Mechanical behavior of black anodic films on 7175 aluminium alloy for space applications

Because of their low outgassing and their thermo-optical properties, black anodized aluminium parts are often used near optical instruments to manage thermal control in space applications. However, critical cases of flaking of the film were observed after simulated thermal ageing. To understand the mechanisms leading to flaking, the influence of the initial porosity of the film on its mechanical behavior during and after the black anodizing process has been investigated. The decrease of limit tensile stress with the porosity, the coloring and the sealing combined to thermal stresses due to the difference of thermal expansion coefficients between film and substrate have been shown to cause crazing in articular conditions. For high initial porosity films, thermal cycling ageing has a detrimental influence on the adhesion measured by scratchtesting. Numerical simulation has been used to simulate the combined effects of thermal stresses and film cracking on the stress field at the interface

Investigations into the coefficient of thermal expansion of porous films prepared on AA7175 T7351 by anodizing in sulphuric acid electrolyte

The aim of this study was to investigate the Coefficient of Thermal Expansion (CTE) of anodic films on 7175 T7351 aluminium alloy and to evaluate the influence of the film characteristics on this value. In particular, effects of porosity and post-treatments, such as coloring and sealing, were studied. Beam bending analysis was used as the experimental method and a numerical finite element model was developed to verify theoretical relationships hypotheses. The values determined and the choice of experimental method were then validated by comparing the experimental cracking temperature of anodic films with a theoretical value directly depending on the previously determined CTE

Análise do impacto de fatores de gestão de pessoas na implementação da metodologia BIM na indústria da construção civil

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2019.O interesse na metodologia BIM tem crescido ao longo dos anos, tanto academicamente quanto no mercado da construção civil. Em alguns países, a metodologia já é mais praticada que modelos tradicionais em CAD. No Brasil, o BIM ainda é incipiente, mas estratégias adotadas pelo governo federal trazem perspectivas de crescimento para sua utilização. Apesar de tida como uma evolução inevitável, organizações em geral resistem à implementação de sistemas BIM em seus processos de produção. A adoção da metodologia é custosa e exige das organizações profundas transformações tecnológicas, processuais e culturais. Os fatores de gestão de pessoas que influenciam a implementação tendem a ser especialmente impactantes. Este trabalho objetiva levantar quais são esses fatores, identificando aqueles que são críticos para a realidade brasileira. Por fim, o trabalho objetiva propor estratégias de gestão de pessoas a serem adotadas pelas organizações brasileiras com a finalidade de alavancar a implementação da metodologia BIM.The interest in BIM methodology has grown over the years, both academically and in the construction industry. In some countries, the methodology is already more practiced then traditional CAD models. In Brazil, BIM is still incipient, but strategies adopted by the Brazilian federal government bring growth perspectives for its use. Even though considered inevitable, organizations in general tend to resist BIM systems implementation in its production processes. Its adoption is costly, and demands profound technology, process and cultural transformation in organizations. People management factors that affect BIM implementation tend to be especially influencing. This paper objects to raise which are those factors, identifying and classifying the ones that are critical for the Brazilian reality. It also proposes people management strategies to be adopted by Brazilian organizations in order to leverage BIM implementation

Análise do impacto de fatores de gestão de pessoas na implementação da metodologia BIM na indústria da construção civil

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2019.O interesse na metodologia BIM tem crescido ao longo dos anos, tanto academicamente quanto no mercado da construção civil. Em alguns países, a metodologia já é mais praticada que modelos tradicionais em CAD. No Brasil, o BIM ainda é incipiente, mas estratégias adotadas pelo governo federal trazem perspectivas de crescimento para sua utilização. Apesar de tida como uma evolução inevitável, organizações em geral resistem à implementação de sistemas BIM em seus processos de produção. A adoção da metodologia é custosa e exige das organizações profundas transformações tecnológicas, processuais e culturais. Os fatores de gestão de pessoas que influenciam a implementação tendem a ser especialmente impactantes. Este trabalho objetiva levantar quais são esses fatores, identificando aqueles que são críticos para a realidade brasileira. Por fim, o trabalho objetiva propor estratégias de gestão de pessoas a serem adotadas pelas organizações brasileiras com a finalidade de alavancar a implementação da metodologia BIM.The interest in BIM methodology has grown over the years, both academically and in the construction industry. In some countries, the methodology is already more practiced then traditional CAD models. In Brazil, BIM is still incipient, but strategies adopted by the Brazilian federal government bring growth perspectives for its use. Even though considered inevitable, organizations in general tend to resist BIM systems implementation in its production processes. Its adoption is costly, and demands profound technology, process and cultural transformation in organizations. People management factors that affect BIM implementation tend to be especially influencing. This paper objects to raise which are those factors, identifying and classifying the ones that are critical for the Brazilian reality. It also proposes people management strategies to be adopted by Brazilian organizations in order to leverage BIM implementation

