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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Contact stresses in interference-fit joints with application to sugar-mill roller assemblies.

Shoukr, Shoukry Latif. January 1989 (has links)
The interference-fit joint is widely used in machine design to connect two cylindrical machine elements. Its popularity comes from the simplicity of the assembly and the low cost of the production process. Even so, no study has examined the boundary non-linearities in the assembly of these joints. Moreover, the contact stresses and the stress concentration factors in interference-fit joints under torsional loads have not yet been examined in detail. In addition, the interface stresses and stress concentration factors in interference-fit joints subjected to bending loads have not been approached theoretically before. The sugar-mill roller is one of the oldest and most important examples of the interference-fit joints. The frequent fatigue failure of the sugar-mill rollers under reversed bending causes costly emergency line-shut downs. The versatility of the finite element method and the capability of the point-matching technique in handling contact problems have been combined, in the present work, to produce a surface-matching technique. It has been found that the complete-cohesion contact assumption may be acceptable for coefficients of friction ≥ 0.2, which is the case for most of the normally machined surfaces. An approach combining the semi-inverse displacement finite element method and the surface-matching technique has been developed to perform the torsional analysis. It has been found that the governing non-dimensional quantities are the ratio of the cohesion-length to the interface-length and the coefficient of friction divided by the load-level. The load-level is the ratio between the angle of twist of the shaft per unit length when the torque acts on the shaft alone and the amount of the diametral interference divided by the shaft diameter. A finite element model, using 8-noded solid elements together with linear interface elements, has been employed to locate the cohesion and slippage-zones in the sugar-mill roller under bending. The contact pressure increases along the compression side and decreases along the tension side. On the contrary, the interface shear decreases along the compression side due to bending and increases along the tension side. Subsequently, a larger slippage-length has been detected along the tension side.
192

Etude de la structure et des propriétés de l'acier à béton après déformations à froid

