Master thesis


Implementação computacional de modelos elastoplásticos para análise fisicamente não linear

Danilo Bento Oliveira

Master thesis - 2016

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Abstract

This master’s thesis is concerned about the addition of classic constitutive models of plasticity into the computing environment INSANE (INteractive Structural ANalysis Environment), developed at the Department of Structural Engineering of the Federal University of Minas Gerais. The work starts with a discussion of the theoretical framework necessary for the implementation of the mathematical theory of plasticity. The main plasticity models used in engineering analysis are described in detail: Tresca, von Mises, Mohr-Coulomb and Drucker-Prager. The models of Ottosen and Willam-Warnke used to study the behavior of the concrete are also described. The formulation of the constitutive models based on stress and hardening laws which a material may be subjected are showed. The return mapping algorithms, required for the integration of constitutive relations governing the behavior of the material in the context of computational plasticity, are discussed. Then, the necessary methodology to achieved objectives of this work, explaining the main features of INSANE system and the modules where the implementations were held. Several examples are presented, in order to illustrate the modeling possibilities provided by the plasticity models present in INSANE. The results of these analyzes are compared with those from the literature to verified the stability and accuracy of the models.


Modelo de dano ortotrópico não local aplicado à regularização de resultados na análise fisicamente não linear

Pedro Lúcio Ferreira Brasil de Souza

Master thesis - 2016

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Abstract (in Portuguese)

Este trabalho apresenta um estudo sobre modelos constitutivos de dano ortotrópico, para a solução de problemas fisicamente não lineares de estruturas de concreto, a partir de uma abordagem não local. É apresentado um estudo sobre a análise fisicamente não linear do concreto e sobre o fenômeno de localização de deformações numericamente induzidas, mostrando que este pode conduzir a análise a resultados não representativos. Para lidar com este fenômeno, mecanismos de regularização se fazem necessários, e a partir daí, são apresentados os modelos não locais, que visam minimizar e os problemas de origem unicamente numérica que surgem com a análise não linear. O estudo é consolidado a partir de simulações numéricas que comparam resultados de problemas a partir da análise via modelos de dano ortotrópicos locais e não locais. Para esta etapa será utilizado o software INSANE (INteractive Structural ANalysis Environment) que possui modelos locais e não locais já implementados. Com estas simulações, as limitações de modelos locais podem ser constatadas assim como as melhorias nos resultados proporcionado por meio da utilização de modelos não locais. Além da comparação de modelos, serão realizadas simulações para comparar a análise numérica via modelos não locais com resultados experimentais.


Sistema gráfico interativo para análise de nucleação e propagação de trincas

Leandro Lopes da Silva

Master thesis - 2016

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Abstract (in Portuguese)

O objetivo desta dissertação de mestrado é a implementação computacional de um sistema gráfico interativo que integra pré-processador, modelos constitutivos, solucionadores de equações não lineares e pós-processador, para análise de nucleação e propagação de trincas em meios bidimensionais parcialmente frágeis. A análise fisicamente não linear se inicia empregando-se o Método dos Elementos Finitos Padrão (MEF), sendo a degradação inicial do meio avaliada de forma distribuída através de métodos constitutivos baseados em degradação elástica, ao passo que o estágio limiar de nucleação de fissuras é avaliado através da singularidade do tensor acústico, característica que fornece a condição clássica de localização de deformações. A presença das trincas é simulada através de método cinemático que incorpora as descontinuidades por meio de interpolações enriquecidas, com base no Método dos Elementos Finitos Generalizados (MEFG), sendo a propagação também avaliada através do fenômeno de localização de deformações. Esta combinação de métodos constitutivo e cinemático apresenta a vantagem da não necessidade de definição prévia do caminho da trinca ou de redefinição da malha durante o processamento. A relação entre tensões e deslocamentos no caminho da trinca é baseada em forças coesivas atuantes no plano da trinca. Ao final da análise, o fenômeno de nucleação e os efeitos da presença de trincas, bem como suas propagações, podem ser visualizados utilizando os recursos do pós-processador. As implementações foram realizadas na plataforma INSANE (INteractive Structural ANalysis Environment).


