The possibility of direct preforming in the near net shape of final component structure with load-and shape-conforming fiber orientations is highly essential in composite production, not only to reduce costs but also to attain better mechanical properties and form stability. Based on the concept of varying the reinforcement yarn lengths during the feed-in (warp yarn delivery) and segmented doffing, synchronous working numerically controlled warp yarn delivery and doffing machine modules have been newly developed for multiaxial warp knitting machines to create a resource efficient textile process chain by a single-step, large-scale oriented production of load-and form-conforming warp knitted three-dimensional shell preforms with free-form geometrical surfaces. Such customized preforms in the near component net shape offer higher material utilization and increased lightweight potential.

This paper presents investigations aiming to improve the impregnation of a coating agent and thus increase the mechanical performance of geogrids, especially grid-like non-crimp fabrics (NCF) consisting of carbon fiber heavy tows (CFHT). The squeezing process is industry standard, but the relationship between the machine setting parameters (squeezing pressure and hardness of squeeze roll surface) and the impact on the tensile strength of grid-like NCF is still unexplored. The setting parameters evaluated lead to an increase in tensile strength of up to 10% compared to grid-like NCF coated without the squeezing process. Additionally the first insights into the coating process supported by ultrasonic vibrations based on CFHT single yarns are provided. It is shown that the tensile strength of treated CFHT can be increased by up to 12%, in comparison to CFHT coated without ultrasonic vibrations.

In the wind energy sector, automotive and aviation industries, non-crimp fabrics have been established for many years. Non-crimp fabrics are also increasingly being sought in the construction sector. Due the connection to the concrete, the non-crimp fabrics with a grid-like open structure are used as textile reinforcements. This paper presents the development of alternative stitch-free bonding technologies for non-crimp fabrics based on multiple carbon fiber heavy tows for textile-reinforced concrete components. For this purpose, an initial analysis is carried out to find out the effect of impregnation on the number of roving layers. Further examinations to determine the process-related limits and mechanical process parameters for using this kind of rovings in textile machines are performed on the influence of multiple roving tension on changes width. Finally, the strength of the bonding points of the non-crimp fabrics produced in a laboratory scale is thoroughly investigated by varying the grid geometry, number of roving layers and bonding technology. The investigations show a good potential of the developed bonding technologies for the production of alternative bonded stitch-free non-crimp fabrics. Compared to grid-like open structures, which are connected by stitching threads, the strength of the bonding points can be increased up to 30%, by the developed stitch-free bonding technologies.

Composites have now revolutionized most industries, like aerospace, marine, electrical, transportation, and have proved to be a worthy alternative to other traditional materials. However for a further comprehensive usage, the tailorability of hybrid composites according to the specific application needs on a large-scale production basis is required. In this regard, one of the major fundamental research fields here involves a technology development based on the multiaxial warp-knitting technique for the production of bionic-inspired and application-specific textile preforms that are force compliant and exhibit multi-material design. This article presents a newly developed yarn (warp) path manipulation unit for multiaxial warp-knitting machines that enables a targeted production of customized textile preforms with the above characteristics. The technological development cycle and their experimental validation to demonstrate the feasibility of new technology through production of some patterns for different field of applications are then discussed.

Textile Bewehrungen in Form von bi‐ oder multiaxialen Gittergelegen aus Hochleistungsfilamentgarnen, insbesondere aus Carbon, bieten durch ihre gestreckten Fadenlagen sowie die variablen Anordnungsmöglichkeiten der Verstärkungsgarne ein hohes Festigkeits‐ und Steifigkeitspotenzial entlang der Faserrichtung. Darüber hinaus zeichnen sie sich durch hohe Handhabbarkeit und eine sehr gute chemische Beständigkeit aus. Die bisherigen Forschungen auf dem Gebiet der bautechnischen Verstärkung und Instandsetzung haben gezeigt, dass textile Gitterstrukturen aus Carbongarnen als Bewehrungen im Beton fungieren und eine hervorragende Alternative zur Betonstahlbewehrung sowie Ergänzung zu den bisher verwendeten Verstärkungs‐ bzw. Instandsetzungsmethoden darstellen können. Die Grundlagen für die Entwicklung und Herstellung derartiger textiler Bewehrungen wurden in langjähriger Forschungsarbeit am Institut für Textilmaschinen und Textile Hochleistungswerkstofftechnik (ITM) der Technischen Universität Dresden gelegt und spiegeln im internationalen Maßstab den Stand der Technik auf diesem Gebiet wider. Gleichzeitig wurden am ITM die technischen Voraussetzungen geschaffen, mit modernen und hochproduktiven Multiaxial‐Kettenwirkmaschinen leistungsfähige und anforderungsgerechte Bewehrungsstrukturen unter industriellen Bedingungen fertigen zu können. Diese Textilbewehrungen sind inzwischen in die Industrie überführt worden, haben bereits eine allgemeine bauaufsichtliche Zulassung (abZ) erhalten und werden von TUDATEX GmbH sowie V. FRAAS Solutions in Textile GmbH angeboten.Innovative textile reinforcements for concrete applicationsTextile Reinforcements made of high performance filament yarns in the form of biaxial or multiaxial open‐grid fabrics, esp. carbon, offer high strength and stiffness potential along the fiber direction due to their stretched filament layers and flexible arrangement possibilities of the reinforcing yarns. In addition, they are characterized by high handling capability and excellent chemical resistance. The recent research in the field of structural reinforcements and repair have shown that textile open‐grid fabric structures made of carbon yarns can act as reinforcement in concrete and provide an excellent alternative to the existing concrete steel reinforcement and repair methods. The fundamental work for the development and production of such textile reinforcements have been carried out in many years of research at the Institute of Textile Machinery and High Performance Material Technology (ITM), TU Dresden and is reflects the current state of the art on an international scale. Also, the technical expertise acquired at the ITM enables to produce application‐adapted, high performing textile reinforcements with the help of modern and highly productive multi‐axial warp knitting machines under industrial conditions as well. These textile reinforcements meanwhile have found industrial markets through cooperational activities with TUDATEX GmbH and V. FRAAS Solutions in Textile GmbH. They have received general construction approval as well and are now comercially available.