**4.2.1 Production of non-interlaced uniaxial orthogonal 3-D fabrics**

This method of producing an integrated nonwoven 3D fabric F (Figure 19) comprises disposal of axial yarns Z in a grid form and in accordance with the required cross sectional profile, and traversing horizontal and vertical sets of binding yarns X and Y about the corresponding rows and columns of axial yarns in a closed-loop path to bind the fabric directly. The device is essentially composed of a plate (P) having two sets of profiled tracks (D and C) existing in a mutually perpendicular configuration and in the same plane on the front face of the plate (P); two sets of binder yarn spool carriers (K and L); two pairs of tracking arrangement such that each pair is situated at the terminal sides to contain between it all the tracks of sets D and C respectively for guiding the binder yarn carriers in a closed-loop path; and openings (B) in plate (P), arranged in rows and columns, to allow the axial yarns Z to pass through, a creel (J) to supply axial yarns Z, and a fabric take-up unit (H) (Khokar, 2002).

Fig. 19. Production of a uniaxial 3D fabric on a special designed 3D weaving machine (Khokar& Domeij, 1999)

The warp yarns Y are arranged in multiple layers each of which has a number of yarns which run in one horizontal plane in parallel relation with or at an equal space from adjacent yarns that are passed through a reed 1 through number of holes formed therein at uniform intervals in both horizontal and vertical directions. The warp yarns of the respective layers are in vertical alignment, forming regularly spaced vertical warp rows. Weft inserting device 6 comprises a number of elongated picking plates 7 which are spaced from each other at the same distance for secure insertion of wefts into the spaces between the respective layers of the tensioned warp yarns.

fore end loops formed by the two groups of filling yarns, Y1 and Y2, respectively. Preferably, four harnesses, 11a, 11b, 12a, 12b, are used to control two sets of vertical Z yarns, Za-Zd. One of set of Z yarns, Za, Zb, is inserted for the flange portion of the inverted T shape fabric, and the other set of Z yarns, Zc, Zd, is inserted for the web portion of the

This method of producing an integrated nonwoven 3D fabric F (Figure 19) comprises disposal of axial yarns Z in a grid form and in accordance with the required cross sectional profile, and traversing horizontal and vertical sets of binding yarns X and Y about the corresponding rows and columns of axial yarns in a closed-loop path to bind the fabric directly. The device is essentially composed of a plate (P) having two sets of profiled tracks (D and C) existing in a mutually perpendicular configuration and in the same plane on the front face of the plate (P); two sets of binder yarn spool carriers (K and L); two pairs of tracking arrangement such that each pair is situated at the terminal sides to contain between it all the tracks of sets D and C respectively for guiding the binder yarn carriers in a closed-loop path; and openings (B) in plate (P), arranged in rows and columns, to allow the axial yarns Z to pass through, a creel (J)

inverted T cross-sectional shape fabric (Mohamed&Zhang, 1992).

**4.2.1 Production of non-interlaced uniaxial orthogonal 3-D fabrics** 

to supply axial yarns Z, and a fabric take-up unit (H) (Khokar, 2002).

Fig. 19. Production of a uniaxial 3D fabric on a special designed 3D weaving machine

The warp yarns Y are arranged in multiple layers each of which has a number of yarns which run in one horizontal plane in parallel relation with or at an equal space from adjacent yarns that are passed through a reed 1 through number of holes formed therein at uniform intervals in both horizontal and vertical directions. The warp yarns of the respective layers are in vertical alignment, forming regularly spaced vertical warp rows. Weft inserting device 6 comprises a number of elongated picking plates 7 which are spaced from each other at the same distance for secure insertion of wefts into the spaces between

(Khokar& Domeij, 1999)

the respective layers of the tensioned warp yarns.

**4.2 Production of 3D woven fabrics with 3D weaving** 

Fig. 20. Special designed 3D weaving machine that produces a uniaxial 3-D fabric (Fukuta et al., 1974).

In order to pick in weft yarns X and vertical yarns Z into the horizontally and vertically aligned warp yarns, the weft inserting device 6 is first picked transversely or perpendicularly to the warp yarns while maintaining the upper and lower vertical yarn inserting devices 4 and 5 in the upper and lower retracted positions as shown in Figure 20. Each of the weft yarns X being inserted between the warp layers in double fold forming a loop at the fore end thereof. The weft inserting device 6 is temporarily stopped when the looped fore ends of the weft yarns are projected out of the warp yarns on the opposite side for threading a binder yarn P (Fukuta et al., 1974).

