EE - Trabalhos apresentados em eventos
URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/515
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7 resultados
Resultados da Pesquisa
- ItemConstructal design of perforated steel plates subject to linear elastic and nonlinear elastoplastic buckling(2013) Helbig, Daniel; Real, Mauro de Vasconcellos; Correia, Anderson Luis Garcia; Santos, Elizaldo Domingues dos; Isoldi, Liércio AndréSteel plates are used in a great variety of engineering applications, such as deck and bottom of ship structures, and platforms of offshore structures. Cutouts are often provided in plate elements for inspection, maintenance, and service purposes. So, the design of shape and size of these holes is significant. Usually these plates are subjected to axial compressive forces which make them prone to instability or buckling. If the plate is slender, the buckling is elastic. However, if the plate is sturdy, it buckles in the plastic range causing the so-called inelastic (or elasto-plastic) buckling.Therefore, the goal of this work is to obtain the optimal geometry which maximizes the buckling load for steel plates with a centered elliptical perforation when subjected to linear and nonlinear buckling phenomenon by means of Constructal Design. To do so, numerical models were developed in ANSYS software to evaluate the elastic and elasto-plastic buckling loads of simply supported and uniaxially loaded rectangular plates with elliptical cutouts. The results indicated that the optimal shapes were obtained in accordance with the Constructal Principle of "Optimal Distribution of Imperfections", showing that the Constructal Design method can be satisfactorily employed in mechanic of materials problems.
- ItemConstructal design of non-uniform x-shaped cavity(2013) Link, Fernanda Bichet; Santos, Elizaldo Domingues dos; Isoldi, Liércio André; Rocha, Luiz Alberto de OliveiraThis paper applies constructal design to study a non-uniform X-shaped cavity that penetrates a conductive solid wall. The goal is to minimize the maximal dimensionless excess of temperature between the solid body and cavity. There is a uniform heat generation on the solid body. The total volume and the volume of the cavity are fixed, but the angle formed between the stems of the cavity may vary. The cavity surfaces are isothermal while the solid body has adiabatic conditions in the outer surface. Results indicate that the optimal X-cavity performs 60.1% better than the Cshaped cavity and 44% better than the T-shaped cavity. However, it has a performance approximately 38% inferior than the performance of the optimized H-shaped cavity.
- ItemConstructal design applied to the light resin transfer molding (LRTM) manufacturing process(2013) Isoldi, Liércio André; Souza, Jeferson Avila; Santos, Elizaldo Domingues dos; Marchesini, Renato; Porto, Joseane da Silva; Letzow, Max; Rocha, Luiz Alberto de Oliveira; Amico, Sandro CamposThe Light Resin Transfer Molding (LRTM) is a manufacturing process where a closed mold pre-loaded with a porous fibrous preform is filled by a liquid resin injected through an empty channel (without porous medium) which runs all around the perimeter of the mold, producing polymeric composite parts. Using the capability of FLUENT® package to simulate a multiphase flow (resin and air) in a geometry composed by porous media regions and empty regions, a computational model based on the Finite Volume Method (FVM) was applied to reproduce the resin flow behavior during the LRTM process. The aim of this work was to define the optimal geometry for the empty channel (border) by means the Constructal Design method. To do so, considering a border with a rectangular cross sectional area, the degree of freedom wb/tb (ratio between the width and thickness of the border) can vary while the border volume is kept constant. The results showed that employing the Constructal Design it is possible to decrease the filling time of the LRTM process in almost 20 %, being this an unpublished use for the Constructal Theory.
- ItemNumerical study of resin distribution in two different arrangements of vascular channels by means of constructal design(2013) Machado, Roselaine Neves; Isoldi, Liércio André; Santos, Elizaldo Domingues dos; Rocha, Luiz Alberto de OliveiraIn the present work two different arrangements of vascular channels are studied numerically and their geometry is optimized by means of Constructal Design. The main purpose is to seek for the best geometry which minimizes the resin flow resistance inside the channels. The arrangement of vascular channels consists in two horizontal channels of diameter D2 connected with two vertical channels of diameter D1. The channels of resin flow are distributed in a solid domain with two different ratios of height and length (H/L = 0.67 and 1.5) in order to illustrate the process of regeneration of composite materials. For all of evaluated configurations the ratio between the areas occupied by the channels and by the solid domain are kept fixed (ϕ = 0.1). It is considered a two dimensional, laminar and steady state flow (ReD2 = 1.0). The conservation equations of mass and momentum are solved numerically by means of the finite volume method (FVM). The results showed that the optimal geometric configuration has a flow resistance several times lower than that found with the worst geometry. For example, for H/L = 0.67, the ratio (D1/D2)o = 0.76 conduct to a fluid dynamic performance nearly 32 times superior than that found for D1/D2 = 0.1. It is also noticed that the best shapes are achieved when the pressure and velocity fields has the most homogeneous distribution, i.e., according to the constructal principle of “optimal distribution of imperfections”.
