A multiscale model is proposed to study the influence of interfacial interactions at the nanoscale in carbon nanotube(CNT)-polymer nanocomposites on the macroscale bulk elastic material properties. The efficiency of CNT reinforcement in terms of interfacial load transferring is assessed for the non-functionalized and functionalized interfaces between the CNTs and polymer matrix using force field based molecular dynamic simulations at the nanoscale. Polyethylene (PE) as a thermoplastic material is adopted and studied first because of its simplicity. Characterization of the nanoscale load transfer has been done through the identification of representative nanoscale interface elements for unfunctionalized CNT-PE interface models which are studied parametrically in terms of the length of the PE chains, the number of the PE chains and the "grip" position. Referring to the non-functionalized interface, CNTs interact with surrounding polymer only through weakly nonbonded van der Waals (vdW) forces in our study. Once appropriate values of these parameters are deemed to yield sufficiently converged results, the representative interface elements are subjected to normal and sliding mode simulations in order to obtain the force-separation responses at 100K and 300K for unfunctionalized CNT-PE interfaces. To study the functionalization effects, atomistic interface representative elements for functionalized CNT-PE interface are built based on non-functionalized interface models by grafting functional groups between the PE matrix and the graphene sheet. This introduces covalent bonding forces in addition to the non-bonded vdW forces. A modified consistent covalent force field (CVFF) and adaptive intermolecular reactive empirical bond order (AIREBO) potentials, both of which account for bond breaking, are applied to investigate the interfacial characteristic of functionalized CNT-PE interface in terms of the force-separation responses at 100K in both normal opening and sliding mode separations. In these studies, the focus has been on the influence of the functionalization density on the load transfer at the nanoscale interface. As an important engineering material, Epon 862/DETDA epoxy polymer,a thermoset plastic, has also been used as the polymer matrix material in order to see the difference in interfacial load transfer between a network structured polymer and the amorphous entangled structure of the PE matrix. As for thermoset epoxy polymer, emphasis has been put on investigating the effects of the crosslink density of the epoxy network on the interfacial load transfer ability for both non-functionalized and functionalized CNT-Epoxy interface at different temperatures(100K and 300K) and on the functionalization effect influenceing the interfacial interactions at the functionalized CNT-Epoxy interface. Cohesive zone traction-displacement laws are developed based on the force-separation responses obtained from the MD simulations for both non-functionalied and functionalized CNT-PE/epoxy interfaces. Using the cohesive zone laws, the influence of the interface on the effective elastic material properties of the nanocomposites are observed and determined in continuum level models using analytic and computational micromechanics approaches, allowing for the assessment of the improvement in reinforcement efficiency of CNTs due to the functionalization. It is found that the inclusion of the nanoscale interface in place of the perfectly bonded interface results in effective elastic properties which are dependent on the applied strain and temperature in accordance with the interface sensitivity to those effects, and which are significantly diminished from those obtained under the perfect interface assumption for non-functionalized nanocomposites. Better reinforcement efficiency of CNTs are also observed for the nanocomposites with the functionalized interface between CNTs and polymer matrix, which results in large increasing for the effective elastic material properties relative to the non-functionalized nanocomposites with pristine CNTs. Such observations indicates that trough controlling the degree of functionalization, i.e. the number and distribution of covalent bonds between the embedded CNTs and the enveloping polymer, one can tailor to some degree the interfacial load transfer and hence, the effective mechanical properties. The multiscale model developed in this study bridges the atomistic modeling and micromechanics approaches with cohesive zone models, which demonstrates to deepen the understanding of the nanoscale load transfer mechanism at the interface and its effects on the effective mechanical properties of the nanocomposites. It is anticipated that the results can offer insights about how to engineer the interface and improve the design of nanocomposites. / Ph. D.

