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Abstract(s)
Um aneurisma é uma área frágil na parede de um vaso sanguíneo que faz com que este forme uma protuberância ou aumente de tamanho. Em situações limites, este enfraquecimento pode levar ao rompimento do vaso.
O principal objetivo deste trabalho é o de compreender como ocorre a deformação do aneurisma quando sujeito a uma pressão interna semelhante à pressão sanguínea. O estado de deformação do aneurisma, permitirá definir quais as regiões que estão sujeitas a deformações mais elevadas e que podem dar uma indicação de potencial rotura. Para realizar este estudo realizaram-se duas aproximações distintas, uma numérica e outra experimental.
No estudo numérico utilizou-se o programa comercial de elementos finitos Ansys®. Neste programa calculou-se a pressão provocada pelo fluido, utilizando parâmetros conhecidos através da medição experimental da queda de pressão. Foi possível definir um perfil de velocidades para o fluido e caracterizar o seu escoamento ao longo do canal. Sujeitou-se o aneurisma à pressão já calculada para o fluido, simulando a pressão a que o canal é sujeito pela corrente sanguínea, estes estudos tiveram sempre em consideração que os vasos sanguíneos têm um comportamento hiper-elástico, definido neste estudo através de curvas tensão/deformação.
Para a análise experimental, foi desenvolvido um modelo in vitro do aneurisma, para realização desse modelo recorreu-se a um sistema de prototipagem rápida utilizando uma impressora 3D, Solidoodle®. O material que foi utilizado para a criação do modelo tem um comportamento elástico próximo das paredes arteriais e designa-se por polidimetilsiloxano. Utilizando a técnica da Correlação Digital de Imagem realizaram-se medições de elevada resolução para o campo de deslocamentos do modelo e procedeu-se à comparação dos resultados obtidos nos ensaios.
Pela análise de resultados, confirma-se a potencialidade deste tipo de ensaios para medições em materiais hiper-elásticos.
An aneurysm is a localized weak area in the wall of a blood vessel that can ballooning or increase in size. In extreme situations, this weakening can lead to the rupture of the vessel. The purpose of the present study was to understand how the deformation of the aneurysm occurs when subjected to an internal pressure similar to arterial blood pressure. The deformation of the aneurysm, allowed to define which regions are subjected to higher deformations and can give an indication of potential rupture. To conduct this study there were two distinct approaches, a numerical and experimental. The commercial finite element program Ansys® was used in the numerical study. The program was used to calculate the pressure caused by the fluid, using known parameters through the experimental measurement of pressure. It was possible to define a velocity profile for the fluid and characterize its flow along the model. The aneurysm was subjected to the fluid pressure already calculated, simulating the pressure at which the channel is subjected by the bloodstream, these studies considered that blood vessels have a hyperelastic behavior, defined in this study through the stress/strain curves. For the experimental analysis, an in vitro model of the aneurysm was developed, a rapid prototyping system, Solidoodle® 3D printer, was used for the model creation. The material that was used on the model creation has a elastic behavior close to those of the arterial walls and is called polydimethylsiloxane. The technique of Digital Image Correlation was used to perform high resolution measurements of the model displacement and proceeded to the compare the results obtained in the tests. The analysis of the results, confirms the potential of this type of test for measurements on hyperelastic materials.
An aneurysm is a localized weak area in the wall of a blood vessel that can ballooning or increase in size. In extreme situations, this weakening can lead to the rupture of the vessel. The purpose of the present study was to understand how the deformation of the aneurysm occurs when subjected to an internal pressure similar to arterial blood pressure. The deformation of the aneurysm, allowed to define which regions are subjected to higher deformations and can give an indication of potential rupture. To conduct this study there were two distinct approaches, a numerical and experimental. The commercial finite element program Ansys® was used in the numerical study. The program was used to calculate the pressure caused by the fluid, using known parameters through the experimental measurement of pressure. It was possible to define a velocity profile for the fluid and characterize its flow along the model. The aneurysm was subjected to the fluid pressure already calculated, simulating the pressure at which the channel is subjected by the bloodstream, these studies considered that blood vessels have a hyperelastic behavior, defined in this study through the stress/strain curves. For the experimental analysis, an in vitro model of the aneurysm was developed, a rapid prototyping system, Solidoodle® 3D printer, was used for the model creation. The material that was used on the model creation has a elastic behavior close to those of the arterial walls and is called polydimethylsiloxane. The technique of Digital Image Correlation was used to perform high resolution measurements of the model displacement and proceeded to the compare the results obtained in the tests. The analysis of the results, confirms the potential of this type of test for measurements on hyperelastic materials.
Description
Keywords
Aneurisma Ensaios experimentais e numéricos PDMS Ansys Workbench® Correlação digital de imagem