Síntese e caracterização de nanopartículas magnéticas de Co e Ni com aplicação em magneto hipertermia

Nanoparticles are importante for the study of new phenomena and for the development of new applications. Metallic magnetic nanoparticles like Cobalt and Nickel are important for their applications in nanoscience and nanotechnology. In this work, we report on the synthesis and characterization of Ni and Co nanoparticles. The nanoparticles were prepared by the modi- ed sol-gel method and were formed in the pore-network of the biopolymer quitosan. The reduction occurred in absence of H2 ux. The metallic particles and their monoxides have a face-centered- cubic structure. The metallic particles sizes ranged from 59 to 77 nm and from 19 to 50 nm for Ni and Co, respectively. Their monoxides chemically passivated the metallic cores, and after several weeks we have not observed further increase in oxidation. The synthesis method was tuned to obtain mainly the ferromagnetic phase. The system behaves like a core/shell structure with a ferromagnetic core and an antiferromagnetic shell. Exchange bias e ect was observed at temperatures below the Néel temperature. Both systems were submitted to an alternated magnetic eld and the heat released by the particles increased the temperature to 140°C in an interval of 5 min. Similar studies in samples dispersed in water increased the temperatures to 40-59°C, these results suggest that these materials are candidates for magnetic hyperthermia.

Revestimento decorativo monocamada pigmentado, com resíduo de vidro temperado, para aplicação em fachadas

Although efficient from a technical point of view, mortar layers that make up the traditional masonry coating (slurry mortar, plaster and plaster) have to be in contradiction with the new construction technologies and more efficient methods of consumption and work rationalization. From an environmental point of view, the recovery of waste into new composites for the building has been a growing strand of studies in the scientific community, may prove to be a cost-effective solution in some cases. Thus, this research proposes the development of a mortar Decorative Coating Monolayer (RDM), for use in facades, produced on site, incorporating tempered glass waste (RVT) in the cement matrix, as a partial substitute for aggregate. Therefore, we adopted the binder respect / aggregate of 1: 6 (by volume), consistency index 250mm ± 20, sand substitution levels of glass waste 20%, 50% and 80% and relative water / cement varied in many traits. Two additives were used, a polymer, styrene-butadiene-based, and other chemical, besides mineral and silica fume inorganic pigment in colors red, yellow and blue. Mechanical tests were carried out on fresh pasta and hardened, as well as for the applied coating on masonry, so as to demonstrate the feasibility of the material. In addition, it verified the adequacy of the RDM built environment by means of thermal tests. The results demonstrated the feasibility of the proposed RDM with significantly higher values when compared to norms, especially the dash-added replacement content of 20% and addition of pigment in red. Therefore, the study shows the scientific community as an incentive to the use of technological innovations in construction, increasing the range of alternatives available for housing production, with the proposition of a material that achieves the desired functionality and obtain environmental gain, and may be adopted on construction sites as an alternative industrialized mortars.

Análise de confiabilidade de um moto-ventilador centrífugo: aplicação no sistema de pressurização de subestação industrial para garantia da segurança operacional na indústria petroquímica

The need of the oil industry to ensure the safety of the facilities, employees and the environment, not to mention the search for maximum efficiency of its facilities, makes it seeks to achieve a high level of excellence in all stages of its production processes in order to obtain the required quality of the final product. Know the reliability of equipment and what it stands for a system is of fundamental importance for ensuring the operational safety. The reliability analysis technique has been increasingly applied in the oil industry as fault prediction tool and undesirable events that can affect business continuity. It is an applied scientific methodology that involves knowledge in engineering and statistics to meet and or analyze the performance of components, equipment and systems in order to ensure that they perform their function without fail, for a period of time and under a specific condition. The results of reliability analyzes help in making decisions about the best maintenance strategy of petrochemical plants. Reliability analysis was applied on equipment (bike-centrifugal fan) between the period 2010-2014 at the Polo Petrobras Guamaré Industrial, situated in rural Guamaré municipality in the state of Rio Grande do Norte, where he collected data field, analyzed historical equipment and observing the behavior of faults and their impacts. The data were processed in commercial software reliability ReliaSoft BlockSim 9. The results were compared with a study conducted by the experts in the field in order to get the best maintenance strategy for the studied system. With the results obtained from the reliability analysis tools was possible to determine the availability of the centrifugal motor-fan and what will be its impact on the security of process units if it will fail. A new maintenance strategy was established to improve the reliability, availability, maintainability and decreased likelihood of Moto-Centrifugal Fan failures, it is a series of actions to promote the increased system reliability and consequent increase in cycle life of the asset. Thus, this strategy sets out preventive measures to reduce the probability of failure and mitigating aimed at minimizing the consequences.

