Braiding angle

Braid angle n. The acute angle measured from the axis of a fabric or rope to a braiding yarn. 

Multilayer fabric n. A fabric for reinforced-plastic structures formed by braiding to and fro or overlapping in one direction. Layers may be biaxial or triaxial, fibers mixed, and braid angles varied. 

Illustration of braided structures (a) 1/1, (b) 2/2, (c) circular braid without core, (d) circular braid with core and (e) idealized geometry showing factors, braid angle a and pick spacing x, which affect mechanical properties of braids. 

Figure 16.5 (a) Triaxial regular braid with braiding angle and (b) same modelled with TexGen [39]. 

To evaluate the braided materials properties three references have been investigated, Ref-55, Ref-45 and Ref-35. The structure was braided layer by layer upon a tubular mandrel with a 50-mm diameter. Four layers were braided on the same mandrel for each reference. The spools rotational velocity was held constant during braiding. As the braid was made of several layers, the thickness of each layer increases the apparent diameter on which the next layer will be braided. For this reason, the take-up speed was adjusted in order to keep the same braid angle from one layer to the next. According to the yam count, tubular mandrel geometry and braiding parameters, the cover factor [40] obtained is close to 100%. 

Table 16.2 Manufacturing parameters and braiding angles layer/layer on tubular braid...

Table 16.3 Influence of cutting and opening on braiding angle...

Figure 16.11 Example of a braid prepared with a 55 degree braid angle.

Figure 10.19b shows the BY path in one braid plait projected onto the braid angle. The BY path is assumed here to be constituted by a cosine. The cosine part can then be expressed using (Eq. (10.25)). 

The first critical gap is situated along the braid axis on a plane that cuts the BYs between the MEYs. This gap depends on the width of the BY situated at mid-diameter ( Byp), the pitch, the number of BY, and the braiding angle. This gap is calculated by the following equation... 

The second critical pitch separates the BYs at the surface of the braid and depends on the BY width at surface ( bys), the braid angle, and the pitch divided by half of... 

The factors influencing the area of material inside the braided preform are the total cross-sectional area (Agy. A -y) of the yarn filaments, the number of yarns in each layer (Ngy. b MEY cy)> the braid angle 9), and the crimp ratio Rq), for the n layers. The yarn filament total cross-sectional area is calculated using the fineness (G, in tex or grams per kilometer) divided by the density (p) of each of the constituents of the yarns. 

In an attempt to understand the breakage of the preform no. 1 and 2, useful braid and beam dimensions can be calculated from the braid model presented here and are presented in Table 10.6. The braid angle and braid thickness are... 

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