Igor F S Cotta - Academia.edu (original) (raw)
Papers by Igor F S Cotta
A analise de solidos multi-fraturados com o emprego de metodos numericos tais como o Metodo dos E... more A analise de solidos multi-fraturados com o emprego de metodos numericos tais como o Metodo dos Elementos Finitos em sua forma convencional, pode demandar um excessivo refinamento da malha, tornando o custo computacional demasiadamente alto. Alem disso, a necessidade de obter resultados para diferentes configuracoes de falhas, fissuras e entalhes, os quais introduzem pontos de singularidades na solucao, pode inviabilizar o desenvolvimento de uma abordagem robusta do problema. Assim, o objetivo deste trabalho e desenvolver uma ferramenta computacional para o Metodo da Particao, fundamentalmente dedicada a analise da integridade de elementos estruturais, propiciando um metodo acurado, eficiente e robusto, que podera ser estendido para consideracao da propagacao de trincas e fissuras, bem como dos efeitos de fadiga do material. Dentre os recursos numericos especificos empregados para atingir esta finalidade, destaca-se o Metodo dos Elementos Finitos Generalizados (MEFG), particularment...
A analise de estruturas de forma discretizada, ou seja, separando-a em outras estruturas com cons... more A analise de estruturas de forma discretizada, ou seja, separando-a em outras estruturas com consideracoes simplificadoras, pode conduzir a resultados nao satisfatorios ou o emprego de coeficientes de seguranca muito grandes. Com o advento da informatica e microcomputadores ja e viavel a resolucao de estruturas considerandoas como um todo e portanto tridimensionais. Desta forma, objetivo deste trabalho e realizar a analise nao linear fisica e geometrica de estruturas tridimensionais reticulares compostas por elementos de barra, os quais podem ser unidos por ligacoes monoliticas ou semi-rigidas, como ocorre para estruturas de concreto pre-moldado. Para atingir esta finalidade, desenvolveu-se um programa livre em linguagem TURBO PASCAL, utilizando-se da analise matricial de estruturas, acrescida da consideracao da nao linearidade fisica do concreto a partir da equacao de Branson. A nao linearidade geometrica foi considerada a partir de uma formulacao lagrangiana atualizada. Em ambos o...
Latin American Journal of Solids and Structures, 2016
The aim of this paper is to analyse two-dimensional linear elastic continuum containing multiple ... more The aim of this paper is to analyse two-dimensional linear elastic continuum containing multiple interacting cracks. Both the mechanical model and the numerical approach are addressed throughout the text as key concepts for the computational framework, whose main characteristics will be described. The Splitting Method is a decomposition method considered for mechanical modeling of multiple interacting cracks. Accordingly, the original problem is divided into a set of global and local sub-problems. The Generalized Finite Element Method (GFEM) is adopted aiming at finding accurate numerical solutions for local sub-problems. Such problems are conceived so as to consider the stress concentration and the effects of interaction on the cracks. The main findings are related to the effectiveness of the proposed combination between the Splitting Method and the GFEM to provide accurate results, as well as the versatility of the conceived computational framework for analyzing different scenarios, including cracks of multilinear shapes and mixed mode fractures.Finally, it is possible to verify that the GFEM provides precise results using simpler meshes, in comparison with standard FEM used, for example in Franc2D ® .
The design of complex structures demands the prediction of possible fracture-dominant failure pro... more The design of complex structures demands the prediction of possible fracture-dominant failure processes, due to the existence of unavoidable preexistent flaws and other defects, as well as sharps and cracks. On one hand, the complexity of the structure and the presence of many defects to be accounted for in the modeling can become the computational effort impracticable. On the other hand, it is important to seek the development of a computational framework based on some numerical method to study these problems. A way to overcome the difficulties mentioned, therefore making feasible the analysis of complex structures with many cracks, flaws and other defects, consists of combining a representative mechanical modeling with an efficient numerical method. This is precisely the fundamental aim of this work. Firstly, the Splitting Method is used aiming to build a representative modeling. Secondly, the Generalized Finite Element Method (GFEM) is chosen as an efficient numerical method, in which enrichment strategies of the approximated solution using stress functions in particular can be explored. The GFEM framework also allows avoiding the excessive refinement of the mesh, which increases the computational effort in conventional finite element analysis. In the Splitting Method, a kind of decomposition method, the original problem is subdivided in local and global problems which are then combined by imposing null traction at the crack surfaces. In this work, the Splitting Method was completely programmed in Python language and its use extended to analyze crack propagation including fatigue crack growth. The generated code presents in addition to several features related to Fracture Mechanics concepts, as the computation of the stress intensity factor (mode I and II) trough J Integral. Some examples are presented to depict the propagation of the cracks in multisite damage structures. It is shown that for this kind of problems the enrichment strategy provided by GFEM is essential. Moreover, the final example demonstrates that the computational tool allows for investigation of different possible crack scenarios with a low cost analysis. One concludes about the representativeness and efficiency of the methodology hereby proposed.
