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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.
1

Development of the Weaving Machine and 3D Woven Spacer Fabric Structures for Lightweight Composites Materials

Badawi, Said Sobhey 22 November 2007 (has links) (PDF)
The need for innovative lightweight materials are rapidly increased in the recent years, owing to their cost-effective, high-strength, environmentally-sound use of materials and process technologies, in addition to that they reduce the weight of a product. The characteristics of 3D-spacer fabrics as one of the most important lightweight materials in future are multifaceted not only owing to its extremely light materials, but also because of exceptionally high stiffness to weight ratio compared to other constructions. It is also one possible method for improving the properties of fabric-reinforced composites. It can enhance the through-the-thickness properties, such as shear strength, dimensional stability, damage, tolerance, and fracture toughness that are critical for many structural applications. Spacer fabric has been employed in high-technology applications because of its critical mechanical properties related to high tensile strength, tear strength and stiffness. Furthermore, its multidirectional structures allow with more reinforcement along the thickness direction leading to an increase in stiffness and strength properties. The fundamental aim of this thesis exists in the development of a new kind of woven spacer fabrics for the light weight composites materials, in an effort to weave spacer fabrics that can not be realized with the old technology which are mentioned above. Therefore, the work in brief focuses on two main goals: 1. Development of a new kind of spacer fabrics for composites in the lightweight constructions. 2. Development of special devices of a narrow weaving machine for standing the process of the new kind of spacer fabrics production. The slippage strength test had to be carried out for the floated warp yarns through the ground fabrics by using different elements of woven fabric structures variables represented in different fabric constructions, different weft densities and different repeats of constructions by using different materials. The importance of this test related to the backward-movement of the floated warp yarns which is the crucial stage in the weaving process of spacer fabrics during the backward-movement. The results of this test determine the required forces for the backward-movement, on the other side it is the best method to observe the behavior of structure elements during the backward movement. The results of the slippage strength had been statistically analyzed, and the weaving process for the spacer fabrics had been achieved. It was concluded that the best properties for the woven spacer fabrics and the optimum case for the weaving process on the test weaving machine had been achieved when the following items are realized: Development of the narrow weaving machine is closed in assisting operations, let-off and take-up and enhancement for take-up processes. Extra let-off and take-up devices must be constructed at the weaving machine. Extra let-off device has to be used for controlling the floated warp yarns of ground fabrics. On the other side, extra take-up and the developed take-up devices have to be used for controlling the woven spacer fabrics. The experimental results give fundamental knowledges for the next steps in research and development of woven spacer fabrics made of high-performance yarns on the wide weaving machine. / Die Ziele der Arbeit bestanden in der Entwicklung der Geometrie der Spacer Fabrics und der notwendigen Falteneinrichtung an der Bandwebmaschine. Spacer Fabrics werden ausschließlich aus zwei Deckflächen, die durch eingewebte Stege verbunden sind, gefertigt. Zur Entwicklung der Spacer Fabrics muss eine Doppelnadel-Bandwebmaschine mit zwei Webfächern eingesetzt werden. Für die Faltenwebeinrichtung werden der entwickelte Extra-Kettablass und der Extra-Abzug benötigt. Der Antrieb und die Steuerung des Extra-Abzuges erfolgen durch einen Synchronantrieb und der Antrieb und die Steuerung des Extra-Ablasses durch Pneumatik.Eine frei programmierbare Steuerung der Faltenwebeinrichtung ermöglicht eine sichere und optimierte Synchronisation zwischen Webprozess und Faltenbildung. Im Ergebnis einer systematischen Strukturentwicklung von Spacer Fabrics und der Simulation ihrer günstigen Herstellung mittles eines speziell entwickelten Slippage Strength Tests werden die optimalen Strukturen ermittelt. Die experimentellen Untersuchungen bringen grundlegende Erkenntnisse für die folgenden Forschungsschritte zur Entwicklung von gewebten Spacer Fabrics mit Hochleistungsgarnen auf Doppelgreiferwebmaschinen.
2

Etude du tissage hybride multicouche : réalisation d’une machine par une approche multiaxes synchronisés / Study of hybrid multilayer fabrics : realization of a machine with a multi-axis synchronized approach