Problemas inversos aplicados à inspeção predial

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Civil e Ambiental, 2019.A Inspeção Predial é uma área que vem ganhando visibilidade no Brasil, e com ela, técnicas não destrutivas e de baixo custo também. Neste contexto, a utilização das transformadas de wavelet na localização e quantificação de danos em estruturas de concreto e aço é um método promissor, capaz de detectar a localização e severidade do dano sem a necessidade das respostas da estrutura intacta e com baixo custo de aplicação. A proposta deste trabalho é levantar e avaliar as diferentes formas de aplicar as transformadas de wavelet na identificação de danos em tabuleiros e longarinas de pontes, apontando as particularidades de cada uma com todas suas vantagens aos métodos convencionais e procurando ultrapassar suas limitações, utilizando a modelagem em softwares na obtenção de dados experimentais.Structural Health Monitoring, in Brazil, is a growing topic bringing innovation in nondestructive testing and low cost techniques. Therefore, the use of wavelet transform methods in detecting and evaluating damage in concrete or steel structures is a promising technique, capable of detecting not just the location of the damage but also its severity without the need for the previous response of the undamaged structure or a high cost of implementation. The focus of this research is to raise and evaluate the different wavelet transform techniques of detecting damage in concrete or steel beams and bridges, pointing out each one singularities with all its advantages compared to traditional methods and looking to surpass its limitations, making use of experimental data gathered from modelling structures in softwares.La surveillance de l'état des structures, au Brésil, est un sujet qui est de plus en plus en vogue, et qui innove en matière d'essais non destructifs et de techniques à faible coût. Dans ce cadre, l'utilisation d'une transformée en ondelettes pour détecter et quantifier des dommages dans des structures en béton ou en acier est une technique prometteuse, apte à préciser la localisation et la gravité des dommages, tout en dispensant la réponse des structures préservées et à un bas coût de mise en œuvre. L’objet de ce travail c'est d'identifier et d'évaluer les différentes façons d'utiliser la transformée en ondelettes pour identifier des tabliers de ponts ou poutres endommagés. On souligne les particularités de chacune, leurs avantages par rapport aux vi méthodes traditionnelles et on cherche à surmonter leurs limitations en utilisant des données de tests numériques et réels issues de la bibliographie

Co-grinding significance for calcium carbonate-calcium phosphate mixed cement. Part II: effect on cement properties

In the present study, we aim to evaluate the contribution of the co-grinding process in controlling calcium carbonate-dicalcium phosphate dihydrate cement properties. We set a method designed to evaluate phase separation, usually occurring during paste extrusion, which is quantitative, reliable, and discriminating and points out the determining role of cogrinding to limit filter-pressing. We show that solid phase co-grinding leads to synergistic positive effects on cement injectability, mechanical properties, and radio-opacity. It allows maintaining a low (<0.4 kg) and constant load during the extrusion of paste, and the paste’s composition remains constant and close to that of the initial paste. Analogous behavior was observed when adding a third component into the solid phase, especially SrCO3 as a contrasting agent. Moreover, the cement’s mechanical properties can be enhanced by lowering the L/S ratio because of the lower plastic limit. Finally, unloaded or Sr-loaded cements show uniform and increased optical density because of the enhanced homogeneity of dry component distribution. Interestingly, this study reveals that cogrinding improves and controls essential cement properties and involves processing parameters that could be easily scaled up. This constitutes a decisive advantage for the development of calcium carbonate-calcium phosphate mixed cements and, more generally, of injectable multicomponent bone cements that meet a surgeon’s requirements