[pt] Este trabalho descreve uma metodologia para modelagem de cargas elétricas, utilizando dados de tensão e corrente registrados durante distúrbios no sistema de potência. Estes modelos são utilizados na representação de subsistemas da rede elétrica em simulações computacionais que preveem o comportamento dinâmico do sistema de potência após perturbações em suas condições normais de operação.São apresentados resultados práticos da metodologia proposta, onde a carga é definida como um sistema cuja saída é a variação da potência consumida e a entrada é a variação da tensão, ambas medidas em barramentos de 69 kV da Companhia Hidroelétrica do São Francisco (CHESF), ponto de entrega de energia para concessionárias distribuidoras de energia do nordeste brasileiro. Estas distribuidoras são modeladas como cargas, supridas pelo sistema de transmissão da CHESF e todos os elementos consumidores de energia são agregados nestes modelos equivalentes, parametrizados para simular o maior número de contingências típicas medidas em cada um destes barramentos de carga.A técnica de estimação de parâmetros dos modelos de cargas é o Algoritmo Genético (AG) cujos resultados apresentaram precisão para a simulação de contingências de características bem distintas, caracterizando a abrangência alcançada no processo de identificação de sistemas.Ao final do trabalho são apresentadas curvas de desvios de potência ativa e reativa causadas por afundamentos de tensão, ambos registrados nos barramentos das subestações da CHESF. Estas curvas foram utilizadas para estimar os parâmetros dos modelos, obtidos individualmente para cada uma das subestações estudadas. / [en] This work describes a measurement-based load modeling methodology, using voltage and current data registered during power system disturbances. These load models are used on computational simulations for predicting power system stability after disturbances of system operational points. Practical results are presented of the proposed methodology, defining load as a system whose output is power deviation from its operational state and input is voltage sags, both measured at 69 kV bus bars of São Francisco Hydroelectric Company (CHESF), points of common coupling (PCC) between CHESF and local distribution utilities. Therefore, distribution utilities are seen as loads supplied by CHESF’s transmission system. All devices consuming power from the PCC are aggregated into an equivalent model, parameterized to simulate most typical contingencies measured by these 69kV load bars. Optimization technique used for load model parameter estimation is Genetic Algorithm (GA), showing his flexibility on implementation and good coverage and accuracy in the final results. At the end, it will be presented a set of active and reactive power curves during and after voltages sags, measured on CHESF’s substations. These curves were used as estimation data to parameterize load models for each substation chosen.

It is well known that a crucial factor determining the transmission capacity with regards to the voltage stability limit of a stressed power system, is the limitation of field and stator current of overexcited generators. These limiters are commonly referred to as overexcitation limiters (OEL) and stator current limiters (SCL). This thesis investigates the representation of overexcitation limiters and stator current limiters in the Swedish power system and how they could be implemented in the power system simulator PSS/E. Dynamic simulations in PSS/E are performed to investigate and validate differences between model types and parameters. The thesis compares different types of limiters and presents a representative set of parameters based on the documentation and implements them into PSS/E. The result from the study is a recommendation to migrate to limiter model MAXEX2 for generators without stator current limiters. The MAXEX2 model uses an inverse time characteristic which is becoming more common in installed voltage regulators. This feature makes it possible for extended use of generators before limiter action is applied. The MAXEX2 model is also possible to tune into a fixed time delay to represent older types of limiters.