Almohamad, Ramia 07 May 2014 (has links)
Un tissu classique est réalisé par l’entrecroisement de 2 réseaux de fils (appelé armure), un longitudinal, la chaîne et un transversal, la trame. L’introduction des tissus dans les applications techniques a nécessité le développement de réseaux de fils beaucoup plus complexes permettant la réalisation d’entrecroisement en 3D. Toutefois, ces tissus complexes ne sont constitués que de fils textiles de même nature. Dans un futur proche, il sera nécessaire d’entrecroiser d’une part des fils textiles, mais aussi d’autres éléments tels que des capteurs, des tubes d’alimentation liquide, des fils électriques ou tout autre objet. Le but de notre travail est de développer un nouveau concept de machine pouvant répondre à ces nouvelles exigences. Dans le cadre du développement d’un nouveau concept de tissage, nous souhaitons mettre en mouvement les divers mécanismes de la machine à tisser de manière indépendante et remplacer la synchronisation mécanique de ces mécanismes, par une synchronisation électronique. Ce nouveau type de synchronisation permettra de « déstructurer » l’horloge de tissage et ainsi apporter de nouvelles fonctions. La réalisation de cette nouvelle machine a conduit à la conception d’une partie mécanique et d’une partie électronique.L'automatisation développée lors de la réalisation de cette machine est fondée sur la mise en place d'une structure avancée d'automatisation, constituée d’un contrôleur de mouvement, d’un IHM, d’une automate déporté, connectés sur un bus de terrain CANmotion, essayant de répondre au mieux aux besoins des utilisateurs. La flexibilité et la synchronisation électronique présente dans cette machine architecturée autour de cames électroniques, sont les points forts, et laisse la porte ouverte à l'utilisation de cette machine pour de nouvelles applications. En particulier la réalisation de tissus multicouches hybrides complexes. / Woven fabric is basically produced by interlacing two set of threads, warp yarns, or ends, which run lengthwise in the fabric and the filling yarns (weft), or picks, which run from side to side. The traditional system of ends and picks interlacing is identified as a two dimensional weave or pattern. Involving woven fabrics into technical applications require the evolution of advanced patterns in which ends and picks can be interlaced to build a 3D woven fabric. Moreover, these advanced patterns can allow the integration of new elements other than textile yarns such as sensors, liquid-feeding tubes, electric wires, etc. The goal of this study is to develop a new concept of weaving machine that fill these requirements by moving the various mechanisms of weaving machine independently and replacing the mechanical synchronization by an electronic one. Such a new synchronization will take the timing diagram apart and thus to bring new functions. The new concept of the weaving machine lies on two parts; a mechanical part and an electronic part. The developed automation for this new concept is based on an advanced automation structure. This structure is composed of motion controller, IHM, a distance PLC connected to a CANmotion bus to meet the user's needs, this new concept of weaving machine based on electronic cams which is one of the strongest point. This new machine electronically synchronized allows a great flexibility and gives a great opportunity to develop a wide range of new woven fabric structures
3

Development of the Weaving Machine and 3D Woven Spacer Fabric Structures for Lightweight Composites Materials

