Avaliação da distribuição das forças produzidas com arco lingual removível pelo método de elementos finitos

Pós-graduação em Ciências Odontológicas - FOAR

Simulação numérica de fluxo de águas subterrâneas na bacia do Rio Corrente (BA)

The numeric simulation is an important tool applied in understanding the dynamics of groundwater flow. In a hydrogeological model the processes responsible for groundwater flow are described by numerical formulations that allow the simplification, representation and understanding of the dynamics of the Aquifer System. In this work, a steady state groundwater flow simulation of Urucuia Aquifer System (UAS) part of the Corrente river basin was conducted, using the finite element method through software FEFLOW, to understand the dynamics of groundwater flow and quantify the hydrologic balance. The aquifer system Urucuia lodges in the São Francisco hydrogeological province and corresponds to a set of interconnected aquifers that occur in rocks from Urucuia group in the Urucuia sub-basin described by Campos e Dardenne (1997). The system is a porous media one, in a shape of a thick table mountain, consisting essentially of sandstones. The Corrente river basin is located in UAS in Western State of Bahia and it's one of the main units to maintaining permanent flow (Q95) and average natural flow of the São Francisco river. The simulation performed in this work obtained the following results for the modelled region: horizontal hydraulic conductivity of 3 x 10-4 m/s and vertical one 6 x 10-5 m/s; maximum recharge of 345 mm and minimum of 85 mm/a. It was concluded that: (1) regional groundwater flow has eastbound; with an exception of the extreme northeast portion, where the flow has opposite direction; (2) there are smaller water side dividers with an approximate direction EW, that guide the flow of water to the drainage that cut the aquifer; and (3) the UAS at Corrente river basin can be understood as a free regional aquifer system, isotropic and homogeneous. Regionally, the small lithological variations present in the Urucuia group can be neglected and do not exhibit significant influences on the dynamics of ground water flow

Análise da influência de variantes do método de solução de escoamentos utilizando os métodos de elementos finitos com compressibilidade artificial e pseudo-características

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Modelagem e análise de tensão em estrutura óssea com implante metálico, através do método dos elementos finitos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comportamento biomecânico de estruturas multicamadas em restaurações protéticas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da rigidez torcional do chassi de um protótipo Baja SAE através do método de elementos finitos e de ensaio experimental

The torsional stiffness of chassis is one of the most important properties of a vehicle's structure and therefore its measurement is important. For the first time, the torsional stiffness was considered on the design of a prototype Baja SAE of the team from UNESP - FEG, Equipe Piratas do Vale Bardahl. According to the team's opinion, the increase of stiffness on this prototype, called MB1114, made possible a great improvement in its performance during competitions. In this work, the experimental evaluation of the torsional stiffness from this prototype is performed, detailing the analysis of results, as well as, the hysteresis' effect, least-squares regression and uncertainty analysis. It also shows that it is possible to measure the torsional stiffness of chassis with a low experimental uncertainty without expending many resources. The test rig costed R$ 32,50 due the reuse of materials and the use of instrumentation already available on campus. Furthermore, it is simple to produce and can be easily stocked. Those features are important for Baja and Formula SAE teams. Lastly, the measured value is used to validate the finite element analysis performed by the team during this prototype's design, because similar studies will be performed for the new cars. After investigating the finite element analysis, one result 13,5% higher than the measured value was reached. This difference is believed to be occurred due the imperfections of the finite element model, in other words, for not been possible to simulate every phenomena present on the real model

Simulação da suspensão tipo duplo A de um veículo off-road através do histórico de excitação do solo

The search for mechanical components validation methods, employed in product development sector, becomes more avid for less expensive solutions. As a result, programs that can simulate forces acting on a given part through finite element method are gaining more space in the market, once this process consumes less capital when compared to currently-employed empirical validation. This article shows the simulation of an off-road prototype suspension through such technique, using ground excitation history coming from field measurements and also by making use of a specific tool for obtaining dynamic loads from the model in question. The results shown at the end is key for future enhancements aiming mass reduction, for example, that may be executed on the prototype suspension system discussed here

Contribuição ao estudo de lajes lisas unidirecionais de concreto armado com pilares retangulares ao puncionamento

São apresentadas análises das recomendações para estimar a resistência ao puncionamento de lajes lisas de acordo com a versão atual da norma brasileira, a NBR 6118:2003, que não considera o efeito da retangularidade de pilares internos, e sua predecessora, a NBR 6118:1980. Em seções transversais retangulares, o índice de polarização das tensões de cisalhamento é crescente. Isto altera a forma de ruptura da laje, já que a punção se inicia em torno das extremidades da seção do pilar, não se estendendo para os lados maiores, como prescreve a norma, comportamento este que reduz a resistência última das lajes frente às estimativas normativas. São apresentados os resultados de uma análise numérica por elementos finitos (M.E.F.) e uma proposta para melhorar a ductilidade das lajes lisas através das dimensões mínimas dos pilares. Observou-se que a NBR 6118:1980 mostrou-se conservadora e que as estimativas da NBR 6118: 2003 podem ser melhoradas.

Análise computacional do fenômeno de transferência de calor em paredes divisórias do tipo dry wall

O presente trabalho visa a fornecer uma contribuição ao estudo dos perfis formados a frio sob altas temperaturas, em conseqüência da deflagração de um incêndio. Especificamente, abordam–se assuntos inerentes ao fenômeno da transferência de calor em paredes do tipo steel frame – dry wall com ou sem isolamento térmico na cavidade. Para tanto, propõem–se modelos computacionais capazes de fornecer, com certa precisão, o valor de temperatura em qualquer ponto do sistema estudado. Dessa forma, é possível, então, traçar configurações de distribuição de temperatura (uniforme ou não–uniforme) na seção transversal dos montantes que constituem o painel, fornecendo subsídios para análise de estabilidade e pós–flambagem dos elementos estruturais em questão. As simulações numéricas de transferência de calor são efetuadas com auxílio dos programas computacionais ABAQUS e SAFIR, ambos baseados no método dos elementos finitos.