Tabalaiev, Kostiantyn 10 September 2010 (has links)
Les propriétés généralement demandées aux armatures pour béton armé doivent répondre à des exigences particulières précisées dans des normes nationales, européennes et internationales. Actuellement, dans la pratique de la production de l'acier à béton, on tend à substituer différentes nuances d'armature par une armature unifiée ayant une valeur de limite d'élasticité minimale de 500 MPa. Le remplacement des ronds à béton de nuance 400MPa par cette armature conduit à une économie de métal de l'ordre de 10-20 % d'après les estimations de différents spécialistes.Il existe, généralement, plusieurs techniques de fabrication des armatures, dont la déformation à chaud suivie d'un refroidissement accéléré sous flux d'eau (traitement thermomécanique ou Thermomechanical Control Process - TMCP), ainsi que la déformation à froid (tréfilage â travers une filière conique et une filière à rouleaux, microlaminage...), qui se heurte cependant â l'impossibilité de satisfaire aux exigences des Normes vis-à-vis des propriétés de résistance (Re > 500MPa) et de plasticité.Le présent travail a pour but le développement d'un procédé combiné de production d'acier à béton profitant des aspects positifs de deux types de déformation à chaud ainsi qu'à froid, sous forme du traitement combiné mécano-thermomécanique (post déformations à froid après le TMCP). et d'étudier la possibilité de production d'aciers à béton de qualité 500 MPa (B(A)500), de petits diamètres, en couronne, répondant aux exigences des Normes modernes. L'objectif scientifique de ce travail est d'étudier les mécanismes microstructuraux qui se produisent lors de la déformation à froid de l'acier préalablement traité thermomécaniquement et leurs conséquences sur l'évolution des propriétés mécaniques.Plusieurs nuances d'acier bas carbone de différents diamètres ont été étudiées. De nombreuses techniques de caractérisation macroscopique et microscopique de la structure de l'acier ont été utilisées: traction monotone, essais de microdureté, microscopie optique, microscopie électronique â balayage (MEB) et en transmission (MET), diffraction des rayons X. spectrométrie mécanique..Les résultats des essais montrent qu'il est possible d'obtenir avec assurance l’armature de qualité B(A)500, possédant des propriétés mécaniques qui dépassent les exigences des nonnes, à l'aide d’une déformation par torsion avec un cisaillement maximal de 22%, pour des aciers à 0.15 -0.2 % C(en poids), faiblement alliés en Mn et Si et traités themomécaniquement. La déformation par torsion provoque une augmentation de dureté en surface mais aussi au cœur de l'armature. Cette augmentation de dureté à cœur peut être amplifiée par le traitement thermique de vieillissement à 100°C correspondant à l'utilisation en Génie Civil. Cet effet, lié aux interactions dislocation-impuretés interstitielles, a été expliqué grâce â la MET et à l'étude du frottement intérieur. / Properties which are required from an armature for the reinforced concrete should satisfy the requirements of National, European and International standards. At the present time, in practice of armature production, there is a tendency of replacement of various classes of reinforcing steels by the unified armature with the minimum value of yield strength of 500 MPa. Replacement of the armature of the 400 MPa class by such reinforcing steel brings the economy of metal of an order of 10-20 % according to the estimations of various experts.In general, a set of production technologies of the armature exists, including hot deformation with the subsequent accelerated cooling in water - Thermomechanical Control Process (TMCP), and also cold deformation (drawing in conic die block, drawing in roller die block, microrolling) which nevertheless face the impossibility to provide the required strength (yield strength > 500MPa) and plastic properties.The technological purpose of the given work is:- development of the combined mechano-thermomechanical processing of armature's production which would combine positive aspects of hot and cold deformations (post deformation processing after TMCP);- examination of possibilty to manufacture the reinforcing steel of the class of 500MPa (B(A)500) of the small diameter, in coils, meeting the requirements of modem standards.The scientific objective of the work is the analysis of change of the microstructure of reinforcing steels after the cold deformation which is preliminary subjected to thermomechanical processing, and, also, the examination of the influence of microstructural effect on change of mechanical properties of steels.In the present study, a significant quantity of grades of low-carbon steels of various diameters has been investigated. Also, different techniques for macroscopical and microscopical characterization of the steel structures have been applied: tensile tests, micro-hardness test, optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray analysis and mechanical spectroscopy.Results of tests show that it is possible to obtain, with assurance, the reinforcing steel of the strength class B(A)500, with a complex of the mechanical properties surpassing the requirements of standards. For this purpose it is proposed to use the deformation by cold torsion with the maximum relative shear of 22 %, after thermomechanical processing, for steels with carbon content of 0,15...0,25% and alloyed with Mn and Si. Deformation by torsion provides an increase of hardness not only on the surface, but also in the core of armature. The effect of hardness increase can be strengthened by means of thermal ageing at 100°C corresponding to the use in Civil Engineering. This effect, related to the dislocations- interstitial impurities interactions, was explained thanks to MET and internal friction effect.
193

Teoria de homotopia simples e torção de Whitehead / Simple-homotopy theory and Whitehead torsion

Silva, Luciana Vale 26 April 2007 (has links)
Este trabalho apresenta a teoria de homotopia simples, desenvolvida por J. H. C. Whitehead, com o objetivo de obter um método para classificar espaços com o mesmo tipo de homotopia. Com esta motivação, Whitehead introduz o conceito de equivalência de homotopia simples entre complexos simpliciais, que posteriormente é generalizado para complexos CW, espaços criados pelo próprio Whitehead. Um resultado imediato desta teoria é que quando dois espaços têm o mesmo tipo de homotopia simples, eles têm o mesmo tipo de homotopia. A recíproca desta afirmação é então conjecturada. Mostraremos que trata-se de uma conjectura falsa, contudo a investigação de sua confirmação produz um material que toma rumo próprio. Nosso enfoque são os aspectos algébricos envolvidos nesta investigação / This work presents the simple-homotopy theory, developed by J. H. C. Whitehead, with the goal to get an method to classify spaces with the same homotopy type. So, with this motivation, Whitehead introduced the concept of simple-homotopy equivalence between simplicial complexes, that later was generalized for CW complexes, spaces created by himself. An immediate result of this theory is that, if two spaces have the same simple-homotopy type, they have the same homotopy type. Then, the reciprocal statement is conjectured. We will show that the conjecture is not true, but the research about its truthfulness produces a material that takes its own way. Our approach are the algebraic aspects involved in this research
194

Estudo experimental do comportamento estrutural de barras curvas. / Experimental study of structural behavior of curved bars.

