*3.2.5. Multiaxis woven fabric*

layers to form double picks. Z-yarns lock the other two yarn sets and provide structural

**Figure 12.** (a) Schematic view of 3D orthogonal woven unit cell (b) 3D woven carbon fabric preform [60, 62].

The 3D angle interlock is another type of 3D woven fabric that is produced by 3D weaving loom [63]. The fabric has a total of four yarn sets namely filling yarns, +bias yarns, -bias yarn, and stuffer (warp) yarns. Bias yarns are oriented in the thickness direction. There are two types of this fabric structure such as layer-to-layer and through-the-thickness as shown in Figure 13. In layer-to-layer fabric, bias yarns travel between two successive fabric layers making interlacements with several filling yarns according to the weave pattern. In through-thethickness fabric, on the other hand, bias yarns take a straight path along the fabric thickness until reaching to the top or bottom surface and then reverse its movement to make the same travel until reaching the other surface (Figure 13). This zig-zag movement continues across the fabric length. Bias yarns are locked by several filling yarns in the process depending upon the

**Figure 13.** General view of the five-layer computer aided drawing of traditional (a) 3D angle interlock (b) 3D through-

Three-dimensional circular weaving (i.e., 3D polar weaving) and fabric was developed [64]. The preform has mainly three sets of yarns such as axial, radial and circumferential as shown in Figure 13. In addition, central yarns are inserted to form the rod. Circumferential yarns are laid between adjacent axial yarn layers, whereas radial yarns are inserted between adjacent

the-thickness, and (c) 3D circular orthogonal woven preform structures [60, 61].

axial yarn layers in radial direction.

integrity.

94 Non-woven Fabrics

number of layers [60].

Multiaxis 3D woven fabric, method and machine based on lappet weaving principals were developed by Ruzand and Guenot [65]. The fabric is composed of four yarn sets i.e., +bias, bias, warp, and filling. Bias yarns are oriented across the fabric width. They are placed on the top and bottom surfaces of the fabric and are kept in place by selected weft yarns that are interlaced with warp yarns. Other warp and weft yarns are interlaced together forming the middle layers of the structure.

Uchida et al. [66] developed a five-axis 3D woven fabric. This fabric is composed of five yarn sets such as +bias, -bias, filling, warp, and z-yarn. The fabric is made up of four layers and sequences i.e., +bias, –bias, warp and filling from top to bottom. All the layers are fixed by zyarns. Mohamed and Bilisik [30] developed a multiaxis 3D woven fabric, method and machine. The fabric is made up of five yarn sets such as +bias, -bias, warp, filling, and z-yarn. ±Bias yarns are placed on the front and back face of the structure. These yarns are locked to the other yarn sets by the z-yarns (Figure 14). Many of the warp yarns, on the other hand, lay at the center of the preform. This structure can enhance the in-plane properties of the resulting composites.

**Figure 14.** (a) The unit cell of multiaxis fabric (b) Top surface of multiaxis small tow size carbon fabric [30, 67].

Bilisik [28] developed a multiaxis 3D circular woven fabric, method and machine. The schematic view of the preform is shown in Figure 15 together with a real aramid preform structure. The 3D circular woven fabric consists of axial and radial yarns along with circum‐ ferential and ±bias layers. The axial yarns (warp) are arranged in radial rows and circumfer‐ ential layers within the required cross-sectional shape. ±Bias yarns are placed at the outside and the inside ring of the cylinder surface. Filling (circumferential) yarns lay between each helical corridor of warp yarns. Radial yarns (z-fiber) were locked to the all yarn sets to form the cylindrical 3D preform. Cylindrical preform can be made with thin and thick wall sections depending upon end-use requirements.

**Figure 15.** (a) The unit cell of multiaxis 3D circular woven fabric (b) Multiaxis 3D aramid circular woven fabric [28, 68].

## *3.2.6. Three-dimensional fully braided fabric*

Florentine developed a 3D braided preform and a method [69]. The preform is layered and yarns are intertwined with each other according to a predetermined path. Yarn travels through the thickness of the fabric and is biased such that the width of the fabric is at an angle between 10˚ and 70˚. The representative and the schematic views of the 3D braided preform with yarn paths are shown in Figure 16.

**Figure 16.** (a) Unit cell of 3D braided preform (b) braider yarn path on the edge and inside of the 3D representative braided preform with 4 layers (left) and 6 layers (right) [70], and (c) schematic views of 3D braided I-beam preform [71].

Tsuzuki [71] developed various 3D sectional braided preform in which four yarn carriers can surround a rotor and move in four diagonal directions. The addition and subtraction of braider yarns allow the making of various fabric geometries such as I-beam, H-beam, TT-beam etc.

