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Direct preforming processes have potential for fiber-reinforced semi-finished products, creating 3D structures with strong delamination resistance using double-flat-steel-healds. However, the shedding method limits pattern variety, necessitating alternative options for interlacing diversity. One approach is using weft yarn instead of warp yarn for interlacing. This study explores its impact on mechanical properties, focusing on bending behavior, fiber volume content, and micrograph analysis of infiltrated warp and weft interlaced structures. The result shows interesting differences in mechanical behavior regarding different weave types and test direction as well as communalities within the individual structures. [ABSTRACT FROM AUTHOR]

In the textile sector, the sustainable development and production of high-performance and high-quality textiles has become increasingly important. To enable the processing of new yarn materials at high production speeds, the in-depth understanding of the relationships between machine elements, yarn path, and yarn tension is required. Therefore, the aim of this paper is to analyze the interactions between the warp knitting machine unit and the yarn path during the stitch formation process by means of theoretical modeling and experimental investigation. A vector-based model has been developed to describe the kinematic yarn path and its correlation with yarn demand during the stitch formation process. The model is validated by measurements of yarn path and yarn tension on a warp knitting machine. The model is used to identify both machine and yarn guide elements that influence stitch formation. [ABSTRACT FROM AUTHOR]

Processing carbon fiber reinforced thermoplastic parts includes heating to form the thermoplastic matrix. The needed heat can be applied externally or internally to the preform. One possibility to generate intrinsic heat involves the use of carbon fibers as a resistive element to induce joule heat. So far, most research efforts have been based on contacting continuous carbon fibers on both ends to melt the thermoplastic matrix of a pre-impregnated preform. The objective of this project is to use a dry hybrid yarn textile in a one-step process to impregnate and rapidly consolidate the dry textile in less than a minute. The desired molding process is based on joule heating of carbon fibers due to an applied current in the transverse fiber direction. This article focuses on the detection of the involved macroscopic parameters. The first composites produced by means of this new method exhibit a high potential with heating times of 15 s, a void fraction below 1%, and flexural properties comparable to the state of the art. [ABSTRACT FROM AUTHOR]

The Joule heating of carbon fiber-based textiles enables an energy- and cost-efficient processing of carbon fiber reinforced thermoplastic parts. This article introduces a new method to pass direct current into a dry, not pre-consolidated hybrid yarn textile based on recycled carbon fibers and polyamide 6 fibers. The aim is to melt polyamide fibers, subsequently impregnate carbon fibers, and finally consolidate the material to form a composite part in a single process step. To increase the reliability of this technology, the electrical properties and the behavior of the material during the heating process must be thoroughly investigated. It will be addressed how the material is characterized during the process and how the changing resistivity of the textile affects the current flow between the electrodes to generate intrinsic heat. Moreover, a method to determine the effective material resistivity by finite element simulation on the fiber scale based on a CT scan is presented. Thus, a validated material model with respect to the temperature development in the textile based on ρ = ρ (Τ) was established. [ABSTRACT FROM AUTHOR]

Three-dimensional fabrics have an enormous potential for the manufacturing of semi-finished products in a direct preforming procedure for fiber-reinforced materials. The production of these three-dimensional fabrics involves the processing of coarse reinforcing yarns with high warp density. However, conventional weaving looms have not been designed for such applications, and their maximal achievable warp yarn density is therefore severely limited. Friction and clamping between warp yarns impede the shedding process, and fragments of damaged or fibrillated fibers interfere with the weaving process. Most of the solutions for these issues, which has been presented so far, are based on noncommercial technologies or require extensive modification on standard weaving machines. Hence this paper proposes a new shedding method based on double flat steel heddles, which is suitable for the use in conventional weaving looms. The paper gives a detailed description of the new shedding method including the required materials and the technological framework. Furthermore, a suitable algorithm for the fast pattern conversion under consideration of the special technological framework and requirements of the shedding is presented. [ABSTRACT FROM AUTHOR]