As shown in Figure 21, base 10 supports movable upper and lower frames 12 and 13 with holes for supporting a plurality of filaments 15 that extends in the vertical (Z-axis) orientation. Identically working filament feed units 20 and 20' alternately insert yarns in the X- and Y-axes directions, respectively. First, filaments 21 from supply bobbins are woven through the spaced rows between filaments 15 along the X-axis by advancing the needles 22 by pushing rods 25. A pin 30 is inserted in the Y-axis direction to lie across the top of filaments 21 outside the last row of filaments 15 to tamp filaments 21 down. Needles 22 are then retracted from filaments 15, forming a tightly looped first course of Xaxis filaments that is restrained by pin 30. Similarly, the course of Y-axis filaments is woven next by advancing threaded needles 22', inserting pin 30' on top of filament 21' in the X-axis direction and retracting needles 22'. As the filament layers build up, pins 30 and 30' are removed. To increase the fabric's density, all the filament layers are compressed. The fabric integrity results primarily from inter-yarn friction (King, 1976 as cited Khokar, 2002).

In Weinberg's special designed 3D weaving machine, it is possible to form sheds between layers of planar warp yarns, so that the orthogonal weft yarns can easily be inserted in any predetermined directions. Planar warp yarns are threaded through two parallel and perforated plates. The distance between these two plates is enough to accommodate the shedding and weft insertion. The top plate can slide on the warp yarns. The base plate is used to anchor the ends of the warp yarns (Weinberg, 1995).

Fig. 23. Uniaxial (on the right) and multiaxial (on the left) orthogonal fabrics (Khokar, 2002).

A set of linear yarns Z, X, ±θ, arrayed in multiaxial orientation in the directions of the fabric's length, width, and two bias angles respectively, is bound using a set of binding yarns Y in the fabric-thickness direction. The yarns Y could be of either single or double type. The corresponding bindings occur above and under the set of Z, X, ± θ yarns and they form two surfaces of the fabric. The resulting 3D fabric has the three sets of linear yarns X, Y and Z in a mutually perpendicular configuration and, additionally, the linear yarns ± θ in

Anahara (1993) et al, invented a special weaving machine to manufacture a multiaxial orthogonal 3D fabric. In the aforementioned fabric, there are five axes of yarns used to construct the structure. First of all, there are warp yarns used in the length wise direction of the fabric (z). Similarly, there are weft yarns used in the width direction of the fabric (x). The first and second bias yarns B1 and B2 are arranged at an angular relationship of ±45°. In other words, the 3D fabric F has a five axis structure in which fabrics have four axes in one

plane (Figure 24) and are interconnected by the lines of the vertical yarn y.

Fig. 24. Multiaxial 3D woven fabric structure (Anahara et al., 1993).

bias directions (Khokar, 2002).

Fig. 21. King's special designed 3D weaving machine (King, 1976).

Fig. 22. Weinberg's special designed 3D weaving machine (Weinberg, 1995).

#### **4.2.2 Production of non-interlaced multiaxial orthogonal 3D fabrics**

One of the main problems using multilayer woven fabrics in preforms is insufficient inplane and off-axis properties of composites. Conventional weaving machines which are capable of producing multilayer fabrics cannot produce fabrics that contain fibres or yarns orientated at ±45° in the plane of the preform. With conventional machines, it is only possible to manufacture fabrics with fibres or yarns oriented at angles of 0° and 90°. It is also possible to orient the fibres or yarns at angles of ±45° in through the thickness. However, these oriented yarns at the angle of ±45° in through the thickness will not affect the in-plane and off-axis properties of composites in a positive way. The more recent machinery developments have therefore tended to concentrate upon the formation of preforms with multiaxial yarns (Tong et al., 2002).

Fig. 21. King's special designed 3D weaving machine (King, 1976).

Fig. 22. Weinberg's special designed 3D weaving machine (Weinberg, 1995).

One of the main problems using multilayer woven fabrics in preforms is insufficient inplane and off-axis properties of composites. Conventional weaving machines which are capable of producing multilayer fabrics cannot produce fabrics that contain fibres or yarns orientated at ±45° in the plane of the preform. With conventional machines, it is only possible to manufacture fabrics with fibres or yarns oriented at angles of 0° and 90°. It is also possible to orient the fibres or yarns at angles of ±45° in through the thickness. However, these oriented yarns at the angle of ±45° in through the thickness will not affect the in-plane and off-axis properties of composites in a positive way. The more recent machinery developments have therefore tended to concentrate upon the formation of preforms with

**4.2.2 Production of non-interlaced multiaxial orthogonal 3D fabrics** 

multiaxial yarns (Tong et al., 2002).

