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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]

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]

Weaving technique offers a large potential for the highly productive manufacture of woven 3D-preform structures in lightweight applications. This research work reports on the technological modification to the construction of a double-rapier weaving machine for the low damage production of double-walled shell structures made from glass/polypropylene hybrid yarn multilayered woven fabrics. On this basis, 3D-woven preform structures with integrated stiffeners in the longitudinal and transverse directions for high composite strength and rigidity within a single weaving process were developed and implemented.Furthermore, textile engineering solutions were acquired for the required reinforcement of the gusset area between the stiffener and the skin. This broadens the range of uses for large-scale fiber-reinforced plastics with integrated stiffeners made from 3D-woven preform structures. [ABSTRACT FROM PUBLISHER]

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]

This article reports on the development of thermoplastic composites using innovative curvilinear 3D multi-layer flat knitted spacer fabrics produced by single stage manufacturing. Thermoplastic composites from textile-based, complex-shaped sandwich preforms, for instance, curvilinear-shaped 3D multi-layer spacer fabrics show great potential for lightweight applications. Faster production time and reduction of waste can be achieved by single stage manufacturing of such 3D textile preforms. Spacer-shaped 3D textile preforms were developed using commingled hybrid yarns made of GF and PP filaments. This 3D spacer fabric was consolidated to 3D composite using the developed mechanical tools. In order to predict the mechanical performance of 3D composites, mechanical properties of reinforcement yarns unraveled from 3D spacer fabrics, 2D knit fabrics, and 2D composites using the 2D knit fabrics produced in the same manner as the individual layers of 3D spacer fabrics were studied. The results are promising for applications in high-performance composites. [ABSTRACT FROM AUTHOR]

Abstract: Due to their improved mechanical properties, 3D multi-layer spacer fabrics could be used for lightweight applications such as textile-based sandwich preforms. Modern flat knitting machines using high performance yarns are able to knit complex 3D multi-layer spacer fabrics consisting of individual surface and connecting layers. This paper reports on the development of 3D flat knitted spacer fabric for 3D thermoplastic composites using hybrid yarns made of glass (GF) and polypropylene (PP) filaments. Moreover, mechanical properties of reinforcement yarns, 2D knit fabrics and 2D composites manufactured using various integration methods of reinforcement yarns were also studied. The integration of reinforcement yarns as biaxial inlays (warp and weft yarns) is found to be the best solution for knitting, whereas the tuck stitches show optimal results. [Copyright &y& Elsevier]