Estratégia de enriquecimento para métodos baseados na partição da unidade

Hudson Cleiton Reis Pereira

Master thesis - 2015

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Abstract

The hp-Cloud is a meshless method that present as its main feature the ability to enrich the shape functions of the approximated problem. Working similarly to the Generalized Finite Element Method, the hp-Cloud operates through of enrichment of the Partition of Unity, obtained by the Least Square Method, which is the basis of the Element-Free Galerkin Method. Appeal of the meshless methods is the mesh independence behavior, making them more efficient and more accurate in some special situations. Based on this concept, this work tackle aspects of the implementation of the enrichment strategy, using Object Oriented Programming, and valid for any Partition of Unity Method. Using INSANE platform and the existing implementation of the Element-Free Galerkin, it presented the main concepts relating to the hp-Cloud Method, as well as changes and extensions of INSANE, focusing in linear structural analysis.
The work presents the numerical results for two-dimension Elasticity problems, evaluating their convergence and comparing them with other methods such as the Generalized Finite Element Method and Element-Free Galerkin. The study also checks the behavior of the method related to parameters like influence domain size, degree of the polynomials basis, refinement h, p and the strategy of applying the boundary conditions.


Element Free Galerkin: integração nodal conforme e estabilizada (SCNI) com método da penalidade e dos multiplicadores de Lagrange

Breno Rafael Lopes de Faria

Master thesis - 2014

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Abstract (in Portuguese)

Por utilizar integrandos não polinomiais muitos métodos sem malhas apresentam dificuldades relacionadas à integração numérica. Vários trabalhos mostram que, para estes métodos, é inadequado usar quadratura de Gauss-Legendre e apontam para a necessidade de esquemas alternativos de integração. O esquema SCNI (Stabilized Conforming Nodal Integration) estabiliza a integração nodal através de um campo coerente de deformações assumidas, o que permite resultados mais precisos em relação aos obtidos usando quadratura gaussiana e elimina a necessidade de pré definir uma malha de fundo para integração. Combinado com as técnicas de imposição de condições essenciais (Penalidade e Multiplicadores de Lagrange) o método sem malhas Element Free Galerkin (EFG) torna-se mais robusto e preciso, eliminando problemas devidos à quadratura de Gauss e dificuldades relacionadas ao acoplamento com elementos finitos para a imposição das restrições cinemáticas. Para demonstrar que o critério da completude é atendido e analisar a precisão do método assim proposto serão analisados os resultados de Patch Tests e estudos de convergência. Os parâmetros pertencentes ao EFG-SCNI vão ser domesticados e o problema da viga em balanço com carga de ponta será resolvido com distribuição regular e irregular de nós, mostrando os efeitos da simulação de bordas essenciais infinitesimais e das combinações estudadas neste trabalho.


Modelos de pórtico plano para análise fisicamente não linear de estruturas de concreto armado

Leandro Mota Peres

Master thesis - 2014

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Abstract

The material nonlinear behavior of reinforced concrete structures, using one-dimensional models, has been studied according to two main approaches: the models that consider homogeneous cross sections and use stress-strain generalized relations, and models that decompose the section into smaller areas and use stress-strain laws. In this scenery, this work presents the formulation and computational implementation, into the system INSANE (INteractive Structural ANalysis Environment), of plane frame models for material nonlinear analysis using the Finite Element Method and stress-strain generalized relations. Numerical simulations of concrete structures allow to evaluate the model by comparing with experimental results and numerical results obtained with cross sections decomposed model implemented in the same system by Fonseca (2006).


