Multiaxial Noncrimp Fabrics

Multiaxial NCF with (1) course-wise and (2) noncourse-wise weft insertion 

Multiaxial warp-knitted NCFs with noncourse-wise weft insertion consist of a current maximum of seven iayers of rovings or spread fiber tows oriented in paral-lei. The orientation of the single-fiber layers can be freely adjusted between -20 to +20° relative to the production direction (angle specification analogous to ENl 3473-1). On the top side of the fabric, an additional 0° layer can be attached. The introduction of two surface fabrics, for example nonwovens, is also possible (Fig. 8.10). The mass per unit area, the structure (closed or open) of the fabric, the material, and the thread count of each layer can be varied individually for each layer. The single-fiber layers are fixed together with a warp yarn. 

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Mulberry spinner 48 Multiaxial fabric 240 Multiaxial noncrimp fabrics 244 Multiphase loom 162... 

DOSs are unique multiply fabrics (Au, 2011). In these sfructures, straight ends of absolutely parallel and noncrimped yams are inserted into the stmctures at different angles (Raz, 1988). With these techniques, fabric properties can be engineered to enhance the in-plane properties only in the required orientations, thereby offering the produced fabric the ideal combination of excellent mechanical properties and cost-effective production. DOSs normally include mono-, bi-, tri-, and multiaxial stmctures, which can be produced with weft knitting or warp knitting technologies. 

Weft-knitted NCF can be produced as biaxial and multiaxial fabrics or as two- and three-dimensional near-net-shape textile structures. Warp and weft threads out of rovings are superposed and fixed together with loop systems. Due to the course-wise weft insertion the reinforcing threads remain noncrimped. Through the combination of weft insertion over the entire width or part of the width with or without support of a stitch-transferring device and by changing loop sizes on individual needles, three-dimensional near-net-shape preforms can be produced (Hufenbach, 2007). 

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