Rabelo, Marcos Alves 21 August 2009 (has links)
A presente dissertação trata do estudo experimental do comportamento estrutural de barras helicoidais assentadas sobre superfície cilíndrica e sujeitas a cargas de compressão. Aparato experimental específico foi projetado e construído para este fim. O projeto, bem como a aferição deste aparato, é descrito em detalhes. Este aparato permite ajustar as barras através de um sistema de apoios constituídos por uma série de rolamentos, que podem ser posicionados de forma a conferir liberdade de deslocamento à barra em duas direções distintas: radial (normal à superfície cilíndrica de assentamento) e lateral (tangencial; bi-normal). A aplicação de carga compressiva se faz na direção tangencial à hélice não-deformada. Barras com seção transversal circular e retangular, com diversos comprimentos livres de flambagem e para diferentes ângulos de assentamento, foram ensaiadas. Estudos preliminares, com barras retas, permitiram avaliar as condições efetivas de engastamento proporcionadas pelo aparato. Nestes casos foi possível induzir o fenômeno de flambagem, recuperando-se, consistentemente, os valores de cargas críticas previstas pela teoria de Euler e avaliando-se o grau de engastamento proporcionado pelo aparato experimental. Filmagem com câmera de alta velocidade permitiu observar o fenômeno de instabilidade. O comportamento estrutural das barras curvas, de seção circular e retangular, foi então estudado. Tanto o comprimento livre quanto o ângulo de assentamento foi variado. O estudo permitiu levantar base de dados experimentais do comportamento de barras helicoidais nessas condições de carregamento e de condições de contorno. No entanto, para nenhuma das diversas condições ensaiadas foi possível induzir o fenômeno de instabilidade. Tal fato poderia dar subsídios a inferências acerca do estudo da instabilidade de tubos flexíveis do tipo birdcaging. / This dissertation deals with an experimental study on the structural behavior of bars supported on a helical cylindrical surface and subject to compressive loads. A special experimental apparatus was designed and built for this purpose. The design, as well as the adjustment of such an apparatus is described in details. The device allows one adjusting the bars by using a system consisting of a series of bearings that can be positioned to give freedom to the structure in two different directions: radial (normal to the cylindrical surface) and lateral (tangential or bi-normal). The compressive load is applied in the tangential direction of the helix. Bars with circular and rectangular cross sections, with various buckling lengths and different helix angles, were tested. Preliminary studies with straight bars, have allowed to evaluate the boundary conditions offered by the apparatus. In these cases, it was possible to induce the phenomenon of buckling, obtaining, consistently, the values of critical loads provided by the theory of Euler and to evaluate the boundary conditions provided by the apparatus. The use of a high-speed camera allowed to observe the phenomenon of instability. The structural behavior of curved bars of circular and rectangular sections was also studied. Both, the test free length as the helix angle were varied. The study enabled us to get a huge amount of experimental data about the behavior of helical bars, subjected such loading and boundary conditions. However, the phenomenon of instability could not be induced, for any condition tested. This fact could collaborate for further inferences about the study of the birdcaging instability at flexible pipes.
195

Cálculo e armação de lajes de concreto armado com a consideração do momento volvente / Design of reinforced concrete slabs considering torsion

