Caracterização microestrutural e propriedades mecânicas em pinos para transmissão mecânica de aço inoxidável martensítico e pinos fusíveis de latão em chave de alta tensão

Pós-graduação em Engenharia Mecânica - FEB

Caracterização físico-mecânica de painéis de partículas de bambu com adição de casca de café

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização mecânica e microestrutural de juntas soldadas a laser em aços maraging com posterior tratamento térmico e termoquímico de superfície a plasma

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caracterização experimental de sistemas mecânicos com comportamento não-linear

Pós-graduação em Engenharia Mecânica - FEIS

Análise dinâmica não-linear de um sistema não-ideal, utilizando amortecedor magneto-reológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Una metodología para el autoaprendizaje y la autoevaluación en Mecánica Básica

En la Escuela de Minas de la Universidad Politécnica de Madrid (UPM) se ha llevado a cabo el proceso de adaptación a los principios de Bolonia. Esto ha implicado cambios en la metodología de la enseñanza. En este artículo se describe una nueva metodología aplicada a un curso introductorio de Mecánica ubicado en el primer semestre del grado de dos diferentes títulos de ingeniería. Los diferentes resultados se presentan mediante un índice que permite evaluar el resultado global del proceso de enseñanza-aprendizaje alcanzado con esta metodología

A contribution on modeling methodologies for multibody systems.

Multibody System Dynamics has been responsible for revolutionizing Mechanical Engineering Design by using mathematical models to simulate and optimize the dynamic behavior of a wide range of mechanical systems. These mathematical models not only can provide valuable informations about a system that could otherwise be obtained only by experiments with prototypes, but also have been responsible for the development of many model-based control systems. This work represents a contribution for dynamic modeling of multibody mechanical systems by developing a novel recursive modular methodology that unifies the main contributions of several Classical Mechanics formalisms. The reason for proposing such a methodology is to motivate the implementation of computational routines for modeling complex multibody mechanical systems without being dependent on closed source software and, consequently, to contribute for the teaching of Multibody System Dynamics in undergraduate and graduate levels. All the theoretical developments are based on and motivated by a critical literature review, leading to a general matrix form of the dynamic equations of motion of a multibody mechanical system (that can be expressed in terms of any set of variables adopted for the description of motions performed by the system, even if such a set includes redundant variables) and to a general recursive methodology for obtaining mathematical models of complex systems given a set of equations describing the dynamics of each of its uncoupled subsystems and another set describing the constraints among these subsystems in the assembled system. This work also includes some discussions on the description of motion (using any possible set of motion variables and admitting any kind of constraint that can be expressed by an invariant), and on the conditions for solving forward and inverse dynamics problems given a mathematical model of a multibody system. Finally, some examples of computational packages based on the novel methodology, along with some case studies, are presented, highlighting the contributions that can be achieved by using the proposed methodology.

Fabrico e ensaio balístico em condições reais de conceito melhorado de um projétil de detonação mecânica

A floresta constitui uma das riquezas naturais com maior valor em todo o planeta, assumindo uma vital importância em termos ambientais e económicos, nomeadamente para Portugal. Neste projeto desenvolve-se um potencial meio de combate a incêndios florestais, com base num conceito inovador e complementar aos atuais meios aplicados no combate a este tipo de flagelo. Este projeto de investigação visa o desenvolvimento de um projétil de detonação mecânica, logo inerte, para aplicação no combate a incêndios florestais, e enquadra-se no âmbito de uma parceria alargada de colaboração em I&D entre a Academia Militar e o Instituto Superior Técnico. O conceito deste produto, ao qual foi atribuído o acrónimo: FIREND, foi, inicialmente, desenvolvido no âmbito de um projeto de I&D da Academia Militar. Neste projeto realiza-se o desenvolvimento final do conceito do produto, incluindo a verificação de aspetos chave no projeto mecânico, seleção e aquisição de materiais e fabrico de protótipos para ensaios balísticos em condições reais. Os resultados de funcionalidade e eficiência são apresentados nas fases estabilidade em voo, impacto com o solo, detonação, projeção e dispersão da carga para o exterior e análise de recuperação dos componentes do FIREND, após utilização. Tendo em conta os resultados obtidos relativos ao funcionamento do FIREND durante o disparo do Obus, voo, impacto no solo e detonação e ainda o estado geral dos componentes após os ensaios, pode-se concluir que se trata de um projeto viável.

Estudo de balística interna

O conhecimento e a compreensão dos processos que ocorrem no interior do tubo de uma arma de fogo, desde a ignição da carga propulsora, até à saída do projétil, é importante no desenvolvimento do armamento, de uma forma económica e segura. Com a modelação matemática destes processos, que é uma abordagem muito utilizada atualmente, é possível otimizar a carga explosiva e os materiais utilizados. Este estudo foi realizado no âmbito do projeto FIREND, resultante da colaboração entre a Academia Militar e o Instituto Superior Técnico O modelo desenvolvido foi aplicado a um sistema, arma, carga propulsora e projétil, já existente, tendo os resultados obtidos sido validados com o software PRODAS e tabelas referentes ao presente sistema. Para melhor compreender a importância das variáveis envolvidas, é feita uma análise de sensibilidade a diversos parâmetros balísticos, mantendo constante as dimensões da arma em estudo. Na análise dos resultados verifica-se que a cinta de travamento é um elemento muito importante, alterando significativamente os valores da pressão e da velocidade. Verificou-se também que com cargas propulsoras de maior taxa de queima é possível obter valores mais elevados de pressão máxima e velocidade à saída. Palavras chave: Balística interna; Projétil de Artilharia; Pressão; Velocidade; Modelação matemática; Análise de sensibilidade.

