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Objetivo: Avaliar a distribuição de tensões nas regiões periimplantares dos implantes de titânio (TiCP) e titânio- zircônio (TiZr), de pequeno diâmetro (3,3mm) e comprimento de 12mm, decorrentes de cargas axiais e oblíquas. Método: Foram confeccionados dois modelos fotoelásticos, sendo um com um implante de TiCP e o outro com um implante de titânio-zircônio (TiZr). Sobre os pilares de cicatrização foram aplicadas cargas axiais com angulações de 0, 10, 20 e 30, de 100N e 200N, em relação ao longo eixo do implante, por meio da máquina universal de ensaio conjugada ao polariscópio circular na configuração de campo escuro. As franjas isocromáticas foram analisadas nas regiões periimplantares, nas condições testadas. Resultados: Com angulações de 0 e 10, o implante de TiZr apresentou tensões menores em 80% das situações quando comparado com o implante de TiCP. Com angulação de 20, o TiZr apresentou tensões menores em 10% e com 30 de inclinação o TiZr apresentou tensões menores em 60% das áreas perirradiculares analisadas. Conclusões: O implante de TiZr apresentou tensões menores quando comparado com o TiCP na maioria das regiões avaliadas. / Objective: To evaluate the stress distribution in peri-implant regions of implants with pure titanium and titanium-zirconium (TiZr), small diameter (3.3mm) and a length of 12mm, resulting from axial and oblique loads. Method: Two photoelastic models were made, one with an implant TiCP and the other with an implant Titanium-Zirconium (TiZr) with 15% zirconium in its composition. On the healing abutments centered axial load and oblique 10, 20 and 30 (100N and 200N) to the long axis of the implant were applied by means of a universal testing machine coupled to the circular polariscope field configuration dark. The isochromatic fringes were analyzed in the peri-implant regions, in the tested conditions. Results: With angles of 0 and 10, the implant had lower stress TiZr in 80% of cases compared with the implant cpTi. With angle of 20, the TiZr had lower stress by 10% and with 30 tilt the TiZr had lower stress in 60% of periradicular areas analyzed. Conclusions: The presented implant TiZr showed lower stress compared to the rated cpTi in most regions.

Waterproofing membranes are one of the most commonly used waterproofing insulation materials. These can be found both in assemblies of roof constructions and substructures and are a key component for waterproofing systems. During design process it is necessary to select materials, elements and accessories so that mutual compatibility, waterproof effectiveness and reliability is ensured. In order to protect the main waterproofing layer a composition is therefore completed with construction protection elements, which are meant to prevent from a mechanical damage of waterproofing membrane. Mechanical stress and damage may become evident in variety of situations, which can be caused externally not only as an inappropriate ground bashing procedure but also as a consequence of improper waterproofing construction protection. In practice there are many cases of waterproofing system failures due to stress of elements with higher mechanical durability which affect elements with lower mechanical durability. The dissertation deals with an application of dimpled membranes protected by the layer of waterproofing membranes, which may due to stress and mutual compatibility result in waterproofing system failure and waterproofing reliability decrease. The dissertation is focused on mechanical durability of waterproofing membranes made of folio and modified bitumen membrane against damage from dimple membrane depending on stress category. First, possible waterproofing membrane damage from dimple extrusion is calculated and evaluated. The next part deals with verifying by experiment based on an effect of long-term static stress and short-term dynamic stress caused by ground bashing, where a measurement of ground bashing stress is performed. Experiment interpretation and an acquired knowledge provided the dissertation with an information what combination and order of particular layers results in higher risk of waterproofing system failure and waterproofing reliability decrease

