do ensaio de flexão a três pontos normatizado pela EN 14651 (2007), onde foram utilizadas uma amostra de concreto reforçado com fibras de aço (CRFA) e outra amostragem produzida com fibras poliméricas (CRFP). De acordo com o estudo realizado, verificou-se que o valor de carga máxima não correspondeu ao valor de carga de fissuração para nenhuma viga em análise e, de modo geral, percebeu-se que as cargas são estatisticamente diferentes entre si. Com base nessa diferença, definiu-se analiticamente o posicionamento da linha neutra da estrutura e determinou-se, a partir de equações de equilíbrio, um modelo de cálculo referente à força resultante resistente das fibras na parte tracionada do concreto. A partir disso, os valores obtidos por meio do modelo proposto foram comparados com os resultados determinados em conformidade com o FIB Model Code 2010 (2013) e de acordo com o ACI 544.8R (2016), onde verificou-se que os resultados apresentaram variações. A fim de investigar essas dispersões, fez-se uma análise dos parâmetros de sensibilidade das equações e conclui-se que o modelo de cálculo proposto não apresenta nenhum parâmetro de influência no contexto analisado, o que evidenciou que a equação analítica desenvolvida neste trabalho pode ser preliminarmente validada para o dimensionamento de elementos estruturais de CRF.

5
  • JESSICA PONTES DE VASCONCELOS VALENCA
  • ESTUDO PARAMÉTRICO SOBRE VIDA À FADIGA DE DUTOS EM VÃOS LIVRES SUBMETIDOS À VIV

  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • EDUARDO NOBRE LAGES
  • EMÍLIO CÉSAR CAVALCANTE MELO DA SILVA
  • Data: 26 août 2020


  • Afficher le Résumé
  • A maior parte das reservas petrolíferas brasileiras se encontra em ambientes marinhos, que
    apresentam vários fatores que dificultam sua produção, como lâminas d’águas elevadas, interação
    fluido-estrutura e batimetrias irregulares. Nesses ambientes offshore, os dutos são estruturas
    eficientes para o transporte de fluidos entre plataformas, entre o poço e a plataforma e entre a
    plataforma e um local em terra, sendo utilizados há bastante tempo em larga escala na indústria
    petrolífera. Os dutos suspensos recebem o nome de risers e os apoiados no solo de dutos
    submarinos, pipelines e flowlines. Os dutos são dimensionados de acordo com o tipo de atividade
    que irão desempenhar e a hidrodinâmica do problema.
    Considerando as irregularidades do solo marinho, os dutos apoiados podem apresentar trechos
    com vãos livres, que devem ser considerados no projeto de forma a evitar problemas de segurança
    estrutural por excesso de deformações. As estruturas estão submetidas a diversas formas de
    carregamentos, normalmente agrupados nos referenciais normativos, como: cargas permanentes,
    cargas variáveis (acidentais) e cargas excepcionais. Como as ações ambientais variam de
    intensidade de forma significativa ao longo da vida útil da estrutura, elas são classificadas como
    cargas variáveis e exercem uma grande influência para a análise do comportamento de dutos,
    pois ocasionam carregamentos cíclicos. Dentre os carregamentos ambientais, encontramos: as
    cargas do vento, da corrente, da onda, das marés, entre outros.
    O carregamento combinado de onda e corrente em dutos em vãos livres dá origem às vibrações
    induzidas por vórtices (VIV), objeto de estudo de várias áreas da engenharia, sendo um dos
    principais desafios em projetos offshore. Essas vibrações causam tensões e deformações periódicas,
    podendo levar à falha da estrutura por fadiga. Para evitar que ocorra esse problema, as
    oscilações devem ser minimizadas, estando as frequências de vibrações dos vórtices com valores
    distantes dos valores das vibrações naturais da estrutura. Esta frequência natural depende de
    parâmetros como a rigidez, o comprimento do vão livre, a massa do duto, incluindo a massa do
    fluido interno e a massa adicional.
    O presente trabalho se concentra em fazer um estudo do problema de dutos em vãos livres submetidos
    à VIV. Um estudo paramétrico foi realizado para obter os fatores que mais influenciam
    na vida à fadiga da estrutura, por meio da técnica de Planejamento e Análise de Experimentos
    (DOE), utilizando o software Isight. Análises estática e modal foram elaboradas no Abaqus,
    tendo como resultados principais as frequências naturais da estrutura do duto. Por fim, o estudo
    de vida à fadiga foi realizado, de acordo com a recomendação prática DNVGL-RP-F105, por
    meio da planilha FatFree.