L'objectif de cette thèse est d'étudier un système énergétique intégré dans l'enveloppe des bâtiments permettant de préchauffer l'air neuf.L'originalité du travail repose sur le fait que ce mur est équipé de matériau à changement de phase (MCP).Celui-ci a pour rôle de stocker l'énergie solaire captée en façade puis de la déstocker en préchauffant l'air neuf de ventilation. Notre étude est constituée de deux grandes phases, une phase expérimentale et une phase numérique.La phase expérimentale consiste à effectuer des essais en laboratoire, afin de connaître le comportement du système étudié sous sollicitations thermiques. Ces essais ont été réalisés grâce à un prototype du mur, instrumenté et installé entre deux cellules avec des conditions climatiques contrôlées.Le but de la phase numérique est de mettre en place un modèle ID permettant de simuler le comportement thermique du mur et en particulier celui du MCP. Ce modèle a été validé en comparant les résultats numériques avec ceux obtenus expérimentalement.Pour modéliser le changement de phase nous avons utilisé les paramètres thermophysiques du matériau obtenu par caractérisation expérimentale réalisée dans notre laboratoire. Nous avons ensuite utilisé la méthode de la capacité variable pour simuler le comportement de la paroi stockeuse du mur. Dans la dernière partie du travail numérique le modèle a été utilisé afin de montrer l'influence de quelques paramètres permettant d'optimiser les gains énergétiques.La simulation dynamique du système a été effectuée grâce au logiciel TRNsys, qui nous a permis d'effectuer des bilans énergétiques et d'estimer l'efficacité du système pour des climats variés. / The objective of this thesis is to study an integrated energy system in the building envelope for fresh air preheating. The originality of the work is that the wall is equipped with phase-change material (MCP) packed into briquettes. The main role ofthe wall is to preheat the fresh air (coming from outside) by destocking the solar energy captured in sunny periods.Our study consists of two phases, an experimental phase and a numerical one. The experimental phase involves a series of tests that allow studying the thermal behaviour of the system under thermal stress. These tests were done in laboratory through a prototype of the wall which is instrumented and installed between two airconditioned cells.The purpose of the numerical phase is to develop a one-dimensional model to simulate the thermal behaviour of the wall and especially that of MCP. This model has been validated by comparing numerical results with those obtained experimentally. To model the phase changing we used the thermophysical parameters of the same material obtained by experimental characterization conducted in our laboratory.We used a variable capacity method whose principle is to vary the heat capacity as a function of temperature in order to simulate the phase changing of the wall. The last part of the numerical work is the exploitation of the model, the aim is to determine the optimal configuration of the wall that provides maximum energy savings. Dynamic simulation of the system was performed using the TRNSYS. This one is equipped with weather files which allow carrying out heat balances and the estimation of the system efficiency for various climates.

J'ai étudié deux nouvelles configurations de double-colonne pour distillation hétéroazéotropique. Ces configurations sont appropriées à la récupération simultanée des composants des mélanges binaires hétéroazéotropiques et homoazéotropiques (en utilisant un tiers corps (entraîneur)). Elle sont opérées en système fermé, c'est-à-dire, il n'y a pas de soutirage de produit continu. D'abord, en appliquant un modèle simplifié, j'ai étudié la faisabilité de la séparation d'un mélange hétéroazéotropique (1-butanol – eau), puis celle d'un mélange homoazéotropique (2-propanol – eau) aidé par entraîneur benzène ou cyclohexane, en utilisant le SDC. Puis, j'ai étudié cette configuration par modélisation rigoureuse, en appliquant le simulateur dynamique du logiciel professionnel ChemCAD (CC-DColumn). J'ai comparé la nouvelle configuration avec le RD, sur la base des résultats obtenus par toutes les deux méthodes d'étude. Le SDC s'est avéré faisable et compétitif avec le RD : pendant la même durée ou plus courte, les rendements des composants ont été plus élevés. Puis, on a étendu le SDC à un système plus flexible (système de double-colonne généralisé, SDCG) qui est approprié à la séparation des mélanges binaires homoazéotropiques aidé par entraîneur (en le cas présent : cyclohexane ou n-hexane). J'ai étendu la méthode de faisabilité aussi à l'étude de cette