<p>Glomerulosclerosis (GS) is the irreversible scarring of glomerular tissue which underlies the development of chronic kidney disease (CKD). Increased intraglomerular capillary pressure (P_gc) is a major contributor to the development of GS and can occur in both hypertensive and diabetic patients. With elevated P_gc, <em>in vitro</em> and <em>in vivo</em> evidence suggest that mesangial cells (MC) experience cyclic stretch and secrete pro-fibrotic factors such as connective tissue growth factor (CTGF) which contributes to GS. The signaling pathways that are activated in response to elevated P_gc and lead to extracellular matrix (ECM) production in MCs are the main focus of this thesis.</p> <p>Previous data demonstrated activation of the Rho GTPase, Rac1, with cyclic stretch in MCs. Furthermore, the most characterized effector of Rac1, p21-activated kinase (PAK), has been observed to have a role in endothelial cells (ECs) exposed to mechanical stress. We thus proposed that the Rac1-PAK signaling pathway is involved in mechanical stress signaling in MCs.</p> <p>Our data demonstrate that Rac1-PAK signaling was activated in response to cyclic stretch and required for stretch-induced CTGF production in MCs. RhoA activation was also regulated by Rac1-PAK signaling, and RhoA/ROCK were observed to mediate CTGF upregulation with stretch. Further investigation on the role of Rac1-PAK signaling and how it regulates CTGF in MCs exposed to stretch, will provide insight into potential therapeutic targets to delay the progression of hypertension-mediated CKD.</p> / Master of Science in Medical Sciences (MSMS)

L’évolution de la technologie microélectronique conduit à une densité d’intégration toujours plus forte des transistors. Les structures d’interconnexions en cuivre Damascène suivent cette tendance et doivent être maîtrisées en termes de fabrication, de performance et de robustesse, ces différents aspects étant intimement liés aux contraintes résiduelles et à la résistivité. Cette thèse vise à comprendre les mécanismes de génération de contraintes et identifier les différentes contributions à la résistivité de ces objets en fonction des conditions de recuit et des dimensions (de la centaine de nm à plusieurs µm). Pour ce faire, les rôles respectifs de la microstructure et des dimensions de films et de lignes de cuivre électrodéposés ont été découplés sur la base de modèles analytiques intégrants des paramètres microstructuraux et géométriques. La microstructure a été analysée principalement à partir de cartographies d’orientations cristallines réalisées par EBSD. Dans le cas des lignes de cuivre de 0.2 à 1 µm de large, les contraintes résiduelles ont été déduites de l’exploitation de nano-capteurs pivotants spécialement élaborés. Les résultats obtenus montrent qu’indépendamment de la température de recuit, l’augmentation de résistivité et de contraintes résiduelles observée vers les faibles dimensions est le fruit d’une diminution de la taille moyenne de cristallites et d’un confinement géométrique plus prononcé. En outre, l’augmentation de résistivité résulte également d’une élévation de la probabilité de réflexion des électrons aux joints de grains. Cette dernière a été associée à la réduction de la proportion de joints de grains spéciaux de cohérence atomique élevée. / The evolution of the microelectronic technology leads to a transistors integration density always stronger. The Damascene copper interconnections structures follow this tendency and must be controlled in terms of manufacturing, performance and robustness, these different aspects being intimately related to the residual stresses and resistivity. This thesis aims to understand the mechanisms of the residual stresses generation and identify the different contributions to the resistivity of these objects as a function of annealing conditions and dimensions (from about a hundred of nm to several µm). In order to do this, the respective effects of the microstructure and dimensions of electroplated copper films and lines were separated on the basis of analytical models integrating microstructural and geometrical parameters. The microstructure was principally analysed from mappings of crystalline orientations achieved by EBSD. For the copper lines of width 0.2 and 1 µm, the residual stresses were deduced from the exploitation of nano-rotating sensors specially elaborated. The results obtained show that independently of the annealing temperature, the resistivity and residual stresses increase observed toward the small dimensions arises from the diminution of the average crystallites size and the geometrical confinement more pronounced. Furthermore, the resistivity increase results also of the electrons reflection probability growth at grains boundaries. This last point was associated to the reduction of the proportion of special grains boundaries having a high atomic coherency.