A analise de solidos multi-fraturados com o emprego de metodos numericos tais como o Metodo dos E... more A analise de solidos multi-fraturados com o emprego de metodos numericos tais como o Metodo dos Elementos Finitos em sua forma convencional, pode demandar um excessivo refinamento da malha, tornando o custo computacional demasiadamente alto. Alem disso, a necessidade de obter resultados para diferentes configuracoes de falhas, fissuras e entalhes, os quais introduzem pontos de singularidades na solucao, pode inviabilizar o desenvolvimento de uma abordagem robusta do problema. Assim, o objetivo deste trabalho e desenvolver uma ferramenta computacional para o Metodo da Particao, fundamentalmente dedicada a analise da integridade de elementos estruturais, propiciando um metodo acurado, eficiente e robusto, que podera ser estendido para consideracao da propagacao de trincas e fissuras, bem como dos efeitos de fadiga do material. Dentre os recursos numericos especificos empregados para atingir esta finalidade, destaca-se o Metodo dos Elementos Finitos Generalizados (MEFG), particularment...
A analise de estruturas de forma discretizada, ou seja, separando-a em outras estruturas com cons... more A analise de estruturas de forma discretizada, ou seja, separando-a em outras estruturas com consideracoes simplificadoras, pode conduzir a resultados nao satisfatorios ou o emprego de coeficientes de seguranca muito grandes. Com o advento da informatica e microcomputadores ja e viavel a resolucao de estruturas considerandoas como um todo e portanto tridimensionais. Desta forma, objetivo deste trabalho e realizar a analise nao linear fisica e geometrica de estruturas tridimensionais reticulares compostas por elementos de barra, os quais podem ser unidos por ligacoes monoliticas ou semi-rigidas, como ocorre para estruturas de concreto pre-moldado. Para atingir esta finalidade, desenvolveu-se um programa livre em linguagem TURBO PASCAL, utilizando-se da analise matricial de estruturas, acrescida da consideracao da nao linearidade fisica do concreto a partir da equacao de Branson. A nao linearidade geometrica foi considerada a partir de uma formulacao lagrangiana atualizada. Em ambos o...
Latin American Journal of Solids and Structures, 2016
The aim of this paper is to analyse two-dimensional linear elastic continuum containing multiple ... more The aim of this paper is to analyse two-dimensional linear elastic continuum containing multiple interacting cracks. Both the mechanical model and the numerical approach are addressed throughout the text as key concepts for the computational framework, whose main characteristics will be described. The Splitting Method is a decomposition method considered for mechanical modeling of multiple interacting cracks. Accordingly, the original problem is divided into a set of global and local sub-problems. The Generalized Finite Element Method (GFEM) is adopted aiming at finding accurate numerical solutions for local sub-problems. Such problems are conceived so as to consider the stress concentration and the effects of interaction on the cracks. The main findings are related to the effectiveness of the proposed combination between the Splitting Method and the GFEM to provide accurate results, as well as the versatility of the conceived computational framework for analyzing different scenarios, including cracks of multilinear shapes and mixed mode fractures.Finally, it is possible to verify that the GFEM provides precise results using simpler meshes, in comparison with standard FEM used, for example in Franc2D ® .
The design of complex structures demands the prediction of possible fracture-dominant failure pro... more The design of complex structures demands the prediction of possible fracture-dominant failure processes, due to the existence of unavoidable preexistent flaws and other defects, as well as sharps and cracks. On one hand, the complexity of the structure and the presence of many defects to be accounted for in the modeling can become the computational effort impracticable. On the other hand, it is important to seek the development of a computational framework based on some numerical method to study these problems. A way to overcome the difficulties mentioned, therefore making feasible the analysis of complex structures with many cracks, flaws and other defects, consists of combining a representative mechanical modeling with an efficient numerical method. This is precisely the fundamental aim of this work. Firstly, the Splitting Method is used aiming to build a representative modeling. Secondly, the Generalized Finite Element Method (GFEM) is chosen as an efficient numerical method, in which enrichment strategies of the approximated solution using stress functions in particular can be explored. The GFEM framework also allows avoiding the excessive refinement of the mesh, which increases the computational effort in conventional finite element analysis. In the Splitting Method, a kind of decomposition method, the original problem is subdivided in local and global problems which are then combined by imposing null traction at the crack surfaces. In this work, the Splitting Method was completely programmed in Python language and its use extended to analyze crack propagation including fatigue crack growth. The generated code presents in addition to several features related to Fracture Mechanics concepts, as the computation of the stress intensity factor (mode I and II) trough J Integral. Some examples are presented to depict the propagation of the cracks in multisite damage structures. It is shown that for this kind of problems the enrichment strategy provided by GFEM is essential. Moreover, the final example demonstrates that the computational tool allows for investigation of different possible crack scenarios with a low cost analysis. One concludes about the representativeness and efficiency of the methodology hereby proposed.