configuration. Le SDCG s'est avéré aussi faisable. En appliquant modélisation rigoureuse, j'ai étudié les effets des nouveaux paramètres opératoires sur la durée, et j'ai comparé le DCG avec le SDC. Le SDCG s'est avéré encore plus avantageux que le SDC : la durée a été plus courte, et les besoins spécifiques d'énergie des produits ont été plus bas. J'ai étudié le SDC et le SDCG aussi par des manipulations exécutées sur installations de taille laboratoire et pilote. D'abord, j'ai fait des manipulations laboratoires pour la séparation du mélange binaire hétéroazéotropique, en utilisant une installation en verre qui a été opérée aussi comme RD et SDC. Le SDC s'est avéré faisable et compétitif avec le RD aussi sur la base des résultats de ces manipulations : pendant la même durée, les rendements des tous les deux composants ont été plus élevés. Puis, en utilisant l'installation pilote comme SDC, j'ai étudié la séparation ci-dessus. Après cette manipulation, j'ai étudié la séparation du mélange binaire homoazéotropique en appliquant n-hexane comme entraîneur, en opérant le système comme RD et SDCG. La manipulation faite avec le SDCG a montré que la production simultanée de deux composants est faisable avec cette configuration. / Distillation is the method the most frequently applied for the separation of liquid mixtures, e.g. for the recovery of the components of the waste solvent mixtures. Because of the high energy demand of these processes the optimal design and operation of the distillation equipments are important from economic and also environmental points of view. The separation of the azeotropic mixtures needs special distillation methods like heteroazeotropic distillation. In the pharmaceutical and fine chemical industries it is often applied in batch mode. The aims of the thesis are to study the feasibility of a new Double-Column System (DCS) for batch heteroazeotropic distillation and to compare it with the traditional Batch Rectifier (BR) equipped with a decanterto study the above configurations by rigorous simulationto extend the DCS (Generalised Double-Column System, GDCS) and to study this new configuration by the above methodsto do laboratory experiments for both configurations in order to prove the feasibility of the separation and validate the calculations, respectively. Two new double-column configurations for batch heteroazeotropic distillation were studied. These configurations are designed to produce simultaneously the components of binary heteroazeotropic and homoazeotropic mixtures (by using an entrainer). They are operated in closed system (without continuous product withdrawal). First the feasibility of the separation of a heteroazeotropic mixture (1-butanol – water) and that of a homoazeotropic one by using an entrainer (isopropanol – water + benzene or cyclohexane) in the DCS were investigated by a simplified model. Then the operation of this configuration was modelled by rigorous simulation by using the dynamic simulator of the professional flowsheet simulator ChemCAD (CC-DColumn). On the basis of the results obtained by both methods the new configuration was compared with the BR. The DCS proved to be feasible and competitive with the BR: during the same or shorter time the recoveries of the components were higher. Then the DCS was extended to a more flexible version (Generalised Double-Column System, GDCS), which is suitable for the separation of binary homoazeotropic mixtures (by using an entrainer, in this work: cyclohexane or n- exane). The feasibility method was extended for the study of this configuration, as well. The GDCS proved to be feasible. Then the effects of its additional operational parameters on the duration were studied by rigorous simulation. The GDCS was compared with the DCS by rigorous simulation, as well. The GDCS proved to be more advantageous than the DCS: the duration was shorter and the specific energy demands of the products were lower. The DCS and GDCS were also investigated by laboratory and pilot plant experiments. First laboratory experiments were done for the separation of the binary heteroazeotropic mixture in a simple small size glass equipment operated as BR and DCS. The DCS proved to be feasible and competitive with the BR also on the basis of the results of these experiments: during the same time the recovery of both components were higher. Then a pilot plant was used for the same separation as a DCS. After this experiment the separation of the binary homoazeotropic mixture by using n-hexane as entrainer was studied in the equipment operated as BR and GDCS. The experiment showed that the simultaneous production of two components is feasible also in the GDCS.