Le stockage des céréales se fait en milieu rural au nord du Bénin dans des greniers (silo) en terre qui ont une contenance limitée. Les nombreuses tentatives d’introduction de magasins modernes ont essuyé le rejet des populations. Le présent travail a pour but d’étudier la possibilité d’augmenter le volume de stockage du grenier de type Yom sans changer ni sa forme architecturale, ni le composite argile-paille-décoction de néré. La caractérisation expérimentale du comportement mécanique du banco, matériau de construction de ces greniers a permis de définir le meilleur dosage pour des caractéristiques maximales. En faisant varier la proportion de paille et de décoction de néré, l’influence sur la terre crue de la paille et de la décoction est mise en évidence. La simulation de l’action des grains, à la vidange et au remplissage sur la paroi du grenier et l’analyse des déformations induites montrent qu’il y a possibilité de construire des greniers de plus grande taille. Une optimisation paramétrique des dimensions a été faite. L'effet des échauffements successifs sur la paroi du grenier a été pris en compte à travers la modélisation des transferts thermiques. La modélisation des profils de température dans diverses coupes orientées du silo montre que le flux est bien amorti et les conditions d'ambiance dans le grenier garantissent une bonne conservation. Il est donc possible de construire des greniers de grande capacité de stockage qui serviraient de greniers communautaires ou banques de céréales à disposition des coopératives villageoises. Cette solution règlerait le problème de l’insécurité alimentaire au niveau du monde rural / The storage of cereals is done in rural areas in northern Benin in earth silo that have a limited capacity. The numerous attempts to introduce modern shops have been rejected by the population. This work aims to study the possibility of increasing the storage volume of Yom type silo without changing its architectural form, nor the clay-straw-nere composite. The experimental characterization of the mechanical behaviour of the banco, the construction material of these silo made it possible to define the best dosage for maximum characteristics. By varying the proportion of straw and decoction of nere, the influence on the raw earth of the straw and the decoction is highlighted. The simulation of grain action (filling and discharging) on the silo wall and the analysis of the induced deformations shows that there is a possibility of building larger earth silo. A parametric optimization of the dimensions was made. The effect of successive heating on the silo wall has been considered by modelling heat transfer. The modelling of the temperature profiles in various silo-oriented sections shows that the flow is well damped and the ambient conditions in the attic guarantee good conservation. It is therefore possible to build earth silo with large storage capacity that could be used as community silo or cereal banks for village cooperatives. This solution would solve the problem of food insecurity in rural areas

As lesões do ligamento cruzado posterior (LCP) geralmente estão associadas a traumas de alta energia. Ainda existem muitas controvérsias sobre a técnica cirúrgica ideal para o tratamento dessas lesões, no que diz respeito aos métodos de seleção e fixação do enxerto. A técnica onlay, recentemente descrita, permite a fixação direta de um autoenxerto de tendões flexores ao aspecto posterior da tíbia com parafuso esponjoso e arruela dentada plástica, com proteção às estruturas neurovasculares e evitando a chamada \"curva assassina\". O objetivo deste estudo foi realizar uma avaliação biomecânica da técnica onlay, comparando entre si as fixações tibiais unicortical e bicortical de enxertos, imediatamente após o implante (tempo zero). O ensaio biomecânico e a coleta de dados foram realizados no Thompson Laboratory for Regenerative Orthopaedic da Universidade de Missouri (Columbia, Missouri, EUA). Para isso, oito joelhos de espécimes cadavéricos foram distribuídos aleatoriamente em uma das duas técnicas de fixação do LCP (n = 4 joelhos/técnica), que foram realizadas por cirurgiões experientes no procedimento. O teste biomecânico consistiu em uma força com direção posterior aplicada a região proximal da tíbia, em quatro ângulos de flexão do joelho, 10o, 30o, 60o e 90o. O teste foi realizado com uma taxa de deslocamento de 1 mm/s, em uma máquina servo-hidráulica (8821s, Instron, Norwood, MA). As variáveis medidas foram: carga para 5 mm de deslocamento posterior, deslocamento máximo (com carga de 100 N) e