Parsekian, Guilherme Aris 03 May 1996 (has links)
Para calcularem-se lajes de concreto armado considerando todos os esforços resistentes, incluindo o momento volvente, é necessário o conhecimento de procedimentos para determinar momentos normais a duas direções escolhidas, segundo as quais serão dispostas as armaduras, que cubram o terno de esforços Mx, My e Mxy. No presente trabalho são estudados e comparados dois métodos para armaduras ortogonais e um método para o caso de armaduras oblíquas entre si. Com a finalidade de se considerar a resistência do concreto ao momento volvente no detalhamento das armaduras, são estudadas as resistências do concreto às tensões cisalhantes devidas à força cortante e ao momento torçor e as maneiras de se combinarem essas tensões. Outra finalidade do trabalho foi a de desenvolver pré-processadores para facilitar a modelagem de pavimentos por elementos finitos e um pós-processador que permitisse a análise dos resultados utilizando os conceitos estudados. Utilizando estes \"softwares\" fez-se um pequeno estudo de lajes retangulares apoiadas nos quatro lados, procurando avaliar as recomendações existentes na bibliografia especializada, sobre as armaduras de canto necessárias a esse tipo de laje. Fez-se, também uma comparação de detalhamentos das lajes de um pavimento tipo calculadas pelo método das charneiras plásticas, pelo método dos elementos finitos sem a consideração da rigidez à torção e pelo método dos elementos finitos considerando a rigidez à torção. / In order to design reinforced concrete slabs considering all the resisting moments, including the torsional moment, it is necessary to know procedures to determine normal moments, in two chosen reinforcement directions, that are equivalent to the field of moments Mx, My and Mxy. In this work, two methods for orthogonal reinforcement are studied and compared and one for skew reinforcement is studied. In an attempt to consider the resistance of concrete to the torsional moment, the shear stress due to shear carried by concrete and the shear stress due to torsion carried by concrete and the ways of combining them are studied. Another aim of this work was to develop pre-processors to facilitate the process of modeling building floors in finite elements and one post-processor that permits the analysis of the results, using the concepts of this work. Using these softwares, a short study of simply supported rectangular slabs was made, in an attempt to evaluate the recommendations, found in the specialized bibliography, about the corner reinforcement necessary in these kinds of slabs. A comparison of the slabs design of one building floor, calculated using the yield line theory, using the finite element method without the torsional strength and using the finite element method with the torsional strength was also made.
196

Uma metodologia para a análise da influência do tráfego de veículos pesados na resposta dinâmica de pontes rodoviárias. / A methodology to assess the influence of heavy vehicles traffic on the dynamic responses of highway bridges.

Moroz, Felipe Vieira 20 October 2009 (has links)
Esse trabalho trata do problema de interação dinâmica entre veículos de carga e estruturas de pontes rodoviárias, incluindo o aprimoramento de um modelo veicular de oito graus de liberdade usualmente utilizado na modelagem de veículos classe 3C, introduzindo o nono grau de liberdade, referente à rotação em torno de seu eixo longitudinal ou movimento roll. Foram calculados os carregamentos provenientes do veículo modelado sobre pavimento inicialmente indeslocável, com perfis iguais ou distintos de rugosidade e diferentes sob cada linha de pneus, assim como a participação da energia modal do veículo para cada caso. Tais carregamentos foram condensados estaticamente e aplicados em modelo estrutural simplificado (unifilar) de uma ponte em seção celular, visando a identificar as flutuações dos esforços de torção provenientes da diferença de perfil de rugosidade sob cada linha de pneus do veículo estudado. Ainda foram confrontados resultados para duas situações de tráfego, sendo a primeira para veículo isolado trafegando sobre estrutura e a segunda para um comboio de veículos. Também, verificou a aproximação implícita na adoção de pavimento indeslocável para a obtenção dos esforços da interação veículo-pavimento, utilizando um método iterativo até que se garantisse convergência para os deslocamentos. / This work is concerned with the problem of dynamic interaction between heavy vehicles and bridges structures and also with the improvement of an eight-degree-of-freedom model of a 3C class vehicle, by introducing the ninth degree of freedom referring to the rotation about the vehicle longitudinal axis, or roll movement. The loads applied by the vehicle to the bridge deck were evaluated, assuming initially a rigid structure under the pavement, for both equal and distinct roughness profiles under each tire line, as well as the vehicle modal energy participation for each case. Such loads were statically condensed and applied to a simplified (unifilar) structural model of a girder box bridge, aiming at estimating the fluctuation of the torsion moments due to the differences in the roughness profiles under each tire line. The differences in the dynamic response were evaluated considering two traffic situations, namely a single vehicle or an ensemble of vehicles moving along the bridge. It was further checked the approximation implied in the assumption of a rigid structure under the pavement for the evaluation of the vehicle-structure interaction loads, by means of an iterative procedure until convergence was obtained for the displacements. Besides, it was compared the dynamic responses considering two different traffic situations. The first situation is a unique vehicle moving on a bridge whereas the second is a train of vehicle moving on the bridge. Ahead, it was verified the error in adopt the hypothesis of unmoved pavement in the vehicles model to obtain iteration forces pavement-vehicle, using an iterative methodology to rebuild the original vehicles displacement.
197