Solução de problemas estruturais dinâmicos lineares pelo Método dos Elementos Finitos Generalizado

Yuri Oselieri Milione

Master thesis - 2014

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Abstract (in Portuguese)

Este trabalho trata da implementação do Método dos Elementos Finitos Generalizado (MEFG) para solução de problemas estruturais dinâmicos lineares, em um ambiente computacional construído em Programação Orientada a Objetos (POO). Esse ambiente, de nome INSANE (INteractive Structural ANalysis Environment), é desenvolvido no Departamento de Engenharia de Estruturas (DEES) da Universidade Federal de Minas Gerais (UFMG), e já é capaz de executar análises estáticas e dinâmicas pelo Método dos Elementos Finitos (MEF) e análises estáticas pelo MEFG. O conteúdo implementado neste trabalho engloba tanto métodos de integração direta quanto métodos de superposição modal, para solução dos problemas dinâmicos lineares de modelos uni, bi e tridimensionais. Dois tipos de funções de enriquecimento foram abordados: funções polinomiais e funções trigonométricas. O uso de funções de enriquecimento polinomiais aprimora a qualidade de aproximação da discretização, mantendo a malha inicial inalterada e sem acréscimo de nós internos aos elementos finitos. A principal vantagem da aplicação de funções de enriquecimento trigonométricas é a obtenção de autovalores mais precisos para frequências elevadas do que os calculados pelo MEF convencional. Os resultados das análises realizadas pelo MEFG foram confrontados com resultados analíticos e resultados de análises realizadas pelo MEF, para validação do conteúdo implementado.


Ambiente teórico computacional unificado para modelos constitutivos: inclusão de modelo de microplanos

Anderson Renato Vobornik Wolenski

Master thesis - 2013

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Abstract

The physically nonlinear behavior of concrete has been object of many researches which aim, through the formulation of new models or the improvement of the existing ones, representing the material medium of the nearest manner of its constitutive reality. In this scenario, this dissertation investigates the models in which the material behavior is described according to the called Microplane Models. To achieve it, the INSANE (INteractive Structural ANalysis Environment) system, whose numerical core contains the Unified Theoretical-Computational Environment to Constitutive Models proposal by Penna (2011), has been used. Preserving the generic nature of this environment, the model of Leukart and Ramm (2006) has been incorporated on it, considering four equivalent strains, four damage evolution laws, as well as three incremental constitutive tensor approximations. The software project of this incorporation has been conceived in order to enable the future inclusion of any Microplane Models. Numerical simulations allowed evaluating the adequacy of the material parameters, the numerical stability of the model and the proximity of the results with experimental tests available in the literature.


Ambiente teórico-computacional unificado para modelos constitutivos: inclusão de modelo elastoplástico com dano

Anelize Borges Monteiro

Master thesis - 2013

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Abstract

The formulation of constitutive models combined with computational mechanics is a recurrent theme in several researches and it has encouraged the investigation of material nonlinear responses and their influences on structural behavior. In this context, this work investigates an elastoplastic damage model. To achieve this, the INSANE (INteractive Structural ANalysis Environment), whose numerical core contains the Unified Theoretical and Computational Environment to Constitutive Models proposal by Penna (2011), has been used. The Elastoplastic Damage Model of Lemaitre (1985a,b) has been incorporated on it and three hardening or softening laws have been considered. The software project of this inclusion was efficient and generic, making possible to implement different evolution functions of the inelastic modulus. Numerical simulations allowed evaluating the adjustment of the material parameters, the numerical stability of the model as well as validating it through the reproduction of examples, comparing the obtained results with the ones available in the literature.


Framework teórico e computacional para estruturas de concreto armado: implementação de modelos de armadura e aderência

Saulo Silvestre de Castro

Master thesis - 2013

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Abstract

With the advent of digital computers, together with accumulated knowledge after years of study on the behavior of simple and reinforced concrete, several numerical models have been developed. Among several developed models, the models based on the Finite Element Method have shown to be powerful tools for the analysis of reinforced, simple and prestressed concrete structures. In this context, the inclusion of the reinforcement in the analysis of reinforced concrete structures can be made using three different models: smeared reinforcement models, discrete reinforcement models, embedded reinforcement models. In the first two models, the phenomenon of bond-slip can be included, making them more realistic and, therefore, more popular.
This dissertation presents the discrete reinforcement models, the embedded reinforcement models and link and contact element to include bond-slip. Those models were incorporated into INSANE (INteractive Structural ANalysis Environment), computer system for structural analysis developed at the Department of Structural Engineering of UFMG. Several problems were analyzed using the models included, aiming to validate the implementation made.