rigidez. Para a análise estatística, os dados de cada joelho foram normalizados para o joelho com LCP nativo intacto e depois agrupados nas categorias unicortical ou bicortical, de acordo com a fixação realizada. Dados obtidos, nas variáveis mencionadas, para os grupos joelho intacto, joelho desbridado, unicortical e bicortical, foram comparados por meio da análise de variância simples (one-way ANOVA) para avaliar diferenças estatisticamente significativas (p < 0,05). Quando comparadas aos joelhos com LCP desbridado, as técnicas de fixação unicortical e bicortical apresentaram menor frouxidão a uma carga máxima de 100N. Quando comparados com os joelhos intactos, o grupo unicortical apresentou maior frouxidão em todos os ângulos e o grupo bicortical apresentou maior frouxidão apenas a 90o de flexão (p < 0,001). Na avaliação da força relativa do enxerto, ou seja, a carga necessária para atingir 5 mm de deslocamento na gaveta posterior, as técnicas unicortical e bicortical exigiram menos carga que os joelhos com LCP intacto. O grupo com fixação bicortical, no entanto, foi superior ao unicortical em todos os ângulos (p < 0,001), na avaliação da força relativa. Em relação à rigidez, não houve diferenças significativas entre os grupos unicortical e bicortical e ambos foram superiores aos joelhos desbridados e inferiores aos joelhos com LCP intacto. Com base nos testes biomecânicos de cadáveres, nenhuma das técnicas de reconstrução do LCP foi capaz de reproduzir os resultados do joelho com LCP intacto, mas ambas as técnicas foram superiores aos joelhos com deficiência de LCP. Ao se optar pela técnica onlay de reconstrução do LCP, a técnica de fixação tibial bicortical parece ter vantagens biomecânicas em relação à técnica de fixação unicortical. / Posterior cruciate ligament (PCL) injuries are generally associated with high energy trauma. There are many controversies regarding optimal surgical technique in regard to graft selection and fixation methods. The recently described onlay technique allows for direct fixation of a hamstring autograft to the posterior aspect of the tibia, protecting the neurovascular structures and avoiding the so-called \"killer turn\". The onlay technique requires a cancellous screw and spiked washer to secure the graft to the tibia. The objective of this study was to compare immediate post-implantation biomechanics of unicortical versus bicortical tibial fixation of onlay PCL grafts. Biomechanical testing and data collection were performed at the Thompson Laboratory for Regenerative Orthopedics at the University of Missouri (Columbia-Missouri-USA). For that, eight knees were randomly assigned to one of two onlay PCL techniques (n= 4 knees/technique), performed by surgeons experienced with the procedure. Testing consisted of a posterior-directed force at four knee flexion angles, 10, 30, 60, and 90 degrees, at a displacement rate of 1 mm/s, performed in a servo-hydraulic machine (8821s, Instron, Norwood, MA). Measured variables were: load to 5 mm of posterior displacement, maximum displacement (at 100 N load) and stiffness. For statistical analyses, data for each knee were normalized to the native PCL-intact knee and then grouped into unicortical or bicortical groups accordingly. Data for load to 5 mm (strength), displacement at 100 N, and stiffness were compared among PCL-intact, PCL-deficient, unicortical fixation, and bicortical fixation categories using one-way analysis of variance (ANOVA) to assess for statistically significant (p < 0.05) differences. When compared to PCL-deficient knees, both unicortical and bicortical fixation techniques had less laxity at a maximum load of 100N. When compared with PCL-intact knees, unicortical had more laxity at all angles and bicortical had more laxity only at 90 degrees (p < 0.001). For relative graft strength, namely the load required to reach 5mm of displacement in posterior drawer, unicortical and bicortical techniques required less load to 5 mm of posterior drawer than for PCL-intact knees. Bicortical, however, outperformed unicortical at all angles (p < 0.001) for relative strength. Regarding stiffness of each construct, there were no significant differences between unicortical and bicortical and both were superior to PCL-deficient and inferior to PCL-intact knees. Based on cadaveric biomechanical testing, none of the reconstructed PCL knees was able to replicate the intact native PCL, but both techniques were superior to PCLdeficient knees. The bicortical tibial fixation technique appears to have biomechanical advantages when opting for onlay PCL reconstruction.