6
  • LUCAS HENRIQUE OLIVEIRA MUNIZ
  • DESENVOLVIMENTO DE MÓDULOS COMPUTACIONAIS PARA AUTOMATIZAÇÃO DO PROJETO ESTRUTURAL DE PAREDE DE CONCRETO MOLDADA IN LOCO

  • Leader : WILLIAM WAGNER MATOS LIRA
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • MARCIO ROBERTO SILVA CORRÊA
  • WILLIAM WAGNER MATOS LIRA
  • Data: 16 sept. 2020


  • Afficher le Résumé
  • O objetivo deste trabalho é automatizar o processo de análise, dimensionamento e detalhamento do sistema estrutural de uma parede de concreto moldada in loco. A automatização é realizada com base em um ambiente computacional, elaborado a partir do desenvolvimento e customização de módulos computacionais. O sistema estrutural de parede de concreto pode ser projetado através de diferentes metodologias, entretanto, a solução utilizando métodos numéricos proporciona uma série de pontos positivos que colaboram para uma melhor compreensão dos fenômenos com um bom balanceamento entre tempo, custo e qualidade. Nesse contexto, o presente trabalho apresenta o desenvolvimento de um estudo voltado as principais premissas do projeto estrutural de parede de concreto moldada in loco, com o intuito de promover a criação de um ambiente computacional integrado. O ambiente é elaborado a partir da customização da interface do software comercial ABAQUS/CAE®, integrando módulos computacionais já existentes que realizam a modelagem e a análise estrutural via Método dos Elementos Finitos com outros módulos que incorporam algoritmos utilizados nas fases de dimensionamento e detalhamento das paredes, com base nas premissas da NBR 16055 (2012). Utilizou-se como estudo de caso um projeto de uma edificação de parede de concreto do programa “Minha Casa Minha Vida”. A ideia é que o estudo realizado neste trabalho se torne útil ao meio técnico-científico por desenvolver um ambiente computacional que permite a realização automatizada de um projeto estrutural de uma parede de concreto moldada in loco.

     
7
  • PAULO CHAGAS DO CARMO
  • Detecção de danos em elementos de concreto por meio de Correlação de Imagens Digitais

  • Leader : ALINE DA SILVA RAMOS BARBOZA
  • MEMBRES DE LA BANQUE :
  • ALINE DA SILVA RAMOS BARBOZA
  • ISAAC GALOBARDES REYES
  • KAROLINE ALVES DE MELO MORAES
  • Data: 18 sept. 2020


  • Afficher le Résumé
  • A análise de danos em estruturas é um tema de pesquisa muito importante para diversos campos
    da engenharia, capaz de fornecer informações relevantes frente à sua integridade estrutural,
    norteando as decisões relacionadas às ações de intervenção. Diante da necessidade e importância
    do tema, diversos estudos vêm sendo desenvolvidos com o intuito de conceber técnicas, para
    auxiliar na quantificação do dano por meio de procedimentos técnicos que envolvam atividades
    laboratoriais. É exatamente nesse aspecto que o presente trabalho se insere. Nesta pesquisa, é
    estudada a aplicação de uma técnica óptica-numérica, a Correlação de Imagens Digitais (CID),
    como suporte à aquisição de informações para análise quantitativa de danos, na qual se buscará
    analisar a integridade estrutural de elementos de concreto por meio da perda de rigidez à flexão.
    Para a quantificação do dano, as informações obtidas pela CID, por meio de um software de
    código aberto, o ITOM, são comparadas com métodos tradicionais de aquisição, como LVDT’s
    (Transdutores de Deslocamento Linear). Para avaliação da perda de rigidez, foram analisadas oito
    vigas, através do ensaio de flexão, fornecendo assim um ambiente controlado para o emprego
    desse ensaio não destrutivo. Diante dos resultados obtidos, foi possível verificar o potencial da
    CID, por meio do ITOM, que, mesmo em fase de desenvolvimento e aprimoramento, mostrou-se
    capaz de quantificar aberturas de fissuras diretamente em imagens e gerar deslocamentos e
    deformações nodais para construção de mapas de cores, dando suporte para análises de estruturas
    em Estado Limite Último (ELU) e de Serviço (ELS).

8
  • FRANCISCO DE ASSIS VIANA BINAS JUNIOR
  • Trajectory and torque & drag models applied to casing wear analysis
  • Leader : EDUARDO TOLEDO DE LIMA JUNIOR
  • MEMBRES DE LA BANQUE :
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • JOAO PAULO LIMA SANTOS
  • JOÃO CARLOS RIBEIRO PLÁCIDO
  • Data: 10 déc. 2020


  • Afficher le Résumé
  • In the drilling stage of oil and gas wells, the drilstring can come into contact with the casing
    strings, generating lateral forces that, associated to the rotation of the drillstring, cause the
    removal of material from the inner wall of the tubulars. High casing wear values induce a
    reduction in mechanical strength of casing string and may compromise the well integrity. This
    work deals to the implementation and comparative analysis between methodologies for casing
    wear evaluation, comprising models for trajectory planning, lateral forces calculation and wear
    volume estimate. Torque and drag models are employed to quantify the lateral forces, using the
    soft-string and stiff-string approaches. The latter differs from the soft-string model by taking
    into account effects related to the drillstring stiffness, besides inserting the contact angle into the
    formulation. The stiff-string model depends on directional parameters as torsion and curvature,
    for which a model based on cubic splines is applied. The spline-based model is then compared
    with the minimum curvature method, widely employed by industry. The results show that the
    model based on splines provides smooth curvature and non-zero torsion. The influence of spacing
    between the survey stations on the accuracy of the trajectory models is also analyzed. Finally,
    a complete case study is developed, allowing to conclude that the use of stiff-string model can
    reduce the predicted wear on the casing string, due to its distribution as a function of the contact
    angle.
9
  • IGOR DE MELO NERY OLIVEIRA
  • DATA INFERENCE AND PREDICTION TECHNIQUES AS A SUPPORT TO THE INTEGRITY ANALYSIS OF COATINGS