- ItemTwo-dimensional geometric optimization of an oscillating water column converter of real scale(2013) Gomes, Mateus das Neves; Santos, Elizaldo Domingues dos; Isoldi, Liércio André; Rocha, Luiz Alberto de OliveiraThe present paper presents a two-dimensional numerical study about the geometric optimization of an ocean Wave Energy Converter (WEC) into electrical energy. The operational principle is based on the Oscillating Water Column (OWC). The main goal is to seek for the optimal geometry which maximizes the absorbed power take off (PTO) when it is subjected to a defined wave climate. To do so, Constructal Design is employed varying the degree of freedom (DOF) H1/L (ratio between the height and length of OWC chamber) and H3 (lip submergence), while the other DOF H2/l (ratio between height and length of chimney) is kept fixed. Moreover, the chamber and total areas of OWC device are also kept fixed, being the problem constraints. In this study was adopted a regular wave with real scale dimensions. For the numerical solution it is used the Computational Fluid Dynamic (CFD) commercial code FLUENT®, based on the Finite Volume Method (FVM). The multiphasic Volume of Fluid (VOF) model is applied to tackle with the water-air interaction. The computational domain is represented by an OWC device coupled with the wave tank. The results led to a theoretical recommendation about the chamber geometry which maximizes the device performance, indicating that the higher efficiency (around 40 %) is obtained when H1/L = 0.13 and H3 = 9.50 m. On the other hand, the chamber geometry that generate the lower efficiency (around 4.4 %) is formed by H1/L = 0.03 and H3 = 9.00 m. One can note that the optimal shape is approximately 10 times more efficient than the worst geometry, showing the applicability and relevance of the Constructal Design method in the design of OWC-WEC.
- ItemOtimização geométrica de placas com enrijecedores submetidas à flexão(2012) Silveira, Thiago da; Correia, Anderson Luis Garcia; Silva, Caio César de Castro da; Rocha, Luiz Alberto de Oliveira; Real, Mauro de Vasconcellos; Santos, Elizaldo Domingues dos; Isoldi, Liércio AndréAs placas enrijecidas são muito utilizadas em estruturas navais. Quando estas estruturas estão sob forte ação de cargas de flexão, é necessário que os reforços contribuam para a redução da deflexão da placa. O Método de Elementos Finitos (MEF) pode ser utilizado para obter os valores da deflexão resultante de cargas de flexão sobre a placa. Para otimizar a geometria da placa enrijecida faz-se uso da Teoria Constructal desenvolvida por Adrian Bejan. Com as geometrias otimizadas, é possível a obtenção de deflexões que apresentam melhoria de aproximadamente 84% em relação às placas sem enrijecedores.
- ItemConstructal design de caminhos não-uniforme de alta condutividade térmica em forma de “y” para a refrigeração de corpos geradores de calor(2014) Beckel, Cássia Cris; Horbach, Cristina Santos; Isoldi, Liércio André; Santos, Elizaldo Domingues dos; Rocha, Luiz Alberto OliveiraEste estudo numérico utiliza o método Constructal Design para reduzir os pontos quentes de um sólido com geração de calor uniforme por unidade de volume através da transferência de calor por condução. A ideia é facilitar o acesso do fluxo de calor através de uma via em forma de “Y” empregando condutividades térmicas não-uniformes para a base e ramos do Y. A função objetivo consiste em minimizar o excesso de temperatura máxima adimensional de todo o sistema (materiais de alta e de baixa condutividade térmica). A configuração do sistema pode variar sujeita a duas restrições: o volume total e o volume das vias de alta condutividade. Materiais de várias condutividades e frações de áreas são estudados. Os resultados mostram a aplicabilidade do Constructal Design para a melhoria do desempenho térmico do sistema. Utilizando condutividades diferentes para a base e os ramos obteve-se uma melhora de mais de 30%. A geometria otimizada é aquela que melhor distribui as imperfeições, isto é, os pontos quentes (pontos de temperatura máxima), o que está de acordo com o princípio da ótima distribuição das imperfeições.