Knitted reinforcement

The tensile and compressive properties of knitted fabric composites are poor in comparison with the other types of fabric already discussed, but they are more likely to be chosen for their processability and energy-absorbing characteristics than their basic in-plane properties. 

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If the filaments are unidirectional oriented the strength of the composite is of the order of that of the filament it may be tenfold the strength of the matrix. A composite may be stronger than a metal in one direction. With a three-dimensional woven or knitted reinforcing network it may be stronger than metals in all directions. The adhesion between the components is crucial. 

Manufacturers of composite structures have traditionally used prepreg tape to manufacture structural components. Fibres are initially combined into unidirectional tows (bundles) of fibres combined into fabrics, e.g. by weaving or knitting. The vast majority of the tows employed in woven, braided or knitted reinforcements comprise low twist or untwisted continuous filament yams. Three-dimensional technical textiles can be produced by weaving [5], knitting [6] and braiding [7] or as non-crimp fabrics. 

Flexible knitted reinforcement for complex shapes Syncoflex (from Syncoglas), provides a regular strength distribution across the whole surface (virtually equal values in all directions). The reinforcement has many holes allowing quick and thorough wetting out. 

Fig. 1.7 Schematic diagrams of (a) weft-knitted and (b) warp-knitted reinforcement. Reprinted from Ramakrishna S. Composites Sci Technol 1997 57 1-22, with permission from Elsevier Science. ...

Knitted reinforcements Jones FR ed.. Handbook of Polymer—Fibre Composites, Longman Scientific and Technical, Essex, 341, 1994. 

Cylindrical Weave n A type of woven, knitted, or braided sleeve generated as reinforcement in tubular reinforced-plastic structures such as pipe. Typically, the reinforcement will constitute about half the volume of the finished product but it can be much less, as in knit-reinforced garden hose. 

So far, the bulk of literature has concentrated on characterizing the mechanical properties of both thermosetting- - - and thermoplastic-based - knitted composite materials. The modeling of the mechanical properties (mainly stiffness and tensile) has also been popular. However, limited literature exists on the forming property characteristics of knitted fabric-reinforced thermoplastics - and their processing properties are still poorly understood. In fact, most of the literature on forming properties deals with unidirectional, - mostly woven and, to a lesser extent, braided reinforcements, rather than knitted reinforcements. 

The flexible, tubular hner of a CIPP is typically made of polyester fabric that is a needled, woven or knitted reinforced fibre sheet using carbon, glass or aramid fibres or a combination of both. Depending on its application, the hner is coated with an impervious film such as polyethylene for the transport of drinking water or polyester for gas pipes. Other coatings include urethane and polyvinyl chloride (PVC). The final smooth surface reduces the surface friction and provides an additional corrosion barrier for the pipe. Liner tube sizes range from 100 to 2500 mm in diameter with... 

A large variety of hose constructions are produced by the rubber industry for a wide range of applications. To contain transported liquids, usually under pressure, it is necessary to reinforce the hose construction with fabric, yam or short fibres to constrain expansion of the rubber. Although hand-built construction using fabric still represents a proportion of the production, it is also very common to use yams either braided or knitted directly onto the hose liner. For heavy duty purposes it is also necessary to use wire, in a braided form, to either reinforce or protect the hose from external damage. Use of short fibres as reinforcement represents a small proportion of hose production and requires specialised dies for extrusion to orientate the fibres circumferentially. 

A former having roughly the shape of the article to be moulded is immersed in a suitable liquid compound that forms a deposit onto the former, which is possibly heated to ease the increase in thickness of the deposit. The former can be first sheathed with a knitted fabric to reinforce the dipped polymer. This process is used in special cases ... 

D reinforcing products mats, woven or knitted fabrics, braidings from yarns or rovings. 

Ko, F.K., Oastorc, C.M., Yang, J.M. and Chou, T.W. (1986). Structure and properties of multi-layer, multidirectional warp knit fabric reinforced composites. In Composites 86 Recent Advances in Japan and the United Slates, Japan Society for Composite Materials, Tokyo. 

To attract new adherents and political allies, social movement actors must construct collective action frames that resonate with the audiences they re attempting to mobilize (Snow and Benford 1988). For this very practical reason, most collective action frames are knit from existing cultural resources—the values, beliefs, and ideas that are embedded in cultural tradition. Collective action frames are not, in other words, cut primarily from new cloth. Rather, they are stitched together from the old and familiar. However, frames constructed from the existing popular culture may reinforce complacency rather than inspire action to the extent that they embody and reflect normative social arrange-... 

Many film adhesives have a supporting carrier or reinforcement fabric incorporated into the adhesive to improve handling of the film and provide control of bond line thickness. The carriers are usually glass, polyester, or nylon fabrics of knitted, woven, or nonwoven construction. The difficulty with such carriers is that they can provide an effective way of moisture entering the bulk of the adhesive. Moisture can wick along the fiber-adhesive interface. Nylon carriers should especially be reviewed since they have a strong tendency to absorb moisture. 

Since for the application of fibres in textile products (knitted and woven products, tire yam canvas, reinforcement of plastics) a high specific weight is a disadvantage, it is customary also to express modulus and strength in another way, viz. as specific quantities this is done by division of E and a by the density p.E/p and a/p have the dimension Nm/kg = J/kg. In order to relate these quantities to the yarn count number (expressed in Tex), the specific quantities are also expressed in N/tex. 

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