Avaliação da rigidez torcional do chassi de um protótipo Baja SAE através do método de elementos finitos e de ensaio experimental

The torsional stiffness of chassis is one of the most important properties of a vehicle's structure and therefore its measurement is important. For the first time, the torsional stiffness was considered on the design of a prototype Baja SAE of the team from UNESP - FEG, Equipe Piratas do Vale Bardahl. According to the team's opinion, the increase of stiffness on this prototype, called MB1114, made possible a great improvement in its performance during competitions. In this work, the experimental evaluation of the torsional stiffness from this prototype is performed, detailing the analysis of results, as well as, the hysteresis' effect, least-squares regression and uncertainty analysis. It also shows that it is possible to measure the torsional stiffness of chassis with a low experimental uncertainty without expending many resources. The test rig costed R$ 32,50 due the reuse of materials and the use of instrumentation already available on campus. Furthermore, it is simple to produce and can be easily stocked. Those features are important for Baja and Formula SAE teams. Lastly, the measured value is used to validate the finite element analysis performed by the team during this prototype's design, because similar studies will be performed for the new cars. After investigating the finite element analysis, one result 13,5% higher than the measured value was reached. This difference is believed to be occurred due the imperfections of the finite element model, in other words, for not been possible to simulate every phenomena present on the real model

Simulação da suspensão tipo duplo A de um veículo off-road através do histórico de excitação do solo

The search for mechanical components validation methods, employed in product development sector, becomes more avid for less expensive solutions. As a result, programs that can simulate forces acting on a given part through finite element method are gaining more space in the market, once this process consumes less capital when compared to currently-employed empirical validation. This article shows the simulation of an off-road prototype suspension through such technique, using ground excitation history coming from field measurements and also by making use of a specific tool for obtaining dynamic loads from the model in question. The results shown at the end is key for future enhancements aiming mass reduction, for example, that may be executed on the prototype suspension system discussed here

REALISTIC IVUS IMAGE GENERATION IN DIFFERENT INTRALUMINAL PRESSURES

Intravascular ultrasound (IVUS) phantoms are important to calibrate and evaluate many IVUS imaging processing tasks. However, phantom generation is never the primary focus of related works; hence, it cannot be well covered, and is usually based on more than one platform, which may not be accessible to investigators. Therefore, we present a framework for creating representative IVUS phantoms, for different intraluminal pressures, based on the finite element method and Field II. First, a coronary cross-section model is selected. Second, the coronary regions are identified to apply the properties. Third, the corresponding mesh is generated. Fourth, the intraluminal force is applied and the deformation computed. Finally, the speckle noise is incorporated. The framework was tested taking into account IVUS contrast, noise and strains. The outcomes are in line with related studies and expected values. Moreover, the framework toolbox is freely accessible and fully implemented in a single platform. (E-mail: fernando.okara@gmail.com) (c) 2012 World Federation for Ultrasound in Medicine & Biology.

Analysis of elastic functionally graded materials under large displacements via high-order tetrahedral elements

The purpose of this study is to present a position based tetrahedral finite element method of any order to accurately predict the mechanical behavior of solids constituted by functionally graded elastic materials and subjected to large displacements. The application of high-order elements makes it possible to overcome the volumetric and shear locking that appears in usual homogeneous isotropic situations or even in non-homogeneous cases developing small or large displacements. The use of parallel processing to improve the computational efficiency, allows employing high-order elements instead of low-order ones with reduced integration techniques or strain enhancements. The Green-Lagrange strain is adopted and the constitutive relation is the functionally graded Saint Venant-Kirchhoff law. The equilibrium is achieved by the minimum total potential energy principle. Examples of large displacement problems are presented and results confirm the locking free behavior of high-order elements for non-homogeneous materials. (C) 2011 Elsevier B.V. All rights reserved.

BEM modeling of saturated porous media susceptible to damage

This paper deals with the numerical analysis of saturated porous media, taking into account the damage phenomena on the solid skeleton. The porous media is taken into poro-elastic framework, in full-saturated condition, based on Biot's Theory. A scalar damage model is assumed for this analysis. An implicit boundary element method (BEM) formulation, based on time-independent fundamental solutions, is developed and implemented to couple the fluid flow and two-dimensional elastostatic problems. The integration over boundary elements is evaluated using a numerical Gauss procedure. A semi-analytical scheme for the case of triangular domain cells is followed to carry out the relevant domain integrals. The non-linear problem is solved by a Newton-Raphson procedure. Numerical examples are presented, in order to validate the implemented formulation and to illustrate its efficacy. (C) 2011 Elsevier Ltd. All rights reserved.

A new enrichment space for the treatment of discontinuous pressures in multi-fluid flows

In this work, a new enrichment space to accommodate jumps in the pressure field at immersed interfaces in finite element formulations, is proposed. The new enrichment adds two degrees of freedom per element that can be eliminated by means of static condensation. The new space is tested and compared with the classical P1 space and to the space proposed by Ausas et al (Comp. Meth. Appl. Mech. Eng., Vol. 199, 10191031, 2010) in several problems involving jumps in the viscosity and/or the presence of singular forces at interfaces not conforming with the element edges. The combination of this enrichment space with another enrichment that accommodates discontinuities in the pressure gradient has also been explored, exhibiting excellent results in problems involving jumps in the density or the volume forces. Copyright (c) 2011 John Wiley & Sons, Ltd.