From Warp-Knit to Multiaxial Fabric

The conventional principle for the production of warp-knitted fabrics has been explained in Chapter 5. Such warp-knitted fabrics are characterized by, among other things, their extremely elastic and direction-dependent behavior when subjected to tensile stress (Fig. 8.2). 

For the production of composites, it is normally desired that textiles used for reinforcement possess great tensile strength and an extreme stiffness. The Young s modulus of textiles has to be significantly higher than that of the matrices used (for example, plastics). Conventional warp-knitted fabrics cannot fulfill these demands. Therefore, weft-reinforced, warp-knitted fabrics (Fig. 8.3) were developed to increase the stiffness of warp-knitted fabrics. 

Production of monoaxiai reinforced warp-knitted fabrics (LiBA, 2010) 

The reinforcement threads that are oriented at an angle to the direction of production are connected to one another by stitches. Essentially, such a monoaxial-rein-forced textile has the demanded strain only in the longitudinal direction of the reinforcement threads because only this orientation has the required stiffness. An additional reinforcing direction can be achieved by the insertion of stationary yarns (also called standing ends Fig. 8.4). 

---