Processing carbon fiber reinforced thermoplastic parts includes heating to form the thermoplastic matrix. The needed heat can be applied externally or internally to the preform. One possibility to generate intrinsic heat involves the use of carbon fibers as a resistive element to induce joule heat. So far, most research efforts have been based on contacting continuous carbon fibers on both ends to melt the thermoplastic matrix of a pre-impregnated preform. The objective of this project is to use a dry hybrid yarn textile in a one-step process to impregnate and rapidly consolidate the dry textile in less than a minute. The desired molding process is based on joule heating of carbon fibers due to an applied current in the transverse fiber direction. This article focuses on the detection of the involved macroscopic parameters. The first composites produced by means of this new method exhibit a high potential with heating times of 15 s, a void fraction below 1%, and flexural properties comparable to the state of the art. [ABSTRACT FROM AUTHOR]

Abstract: An innovative weaving technology for the manufacturing of 3D woven double-walled spacer fabrics from high performance hybrid yarns was developed and implemented. Based on the gained technical and technological experience the woven multi-layered structures with load-oriented non-crimp fiber arrangement are realized and improved for high preform stiffness and a reproducible manufacturing. The article provides an overview of the technology for weaving of 3D spacer preforms in one production step with the required machine modifications. Furthermore the advantages of multi-layered woven fabric as well as the development of special pattern to forming and stiffening of the critical areas (joint areas) will be presented. [Copyright &y& Elsevier]

This article focuses on the improved strength and stiffness of woven three-dimensional (3D) spacer fabrics used in fiber-reinforced plastics. The spacer fabrics were manufactured using E-glass/polypropylene (GF/PP) hybrid yarns and are intended for lightweight engineering applications. The two-dimensional (2D) woven fabrics used for the outer layers of 3D spacer fabrics were produced from GF/PP hybrid yarns with different yarn alignments and weft densities. Furthermore, the implemented hybrid yarns and the 2D composites constructed of multi-layer fabrics were tested for mechanical properties. The processing of the GF/PP hybrid yarn, as well as the geometry of the woven fabrics, is proven to strongly influence the mechanical properties of the end composites. Multi-layer fabrics can be used for manufacturing woven 3D spacer fabrics with minimal yarn damage and high mechanical properties. [ABSTRACT FROM PUBLISHER]

Flat knitted spacer fabrics offer a strong potential for complex shape preforms, which could be used to manufacture composites with reduced waste and shorter production times. A reinforced spacer fabric made of individual surface layers and joined with connecting layers shows improved mechanical properties for lightweight applications such as textile-based sandwich preforms. We report the development of different flat knitted spacer fabrics from hybrid yarns consisting of glass filament (GF) and polypropylene (PP) filaments. Moreover, the mechanical properties of these reinforcement yarns and two-dimensional composites manufactured using various knit structures and knitting parameters were also studied. The composite structure with reinforcement yarn in weft direction is found to be the best in this regard. [ABSTRACT FROM AUTHOR]

The systematic analysis and modification of the spinning parameters in Vortex spinning enables the achievement of yarn qualities and yarn structures for the successful use and economic processing on warp knitting machines in connection with a dynamic warp yarn length balancing element. [ABSTRACT FROM AUTHOR]

In this article, the development of the two spacer fabrics on flat knitting machine is described. These fabrics have two outer surfaces connected together with U and V shaped knitted cross-links which are particularly developed for the light weight applications. [ABSTRACT FROM AUTHOR]

The article offers information on the IGF research project 16420 BR which aims to create technical and technological prerequisites for the production of fabrics with twist-free tape yarns. It was found that twists in weft direction can be completely avoided with the desired modifications and a tensile force-controlled pre-coil machine.

The results acquired in this project illustrate ways to achieve an enormous productivity and quality gain as well as an improvement of the exploitation of all material characteristics for dense fabrics made of ribbon-shaped warp yarns. Hence, the application spectrum for this fabric can be extended. These improvements can be realized without much effort already today with components available on the market. With the modifications carried out, a minimization of the free paths between the warp beam and the knitting head, a homogenization of the warp yarn tension, a yarn guidance according to the geometry of the tape yarns from the warp beam to the knitting head as well as the application of special heddles, a significant reduction or entire avoidance of the twists in warp direction can be achieved. [ABSTRACT FROM AUTHOR]