Badawi, Said Sobhey 06 November 2007 (has links)
The need for innovative lightweight materials are rapidly increased in the recent years, owing to their cost-effective, high-strength, environmentally-sound use of materials and process technologies, in addition to that they reduce the weight of a product. The characteristics of 3D-spacer fabrics as one of the most important lightweight materials in future are multifaceted not only owing to its extremely light materials, but also because of exceptionally high stiffness to weight ratio compared to other constructions. It is also one possible method for improving the properties of fabric-reinforced composites. It can enhance the through-the-thickness properties, such as shear strength, dimensional stability, damage, tolerance, and fracture toughness that are critical for many structural applications. Spacer fabric has been employed in high-technology applications because of its critical mechanical properties related to high tensile strength, tear strength and stiffness. Furthermore, its multidirectional structures allow with more reinforcement along the thickness direction leading to an increase in stiffness and strength properties. The fundamental aim of this thesis exists in the development of a new kind of woven spacer fabrics for the light weight composites materials, in an effort to weave spacer fabrics that can not be realized with the old technology which are mentioned above. Therefore, the work in brief focuses on two main goals: 1. Development of a new kind of spacer fabrics for composites in the lightweight constructions. 2. Development of special devices of a narrow weaving machine for standing the process of the new kind of spacer fabrics production. The slippage strength test had to be carried out for the floated warp yarns through the ground fabrics by using different elements of woven fabric structures variables represented in different fabric constructions, different weft densities and different repeats of constructions by using different materials. The importance of this test related to the backward-movement of the floated warp yarns which is the crucial stage in the weaving process of spacer fabrics during the backward-movement. The results of this test determine the required forces for the backward-movement, on the other side it is the best method to observe the behavior of structure elements during the backward movement. The results of the slippage strength had been statistically analyzed, and the weaving process for the spacer fabrics had been achieved. It was concluded that the best properties for the woven spacer fabrics and the optimum case for the weaving process on the test weaving machine had been achieved when the following items are realized: Development of the narrow weaving machine is closed in assisting operations, let-off and take-up and enhancement for take-up processes. Extra let-off and take-up devices must be constructed at the weaving machine. Extra let-off device has to be used for controlling the floated warp yarns of ground fabrics. On the other side, extra take-up and the developed take-up devices have to be used for controlling the woven spacer fabrics. The experimental results give fundamental knowledges for the next steps in research and development of woven spacer fabrics made of high-performance yarns on the wide weaving machine. / Die Ziele der Arbeit bestanden in der Entwicklung der Geometrie der Spacer Fabrics und der notwendigen Falteneinrichtung an der Bandwebmaschine. Spacer Fabrics werden ausschließlich aus zwei Deckflächen, die durch eingewebte Stege verbunden sind, gefertigt. Zur Entwicklung der Spacer Fabrics muss eine Doppelnadel-Bandwebmaschine mit zwei Webfächern eingesetzt werden. Für die Faltenwebeinrichtung werden der entwickelte Extra-Kettablass und der Extra-Abzug benötigt. Der Antrieb und die Steuerung des Extra-Abzuges erfolgen durch einen Synchronantrieb und der Antrieb und die Steuerung des Extra-Ablasses durch Pneumatik.Eine frei programmierbare Steuerung der Faltenwebeinrichtung ermöglicht eine sichere und optimierte Synchronisation zwischen Webprozess und Faltenbildung. Im Ergebnis einer systematischen Strukturentwicklung von Spacer Fabrics und der Simulation ihrer günstigen Herstellung mittles eines speziell entwickelten Slippage Strength Tests werden die optimalen Strukturen ermittelt. Die experimentellen Untersuchungen bringen grundlegende Erkenntnisse für die folgenden Forschungsschritte zur Entwicklung von gewebten Spacer Fabrics mit Hochleistungsgarnen auf Doppelgreiferwebmaschinen.
4

Etude du tissage de filaments de très faibles diamètres : conception d'une machine de micro tissage / Study of very small diameter filaments weaving : design of a micro weaving machine

Farra, Fadi 21 December 2009 (has links)
Le but du travail est de montrer la faisabilité du tissage de filament de très faible diamètre (de l'ordre de 10 à 25 -tm) et de matières différentes (cuivre, or, polyester...). Les essais du comportement mécanique (traction, fatigue) du micro filament de cuivre ont montré la possibilité du tissage de ce type du filament à cette échelle. A partir de ces résultats, il est possible d'entrevoir des solutions techniques de tissage pour réaliser des tissus à partir de ces filaments. Ce travail a permis donc de concevoir les différentes parties de la machine de micro tissage : système d'alimentation des fils de chame, système de formation de la foule, système d'insertion du fil de trame, système de mouvement du peigne, système d'appel et de stockage du tissu. Le système de formation de la foule de type Jacquard représente le cœur de la machine à tisser. Il lève un verrou technologique persistant depuis de très nombreuses années. Les résultats prometteurs des micros actionneurs fluidiques ont permis de montrer la faisabilité du micro tissage. Ils ont permis également de valider le procédé de la fabrication d'un bloc des plusieurs actionneurs capable de séparer les filaments de chaîne pour former la foule. Le logiciel de contrôle et de dessin conçu permet à la fois de réaliser des armures et de les compiler en format convenable pour pouvoir les transmettre à la carte de contrôle. Cette dernière permet de contrôler les différentes parties de la machine à tisser. / The aim of this work is to demonstrate the feasibility ofweaving filaments of very small diameter (about 10 to 25 -tm) made ofvarious materials (copper, gold, polyester, etc...). The possibility of weaving copper micro filaments at this scale has been proved via the fatigue and traction mechanical tests. According to these results, it was possible to foresee weaving technical solutions to produce fabrics from these micro filaments. This work has permitted the design of the different parts of the micro weaving machine: warp let-off system, warp shedding system, filling insertion system, beat-up system and take-up system. Warp shedding system of Jacquard type represents the heart of the weaving machine. It solved the complicated technical problem ofweaving materials that persists since many years. The positive results of micro fluidic actuators have demonstrated the feasibility of micro weaving. They have also validated the process of manufacturing a block of severa! actuators capable of separating the warp filament's to form the shed. The created software of control and design allows to make weaves and to compile them into a convenient format to be transmitted to the control card. This card controls the different parts of the weaving machine.

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