#### *3.2.7. Three-dimensional axial braided fabric*

The 3D circular axial braided preform can be manufactured by maypole technique which requires two yarn sets such as warp (axial) and braider yarns. The axial yarns are fixed and the braiders intertwine with axial yarns by making radial movements along circumferential paths. This allows more flexibility in the preform size, shape and microstructure. This type of braided structure is also called "solid braided fabric," as shown in Figure 17 [72].

**Figure 17.** Solid braid fabrics (a) 4×4 axial braided fabric (b) axial round core braided fabric, and (c) axial spiral core braided fabric [72].

A tubular fabric with a helical structure was developed by Brookstein et al. [73]. This fabric is made up of warp (axial) yarns and braiders (±bias yarns) (Figure 18). Each axial yarn is held in place by braiders through an intertwine-type pattern. It is well suited to produce thick tubular structures and also has a potential for other geometries with a mandrel. Another 3D braided preform in a 1×1 braid pattern was developed. The braider carrier and the axial yarns are arranged in a matrix of rows and columns. The braider yarns are intertwined around each axial yarn row and column to the through-the-thickness direction as shown in Figure 18. McConnell and Popper developed a 3D axial braided fabric with a layered structure [74]. The fabric consists of axial and braider yarns. Axial yarns are positioned with regard to a predetermined cross-section whereas braider yarns travel through the gaps between axial yarns in the row and column directions. In this way, the braided yarns are intertwined to make a bias orientation through the thickness and on the surface of the structure.

**Figure 18.** (a) Unit cell of the 3D braided preform [73], (b) 3D axial braided preform and unit cell [75], (c) schematic view of 3D axial braided preform [76].

#### *3.2.8. Multiaxis 3D braided fabric*

**Figure 15.** (a) The unit cell of multiaxis 3D circular woven fabric (b) Multiaxis 3D aramid circular woven fabric [28, 68].

Florentine developed a 3D braided preform and a method [69]. The preform is layered and yarns are intertwined with each other according to a predetermined path. Yarn travels through the thickness of the fabric and is biased such that the width of the fabric is at an angle between 10˚ and 70˚. The representative and the schematic views of the 3D braided preform with yarn

**Figure 16.** (a) Unit cell of 3D braided preform (b) braider yarn path on the edge and inside of the 3D representative braided preform with 4 layers (left) and 6 layers (right) [70], and (c) schematic views of 3D braided I-beam preform

Tsuzuki [71] developed various 3D sectional braided preform in which four yarn carriers can surround a rotor and move in four diagonal directions. The addition and subtraction of braider yarns allow the making of various fabric geometries such as I-beam, H-beam, TT-beam etc.

The 3D circular axial braided preform can be manufactured by maypole technique which requires two yarn sets such as warp (axial) and braider yarns. The axial yarns are fixed and

*3.2.6. Three-dimensional fully braided fabric*

*3.2.7. Three-dimensional axial braided fabric*

paths are shown in Figure 16.

96 Non-woven Fabrics

[71].

Multiaxial 3D braided structure is shown schematically in Figure 19. This fabric is constituted from ±braider yarns, warp (axial), filling, and z-yarns. The braider yarns are intertwined with the orthogonal yarn sets to form the multiaxis 3D braided preform. This preform structure has enhanced properties especially in transverse direction. Moreover, it has identical directional Poisson's ratios throughout its structure [77]. Another multiaxial 3D braided structure has ±bias yarns placed in-plane, and warp (axial), radial (z-yarns), and ±braider yarns placed outof-plane [78]. The braider yarns are intertwined with the axial yarns whereas ±bias yarns are oriented at the surface of the structure and locked by the radial yarns to the other yarn sets. Figure 19 shows the multiaxial cylindrical and conical para-aramid 3D braided structures. The properties of the multiaxial 3D braided structure in the transverse direction can be enhanced and the non-uniformity in the directional Poisson's ratios can be decreased [78].

**Figure 19.** (a) The unit cell of multiaxis 3D braided preform [77]; multiaxis 3D braided para-aramid preforms (b) cylin‐ drical Kevlar® preform and (c) conic Kevlar® preform [78].

## *3.2.9. Three-dimensional knitted fabric*

Wunner [32] developed a multiaxis warp knit machine for Liba GmbH. The machine uses a total of four yarn sets such as ±bias, warp and filling. These yarn sets are placed as separate layers and these layers are locked by stitching yarn by using tricot pattern, as shown in Figure 20.

**Figure 20.** Multiaxis warp knit structure [32].