Implementação da teoria de Reissner para placas com o Método dos Elementos de Contorno em ambiente computacional orientado a objetos

Adimar Fernandes Maia

Master thesis - 2013

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Abstract

The solution of linear problems of plates for isotropic and homogeneous materials must be satisfied within the context of the respective governing differential equations. Due to the diversities in the structural configuration, such as unusual boundary conditions, the analytical approach becomes more complex. This work deals with the formulation of the boundary integral equation of the bending plate problem taking into account the Reissner’s theory and the numerical solution by means of the boundary element method (BEM). The Reissner’s theory considers the strain energy not only from bending deformation but also from transversal shear deformation which leads to a partial differential equation of sixth order. It results in a more consistent numerical procedure in which three physical conditions along the boundary plate can be enforced. The implementation has been performed as an extension of a computational system based on object-oriented programming in Java called INSANE, developed at the Structural Engineering Department of UFMG. The current applications are focused in the analysis of flat plate slabs with supports inside the domain, which is a very frequent problem in the design of structural reinforced concrete buildings. The efficiency and accuracy results obtained from several examples were compared with classical analytic solutions, numerical solution available in the literature and results of finite element analysis using Abaqus software as well.


Estratégia global-local aplicada ao Método dos Elementos Finitos Generalizados

Phillipe Daniel Alves

Master thesis - 2012

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Abstract

The aim of this work is to generalize the implementation of Global-Local Generalized Finite Element Method (GF EMgl) formulation. This generalization has been performed in INSANE (INteractive Structural ANalysis Environment), a computational environment developed by the Department of Structural Engineering (DEEs) at the Federal University of Minas Gerais (UFMG), which has been implemented using Object Oriented Programming (OOP).
In the conventional version of GFEM, the shape functions of finite elements are hierarchically enriched by analytical functions, according to the problem behaviour. In GF EMgl, however, the enrichment functions are constructed numerically from the solution of a local problem.
This approach allows the use of coarse global meshes around domains with complex stresses distribution. The local problem, however, can be refined by using a large number of elements and different enrichment functions. The results of the local problem are used to enrich the global problem. The advantage of this approach is to allow a well-refined description of the local problem and avoiding an overburden for the computation of the global solution.


Análise viscoelástica e viscoplástica de sólidos bidimensionais pelo Método dos Elementos de Contorno

Filipe Emanuel Souza Anacleto

Master thesis - 2010

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Abstract (in Portuguese)

Neste trabalho duas formulações do método dos elementos de contorno (MEC) quase-estáticas dependentes do tempo são estudadas. A primeira e desenvolvida para analisar um meio viscoelástico, no qual o modelo de Kelvin-Voigt e utilizado para simular o comportamento dependente do tempo. A segunda lida com a análise de um meio viscoplástico utilizando uma técnica de sub-regiões. Um modelo de material elasto/viscoplástico é utilizado juntamente com a regra de fluxo de Perzyna para representar o comportamento dependente do tempo. Utiliza-se um algoritmo para geração automática de células nas partes do domínio que sofrem escoamento. Para considerar as sub-regiões emprega-se uma técnica conhecida como método da matriz de rigidez. Exemplos utilizando ambas as formulações são analisados e comparados com as soluções analíticas e com resultados provenientes do método dos elementos finitos (MEF).