Estudo e aplicação da transformada de Fourier na regularização de dados sísmicos na exploração de petróleo

In the oil prospection research seismic data are usually irregular and sparsely sampled along the spatial coordinates due to obstacles in placement of geophones. Fourier methods provide a way to make the regularization of seismic data which are efficient if the input data is sampled on a regular grid. However, when these methods are applied to a set of irregularly sampled data, the orthogonality among the Fourier components is broken and the energy of a Fourier component may "leak" to other components, a phenomenon called "spectral leakage". The objective of this research is to study the spectral representation of irregularly sampled data method. In particular, it will be presented the basic structure of representation of the NDFT (nonuniform discrete Fourier transform), study their properties and demonstrate its potential in the processing of the seismic signal. In this way we study the FFT (fast Fourier transform) and the NFFT (nonuniform fast Fourier transform) which rapidly calculate the DFT (discrete Fourier transform) and NDFT. We compare the recovery of the signal using the FFT, DFT and NFFT. We approach the interpolation of seismic trace using the ALFT (antileakage Fourier transform) to overcome the problem of spectral leakage caused by uneven sampling. Applications to synthetic and real data showed that ALFT method works well on complex geology seismic data and suffers little with irregular spatial sampling of the data and edge effects, in addition it is robust and stable with noisy data. However, it is not as efficient as the FFT and its reconstruction is not as good in the case of irregular filling with large holes in the acquisition.

Estudo e aplicação da transformada de Fourier na regularização de dados sísmicos na exploração de petróleo

In the oil prospection research seismic data are usually irregular and sparsely sampled along the spatial coordinates due to obstacles in placement of geophones. Fourier methods provide a way to make the regularization of seismic data which are efficient if the input data is sampled on a regular grid. However, when these methods are applied to a set of irregularly sampled data, the orthogonality among the Fourier components is broken and the energy of a Fourier component may "leak" to other components, a phenomenon called "spectral leakage". The objective of this research is to study the spectral representation of irregularly sampled data method. In particular, it will be presented the basic structure of representation of the NDFT (nonuniform discrete Fourier transform), study their properties and demonstrate its potential in the processing of the seismic signal. In this way we study the FFT (fast Fourier transform) and the NFFT (nonuniform fast Fourier transform) which rapidly calculate the DFT (discrete Fourier transform) and NDFT. We compare the recovery of the signal using the FFT, DFT and NFFT. We approach the interpolation of seismic trace using the ALFT (antileakage Fourier transform) to overcome the problem of spectral leakage caused by uneven sampling. Applications to synthetic and real data showed that ALFT method works well on complex geology seismic data and suffers little with irregular spatial sampling of the data and edge effects, in addition it is robust and stable with noisy data. However, it is not as efficient as the FFT and its reconstruction is not as good in the case of irregular filling with large holes in the acquisition.

Estudo de famílias wavelets para aplicação na análise em DOAS

Trace gases are important to our environment even though their presence comes only by ‘traces’, but their concentrations must be monitored, so any necessary interventions can be done at the right time. There are some lower and upper boundaries which produce nice conditions for our lives and then monitoring trace gases comes as an essential task nowadays to be accomplished by many techniques. One of them is the differential optical absorption spectroscopy (DOAS), which consists mathematically on a regression - the classical method uses least-squares - to retrieve the trace gases concentrations. In order to achieve better results, many works have tried out different techniques instead of the classical approach. Some have tried to preprocess the signals to be analyzed by a denoising procedure - e.g. discrete wavelet transform (DWT). This work presents a semi-empirical study to find out the most suitable DWT family to be used in this denoising. The search seeks among many well-known families the one to better remove the noise, keeping the original signal’s main features, then by decreasing the noise, the residual left after the regression is done decreases too. The analysis take account the wavelet decomposition level, the threshold to be applied on the detail coefficients and how to apply them - hard or soft thresholding. The signals used come from an open and online data base which contains characteristic signals from some trace gases usually studied.

