Recent developments in multi-layer flat knitting technology for waste free production of complex shaped 3D-reinforcing structures for composites

Trümper, Wolfgang; Lin, Huangmei; Callin, Tim; Bollengier, Quentin; Cherif, Chokri; Krzywinski, Sybille

doi:10.1088/1757-899x/141/1/012015

Cited by 8 publications

(6 citation statements)

References 2 publications

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“…In the evaluation and mechanical testing of these structures, it becomes clear that the structure and arrangement of the reinforcing fibers within the weft-knitted mesh structure in particular have a negative effect on the properties of the panels made from them. An approach to remedy this deficit is described by Trümper et al 21 whereby the developed knitted structures are reinforced by additionally introduced yarn systems with stretched lengthwise and crosswise yarns, thereby achieving significantly better mechanical properties in the FRP. In addition to knitting technology approaches, lightweight panels can likewise be manufactured on the basis of warp-knitting technology, as described in a study by Liu et al 22 and Yu et al 23 The extension of these approaches is presented by Franz 24 and Dallmann et al, 25 where the knitted spacer structures have been reinforced by additional yarn systems in analogy to the work of Trümper et al…”

Section: Introductionmentioning

confidence: 99%

Lightweight panels with high delamination resistance made of integrally woven truss-like fabric structures

Vorhof

Sennewald

Schegner

et al. 2023

Journal of Industrial Textiles

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Lightweight panels are of high relevance for various applications, such as automotive, aerospace, civil engineering, and achieve high stiffnesses and strengths at low self-weight. The sandwich principle is commonly used to manufacture the panels, although conventional materials and reinforcement structures often limit the design and application of the panels in a wide range of possible applications. The reason for this is that lightweight panels fail either under combined compressive/shear loading or as a result of delamination of the individual layers. In this article, novel fabric structures are presented as a basis for the fabrication of lightweight panels that effectively overcome these deficiencies. These fabrics have a spatial truss-like structure, with the core and top layer being connected by continuously running reinforcing fibers. This results in high panel stability and high delamination resistance, which are evaluated in this article using mechanical tests in compression, flexure and combined tension-shear. The results are related to sample panels with conventional honeycomb core as reference. The high potential and excellent delamination resistance of the new fabric-based lightweight panels is shown in the result of the tests.

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Section: Introductionmentioning

confidence: 99%

Lightweight panels with high delamination resistance made of integrally woven truss-like fabric structures

Vorhof

Sennewald

Schegner

et al. 2023

Journal of Industrial Textiles

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show abstract

“…Shape adaptability can reduce the structural instability caused by tailoring and splicing; Compared with woven fabric, weft knitted fabric has greater shear resistance, better impact toughness and interlaminar strength, less delamination damage and better open hole processing performance. 16 At the same time, the knitting technology has the advantages of wide range of raw materials, high efficiency, diverse products, low cost. 17 Fabric liners have been applied in production practice, therefor, weft knitted fabrics with excellent tribological performance have tremendous potential in engineering application.…”

Section: Introductionmentioning

confidence: 99%

“…This structure makes weft knitted fabrics have good shape adaptability and excellent deformability, and can be fabricated into two‐dimensional, three‐dimensional shape (such as shell and helmet). Shape adaptability can reduce the structural instability caused by tailoring and splicing; Compared with woven fabric, weft knitted fabric has greater shear resistance, better impact toughness and interlaminar strength, less delamination damage and better open hole processing performance 16 . At the same time, the knitting technology has the advantages of wide range of raw materials, high efficiency, diverse products, low cost 17 .…”

Section: Introductionmentioning

confidence: 99%

Surface performance of weft‐knitted fabric composites reinforced with polytetrafluoroethylene fibers

Dong

Zhang

et al. 2021

J of Applied Polymer Sci

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With excellent frictional property, fabric liners are widely employed in automotive, aerospace, and so forth. Weft-knitted fabric composites with single-layer and double-layer fabric structure were prepared by utilizing polytetrafluoroethylene (PTFE), Nomex, and polyester multifilament. The weftknitted fabric composites are expected to combine PTFE low friction coefficient and Nomex magnificent mechanical property, which has potential in manufacturing fabric liners with low friction, easy adhesion, and high wear resistance. Ball-on-disc friction and wear tester, 3D digital microscopy and scanning electron microscopy were applied to test their tribological performance and surface morphology. Fiber friction coefficient was tested, the average friction coefficient, roughness and wear depth of composites were compared and discussed. Results show that PTFE-polyester double-layer structure performs preferable fiction coefficient and good wear resistance. The influence of yarn materials along with their combination form, fabric structure on tribological performance of composites were analyzed. In conclusion, the wear mechanism including resin, fiber, yarn fracture, loop structure damage, PTFE lubricating film formation.

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“…Weft-knitted fabrics offer an excellent formability into complex shapes. In biaxial weft-knitted fabric, yarns are inserted in the warp (wale-wise) and weft (course-wise) directions as a reinforcement [5,6,7,8]. Due to these straight yarns, the mechanical properties of such fabrics are better than those of unreinforced weft-knitted fabrics with the forming capacity still being high.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modelling of the Mechanical Behaviour of Biaxial Weft-Knitted Fabrics on Different Length Scales

et al. 2019

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Weft-knitted fabrics offer an excellent formability into complex shapes for composite application. In biaxial weft-knitted fabric, additional yarns are inserted in the warp (wale-wise) and weft (course-wise) directions as a reinforcement. Due to these straight yarns, the mechanical properties of such fabrics are better than those of unreinforced weft-knitted fabrics. The forming process of flat fabrics into 3D preforms is challenging and requires numerical simulation. In this paper, the mechanical behavior of biaxial weft-knitted fabrics is simulated by means of macro- and meso-scale finite element method (FEM) models. The macro-scale modelling approach is based on a shell element formulation and offers reasonable computational costs but has some limitations by the description of fabric mechanical characteristics and forming behavior. The meso-scale modelling approach based on beam elements can describe the fabric’s mechanical and forming characteristics better at a higher computational cost. The FEM models were validated by comparing the results of various simulations with the equivalent experiments. With the help of the parametric models, the forming of biaxial weft-knitted fabrics into complex shapes can be simulated. These models help to predict material and process parameters for optimized forming conditions without the necessity of costly experimental trials.

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Recent developments in multi-layer flat knitting technology for waste free production of complex shaped 3D-reinforcing structures for composites

Cited by 8 publications

References 2 publications

Lightweight panels with high delamination resistance made of integrally woven truss-like fabric structures

Lightweight panels with high delamination resistance made of integrally woven truss-like fabric structures

Surface performance of weft‐knitted fabric composites reinforced with polytetrafluoroethylene fibers

Numerical Modelling of the Mechanical Behaviour of Biaxial Weft-Knitted Fabrics on Different Length Scales

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