Implementação computacional de um modelo de fissuração para o concreto baseado no Método dos Elementos Finitos Estendido (XFEM)

Kelson Pothin Wolff

Master thesis - 2010

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Abstract

This master’s thesis is concerned about computational implementation of a model able to describe concrete behavior under cracking. The concrete cracked region is represented by a constitutive relation based on Cohesive Crack Model, while the undamaged bulk keeps a linear elastic response. These constitutive relations are integrated with eXtended Finite Element Method assumptions to form a model that introduces a jump in displacements field of a standard finite element. Thus, a discrete crack propagation is simulated due a discontinuity that is induced in standard finite element approximation fields. The propagation criterium is based on tensile strength material parameter and the crack geometry is defined by a set of linear segments. In this way, the conceived model allows freely crack propagation over the standard mesh, even at the element’s interface. The model was implemented in numerical nucleus of computational system INSANE (INteractive Structural ANalysis Environment), enabling the simulation of crack propagation problems involving concrete specimens under modes I, II and mixed mode loadings. The results are found within expected response range. The main drawback found is related to the chosen propagation criterium that is not reliable in predicting the correct direction of crack when the analysis reaches high stresses levels.


Abordagem orientada a objetos para implementação computacional de elementos finitos de cascas planos

Flávio Henrique Ajeje

Master thesis - 2009

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Abstract

One of the simplest ways of studying the behavior of a shell, using the Finite Element Method (FEM), is to approximate the geometry of its middle surface by plane finite elements obtained from the combination of plate and membrane elements. This master’s thesis discusses the computational implementation of such elements using the object-oriented programming methodology. The base of this implementation is the numerical core of INSANE (INteractive Structural ANalysis Environment), an object-oriented, modular, expansible and change-friendly computational system that is been developed by the Structural Engineering Department of Federal University of Minas Gerais. After the presentation of Reisnner-Mindlin and Kirchhoff shell theories and the corresponding FEM models, the implementation of these models is discussed in such a way that details the main changes performed in the numerical core of INSANE. Numerical simulations concerning Patch Tests, convergence study and application examples are presented. The obtained results are compared with analytic solutions and with numerical results from literature or from other computational systems.


Pré-processador para modelos reticulados e planos do Método dos Elementos Finitos

Reginaldo Lopes Ferreira

Master thesis - 2008

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Abstract

This master’s thesis describes a pre-processing program, that is part of the INSANE (INteractive Structural ANalysis Environment) system, for the creation of Finite Element Method models. With it is possible to combine bar, plane state and plate elements.
The software, implemented in JAVA, was developed according with object oriented programming paradigm and have a layered architecture based in three design patterns combination: the pattern Model-View-Controller (MVC), that allows the independence between the layers model and view; the pattern Observer that, through a mechanism of propagation of changes, it allows the synchronization of the model with various pairs ”view-controller”; and the pattern Command that encapsulates the actions of the program in separate class in an organized way. This segmentation favors the expansion of the program and the creation of new commands.
To allow different discretizations of one same geometric model, the pre-processor was divided in two modules: GEOMETRY and MESH. The first one allows the
creation and the edition of points, lines, curves and regions. The second provides resources for the discretization of geometric objects and the attributes definition.
On the regions, meshes of plain state and plates elements can be generated through the Transfinite Mapping (Lofting, Bilinear or Trilinear). The geometric model and the mesh model data are stored in data structures for planar subdivision that uses the half-edge concept. It allows the storage in an organized way and establishes the relations of adjacencies, making possible a fast access to the data. Euler operators are used to create and to manipulate the topological entities that compose the model (vertices, edges and faces) and to represent it in the data structure.
The use of multiple views, combined with the application of geometric transformations and projections, allows different visualizations of a model and more than one model can be simultaneously observed.
The models can be serialized as JAVA objects or XML files.


Sistema computacional para análise dinâmica geometricamente não-linear através do Método dos Elementos Finitos

Flavio Torres da Fonseca

Master thesis - 2008

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Abstract

This master’s thesis refers to the computational implementation, according to the object-oriented programming, of dynamic geometrically non-linear solution of Finite Element Method models. Some ways of considering damping in dynamic analysis are discussed. Many methods of dynamic solution are presented, not only those based on modal superposition, but also those based on direct integration. The Total Lagrangean and Updated Lagrangean formulations for non-linear analysis are discussed. Methods for solution of non-linear equations are also presented. The implementation is done in the numerical nucleus of INSANE computational system, which is developed in the Structural Department of UFMG. The object-oriented project of this system is presented, as well as the necessary modifications to add the proposed solution. Many numerical simulations are presented to validate the implementation, comparing the results obtained by the implementation with analytical and numerical results found in literature.