Estudo de famílias wavelets para aplicação na análise em DOAS

Trace gases are important to our environment even though their presence comes only by ‘traces’, but their concentrations must be monitored, so any necessary interventions can be done at the right time. There are some lower and upper boundaries which produce nice conditions for our lives and then monitoring trace gases comes as an essential task nowadays to be accomplished by many techniques. One of them is the differential optical absorption spectroscopy (DOAS), which consists mathematically on a regression - the classical method uses least-squares - to retrieve the trace gases concentrations. In order to achieve better results, many works have tried out different techniques instead of the classical approach. Some have tried to preprocess the signals to be analyzed by a denoising procedure - e.g. discrete wavelet transform (DWT). This work presents a semi-empirical study to find out the most suitable DWT family to be used in this denoising. The search seeks among many well-known families the one to better remove the noise, keeping the original signal’s main features, then by decreasing the noise, the residual left after the regression is done decreases too. The analysis take account the wavelet decomposition level, the threshold to be applied on the detail coefficients and how to apply them - hard or soft thresholding. The signals used come from an open and online data base which contains characteristic signals from some trace gases usually studied.

Análise tribo-termodinâmica da aplicação de nanopartículas de Al2O3 como aditivo lubrificante em compressor hermético de refrigeração

The thermodynamic performance of a refrigeration system can be improved by reducing the compression work by a particular technique for a specific heat removal rate. This study examines the effect of small concentrations of Al2O3 (50 nm) nanoparticles dispersion in the mineral oil based lubricant on the: viscosity, thermal conductivity, and lubrication characteristics as well as the overall performance (based on the Second Law of Thermodynamics) of the refrigerating system using R134a or R600a as refrigerants. The study looked at the influences of variables: i) refrigerant charge (100, 110, 120 and 130 g), ii) rotational speed of the condenser blower (800 and 1100 RPM) and iii) nanoparticle concentration (0.1 and 0.5 g/l) on the system performance based on the Taguchi method in a matrix of L8 trials with the criterion "small irreversibility is better”. They were carried pulldown and cycling tests according to NBR 12866 and NBR 12869, respectively, to evaluate the operational parameters: on-time ratio, cycles per hour, suction and discharge pressures, oil sump temperature, evaporation and condensation temperatures, energy consumption at the set-point, total energy consumption and compressor power. In order to evaluate the nanolubricant characteristics, accelerated tests were performed in a HFRR bench. In each 60 minutes test with nanolubricants at a certain concentration (0, 0.1 and 0.5 g/l), with three replications, the sphere (diameter 6.00 ± 0.05 mm, Ra 0.05 ± 0.005 um, AISI 52100 steel, E = 210 GPa, HRC 62 ± 4) sliding on a flat plate (cast iron FC200, Ra <0.5 ± 0.005 um) in a reciprocating motion with amplitude of 1 mm, frequency 20 Hz and a normal load of 1,96 N. The friction coefficient signals were recorded by sensors coupled to the HFRR system. There was a trend commented bit in the literature: a nanolubricant viscosity reduction at the low nanoparticles concentrations. It was found the dominant trend in the literature: increased thermal conductivity with increasing nanoparticles mass fraction in the base fluid. Another fact observed is the significant thermal conductivity growth of nanolubricant with increasing temperature. The condenser fan rotational speed is the most influential parameter (46.192%) in the refrigerator performance, followed by R600a charge (38.606%). The Al2O3 nanoparticles concentration in the lubricant plays a minor influence on system performance, with 12.44%. The results of power consumption indicates that the nanoparticles addition in the lubricant (0.1 g/L), together with R600a, the refrigerator consumption is reduced of 22% with respect to R134a and POE lubricant. Only the Al2O3 nanoparticles addition in the lubricant results in a consumption reduction of about 5%.

Análise tribo-termodinâmica da aplicação de nanopartículas de Al2O3 como aditivo lubrificante em compressor hermético de refrigeração