Investigação das solicitações de cisalhamento em edifícios de alvenaria estrutural submetidos a ações horizontais / Shear stress analysis on masonry buildings under lateral loads

Nascimento Neto, Joel Araújo do 24 March 1999 (has links)
Este trabalho apresenta uma análise minuciosa das solicitações de cisalhamento nas paredes de edifícios em alvenaria estrutural submetidos a ações horizontais. O estudo compreende a análise do comportamento global da estrutura, empregando-se diferentes modelagens numéricas para o sistema de contraventamento do edifício. Os modelos utilizados incluem a deformabilidade por cisalhamento das paredes e os efeitos provenientes da torção do edifício. Os resultados apresentados consistem em deslocamentos horizontais, distribuição dos esforços cortantes e momentos fletores entre as paredes, e análise das tensões de cisalhamento das paredes e lintéis. Avaliam-se, também, os diagramas de esforço cortante e momento fletor das paredes mais solicitadas. / This work presents a shear stress study of the shear walls of masonry buildings under lateral loads. The study consists of building overall structural behavior, with the use of different theoretical models for the lateral-load-resisting system of the building. The models include shear deformation and torsion effects. The results comprise horizontal displacement, shear force and bending moment distribution on shear walls, enhancing the shear stress verification of greater internal-forces values in walls and lintels. Shear force and bending moment diagrams related to the walls with the greater internal forces are also shown.
198

Controlling Dynamic Torsion Loading

Benjamin J. Claus (5929598) 03 January 2019 (has links)
<div>Two new Kolsky bar techniques were developed to address a lack of capability in existing torsion Kolsky bar experiments. The side-impact torsion Kolsky bar provides for controllable duration, amplitude, and shape of the incident torsion wave, allowing for more ideal conditions during dynamic torsion experiments. The technique provides an ideal platform to study dynamic friction as well as dynamic shear of a material. The technique makes use of soft pulse shapers to convert longitudinal loading into torsional loading. The technique also brought forth a secondary technique to allow combined dynamic compression and dynamic torsion for soft materials. The combined loading was applied to study both shear properties and the friction behavior of a</div><div>particle composite, which was imaged using x-ray phase contrast imaging. The same composite was studied with different surface conditions on the side-impact torsion Kolsky bar to discover the differences in behavior brought about by the choice of manufacturing method. The composite showed different friction behavior to metallic</div><div>materials, and exhibited much more shear deformation during the experiment. The composite was also prone to surface evolution, leading to complex friction behavior.</div>
199