[pt] O tema abordado neste trabalho é a observação e análise, em regime permanente e dinâmico, da ocorrência de um fenômeno que já foi observado em condições reais de operação do sistema elétrico brasileiro, que é a relação oposta à usual entre a grandeza controlada e a grandeza controladora. Nestes caso, mesmo que haja margem de recursos para manter a tensão controlada, ela não é útil. Por exemplo, uma diminuição na relação de transformação num transformador de tapes variáveis, com intuito de aumentar a tensão controlada acaba por reduzí-la, até que os limites de troca de tapes sejam atingidos ou o sistema entre em colapso. Para demonstrar a existência do problema, foram executadas simulações, em regime permanente e dinâmico, e verificado o efeito do controle de tensão por um transformador com tapes variáveis e por compensadores estáticos de potência reativa, situações corriqueiras de um sistema de potência. Foram demonstradas situações em que foi possível verificar a mudança da região de operação. Para a análise em regime permanente foi utilizado um algoritmo de fluxo de carga, e para a análise dinâmica, uma simulação no domínio do tempo. Nas simulações envolvendo transformadores de tapes variáveis, foi possível verificar a existência o efeito reverso da ação de controle de tensão nas análises estática e dinâmica. Nas simulações utilizando o compensador estático de potência reativa houve divergência entre os resultados das duas análises. / [en] This work presents the observation and analysis, in steady state and dynamic performance, of the phenomenon already observed in real operation conditions of the Brazilian Electric System, which is the opposite relationship between the controlled value and the target value. In this case, even if the resources have margin to keep the voltage controlled, this is not useful. For example, the reduction in the turn ratio on load tap changer transformer, with the aim of increase in the controlled voltage, result in its reduction, until the tap changer limit is reached or the system is led to the collapse. To demonstrate the existence of this problem, steady state and dynamic performance simulations were done, and the voltage control effect by on load tap changer transformer and static var compensator , current situations in a power system. Several situations where is possible verify the operation region changing was demonstrated. For steady state analysis was used a load flow algorithm and, for the dynamic analysis, a time domain simulation. In the simulations with on load tap changer transformer, it was possible to verify the existence of the reverse effect of the voltage control action in the static and dynamic analysis. In the simulations using static var compensator, a divergence was found between the results in the two analyses.

A fim de garantir a inocuidade, alguns alimentos industrializados são termicamente tratados por um processo contínuo denominado pasteurização, o qual visa inativar os micro-organismos patogênicos, mantendo, ao mesmo tempo, a sua qualidade sensorial e nutricional. Essa operação é aplicada a produtos como sucos, leite, cervejas, polpas, entre outros. A modelagem matemática deste processo tem como intuito auxiliar no entendimento, controle e posterior otimização desta operação. O principal objetivo deste trabalho foi o desenvolvimento da modelagem do processo contínuo da pasteurização HTST do leite e a validação experimental do modelo empírico da incrustação do produto nas placas do trocador de calor, em malha aberta (sem PID). A modelagem fenomenológica foi composta por balanços diferenciais de energia, para temperatura, e de material, para letalidade, nos canais, nas placas, no tubo de retenção e nas conexões do pasteurizador. Também foi realizada a modelagem empírica da incrustação do leite na seção de aquecimento. Os modelos desenvolvidos representam um conjunto de equações diferenciais ordinárias de primeira e segunda ordem, o qual foi resolvido pelo método das diferenças finitas, pelo uso do software gPROMS. O modelo foi aplicado para representar o comportamento de um pasteurizador a placas de escala laboratorial, com e sem incrustação, com e sem perturbações no sistema e durante a partida do equipamento, através de estudo de caso. Os dados simulados foram apresentados pela distribuição unidimensional e temporal de temperatura e da letalidade do tratamento, ao longo do processo, e do perfil do coeficiente global de troca térmica na seção de aquecimento. Para a validação do modelo de incrustação foi realizado um ensaio experimental da pasteurização de solução proteica (similar ao leite). Inseriu-se termopares em diversos pontos do equipamento e as temperaturas foram registradas ao longo do tempo. As placas do trocador foram pesadas e fotografadas antes e depois do teste para controle da quantidade de material depositado. A partir dos resultados laboratoriais, fez-se o ajuste dos parâmetros do modelo de incrustação, simulando novamente. Esses resultados foram comparados aos experimentais, sendo, então, o modelo validado. / In order to guarantee harmlessness, some processed foods are thermally treated in a continuous process named pasteurization, in which the purpose is to eliminate pathogenic microorganisms, while avoiding sensorial and quality losses. This operation is used in products such as