The thermodynamic performance of a refrigeration system can be improved by reducing the compression work by a particular technique for a specific heat removal rate. This study examines the effect of small concentrations of Al2O3 (50 nm) nanoparticles dispersion in the mineral oil based lubricant on the: viscosity, thermal conductivity, and lubrication characteristics as well as the overall performance (based on the Second Law of Thermodynamics) of the refrigerating system using R134a or R600a as refrigerants. The study looked at the influences of variables: i) refrigerant charge (100, 110, 120 and 130 g), ii) rotational speed of the condenser blower (800 and 1100 RPM) and iii) nanoparticle concentration (0.1 and 0.5 g/l) on the system performance based on the Taguchi method in a matrix of L8 trials with the criterion "small irreversibility is better”. They were carried pulldown and cycling tests according to NBR 12866 and NBR 12869, respectively, to evaluate the operational parameters: on-time ratio, cycles per hour, suction and discharge pressures, oil sump temperature, evaporation and condensation temperatures, energy consumption at the set-point, total energy consumption and compressor power. In order to evaluate the nanolubricant characteristics, accelerated tests were performed in a HFRR bench. In each 60 minutes test with nanolubricants at a certain concentration (0, 0.1 and 0.5 g/l), with three replications, the sphere (diameter 6.00 ± 0.05 mm, Ra 0.05 ± 0.005 um, AISI 52100 steel, E = 210 GPa, HRC 62 ± 4) sliding on a flat plate (cast iron FC200, Ra <0.5 ± 0.005 um) in a reciprocating motion with amplitude of 1 mm, frequency 20 Hz and a normal load of 1,96 N. The friction coefficient signals were recorded by sensors coupled to the HFRR system. There was a trend commented bit in the literature: a nanolubricant viscosity reduction at the low nanoparticles concentrations. It was found the dominant trend in the literature: increased thermal conductivity with increasing nanoparticles mass fraction in the base fluid. Another fact observed is the significant thermal conductivity growth of nanolubricant with increasing temperature. The condenser fan rotational speed is the most influential parameter (46.192%) in the refrigerator performance, followed by R600a charge (38.606%). The Al2O3 nanoparticles concentration in the lubricant plays a minor influence on system performance, with 12.44%. The results of power consumption indicates that the nanoparticles addition in the lubricant (0.1 g/L), together with R600a, the refrigerator consumption is reduced of 22% with respect to R134a and POE lubricant. Only the Al2O3 nanoparticles addition in the lubricant results in a consumption reduction of about 5%.

Degradação de paracetamol empregando tecnologia oxidativa avançada baseada em fotocatálise heterogênea usando irradiação artificial e solar

In this work, the oxidation and mineralization of paracetamol, based in an advanced oxidative process promoted by heterogeneous photocatalysis, was evaluated. The action of two photocatalysts (titanium dioxide, and a composite based on the association between titanium dioxide and zinc phthalocyanine dye) was studied. First of all, experiments in laboratory scale were performed using as radiation font a 400 W high pressure mercury lamp. The mineralization of paracetamol, promoted by both photocatalysts, was evaluated working with 4L of solution containing 10 mg L-1 of paracetamol and 100 mg L-1 of photocatalyst. To find the best experimental conditions, the influence of hydrogen peroxide concentration and pH was evaluated for the reactions. The best results for the reactions in laboratory scale was obtained using 33,00 mg L-1 of hydrogen peroxide in natural pH (6,80). Under these conditions, 100% oxidation was reached in just 40 minutes of reaction using TiO2 P25, while the mineralization was 78%. Using the composite, the mineralization was 63% in 2 hours of reaction and a oxidation of almost 100% was reached after 60 minutes. A CPC reactor (compound parabolic concentrator) was employed in the expanded work scale, using the sun as irradiation source. In this case the experiments were performed using 50 L of aqueous solution containing 10 mg L-1 of paracetamol and 100 mg L-1 of photocatalyst. The assays were done at pH 3,00 and natural pH (6,80). The used concentration of hydrogen peroxide was 33,00 mg L-1, adopted after laboratory scale studies. The reaction at pH 3,00 shows to be more advantageous, since under natural pH (6,80), the use of deionized water was necessary to prepare the solutions, probably because the deleterious action of carbonate ions, known hydroxyl radical scavengers. Using solar irradiation, the reaction mediated by the composite was more efficient when compared with the assays under laboratory scale since the composite presents the advantage of promoting a better use of visible radiation. Under these conditions, the mineralization increased from 40% to 56% under pH 3,00. At natural pH the oxidation occurred more slowly and the mineralization decreased from 56% to 50%. Thus, the use of pH 3,00 will be more interesting in real scale applications, even if it is necessary the pH correction before the discard of the treated effluent to the environment.

