Dans le cadre de cette thèse, une modélisation par éléments finis continue renforcée discrète est développée. Le modèle est basé sur le concept de la cellule élémentaire, avec utilisation de connecteurs pour prendre en compte la rigidité en tension de la structure, et modéliser l'anisotropie du tissu et un élément coque pour décrire la rigidité en cisaillement et gérer le frottement et le contact avec les outils lors de la simulation du procédé de préformage. Les différents éléments de ce maillage spécifique sont générés automatiquement à l'aide des scripts pythons. Associés à ce choix de modélisation, les caractéristiques du comportement sont déterminées à l'aide d'essais expérimentaux conduits sur le renfort et d'une démarche de méthode inverse. Le comportement de ces différents éléments est choisi d'être linéaire élastique en premier lieu, et par la suite à évoluer pour devenir non linéaire. Ces développements numériques sont réalisés dans le logiciel Abaqus/ Explicit. Dans un second temps le modèle développé est utilisé dans le cadre de simulation de l'étape de préformage des renforts secs. A ce titre un démonstrateur expérimental développé dans le cadre de la thèse sert à obtenir des résultats expérimentaux pour corréler ces travaux de simulations. Des comparaisons avec des simulations mono-couche, hémisphérique, permettre de mettre en évidence l'influence des paramètres de simulations mises en jeu. Dans le cadre de préformages de plusieurs plis, l'influence des caractéristiques du contact / frottement est mise en évidence. Finalement une procédure d'automatisation afin de rendre la simulation plus ergonomique dans un contexte industriel est présentée. Cette procédure consiste à générer le maillage spécifique et mettre la simulation en donné dans Catia. Les simulations peuvent ainsi se réaliser sans le passage par Abaqus/CAE. / In this work, a discrete approach for the simulation of the preforming of dry woven reinforcementis proposed. A “unit cell” is built using elastic isotropic shells and axial connectors instead of bars and beams used in previous studies. Shell elements are used to take into account the in-plane shear stiffness and to manage contact phenomenon with the punch and die. Connectors reinforce thestructure in the yarn directions and naturally capture the specific behavior of the fabric. To identify the material parameters, uniaxial tensile tests and bias tests have been employed. A numerical algorithm,coupling Matlab and Abaqus/Explicit, is used to determine the shear parameters by an Inverse method. The model has been implemented in Abaqus to simulate hemispherical stamping.Experimental results are compared to numerical simulations, good agreement between both resultsis shown for the case of single layer forming.This model has been then used to simulate a multilayer performing and a numerical study of the effect of fiction coefficient has been performedFinally a tool which interfaces a CAD Software to the Abaqus/code has been developed.

The task performed in this assignment is to improve the reliability of Norden Machinery ABs product family. This is to be done by examining and replacing the belt used to stop the spreading of tubes from ingoing shipping crate to the infeed of the machine. The way that this was approached was by testing different candidates on a spectrum of their rigidity to find if a flexible or more rigid belt would perform better than the current context of the system. The testing was conducted for a period of 4 weeks and results were gathered by examining damages to the belts by the use of microscope. After the damage had been analyzed the conclusion was drawn that flexible alternatives seems to perform the task better than their rigid counterparts however more work is needed in the fields regarding the fastening and operation of the machine to use the best suited candidates derived from this test, the monolithic belt FMT-02TXCT-U1.

Made available in DSpace on 2014-12-17T14:07:22Z (GMT). No. of bitstreams: 1 JorgeFSO_TESE.pdf: 9384301 bytes, checksum: 94f6528a142b55c3b875e331722c4d8d (MD5) Previous issue date: 2013-12-09 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / As most current studies, reinforced plastics have been, in recent years, a viable alternative in building structural elements of medium and large, since the lightness accompanied by high performance possible. The design of hybrid polymer composites (combination of different types of reinforcements) may enable structural applications thereof, facing the most severe service conditions. Within this class of composite materials, reinforced the underlying tissues hybrid high performance are taking space when your application requires high load bearing and high rigidity. The objective of this research work is to study the challenges in designing these fabrics bring these materials as to its mechanical characterization and fracture mechanisms involved. Some parameters associated with the process and / or form of hybridization stand out as influential factors in the final performance of the material such as the presence of anisotropy, so the fabric weave, the process of making the same, normative geometry of the specimens, among others. This sense, four laminates were developed based hybrid reinforcement fabrics involving AS4 carbon fiber, kevlar and glass 49-E as the matrix epoxy vinyl ester resin (DERAKANE 411-350). All laminates were formed each with four layers of reinforcements. Depending on the hybrid fabric, all the influencing factors mentioned above have been studied for laminates. All laminates were manufactured industrially used being the lamination process manual (hand-lay-up). All mechanical characterization and study of the mechanism of fracture (fracture mechanics) was developed for laminates subjected to uniaxial tensile test, bending in three and uniaxial compression. The analysis of fracture mechanisms were held involving the macroscopic, optical microscopy and scanning electron microscopy / Conforme estudos mais atuais, os pl?sticos refor?ados v?m sendo, nos ?ltimos anos, uma alternativa vi?vel na constru??o de elementos estruturais de m?dio e grande porte, desde que a leveza acompanhada de alto desempenho seja poss?vel. A concep??o de comp?sitos polim?ricos h?bridos (combina??o entre tipos diferentes de refor?os) pode possibilitar aplica??es estruturais dos mesmos, frente ?s mais adversas condi??es de servi?os. Dentro dessa classe de materiais comp?sitos, os refor?ados a base de tecidos h?bridos de alto desempenho v?m tomando espa?o quando a sua aplica??o requer alto suporte de carga e alta rigidez. O objetivo desse trabalho de investiga??o ? o estudo da influ?ncia que esses tecidos trazem na concep??o desses materiais quanto a sua caracteriza??o mec?nica e mecanismos de fratura envolvidos. Alguns par?metros associados ao processo e/ou forma de hibridiza??o se destacam como fatores influenciadores no desempenho final do material tais como a presen?a de anisotropia, forma da trama tecido, processo de confec??o dos mesmos, geometria normativa dos corpos de prova, entre outros. Neste sentido, quatro laminados comp?sitos foram desenvolvidos ? base de tecidos de refor?os h?bridos envolvendo fibras de carbono AS4, kevlar 49 e vidro-E e como matriz a resina ep?xi ?ster vin?lica (DERAKANE 411-350). Todos os laminados comp?sitos foram constitu?dos com quatro camadas de refor?os. Dependendo do tipo de tecido h?brido, todos os fatores influenciadores acima mencionados foram estudados para os laminados. Todos os laminados foram fabricados industrialmente sendo empregado o processo de lamina??o manual (hand-lay-up). Todo o estudo da caracteriza??o mec?nica e do mecanismo de fratura (fratura mec?nica) foi desenvolvido para os laminados submetidos aos ensaios mec?nicos de tra??o uniaxial, flex?o em tr?s e compress?o uniaxial. As an?lises dos mecanismos de fratura foram realizadas envolvendo a macroscopia, microscopia ?tica e eletr?nica de varredura