juice, beers, milk and dairy food, pulp, and so on. Mathematical modeling of this process seeks to help its understanding, controlling, and optimization. Thus, the aim of this work was to develop and simulate a model of a continuous process pasteurization, and to conduct the experimental validation of a fouling model in the plates of the heat exchanger plates, without a process controller (PID). The phenomenological modeling was composed by differential energy and material balances, for temperature and lethality, respectively, in the channels, plates, holding tube and its connections of the pasteurizer. It was also developed an empirical fouling model for the product in the heating section. All these models represent a set of first and second order differential equations which were solved by a finite difference method through the gPROMS software. This modeling was used to express the behavior of a laboratory scale plate pasteurizer, with and without fouling, with and without system disturbances and during the equipment startup, in a case study. The simulated data was presented by the unidimensional spatial and temporal distribution of temperature and lethality along the process, and overall heat transfer coefficient profile in the heating section. To validate the fouling model, an experimental test by using a protein solution (similar to cow milk) was conducted. The temperature logging over time was done by various thermocouples inserted in the pasteurizer. All the plates were weighed and photographed before and after the tests to quantify the amount of deposits. From laboratory results, fouling model parameters were adjusted and simulation was performed again. These results were compared to the experiments, being the model validated adequately.

A indústria de papel e celulose passa por constantes desafios para solucionar problemas relacionados ao alto consumo de água industrial. Uma alternativa é utilizar ferramentas como a Integração de Processos, onde é possível aplicar técnicas gráficas como o \"Water Pinch\" ou técnicas com programação matemática para otimizar o circuito de água. Para contribuir com o setor, as técnicas foram aplicadas no presente trabalho utilizando-se dados reais coletados em uma unidade produtora de polpa termomecânica e papel imprensa. Com os dados, um caso base em um simulador foi desenvolvido para iniciar a análise por Integração de Processos. A análise é baseada no aproveitamento das correntes de águas residuais em outras etapas do processo sob restrições na concentração limite de contaminantes, especificamente finos e sólidos dissolvidos. Diferentemente dos trabalhos apresentados na literatura que alegam que a solução encontrada trata-se de valores otimizados, os resultados mostram que os valores encontrados através da programação matemática e do método Pinch são teoricamente corretos, porém, quando novamente simuladas sob estas novas condições obtidas por Integração de Processos, as condições operacionais da unidade industrial mostram-se inadequadas. As concentrações limites de contaminantes previamente estabelecidos pelas técnicas utilizadas são frequentemente ultrapassadas nos resultados de recálculo por simulação, e portanto, as soluções de Integração de Processos devem ser corrigidas antes de implantação. Por isso, os valores previstos, por exemplo, de redução de consumo de até 38% no projeto realístico atinge o valor de 23%, o que ainda é um bom resultado. O trabalho ainda mostra que a programação matemática é eficaz e rápida para encontrar soluções com múltiplos contaminantes, enquanto o método Pinch é mais voltado para casos com contaminante simples. / The Pulp and Paper industry has constantly struggled to solve problems related to high water consumption. One alternative is to use tools like Process Integration, where graphical methods and mathematical programming can be applied to optimize the water circuit. To contribute to the Pulp and Paper sector, the methods were applied in the present work using real process data that have been collected in an integrated thermomechanical and newsprint mill. With these data, a base case simulation was developed to initiate the analysis by Process Integration. The analysis is based on residual water reuse in other process stages under propriety constraints like contaminants concentration limits, specifically the dissolved solids and fine fibers. Differently from works presented in the references that claim that solutions found are optimized values, the results of this work show that values found by mathematical programming and pinch method are theoretically correct, however, the operational conditions of the mill become inadequate when simulated under new conditions achieved by Process Integration. The concentration limits of contaminants previously established for the methods have their values frequently exceed after recalculation by simulation, and thus, the solutions by Process Integration must be corrected before using them. So, if the predicted value for reduction of fresh water consumption is, for example, 38%, in the realistic project this value will reach only 23%, which is still a good result. The work also shows that mathematical programming is efficient to find solutions when there are multiple contaminants, while pinch method is more adequate for those cases with single contaminant.