Implementacão computacional e análise crítica de elementos finitos de placas

Samir Silva Saliba

Master thesis - 2007

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Abstract

This master’s thesis describes the computacional implementation of several plate finite elements based in the Kirchhoff theory, for thin plates, and Reissner-Mindlin theory, that is applicable to plates of any thickness. It presents a brief discussion about the formulations for the mathematical and discrete models based in these theories, showing their main differences and particularities, as well as the need of the use of special techniques for the use of the Reissner-Mindlin theory in the study of thin plates.
Among the several finite elements for analysis of plates based on the Kirchhoff theory, it has been implemented the rectangular elements developed by Melosh, Zienkiewicz and Cheung (MZC) and by Bogner, Fox and Schmit (BFS) and the triangular elements developed by Cheung, King and Zienkiewicz (CKZ) and by Cowper, Kosko, Lindberg and Olson (Cowper); the elements based on the ReissnerMindlin theory chosen for the analysis of thick plates were the quadrilaterais of four node (Q4), eight node (Q8), nine node (Q9), nine node Heterosis, developed by Hughes and Cohen (Q9H), and the triangular of three node (T3), of six node (T6) and the of ten node (T10); for use of the Reissner-Mindlin theory in the modelling of thin plates, are adopted the Reduced Integration or Selective Integration with the elements quadrilaterais mentioned previously and the technique of Substitute Shear Strain Fields with the elements Q4, Q8, Q9 and T6.
The implementation of these models was made in the numerical nucleus of INSANE (INteractive Structural ANalysis Environment) that is a system developed according to the Object Oriented Programming (OOP) paradigm using the JAVA language. This implementation is detailed through the use of UML (Unified Modelling Language) diagrams, where the several classes and interfaces used in the numerical nucleus are presented.
To know the implemented elements better, mesh tests and convergence studies, besides several numerical simulations, are presented.


Pós-processador para modelos bidimensionais não-lineares do Método dos Elementos Finitos

Samuel Silva Penna

Master thesis - 2007

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Abstract

This master’s thesis presents a post-processor program for two dimensional Finite Element Method models. The program can represent linear and nonlinear models through graphics interactive resources. The program makes use of an adjacency structure based on half-edges to manipulate the geometrical information and the data of the models, as well to allow the post-processor generalization.
The representation of results by isoranges of values uses domain subdivision techniques, based on Delaunay’s triangulation and on the model’s mesh. Techniques for results extrapolation and smoothness are available.
The implementation, according to the object-oriented programming paradigm, uses the JAVA programming language and several API’s (Application Program Interface) and graphical packages available in this language. Through the use of various technological solutions for software development, the
implementation takes place with the progressive rearrangement and extension of the INSANE (INteractive Structural ANalysis Environment) system resources, a segmented and friendly to change computational environment . The system applications organization, as well all design patterns used, are present, and the post-processor’s object-oriented design is, then, detailed.
Several examples are used to demonstrate the functionalities and main features of the program.


Um serviço web para o Método dos Elementos Finitos

Luciana Sampaio Câmara

Master thesis - 2007

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Abstract

The evolution and popularization of the Internet lead to its utilization as a platform, an environment that offers softwares and where it’s possible to save and access files. The Web Services appear, at this scenario, as a solution to the increasing need of exchanging informations among different systems through simple and public Internet’s established standards (XML, HTTP, TCP/IP ) and open technologies such as WSDL, UDDI and SOAP.
The INSANE is a computational system of finite element models analysis. The goal of this master’s thesis was to make its numerical kernel available as a Web Service to solve finite element models through the Internet.
The developed Web Service may be consumed by different applications (Web applications, Desktop pre and post-processing graphics interfaces, microelectronics devices such as PDA and cellular phones, among others), since it adds to the system the Web Services features such as loose coupling, interoperability, reuse and flexibility.
The system’s updates occur in a transparent way to the user, since its implementation is concentrated at a single place, the server where the service is hosted. This service’s use can avoid the frequent re-implementation of already consolidated resources, available in finite element method softwares.
Three examples of INSANE Web Service’s consumers are presented and one of them, the Web client, allows its use through the Internet, without the need of any other software besides the Web browser.