Braid-winding of quadriaxial composite tubes

Roy, Sree Shankhachur January 2014 (has links)
This research investigates composite tubes developed with hybrid preform manufacturing techniques of braiding and filament winding (FW). A quadriaxial braid-wound (QBW) preform [(±45°/0°/90°)2/(±45°/0°)] and a triaxial braided (TB60) preform [(±60°/0°)3] were developed. Quasi-isotropic (QI) fibre orientations were selected for both the lay-ups for comparison of mechanical properties. The large diameter of the tubes led to incomplete surface coverage with (±45°/0°)3 braided preforms (TB45). Circumferential distribution of multiple layers improved the coverage by reducing through the thickness resin pockets. Also addition of hoop winding improved the coverage and consolidated the braided preform. The use of braiding together with FW resulted in an improved fibre volume fraction. Also predicting surface coverage was a fundamental interest for a triaxial braided preform. An equation was proposed for cover factor estimation and was verified by using image analysis. Resin infusion of the preforms was carried out and composite tubes were fabricated. During resin infusion of braided preforms wrinkles were formed. A brief study on wrinkle formation was carried out and the reasons of wrinkle formation for braided tubes were identified based on existing literature. Longitudinal tensioning in conjunction with optimization of fibre amount in a layup and over-winding on braid was established to minimize wrinkle formation. This was primarily due to compaction of braided layers with hoop winding. Hence braid-winding has the additional advantage of manufacturing wrinkle free composite tubes. Finally composite tubes were tested under tension and torsion loads. One of the major findings was the effect of hoop winding on transverse deformation of the braid-wound tubes. As axial fibre percentage for QBW tube was less than that of TB45, the tensile strength was compromised. However presence of hoop winding resulted in lower transverse strain contributing to higher tensile modulus of QBW tubes along with lower Poisson's ratio. Although shear modulus of TB60 tube was exceptionally high for its fibre orientation, for QBW tubes, shear modulus was not significantly higher than that of other tubes. An aluminium tube was also tested for comparing the elastic properties of the QI tubes with those of an isotropic material. QBW tubes specific modulus was higher than that of the aluminium. The shear modulus of the QI and aluminium tubes was estimated by applying the theory for isotropic materials. In comparison to aluminium, for QBW tube the differences between estimated and actual shear modulus was higher. However QBW tube properties were in closer relation to those of the aluminium tube than TB60 tubes. Hence a QBW hybrid layup technique has the potential for manufacturing composite tubes without losing comparative composite material properties.
200

Avaliação dos testículos de ratos submetidos à torção testicular antes, durante e após a puberdade e o efeito do tratamento com resveratrol / Assessment of the testes of rats testicular torsion before, during and after puberty and the effect of treatment with resveratrol.

