Seminários e Teses

Próximos- Anteriores-
Esta semana (de 17/02 a 23/02)
Dissertação de Mestrado
21/02
Numerical investigation of the evolution of blood flow patterns of different years in patients with ascending aortic aneurysm
Gabriela de Castro Almeida, PUC-Rio

Data: 21/02/2019 às 14h e 0min
Local: Sala 106L


Orientador: Angela Nieckele e Bruno Gomes
Área de Concentração: Termociências

Resumo

Arterial aneurysmal is defined as an excessive dilation of the normal diameter of an artery. Ascending aortic aneurysm is generally asymptomatic, so it is often accidentally identified during routine imaging examinations. After the aneurysm has been identified, if there is no surgical indication, the patient should be followed adequately, since arterial rupture can be fatal. The influence of blood flow on aortic remodeling is an important area of investigation. The aim of this study is to identify hemodynamic patterns in ascending aortic aneurysms that may be related to aneurysm enlargement. Each patient in the study was evaluated at two different times. A three-dimensional model of the ascending aortic aneurysm was generated for each patient from aortic angiotomography examinations. The flow field was numerically determined with a commercial software. It has been shown that the angle between the entrance of the main flow and the brachiocephalic trunk can induce an incident jet on the aortic wall, causing areas of recirculation in the posterior region of the jet, besides high values of pressure and wall shear stress. The present hemodynamics findings may be related to remodeling of the ascending aortic.


Dissertação de Mestrado
21/02
Toughness Evaluation and Fracture Predictions in Elastoplastic Materials
Eduardo Enes, PUC-Rio

Data: 21/02/2019 às 14h e 0min
Local: Sala de aula do 6 andar


Orientador: Jaime Tupiassu
Área de Concentração: Mecânica Aplicada

Resumo

Understanding how to analyze crack-like defects is essential for many industries to avoid potentially catastrophic accidents. It is well known that structural Integrity standards use conservative procedures to evaluate the safety of cracked plate-like components like pipes and pressure vessels. To quantify how conservative such procedures are, critical loads predictions were computed on plate-like specimens of API 5L X80 steel (a high strength low alloy (HSLA) dual-phase steel developed for deep water pipelines) with a though wall crack. The specimens toughness was predicted by level 2 and 3 assessment procedures of the fitness-for-service standard API 579, and then compared with the actual loads needed to induce ductile tearing in them. The fracture toughness of the steel was measured through standard JIc and J-R resistance curve tests, using the elastic compliance technique with unloading/reloading sequences during the tearing process. Additionally, the geometry and type of loading effects, which can significantly change the value of the toughness, were analyzed using Elastoplastic Fracture Mechanics concepts. To do so, SE(B) specimens, which have high plastic transversal constraint, were tested following ASTM E1820-17 procedures. Then, their actual toughness were compared with literature procedures to estimate the toughness of SE(T) specimens, which have low plastic constraint, and with the actually measured date.