Os edifícios são responsáveis por importantes impactos ambientais, principalmente, pelo seu longo ciclo de vida. Neste sentido, as edificações são potenciais redutoras de danos ambientais, já que as decisões sobre seu impacto podem ser feitas em projeto. No Brasil, o Programa Minha Casa Minha Vida (PMCMV) produziu mais de dois milhões de unidades de habitação, sendo um importante gerador de impactos. Foram realizadas pesquisas avaliando impactos sociais, urbanísticos e arquitetônicos do PMCMV, entretanto ainda existe escassez de estudos avaliando os impactos ambientais dessas edificações. Esta pesquisa utiliza a metodologia de Avaliação do Ciclo de Vida (ACV) para quantificar os impactos ambientais potenciais de uma casa do PMCMV. A metodologia considera três fases, com referência no estudo de caso de uma casa térrea situada na região metropolitana de Porto Alegre (sul do Brasil). A Fase 1 quantifica o uso de energia através de simulação termoenergética, testando envoltórias alternativas em comparação à original. A Fase 2 realiza a ACV preliminar, para verificar as contribuições de impacto mais relevantes em dois modelos selecionados. A Fase 3 desenvolve a ACV final com dados adaptados para a realidade brasileira. Os resultados demonstram que os impactos operacionais da edificação são os mais importantes ao longo do ciclo de vida de 50 anos, para as duas alternativas de envoltória avaliadas. Mesmo assim, os requerimentos incorporados da edificação podem representar impactos importantes, ultrapassando 40% em categorias como aquecimento global e depleção da camada de ozônio. O transporte de materiais de construção e matérias primas é um dos maiores causadores dos impactos incorporados. Além desse, a recorrência de manutenções mostra-se importante, assim como a durabilidade dos materiais de construção. A aplicação da ferramenta de ACV confirma sua importância como instrumento para a tomada de decisão, identificando processos mais relevantes na qualificação ambiental de edificações. / Buildings are responsible for expressive environmental impacts, especially for its long life-cycle. In fact, buildings are important potential reducers of environmental damages, because decisions concerning its future impacts can be made at design stage. In Brazil, “My House My Life” program (MHMLP) produced more than two million dwellings, generating significant impacts. Some of MHMLP impacts were already addressed, such as social, urban and architectural, however there is a lack on environmental impacts studies focused on these buildings. This research applies Life Cycle Assessment method to quantify potential environmental impacts of a MHMLP dwelling. Methodology considered three phases, using as reference the case study of a single-story house located at the metropolitan area of Porto Alegre (southern Brazil). Phase 1 quantifies energy use through thermal dynamic simulations, considering different encloses types in comparison to the original option. Phase 2 applies streamlined Life Cycle Assessment (LCA) framework to evaluate the most important contributions to the environmental impacts of the two previously selected models. In phase 3, LCA was developed considering data regionalization and adaptation to the Brazilian context. Results show that operational impacts are the most important ones on the 50 years dwelling life cycle, for both evaluated alternatives. Nevertheless, embodied impacts can represent more than 40% of total global warming and ozone depletion potential impacts. Transportation of raw and construction materials is one of the most important contributors to embodied impacts. Furthermore, recurrent embodied impacts are important, as well as construction materials durability. LCA application validates its importance as a framework to support decision-making, identifying hotspots on buildings environmental qualification.