Os objetivos deste estudo foram comparar, através de análise de elementos finitos, a distribuição de tensões em modelos que representam arranjos experimentais nor-malmente utilizados em testes de cisalhamento e micro-cisalhamento, verificar a tendência de variar o local de início e o modo de fratura em função de mudanças nos parâmetros dos ensaios e analisar a influência de dois modos de fixação do substrato sobre a concentração de tensões. Os modelos bidimensionais em estado plano de deformações representaram o compósito (híbrido ou flow) aderido à dentina através de uma camada de adesivo de 50 &#956;m. Duas condições de fixação da dentina foram estabelecidas: na primeira (mais rígida), os deslocamentos foram restritos em todas as direções nos nós das arestas que representam as três superfícies livres de adesão e na segunda, a restrição foi colocada apenas na parte posterior da dentina. Foi aplicado um carregamento pontual a várias distâncias da interface dentina-adesivo, de modo a obter um tensão nominal constante de 4MPa. Foram analisadas as tensões máximas de tração e cisalhamento, a distribuição das tensões ao longo dos nós da interface dentina-adesivo e os vetores de tensão máxima principal, como indicativos do local de início e o provável modo de fratura. A distribuição de tensões ao longo da interface aderida foi sempre não uniforme e apresentou picos muito ele-vados em todos os casos, o que conduz a pensar que os valores de resistência nominal não são representativos da máxima tensão suportada no momento da fratura. A tensão de tração predominou sobre a de cisalhamento. O módulo de elasticidade do compósito aderido, a espessura relativa da camada de adesivo e a distância de aplicação da carga influenciam a concentração de tensões e devem ser padroniza-dos. Para o teste de micro-cisalhamento, a camada de adesivo relativamente mais espessa e o uso do compósito com baixo módulo de elasticidade propiciaram a in-tensificação das tensões. O ensaio de cisalhamento parece mais suscetível que o de micro-cisalhamento para que o início da ruptura ocorra no substrato, pois o ponto de maior concentração de tensões localizou-se na dentina em alguns casos e verifica-se pequena diferença de módulo entre os maiores vetores localizados no adesivo e na dentina de base. O teste de micro-cisalhamento, embora mais favorável a que as fraturas se iniciem no adesivo, concentra muito a tensão, especialmente com a utili-zação de resinas do tipo flow, o que o torna menos representativo da máxima tensão que o espécime realmente resistiu no momento da fratura. / The objectives of this study were to compare the stress distribution in finite element models that represented experimental designs commonly used for shear and micro-shear bond strength testing, to verify the tendency to vary the location and mode of fracture as a consequence of changes in the studied parameters, and to analyze the influence of two substrate restriction conditions on stress concentration. Bi-dimensional plane strain models represented a composite (hybrid or flow) bonded to dentin through a 50 &#956;m adhesive layer. Two dentin restriction conditions were estab-lished: in the first (more rigid), movements were restricted in all directions on the nodes located in the dentin surface edges free of adhesion, and in the second, re-striction was imposed only to the posterior dentin surface. Concentrated loading was applied at several distances from the dentin-adhesive interface so as to obtain con-stant nominal bond strength of 4MPa. Maximum tensile and shear stress values, stress distribution along the dentin-adhesive interfacial nodes and the principal maximum stress vectors as indicative of the most probable location and mode of frac-ture were analyzed. Stress distribution along bonded interfaces was always non-uniform and presented very high stress peaks for all cases. This led to the assump-tion that nominal bond strength values are non-representative of the maximum stress supported at fracture. Tensile stresses were always predominant over shear stresses. The composite elastic modulus, relative adhesive layer thickness and different load application distances influenced stress concentration and should be stan-dardized. For micro-shear tests, the relatively thicker adhesive layer and use of a low modulus composite propitiated stress intensification. The shear test seems to be more susceptible than micro-shear to fracture initiation in the substrate, once the point of highest stress concentration was in some cases located in dentin, and small modulus difference was verified between the greatest stress vectors located both on the adhesive and dentin base. Although more favorable to fracture initiation in the adhesive, the micro-shear test design highly concentrated stresses, especially when flow composite was modeled, hence it might be less representative of the maximum stress the specimen resisted at fracture.