  • Leader : EDUARDO TOLEDO DE LIMA JUNIOR
  • MEMBRES DE LA BANQUE :
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • JOAO PAULO LIMA SANTOS
  • RICARDO EMANUEL VAZ VARGAS
  • Data: 21 déc. 2020


  • Afficher le Résumé
  • The design of an oil well is a complex and multidisciplinary activity, which has as a
    of its main premises the adequate prediction of well integrity throughout its life cycle.
    life. Despite all the care taken in the design of its structure, eventually the same
    may be exposed to an unforeseen loading condition. With regard to monitoring
    of wells in service, the acquisition of data referring to variables such as pressure and temperature
    allows to identify if the well is operating within the parameters foreseen in the project. Through
    of time series forecasting techniques, the information from these sensors has
    potential to be used not only to diagnose a problem that has already occurred, but also
    to prevent its occurrence, creating a supervisory system in real time that is capable of
    anticipate future loading states. However, in the context of well projects, with
    the evolution of coating design standards, the use of probabilistic methods is suggested
    in its dimensioning, highlighting the importance of a better knowledge about the
    design variables. Statistical inference about manufacturing data is driven by demand
    for a better understanding of the uncertainties about these parameters, in terms of the dimensions
    of the tubular and the properties of the metallic alloy that constitutes it. This dissertation is about
    a set of statistical inference and data prediction techniques, as support for practices
    modern design and structural integrity monitoring of wells.

10
  • GUSTAVO TEIXEIRA DA SILVA
  • Numerical Analysis of Collapse Resistance in Well Lining Tubes with Manufacturing and Wear Imperfections

  • Leader : EDUARDO TOLEDO DE LIMA JUNIOR
  • MEMBRES DE LA BANQUE :
  • EDUARDO TOLEDO DE LIMA JUNIOR
  • EDUARDO NOBRE LAGES
  • EMÍLIO CÉSAR CAVALCANTE MELO DA SILVA
  • Data: 22 déc. 2020


  • Afficher le Résumé
  • Casing systems for oil and gas wells consist of tubular elements installed along the depth,
    providing stability and tightness, and must meet the strict premises of structural integrity,
    especially in the case of offshore scenarios. Given this, some events may expose the casing to
    high differentials. pressure, leading the tubular to failure under external pressure, called collapse.
    Imperfections associated with casing tubular manufacturing processes, such as eccentricity,
    ovality of the cross section, and the residual stress of the steel, can have a significant influence
    on the failure mechanism by collapse. In addition to these, there is the presence of wear in
    wells performed, caused predominantly by the contact of the drilling column with the inner wall
    of the casing. In many cases, these imperfections can lead to a considerable reduction in the
    collapse strength, especially in thin-walled tubes, whose failure mechanism is associated with
    geometric instability caused by high transverse slenderness. Robust section tubes tend to fail
    under stress levels near to the yield limit or material tensile strength limit. This work presents a
    numerical analysis of the collapse strength of imperfect and internally worn tubulars, admitting
    the deformation plane state, in a physically and geometrically nonlinear regime. The finite
    element method is used in the analysis and verification of the collapse pressure of the tubes, as
    used by ABAQUS® software. The mechanical behavior of steel is described by the constitutive
    elastoplastic model with nonlinear hardening provided by the ASME BPVC (2015). Evaluation
    of finite element models is performed based on the responses obtained by the formulations and
    experimental results proposed by Clinedinst et al. (1939), Klever e Tamano (2006), and Moreira
    Junior (2012), for perfect tubes or with manufacturing and wear imperfections. The consideration
    of internal wear is made by removing material from the section in groove wear zones or by data
    obtained from profiling, based on real measurements of the internal wall of the casing. Parametric
    studies are presented to assess the influence of slenderness, wear, and imperfection parameters
    on the collapse strength. From the results obtained, it appears that the presence of manufacturing
    imperfections, depending on their levels, promotes considerable reduction of collapse strength,
    the most pronounced of which being ovality. Regarding the worn specimens, it is noted the
    influence of parameters such as wear depth, diameter of the tool joint that produces the groove,
    and their angular positions. In the case of profiled tubulars, it is verified that in addition to the
    depth of wear, its extension along the inner wall can imply a considerable decrease in collapse
    pressure.

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