Aplicação orientada a objetos para análise fisicamente não-linear com modelos reticulados de seções transversais compostas

Marcos Torres da Fonseca

Master thesis - 2006

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Abstract

This master’s thesis refers to the computational implementation, according to object-oriented paradigm, of material nonlinear solution of finite element models of framed structures with composed and geometrically arbitrary cross sections.
These sections are represented by decomposition in smaller areas, in which the materials’ nonlinear stress-strain relations are monitored. In such way, it is possible to determine the constitutive equation of each section, the stiffness matrix and the internal efforts of the finite element. Then, the equilibrium paths for certain degrees of freedom of the model are obtained through an incremental-iterative procedure.
The mathematical and discrete models formulations, based on Timoshenko and Euler-Bernoulli bending theories, are presented, considering the most general framed structural model, the space frame. The nonlinear solution of equilibrium equations is discussed briefly.
Through the use of various software development solutions, the related implementation takes place with the progressive rearrangement and extension of the numerical nucleus of INSANE (INteractive Structural ANalysis Environment), a computational environment segmented and friendly to changes. The numerical nucleus conception and the set of segments that represent the necessary abstractions to a numerical resolution of a finite element model are discussed.
Some numerical simulations are presented to validate the implementation and to show the application modeling potential.


Sistema gráfico interativo para ensino de análise estrutural através do Método dos Elementos Finitos

Renata Nicoliello Moreira

Master thesis - 2006

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Abstract

This master’s thesis refers to the expansion of INSANE (INteractive Structural ANalysis Environment): a computational system for finite element method (FEM) structural analysis discrete models, in Java language and object oriented programming (OOP). The work consists in an interactive graphic application to assist the FEM teaching for structural engineering.
A study of the diverse approaches for FEM in engineering courses is presented, identifying its generalities and the possibilities that INSANE offers to facilitate learning process. It is argued, then, available suggestions in literature for characterization of stages for the solution of FEM problems.
It is verified that the OOP is quite appropriated for the implementation and the use of language Java has great advantages. An object oriented analysis to identify the main necessary classes for exposition of the numerical nucleus of the computational system to the user is done.
This work documents and focuses on object-oriented Analysis, Project and Implementation. Admittedly efficient software design patterns are adopted in the implementation of the application. To separate the model from its representation, the implementation is based on Model-View-Controller (MVC) programming metaphor. Such approach allows the graphical, interactive and didactic presentation of the processing of FEM models.
The implementation’s object oriented project is shown with unified modelling language (UML).
The resources of the new graphical interface are presented through examples and the possibilities of enrichment of the learning process are shown.


Elementos finitos paramétricos implementados em Java

Marcelo Lucas de Almeida

Master thesis - 2005

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Abstract

This master’s thesis refers to the implementation of parametric formulation of finite element method (FEM) in Java language. All this work was implemented in numeric core of INSANE (INteractive Structural ANalysis Environment), a computational system which aims the appropriation of modern recourses for software development to help research in computational and numeric methods applied to engineering.
The parametric formulation of FEM is studied, enumerating its generalities and correlations with object oriented programming (OOP). It is verified that the OOP are quite appropriated for the implementation of FEM parametric formulation.
An object oriented analysis to identify the main necessary classes of the problem representation is done.
The implementation’s object oriented project is shown with unified modelling language (UML).
The implemented FEM recourses in this work are several types of parametric elements including one-dimensional elements with two, three an four nodes; two-dimensional quadrilateral and axisymmetric quadrilateral elements with four, eight and nine nodes; two-dimensional triangular and axisymmetric triangular elements with three, six and ten nodes; and three-dimensional hexahedral elements with eight and twenty nodes. The analysis models implemented are: one-dimensional; two dimensional plane stress and plane strain and axisymmetric; and three-dimensional. For the integral calculus related
to parametric formulation a Gauss numeric integration was implemented. The implemented distributed loads are in lines, areas and in volumes. It was implemented linear elastic isotropic material and solution by equilibrium for problems of stress analysis.
The recourses correct functioning are validated by several examples shown.