Caracterização mecânica da liga AlSi10Mg obtida por SLM para aplicação em componentes automóveis

Este projeto visa efetuar a caracterização mecânica da liga AlSi10Mg obtida por SLM (Fundição de Metal por Laser) para aplicação em componentes automóveis. Ao longo deste projeto é efetuada uma pesquisa bibliográfica das tecnologias de fabrico rápido mais frequentemente aplicadas ao processamento de alumínios, abordando de forma específica a tecnologia SLM, bem como a influência dos seus parâmetros no processamento de ligas de alumínio. Será levado a cabo um estudo comparativo da liga AlSi10Mg fabricada por fundição em molde permanente com a obtida por SLM, analisando-se a microestrutura das ligas, bem como as suas propriedades mecânicas, através da realização de ensaios de dureza, tração, análise dinâmico-mecânica e fadiga. Deste modo será possível perceber as diferenças entre o comportamento mecânico da liga obtida por SLM e a liga obtida pelo método convencional. Em resultado do estudo realizado, observou-se que a liga AlSi10Mg obtida por SLM apresenta uma microestrutura muito mais fina do que a liga fabricada por fundição em molde permanente, o que lhe permite ter um comportamento mecânico superior na maioria dos ensaios mecânicos realizados. Assim, é possível aplicar a tecnologia SLM ao fabrico de componentes em alumínio no sector automóvel, visto ser possível obter propriedades mecânicas superiores ou equivalentes aos componentes fabricados pelos processos de fabrico convencionais.

Gestão de projetos: aplicação numa empresa de serviços de consultoria estudo de caso da capgemini Portugal

A gestão de projetos tem ganho preponderância nas organizações ao longo dos últimos anos. As abordagens organizativas de gestão de projetos, ao contrário das tradicionais, permitem integrar esforços complexos e reduzir o nível de burocracia, dando respostas mais efetivas e adequadas às elevadas exigências dos clientes, que frequentemente se traduzem em solicitações de alterações no decorrer da execução dos projetos. Face ao exposto e tendo em consideração que o core business da empresa facilitadora do estágio curricular do Mestrado em Gestão da Escola Superior de Tecnologia e Gestão (ESTG) do Instituto Politécnico de Leiria (IPL) é a Capgemini Portugal, que se dedica à prestação de serviços de Consultoria, Tecnologia e Outsourcing e adota o modelo de gestão de projetos, atribuindo especial atenção à gestão de alterações, como área chave para o desenvolvimento de projetos bem-sucedidos, o presente relatório de estágio abordará essa temática. Assim, com base na observação participativa e na execução de tarefas de estágio na Capgemini Portugal, entre o mês de setembro de 2015 e o mês de janeiro de 2016, desenvolveu-se um estudo de caso sobre a aplicação do modelo de gestão de projetos na empresa, particularmente no processo de gestão de alterações. Adicionalmente, foi sugerida uma proposta com soluções de melhoria baseadas em abordagens de referência. Para o efeito, foi realizada uma revisão da bibliografia publicada sobre gestão de projetos, que serviu de suporte à realização de um estudo empírico baseado na aplicação da metodologia de trabalho científico indutivo. Assim, foi desenvolvida uma pesquisa de campo de natureza qualitativa, onde a recolha de dados foi efetuada por observação participativa, de uma entrevista semi-estruturada, da análise de documentos facilitados pela empresa e de conteúdos de páginas da internet. Concluiu-se que o tratamento de alterações num projeto é um processo crucial da gestão de projetos e deve ser abordado com extrema minúcia. A Capgemini detém uma metodologia própria de gestão de projetos que lhe permite monitorizar e controlar todos os fatores associados a um projeto.

Aplicação dos princípios LEAN MANAGEMENT ao projeto de moldes para injeção

Num mercado globalizado e extremamente competitivo, a escolha de uma metodologia de gestão é determinante para ditar o sucesso ou fracasso de uma empresa. O investimento em capital humano e tecnológico deve ser acompanhado por uma gestão de processos, rápida e eficaz, que direcione a organização para uma redução dos custos de um produto ou serviço. Nos últimos anos, vários autores têm demonstrado que uma das estratégias utilizadas para atingir este objetivo tem sido a aplicação da metodologia Lean Management, que ganhou reputação pelos resultados positivos alcançados. Este projeto foi elaborado em contexto industrial, no departamento de projeto da empresa Tecnifreza S.A., e teve como principal objetivo demonstrar que é possível obter uma diminuição do tempo de execução do projeto de um molde (lead time), através da aplicação dos princípios Lean Management. A metodologia utilizada assentou no registo detalhado de atividades predefinidas, ocorridas durante o projeto, baseada numa amostra constituída por nove moldes que melhor representam a realidade/tipologia produtiva da empresa. Após a análise dos dados obtidos, verifica-se que o desvio médio é de 91,7% entre o tempo de projeto inicialmente previsto pela direção e o tempo efetivo registado. Identificaram-se ainda as principais atividades que não acrescentaram valor aos projetos em estudo. Estas atividades, consideradas como desperdícios, perfazem no seu conjunto 34,6% do tempo total. Foram então sugeridas propostas de melhoria, de modo a reduzir ou eliminar estes tempos. De forma a avaliar o impacto destas propostas, foram realizadas estimativas tendo por base os dados de um molde tipo. Os resultados obtidos demonstram que, com a implementação das propostas de melhoria, são alcançados ganhos significativos na redução do lead time do projeto e consequentemente no tempo total de fabrico do molde. A antecipação na entrega dos desenhos 3D para a fabricação revela-se bastante evidente, existindo ainda um aumento no nivelamento da entrega de projetos para a fabricação. Face aos resultados apresentados verifica-se que a implementação de princípios Lean no departamento de projeto mostra-se potencialmente vantajosa, em particular com a introdução de células de trabalho e a realização do ciclo PDCA.

