Innovative 3D spacer fabrics made from individual planes and connecting layers present great potential as complexly shaped textile preforms in lightweight composite applications. As one of the most flexible textile manufacturing methods, flat knitting enables the production of intricately shaped textile structures. The major advantages coupled with flat knitting techniques include the ability to produce multi-layer reinforcements, a diminishing waste, reducing production time and near-net shaping. This research includes the further development of flat knitting technology and the manufacturing processes of innovative, customized 3D spacer fabrics for high performance composite applications. Novel 3D spacer fabrics have been developed in different geometries using glass-polypropylene commingled hybrid yarns for complex shaped thermoplastic composite components. Reinforcement yarns have been integrated into spacer fabric structures with up to 4 reinforcement layers to improve mechanical performance. Furthermore, the successful addition of “sensor networks” created by integrating functional yarns into the 3D spacer fabrics could be used for structural health monitoring. Innovative integration concepts, which accommodate different positioning of the reinforcement yarns into the knit structures, can be used to adjust the mechanical properties of the finished knit composites. Moreover, the tensile properties have been accurately predicted based on the mathematical models formulated. The developed flat knitted 3D spacer fabrics are very promising for applications in lightweight composites, mechanical engineering, protective textiles, civil engineering and architectural designs. / Innovative 3D-Spacer Fabrics bestehend aus individuellen Deckflächen und Verbindungsstegen bieten ein großes Potential als komplex geformte textile Halbzeuge für Leichtbauverbundwerkstoffanwendungen. Mit Hilfe des Flachstrickens, welches einer der flexibelsten textilen Herstellungsprozesse ist, lassen sich komplex geformte textile Strukturen herstellen. Belastungsgerechte Verstärkungen, Abfallreduzierung, endkonturnahe Fertigung sind nur einige der großen Vorteile der modernen Flachstricktechnik. Die Forschungsarbeit beinhaltet die Entwicklung der Flachstricktechnologie und des Herstellungsprozesses für innovative 3D-Spacer Fabrics für Hochleistungsverbundwerkstoffe. Neuartige 3D-Spacer Fabrics wurden in unterschiedlichen Geometrien entwickelt, in dem Glas-/ Polypropylen Commingling-Hybridgarn für komplex geformte thermoplastische Verbundwerkstoffkomponenten eingesetzt wird. Verstärkungsfäden wurden für hochmechanische Belastungen in die Spacer-Fabric-Strukturen in bis zu 4 Verstärkungschichten integriert. Die erfolgreiche Umsetzung und Entwicklung von Sensornetzwerken durch die Integration von funktionalen Fäden in die 3D-Spacer Fabrics kann für die strukturelle Zustandsüberwachung genutzt werden. Die innovativen Integrationskonzepte erlauben die differenzierte Orientierung von Verstärkungsfäden in den Gestrickstrukturen, wodurch eine starke Beeinflussung der mechanischen Eigenschaften der Gestrickverbundwerkstoffe herbeigeführt wird. Darüber hinaus wurden die Zugeigenschaften basierend auf den entwickelten mathematischen Modellen vorhergesagt. Die entwickelten flachgestrickten 3D-Spacer Fabrics sind sehr vielversprechend beispielweise für die Anwendung in Leichtbauverbundwerkstoffen, im Maschinenbau, in Schutztextilien, im Bauingenieurwesen und Architekturdesign.

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.

Innovative 3D spacer fabrics made from individual planes and connecting layers present great potential as complexly shaped textile preforms in lightweight composite applications. As one of the most flexible textile manufacturing methods, flat knitting enables the production of intricately shaped textile structures. The major advantages coupled with flat knitting techniques include the ability to produce multi-layer reinforcements, a diminishing waste, reducing production time and near-net shaping. This research includes the further development of flat knitting technology and the manufacturing processes of innovative, customized 3D spacer fabrics for high performance composite applications. Novel 3D spacer fabrics have been developed in different geometries using glass-polypropylene commingled hybrid yarns for complex shaped thermoplastic composite components. Reinforcement yarns have been integrated into spacer fabric structures with up to 4 reinforcement layers to improve mechanical performance. Furthermore, the successful addition of “sensor networks” created by integrating functional yarns into the 3D spacer fabrics could be used for structural health monitoring. Innovative integration concepts, which accommodate different positioning of the reinforcement yarns into the knit structures, can be used to adjust the mechanical properties of the finished knit composites. Moreover, the tensile properties have been accurately predicted based on the mathematical models formulated. The developed flat knitted 3D spacer fabrics are very promising for applications in lightweight composites, mechanical engineering, protective textiles, civil engineering and architectural designs. / Innovative 3D-Spacer Fabrics bestehend aus individuellen Deckflächen und Verbindungsstegen bieten ein großes Potential als komplex geformte textile Halbzeuge für Leichtbauverbundwerkstoffanwendungen. Mit Hilfe des Flachstrickens, welches einer der flexibelsten textilen Herstellungsprozesse ist, lassen sich komplex geformte textile Strukturen herstellen. Belastungsgerechte Verstärkungen, Abfallreduzierung, endkonturnahe Fertigung sind nur einige der großen Vorteile der modernen Flachstricktechnik. Die Forschungsarbeit beinhaltet die Entwicklung der Flachstricktechnologie und des Herstellungsprozesses für innovative 3D-Spacer Fabrics für Hochleistungsverbundwerkstoffe. Neuartige 3D-Spacer Fabrics wurden in unterschiedlichen Geometrien entwickelt, in dem Glas-/ Polypropylen Commingling-Hybridgarn für komplex geformte thermoplastische Verbundwerkstoffkomponenten eingesetzt wird. Verstärkungsfäden wurden für hochmechanische Belastungen in die Spacer-Fabric-Strukturen in bis zu 4 Verstärkungschichten integriert. Die erfolgreiche Umsetzung und Entwicklung von Sensornetzwerken durch die Integration von funktionalen Fäden in die 3D-Spacer Fabrics kann für die strukturelle Zustandsüberwachung genutzt werden. Die innovativen Integrationskonzepte erlauben die differenzierte Orientierung von Verstärkungsfäden in den Gestrickstrukturen, wodurch eine starke Beeinflussung der mechanischen Eigenschaften der Gestrickverbundwerkstoffe herbeigeführt wird. Darüber hinaus wurden die Zugeigenschaften basierend auf den entwickelten mathematischen Modellen vorhergesagt. Die entwickelten flachgestrickten 3D-Spacer Fabrics sind sehr vielversprechend beispielweise für die Anwendung in Leichtbauverbundwerkstoffen, im Maschinenbau, in Schutztextilien, im Bauingenieurwesen und Architekturdesign.

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.