Análise de tensões integrada a sistema de engenharia reversa para projeto e confecção de próteses

This work consists of the conception, developing and implementation of a Computational Routine CAE which has algorithms suitable for the tension and deformation analysis. The system was integrated to an academic software named as OrtoCAD. The expansion algorithms for the interface CAE genereated by this work were developed in FORTRAN with the objective of increase the applications of two former works of PPGEM-UFRN: project and fabrication of a Electromechanincal reader and Software OrtoCAD. The software OrtoCAD is an interface that, orinally, includes the visualization of prothetic cartridges from the data obtained from a electromechanical reader (LEM). The LEM is basically a tridimensional scanner based on reverse engineering. First, the geometry of a residual limb (i.e., the remaining part of an amputee leg wherein the prothesis is fixed) is obtained from the data generated by LEM by the use of Reverse Engineering concepts. The proposed core FEA uses the Shell's Theory where a 2D surface is generated from a 3D piece form OrtoCAD. The shell's analysis program uses the well-known Finite Elements Method to describe the geometry and the behavior of the material. The program is based square-based Lagragean elements of nine nodes and displacement field of higher order to a better description of the tension field in the thickness. As a result, the new FEA routine provide excellent advantages by providing new features to OrtoCAD: independency of high cost commercial softwares; new routines were added to the OrtoCAD library for more realistic problems by using criteria of fault engineering of composites materials; enhanced the performance of the FEA analysis by using a specific grid element for a higher number of nodes; and finally, it has the advantage of open-source project and offering customized intrinsic versatility and wide possibilities of editing and/or optimization that may be necessary in the future

Caracterização mecânica, térmica e acústica de um compósito que utiliza rejeitos de mármore, granito e EPS para a fabricação de blocos para a construção civil

The use of composite materials for the construction industry has been the subject of numerous scientific papers in Brazil and in the world. One of the factors that motivate this quest is the housing deficit that countries especially the third world face. In Brazil this deficit reaches more than 6.5 million homes, around 12% of all US households . This paper presents a composite that was obtained from waste generated in processes for the production of granite and marble slabs, cement, gypsum, sand, crushed EPS and water. These wastes cause great damage to the environment and are thrown into landfi lls in bulk. The novelty of the work is in the combined study thermal, mechanical and acoustic composite obtained in real situation of rooms that are part of an experimental housing. Many blocks were made from cement compositions, plaster, foam, sand, marb le and / or granite, preliminary tests of mechanical and thermal resistance were made by choosing the most appropriate proportion. Will be given the manufacturing processes and assembly units 500 units 10 x 80 x 28 cm produced for the construction of an ex perimental home. We studied what kind of block and residue, marble or granite, made it more feasible for the intended purpose. The mechanical strength of the produced blocks were above 3.0 MPa. The thermal resistance of the blocks was confirmed by the maxi mum temperature difference between the inner and outer walls of rooms built around 8.0 ° C. The sound absorption for optimal room was around 31%. Demonstrated the feasibility of using the blocks manufactured with composite material proposed for construction.

Desenvolvimento de um exoesqueleto para movimentação/reabilita-ção de paraplégicos

People bedridden by paralysis/motor disability are subject to several problems due to lack of movement. Then, it is necessary to use equipments that enable the people bedridden stand up and walk, so as to reduce the problems due to lack of movement and the time of rehabilitation, impacting directly on its quality of life. The aim of this work is the development of an exoskeleton to make the movement of people with paralysis / motor impairment in the lower limbs, without help of third parties, to be activated by the user. To provide support, stability and security to the deficient, it was decided to use a structure formed by four legs, being each leg consisting of a parallel chain. The gait was obtained by combining the movement of two mechanisms: crank/rocker, responsible for oscillatory motion of the leg, and cam/follower, responsible for the foot motion on the desired trajectory. To achieve the aim of this work was conducted a study about the types of exoskeletons for locomotion/rehabilitation of people with lower limb paralysis and presented a study on the movement of the lower limb joints. It also presented a mathematical model to obtain the desired path to the foot of the exoskeleton, the static model and the design of the structure elements. In the sequence is presented the simulation of movements of a people during the human gait, experimental tests and the comparison with the human gait developed by a people without disabilities.

Estágio profissional em gabinete de engenharia, na componente de climatização

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica com Especialização em Energia, Climatização e Refrigeração

Análise e modelagem do escoamento transitório de fluidos de perfuração

Drilling fluids present a thixotropic behavior and they usually gel when at rest. The sol-gel transition is fundamental to prevent the deposit of rock fragments, generated by drilling the well, over the drill bit during eventual stops. Under those conditions, high pressures are then required in order to break-up the gel when circulation is resumed. Moreover, very high pressures can damage the rock formation at the bottom of the well. Thus, a better understanding of thixotropy and the behavior of thixotropic materials becomes increasingly important for process control. The mechanisms that control thixotropy are not yet well defined and modeling is still a challenge. The objective of this work is to develop a mathematical model to study the pressure transmission in drilling fluids. This work presents a review of thixotropy and of different mathematical models found in the literature that are used to predict such characteristic. It also shows a review of transient flows of compressible fluids. The problem is modeled as the flow between the drillpipe and the annular region (space between the wall and the external part of the drillpipe). The equations that describe the problem (mass conservation, momentum balance, constitutive and state) are then discretized and numerically solved by using a computational algorithm in Fortran. The model is validated with experimental and numerical data obtained from the literature. Comparisons between experimental data obtained from Petrobras and calculated by three viscoplastic and one pseudoplastic models are conducted. The viscoplastic fluids, due to the yield stress, do not fully transmit the pressure to the outlet of the annular space. Sensibility analyses are then conducted in order to evaluate the thixotropic effect in pressure transmission.

Fadiga e comportamento tensão-deformação cíclico da liga de alumínio 7050-T7451

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2016.