*3.1.2. Triaxial woven fabric*

Triaxial weave structure consists of three yarn sets such as +bias (+warp), -bias (-warp), and filling [44]. These yarn sets make interlacements as in traditional biaxial fabric (Figure 2). The fabric generally has large hexagonal openings between interlacements. Open-reed process used in the fabrication of this type of fabric does not allow making fabrics as dense as a traditional woven fabric. Triaxial fabrics have two variants, namely, loose-weave and tight-weave. It was shown that loose-weave fabric has certain stability and higher shear stiffness in ±45˚ directions when compared to the biaxial fabrics as well as having a more isotropic structure. Quart-axial fabric has four sets of yarns such as +bias, -bias, warp and filling as shown in Figure 2. All yarns are interlaced to each other to form the fabric structure [45]. Warp yarns are inserted to the fabric at selected places to increase directional strength and stiffness properties. Therefore the fabric structure can be tailored to fulfill various enduse requirements.

**Figure 2.** Triaxial woven fabrics (a) loose fabric (b) tight fabric (c) one variant of triaxial woven fabric, and (d) quartaxial woven fabric [44, 45].

## *3.1.3. Braided fabric*

Two-dimensional braided fabrics are extensively used in industrial textiles and composites. It has one yarn set, braiders oriented in +θ and –θ directions. In order to produce the fabric surface shown in Figure 3, braiders are intertwined with each other. Basic braid patterns that can be produced by traditional methods are diamond, regular and hercules braid [46]. The 2D braided fabric reinforced composite fabrication is similar to that of 2D woven composites. Multiple braided fabrics can be stacked one on top of another to produce reinforced compo‐ sites. These composites suffer from yarn crimp and lack through-the-thickness reinforcement (z-yarns) and thus experience delamination leading to a poor impact behavior [4]. In order to overcome the delamination and related problems, 2D fabric layers can be stitched together in the thickness direction to impart out of plane fiber reinforcement. Stitching was shown to substantially decrease delamination but it can lead to a reduction in in-plane properties due to the holes created by stitching needle which act as stress concentration points.

**Figure 3.** (a) Two-dimensional traditional biaxial braided fabric, and (b) triaxial braided fabric [47].