Transdutores baseados em cascas piezocompósitas têm uma vasta aplicação no campo de estruturas inteligentes, principalmente como atuadores, sensores e coletores de energia. Essas estruturas piezocompósitas são geralmente compostas por dois ou mais tipos de materiais, como por exemplo materiais piezelétricos, ortotrópicos elásticos (possuem fibras de reforçamento) e isotrópicos (materiais homogêneos). Vários fatores devem ser considerados no projeto de transdutores baseados em cascas piezocompósitas, como o tamanho, a forma, a localização e a polarização do material piezelétrico, bem como a orientação das fibras do material ortotrópico. O projeto desses transdutores é complexo e trabalhos anteriores envolvendo esses tipos de materiais sugerem utilizar Método de Otimização Topológica (MOT) para aprimorar o desempenho dos transdutores distribuindo o material piezelétrico sobre substratos fixos de materiais isotrópicos e ortotrópicos, ou otimizar a orientação das fibras dos materiais ortotrópicos com material piezelétrico com tamanho, forma e localização previamente estabelecidos. Assim, nesta tese, propõe-se o desenvolvimento de uma metodologia baseada no MOT para projetar transdutores piezocompósitos de casca considerando, simultaneamente, a otimização da distribuição e do sentido de polarização do material piezelétrico, e também a otimização da orientação das fibras de materiais ortotrópicos, que é livre para assumir valores diferentes ao longo da mesma camada compósita. Utilizando essa metodologia, são obtidos resultados numéricos para atuadores e sensores em regime estático e para coletores de energia com circuito elétrico acoplado, em regime dinâmico amortecido. Para os casos dos sensores e dos coletores de energia, também são consideradas as tensões mecânicas na estrutura, as quais devem obedecer os critérios de von Mises (para materiais isotrópicos) e de Tsai-Wu (para materiais ortotrópicos) para que não haja falhas na estrutura, que está sujeita a esforços mecânicos. / Transducers based on laminated piezocomposite shell structures have a wide application in the field of smart structures, especially as actuators, sensors and energy harvesting devices. These piezocomposite structures are generally composed by two or more kinds of materials, such as piezoelectric, isotropic, and elastic orthotropic (fiber reinforcement) materials. Several factors must be considered in the design of piezocomposite transducers, such as size, shape, location and polarization of the piezoelectric material and the fiber orientation of the orthotropic material. The design of these transducers is complex and previous studies involving these types of materials suggest using \"Topology Optimization Method\" (TOM) to enhance the performance of piezoelectric transducers by distributing piezoelectric material over fixed isotropic and orthotropic substrate or to optimize the fiber orientation of orthotropic materials with piezoelectric patches previously established. Thus, this thesis proposes the development of a methodology based on the TOM to design laminated piezocomposite shell transducers by considering simultaneously the optimization of distribution and the polarization direction of the piezoelectric material, and also the optimization of the fiber orientation orthotropic material, which is free to assume different values along the same composite layer. By using this methodology, numerical results are obtained for actuators and sensors under static response, and energy harvesting devices with an electrical circuit coupled, in dynamic damped analysis. In the case of sensors and energy harvesting devices, which are subjected to mechanical loads, the mechanical stresses in the structure are also considered, which must satisfy two stress criteria to prevent failure: von Mises for isotropic materials and Tsai-Wu for orthotropic materials.