Carina Teixeira Ribeiro 17 July 2013 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / A torção testicular (TT) é uma afecção de relativa frequência, alvo de muitos estudos clínicos e experimentais ao longo dos anos. Pode acometer qualquer idade, no entanto é mais incidente em pacientes com menos de 21 anos de idade. Sua distribuição ocorre em dois picos: um no período neonatal e outro ao redor dos 13 anos de idade. A taxa dessa morbidade em jovens com menos de 25 anos é na ordem de 1/4000. A TT resulta em rotação do cordão espermático, que gera um comprometimento do suprimento sanguíneo testicular, considerada uma urgência urológica. Depois da TT, a artéria testicular e o plexo pampiniforme sofrem oclusão, interrompem o suprimento arterial e a drenagem venosa do testículo, diminuindo o aporte de nutrientes e oxigênio aos tecidos e células, levando à isquemia testicular. Esta condição afeta a produção de espermatozóides do testículo torcido podendo comprometer a fertilidade do indivíduo. Este presente estudo avaliou a função reprodutiva, alguns parâmetros espermáticos e morfologia dos testículos de ratos adultos submetidos à torção testicular antes, durante e após a puberdade, e também o efeito do tratamento com resveratrol. Os testículos direitos dos ratos foram torcidos a 720 por quatro horas em todos os grupos, exceto no grupo controle. A TT foi realizada durante os períodos pré-púbere (4 semanas de idade), púbere (6 semanas de idade) e adulto jovem (9 semanas de idade). Para cada grupo, houve um outro grupo que os animais foram submetidos ao mesmo procedimento e foram tratados com resveratrol, 30 mg/kg resveratrol foi injetado por via intraperitonel, 30 minutos antes da destorção, seguido por gavage por 7 dias. Cada rato na idade adulta acasalou com três fêmeas adultas com 12 semanas de idade para avaliar parâmetros de fertilidade. Todos os animais foram mortos com 14 semanas de idade e os testículos foram removidos para análise de concentração, motilidade e viabilidade dos espermatozóides de amostras colhidas da cauda dos epidídimos. Os parâmetros morfológicos foram avaliados por métodos estereológicos macro e microscópicos. A função reprodutiva dos animais nas diferentes idades não foi afetada pela TT, no entanto, após o tratamento os ratos operados com 4 e 6 semanas de idades tiveram maior potência e os ratos operados com 9 semanas de idade apresentaram maior taxa de fecundidade na idade adulta.. Os parâmetros morfológicos foram afetados em todos os testículos torcidos em todas as idades. Alguns desses parâmetros melhoram após o tratamento com resveratrol, e o efeito adjuvante foi maior nos ratos submetidos à TT com 4 semanas de idade. Entretanto, o resveratrol recuperou o epitélio seminífero no grupo que sofreu TT com 9 semanas de idade, os quais não apresentaram nenhum epitélio após a TT. Os parâmetros espermáticos dos testículos torcidos decresceram em todas as idades, e o resveratrol não foi efetivo, embora tenha recuperado a produção de espermatozóides no grupo que foi submetido à TT com 9 semanas de idade, em que todos os animais foram aspermatogênicos após a TTNão houve nenhum dano nos testículos contralaterais. O resveratrol promoveu efeito protetor para TT, principalmente quando os animais foram submetidos à TT em idade prépúbere. / Testicular torsion (TT) is a disease relatively frequent, which was assessed in many experimental and clinical studies over the years. TT can occur in any age, but is more common in patients under 21 years old, mostly in neonatal period and around 13 years old. The rate of this disease in youths under 25 years is about 1/400. The TT also twists the spermatic cord, which generates an impairment of the testicular blood supply and is considered a urological emergency. After TT, the testicular artery and pampiniform plexus become occluded, disrupting arterial supply and venous drainage of the testis, decreasing provision of nutrients and oxygen for tissues and cells, leading to testicular ischemia. This condition affects sperm production of the twisted testicle and may impair the fertility. This study assessed reproductive function, some morphological and spermatic parameters in adult rats which underwent experimental TT before, during and after puberty and also the effect of the treatment with resveratrol. Right testicles of rats were twisted 720 for 4 hours in all groups except the control group. TT was done during the prepubertal period (4 weeks old), puberty (6 weeks old) and young adult period (9 weeks old). For each group, there was another group which animals underwent the same procedure and were treated with resveratrol, 30 mg/kg resveratrol was injected by an intraperitoneal route, 30 minutes before detorsion, followed by gavage for 7 days. Each rat in adulthood was mated with three adult females at 12 weeks old, in order to assess parameters of fertility. All animals were killed at 14 weeks old and testes were removed for analyses Concentration, motility and viability of spermatozoids were evaluated on samples taken from the tail of the epididymis. Morphological parameters were evaluated by macroscopic and microscopic stereological methods. Reproductive function of animals at different ages was not affected by TT, however, after treatment with resveratrol, rats operated at 4 and 6 weeks old presented greater potency and animals operated at 9 weeks old showed higher fertility rate in adulthood. Morphological parameters were affected in all twisted testes at all ages. Some of these parameters improved after treatment with resveratrol and the adjuvant effect was greater in rats which underwent TT at 4 weeks old. However, resveratrol recovered the seminiferous epithelium in the group that suffered TT at 9 weeks of age, which did not show any epithelium after TT. The spermatic parameters decreased in all ages and the resveratrol did not affect it, despite it has recovered sperm production in group that underwent TT with 9 weeks old, once all animals were azoospermic after the TT. There was almost no damage in the contralateral testis. Resveratrol promoted protective effect for TT, mainly when animals underwent TT at prepubertal age.

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