Contributo para a avaliação do desempenho ambiental de telha cerâmica através da aplicação da pegada ambiental do produto

O presente projeto tem como objetivo principal a aplicação da metodologia da pegada ambiental do produto (PAP) no sector da indústria cerâmica, nomeadamente, para o caso de estudo da telha, permitindo a aferição e comunicação do desempenho ambiental ao longo do ciclo de vida da telha Advance Lusa na tonalidade vermelho natural. Com este intuito procedeu-se à avaliação do ciclo de vida (ACV) dos impactos ambientais gerados pela sua produção, desde a extração de matérias-primas até à fase de distribuição, ou seja, com base numa análise ‘cradle-to-gate’. A implementação da metodologia requer o cálculo dos potenciais impactos ambientais tendo em conta as etapas relevantes no contexto dos limites definidos para o sistema em estudo. O método de avaliação de impactos utilizado é o método ILCD Midpoint + através da utilização do software SimaPro e com recurso às respetivas bibliotecas de bases de dados. A avaliação do perfil de utilização dos recursos e emissões possibilita assim aferir o desempenho ambiental da telha em estudo através da identificação de pontos críticos do sistema considerado. Os resultados indicam que os impactos ambientais se devem, principalmente, à utilização de gás natural na etapa de cozedura e, que a fase de produção e/ou fabrico de telha é a que salienta maiores preocupações do ponto vista ambiental, pelo que deverão ser definidas estratégias com o propósito de verificar a aplicabilidade das melhores técnicas disponíveis (MTDs) e de técnicas emergentes, contribuindo assim, para a procura da sustentabilidade dos processos integrantes do presente estudo.

Aplicação informática para verificação de perfis enformados a frio segundo a EN1993-1-3

Os perfis enformados a frio estão em crescente uso na indústria da construção, utilizados como estruturas secundárias e primárias, por apresentar resistência em relação ao baixo peso, facilidade de utilização em obra e sustentabilidade. A norma europeia EN1993-1-3, também adotada em Portugal, que apresenta as especificações normativas sobre o uso estrutural de perfis enformados a frio é de difícil aplicação para os projetistas devido à quantidade e complexidade de cálculos para que sejam efetuadas as verificações de segurança necessárias, pelas limitações dos programas informáticos e complexidade de compreensão dos fenómenos da instabilidade local e distorcional que condicionam o comportamento deste tipo de secções, classificadas como de classe 4. O presente trabalho procura explicar os procedimentos do eurocódigo e os seus aspetos mais controversos, como, por exemplo, o processo de cálculo da distribuição de tensões numa secção arbitrária constituída por segmentos retos, o cálculo de larguras efetivas e espessuras reduzidas e as verificações de segurança em termos de resistência e estabilidade global requeridos pela norma. O principal objetivo deste trabalho é o desenvolvimento um programa de cálculo para verificar barras com secções de classe 4 que tenha a abrangência das especificações do Eurocódigo (EC3-1-3), que possa auxiliar engenheiros no processo de projeto, dimensionamento e verificação regulamentar de estruturas metálicas que utilizem este tipo de secções. Para isso foi criada uma aplicação informática, em ambiente Windows®, que está ligada ao programa Autodesk® Robot Structural Analisys® para obtenção de dados de cálculo e executar os cálculos de secções efetivas e verificações de segurança de acordo com a norma europeia. São apresentados diagramas de blocos com a sequência do procedimento de cálculo das várias fases de cálculo de secções efetivas e de verificação de barras, com vista a mostrar a lógica de funcionamento interno da aplicação criada no âmbito deste trabalho. Por fim desenvolve-se um manual de utilização da aplicação e um exemplo comparativo, de cálculo das propriedades efetivas de uma secção, entre os resultados do programa e documentos de referência com cálculos manuais