INTRODUÇÃO: O colo dos aneurismas da aorta abdominal infrarrenal é o principal local de interação entre a parede aórtica e as próteses utilizadas no seu tratamento, pela técnica aberta ou endovascular. A dilatação do colo no acompanhamento pósoperatório, levando a falhas no tratamento, demonstra a importância de um colo confiável para um reparo eficiente em longo prazo. OBJETIVOS: Determinar as propriedades biomecânicas e histológicas do colo do aneurisma da aorta abdominal infrarrenal, comparando os resultados com as propriedades da aorta suprarrenal e da parede anterior do aneurisma. MÉTODOS: Dezesseis aneurismas da aorta abdominal infrarrenal encontrados em necrópsia foram removidos e dissecados em laboratório. A anatomia original dos aneurismas foi restabelecida com o auxílio de um balão complacente inserido na luz dos espécimes, sendo que aneurismas com um colo mais curto que 10 mm foram excluídos. Fragmentos transversais similares da parede anterior do aneurisma, do colo e da aorta suprarrenal foram obtidos com o auxílio de um dispositivo de corte apropriado. Testes de tração uniaxiais destrutivos foram realizados para a obtenção das seguintes propriedades biomecânicas: tensão, estresse, energia de deformação e deformação no momento da falência, além da medida da espessura dos fragmentos. A análise histológica destes fragmentos consistiu na quantificação das fibras colágenas, elásticas e espessura da camada média. RESULTADOS: Em doze aneurismas rotos e quatro não rotos, a análise biomecânica dos fragmentos de tecido arterial não demonstrou diferenças estatisticamente significativas entre os valores médios das propriedades biomecânicas de falência (tensão, estresse, energia de deformação e deformação), assim como para a espessura nos três segmentos estudados. O percentual de colágeno para o colo foi significativamente menor que na parede dos aneurismas (p = 0,010) e não foi significativamente diferente da aorta suprarrenal (p = 0,155). A elastina apresentou percentual significativamente maior no colo (p < 0,001) e na aorta suprarrenal (p < 0,001) quando comparados aos aneurismas. Não houve diferença na quantificação da elastina entre o colo e o segmento suprarrenal (p = 0,457). A espessura da camada média não apresentou diferença estatística relevante entre as três regiões avaliadas (p = 0,660). CONCLUSÕES: Os resultados biomecânicos sugerem que o aneurisma da aorta infrarrenal, ao invés de uma processo localizado, seja resultado de um acometimento aórtico difuso. Tanto a resistência quanto a elasticidade do segmento aneurismático apresentam semelhanças quando comparados aos segmentos aórticos não dilatados. Na análise histológica, nota-se preservação da elastina nos segmentos aórticos não dilatados, enquanto há redução na parede aneurismática; além de maior deposição de colágeno nesta região / INTRODUCTION: The neck of the infrarenal abdominal aortic aneurysm is the principal site of interaction between the aortic wall and the devices used in the repair of these aneurysms, by open or endovascular technique. Postoperative aneurysm neck dilation leading to aneurysm exclusion failures demonstrates the importance of a reliable neck for the long-term efficient repair. OBJECTIVE: To access the biomechanical and histological properties of the infrarenal aortic aneurysm neck, comparing the results with the properties of the suprarenal aorta and the anterior wall of the aneurysm. METHODS: Sixteen infrarenal abdominal aortic aneurysms found in necropsies were removed and dissected in laboratory. The original anatomy of the aneurysms was restored with the aid of a compliant balloon inserted in the specimens lumen and aneurysms with a neck shorter than 10 mm were excluded. Similar transverse fragments from the anterior aneurysm wall, aneurysm neck, and suprarenal aorta were obtained with the aid of a cutting device. Uniaxial destructive tensile tests were performed to obtain the following biomechanical properties: tension, stress, strain energy and strain at the moment of fragment failure, and the thickness of the fragments. Histological analysis was performed with the quantification of collagen and elastin, and middle layer thickness in these three fragments. RESULTS: In twelve ruptured and four unruptured aneurysms, the biomechanical analysis of the fragments showed no statiscally signicant differences between the mean values of the biomechanical properties (tension, stress, strain energy and strain), as well as the thickness of the fragments in the three groups. The percentage of collagen in the neck was significantly lower than in the aneurysm wall (p = 0,010) and was not significantly different from the suprarenal aorta (p = 0,155). Higher percentage of elastin was present in the neck (p < 0,001) and in the suprarenal aorta (p < 0,001) when compared to aneurysms. There was no difference in the quantification of elastin between the neck and the suprarenal segment (p = 0,457). The middle layer thickness showed no significant statistical difference between the three evaluated regions (p = 0,660). CONCLUSIONS: Biomechanical results suggest that the infrarenal aortic aneurysm, rather than a localized process, is a result of diffuse aortic involvement. Both the resistance and elasticity of the aneurysmal segment have similarities when compared to non-dilated aortic segments. In the histological analysis, there is preservation of elastin in non-dilated aortic segments, while there is a reduction in the aneurysmal wall; and there is greater collagen deposition in the aneurysmatic region