Implementação orientada a objetos da solução de problemas estruturais dinâmicos via Método dos Elementos Finitos

Leibnitz Germanio

Master thesis - 2005

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Abstract

Often when trying to develop an expansion of a numerical-computational model for engineering problems, the researcher has to implement the whole code for the numerical solution, not only the part respective to the study. This occurs mainly because the use of not suitable technologies, which does not permit an easy separation of the code parts.
The INSANE project is a general purpose application for the engineering field developed by a research group associated with the UFMG Structural Engineering department. The project has adopted the JAVA programming language, which supports the Object Oriented Paradigm. The Object Oriented programming permits the program separation into modules, easing the program build up on complexity.
On its current status, the INSANE project has an implementation of a solver for static structural problems with the Finite Element Method. The work here presented implements an expansion in the INSANE to deal with dynamic structural problems. This expansion accounts for the implementation of modal solvers for the resulting algebraic equations, numerical integrators of the equation of motion based on the modal decomposition and direct integration methods of the equation of motion.
The implementation was validated comparing the solution of selected problems, which were solved using the parametric finite element class of the INSANE, against the results available in the literature.


Geração de malhas bidimensionais de elementos finitos baseada em mapeamentos transfinitos

Marco Antônio Brugiolo Gonçalves

Master thesis - 2004

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Abstract

This master´s thesis is part of development of a computational environment to make available different discreet models of structural analysis. Part of the system, related in this work, is the pre-processor that consists in an interactive graphic application, implemented in Java language, using the object-oriented paradigm for two-dimensional finite elements meshgeneration.
This work documents and focus on object-oriented Analysis, Project and Implementation. Admittedly efficient software design patterns are adopted in the implementation of the application. To separate the model from its representation, the implementation is based on Model-View-Controller (MVC ) programming metaphor. Such metaphor allows the control of mesh generation, through user interaction, and its visualization be implemented independently of the adopted model, minimizing the system maintenance and expansion tasks. Besides, the MVC lets the gradual improvement of application through platform change, creation of several views synchronized with the model and replacement or update of several views.
In the first model made available by the application, the meshes are created through transfinite mappings. The geometry of the model is represented through sub-regions that are defined by boundary curves. These curves are formed by a set of primitives like points, lines, quadratic and cubic curves. The available mappings are lofting, bilinear and trilinear. Otherwise, the finite elements can be serendipity or lagrangean, triangular and quadrilateral. Once created the mesh, it allows the attribution of load, support, material, among others. Finally, the model of created finite elements can be saved either XML or Java object file for posterior application in analysis programs.


Métodos de controle de deformações para análise não-linear de estruturas

Jamile Salim Fuina

Master thesis - 2004

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Abstract

This work discusses the determination of the equilibrium paths in the nonlinear finite element structural analysis. A detailed study about the incremental-iterative procedures, that use load and displacement combinations as the analysis controlling parameters, is presented.
The limitations of the classical methods in physically nonlinear problems are discussed. A method, that includes the mechanics of the material deterioration process, using strain combinations in subdomains of the problem, is proposed. The combinations are strain measures such as mean, invariants, eigenvalues, among others. The subdomains are characterised as groups of integration points, since in the Finite Element Method, usually, the strains are obtained in these points. Such groups can be chosen as the whole finite element mesh, one or more finite elements or just one integration point. The proposed method permits the change of the control subdomain (one integration point or one finite element) during the analysis process. This change is based on the search for region that sampled the largest increase on the standing control combination in the last incremental step.
The computational implementation details of the proposed model into a object oriented finite element program is discussed.
Some numerical simulations of physically or geometrically nonlinear problems are presented. The analysis of the obtained results permits to discuss the adequacy of the classical and proposed methods in the solution of the problems.