Atualmente, a exigência da indústria na construção de estruturas complexas é consequência da acirrada concorrência, principalmente, entre empresas dos segmentos rodoviários. Com o auxílio de ferramentas computacionais, baseadas no Método de Elementos Finitos, é possível dimensionar essas estruturas submetidas a solicitações aleatórias variando no tempo. Nesse caso, é comum a realização de simulações dinâmicas no domínio do tempo que se empregue um modelo de Elementos Finitos de placa ou viga e, assim, obter as tensões nos locais críticos de interesse. Porém, análises no domínio do tempo capturam tensões e deformações com boa precisão, mas costumam ser caras computacionalmente. Na maioria dos casos estudados, a vida em fadiga é fundamental para prever falhas estruturais de elevadas proporções, como o colapso da viga principal da estrutura chassi de um implemento rodoviário. Diante disso, são de interesse tecnológico e industrial as análises no domínio da frequência, a fim de diminuir o custo computacional de simulação dinâmica independente do modelo de Elementos Finitos. Com esse propósito, o presente trabalho propõe uma comparação entre metodologias capazes em estimar a vida em fadiga no domínio do tempo e da frequência, de um caso simples e um segundo caso, mais complexo, que é o da indústria. Os diferentes modelos de Elementos Finitos e métodos de cálculos da vida em fadiga no domínio da frequência são comparados e discutidos, usando-se como referência o método clássico de cálculo da vida em fadiga, domínio do tempo. A metodologia leva em conta os diferentes Elementos Finitos empregados, as simplificações dos modelos estruturais usados e potenciais restrições cinemáticas aplicadas ao modelo. A comparação é feita com a ajuda de ferramentas comerciais que executam as análises modais, harmônicas, transientes, espectrais e rotinas de cálculos. Assim, o analista pode selecionar malhas com quantidade viável de graus de liberdade tornando possível as simulações dinâmicas e, além disso, prever a vida em fadiga no domínio do tempo para modelos simples e complexos. A partir dos resultados, verificou-se que as análises de estimativa da vida em fadiga no domínio da frequência, para modelos complexos, ainda não apresentam resultados confiáveis e, assim, são sugeridas recomendações. / Currently, the industry demand for the construction of complex structures is a consequence of the fierce competition, mainly between companies from semi-trailers segments. With the support of computational tools, based on the Finite Element Method, it is possible to size these structures submitted to random requests varying in time. In this case, it is common to perform dynamic simulations in the time domain to use a Finite Element model of plate or beam and thus obtain the stresses at the critical sites of interest. However, time domain analyses capture tensions and deformations with good accuracy, but they are often computationally expensive. In most of the studied cases, fatigue life is fundamental to predict structural failures of high proportions, such as main beam collapse of the chassis structure of a semi-trailer. Therefore, the semi-trailer industry segments is interested in the frequency domain, in order to reduce the computational cost of dynamic simulation no matter of the Finite Element model. With this purpose, the present work proposes a comparison between methodologies which are able to estimate the fatigue life in time domain and frequency, of a simple and second case, more complex, that of the industry. The different Finite Element models and methods of calculating fatigue life in frequency domain are compared and discussed using the classic time domain fatigue life calculation method as reference. The methodology takes into account the different Finite Elements are used, the simplifications of the structural models used and potential kinematic constraints applied to the model. The comparison is made with not only the following analyses: modal, harmonic, transient, spectral, but also computational routines. Thus, the analyst can select meshes with a viable amount of degrees of freedom making dynamic simulations possible, in addition, to its predict the fatigue life in time domain for simple and complex models. Based on the results, it was verified that the fatigue life estimates in frequency domain, for complex models, do not present reliable results yet. Therefore, recommendations are suggested.