Fig. 23. Uniaxial (on the right) and multiaxial (on the left) orthogonal fabrics (Khokar, 2002).

A set of linear yarns Z, X, ±θ, arrayed in multiaxial orientation in the directions of the fabric's length, width, and two bias angles respectively, is bound using a set of binding yarns Y in the fabric-thickness direction. The yarns Y could be of either single or double type. The corresponding bindings occur above and under the set of Z, X, ± θ yarns and they form two surfaces of the fabric. The resulting 3D fabric has the three sets of linear yarns X, Y and Z in a mutually perpendicular configuration and, additionally, the linear yarns ± θ in bias directions (Khokar, 2002).

Anahara (1993) et al, invented a special weaving machine to manufacture a multiaxial orthogonal 3D fabric. In the aforementioned fabric, there are five axes of yarns used to construct the structure. First of all, there are warp yarns used in the length wise direction of the fabric (z). Similarly, there are weft yarns used in the width direction of the fabric (x). The first and second bias yarns B1 and B2 are arranged at an angular relationship of ±45°. In other words, the 3D fabric F has a five axis structure in which fabrics have four axes in one plane (Figure 24) and are interconnected by the lines of the vertical yarn y.

Fig. 24. Multiaxial 3D woven fabric structure (Anahara et al., 1993).

Fig. 26. Multiaxial 3D orthogonal woven fabric (Mohamed et al., 1995).

desired fabric length (Mohamed et al., 1995).

In the invention of Mohamed et al., the woven preform consists of multiple warp layers 12, multiple weft yarns 14, multiple z yarns 16 that are positioned in the fabric thickness and ±bias yarns as shown in Figure 26. The ±bias yarns 18 are located at the back and front of the fabric which are connected with the other sets of z yarns. In the manufacturing of this preform, warp yarns 12 are arranged in a matrix of columns and rows based on the required cross-sectional shape. After bias yarns oriented at ±45° to each other on the surface of the preform, weft yarns 14 are inserted between the rows of warp yarns and loops of weft yarns are locked with the help of two selvages at both edges of the fabric. Z yarns 16 are then inserted and passed across each other between the columns of warp yarns 12 to cross weft yarns 14 in place. The weft insertion takes place again as mentioned before and the yarns are returned to their initial positions. Z yarns 16 are now returned to their starting positions passing between the columns of warp yarn 12 by locking ±45° bias yarns 18 and weft yarns in their place. The inserted yarns are beaten up against the fabric formation line and a take up system removes the fabric frm the weaving zone. This is only a one cycle of the machine. By repeating this cycle, 3D multiaxial orthogonal woven fabric can be produced within the

A three-dimensional multiaxial cylindrical woven fabric (Figure 27) having a core, comprises five sets of yarns: axial (14), circumferential (16), radial (18) and two sets of bias yarns (12) that are orientated ±45° with reference to the longitudinal axis of the cylindrical fabric. The bias yarns (12) occur at the outer and inner surfaces. The fabric is produced using a multiaxial circular weaving apparatus (100) that comprises mainly four units: feeding unit (110), machine bed (130), beat-up unit (180) and take-up unit (190). The steps in the operation of the weaving machine are: rotation of positive and negative bias yarn carriers by

Fig. 25. Multiaxial 3D woven fabric manufacturing method (Anahara et al., 1993).

In the production of such a fabric F, a flat base 1 is used as shown in Figure 25 (a). There are a number of pins 2 that can be unfastened which allows the yarns to be arranged in different axes. The support bar 3 can be disposed between the pins 2 on the base 1. The lines of the weft x, warp z and first and second bias B1 and B2 are arranged in a way that these yarns run between the pins 2 and to be looped back, in engagement with those pins 2 which are located along the peripheral portion of the base 1. The weft layer, warp layer and bias yarn layers are inter-laminated in order. Firstly, the lines of warp yarns z are arranged in parallel in the length wise direction of the fabric in a way that they are being repeatedly looped back and forth around the pins 2 as shown in Figure 25 (b). Similarly, the lines of weft yarns x are arranged in parallel in the width direction of the fabric in such a way that they are being looped back and forth around pins 2 located at the right and left sides of the base 1 shown in Figure 25 (c). as shown in Figure 25(d), the lines of bias yarns B1 are inserted at an angle of +45° with respect to the lengthwise direction of the fabric while being repeatedly looped back and forth around the pins 2. Similarly, the lines of bias yarns B2 are inserted again in the length wise direction of the fabric that are being repeatedly looped back and forth around pins 2 however at the angle of -45° as shown in Figure 25(e). After the individual layers are completed one on another in a predetermined order, the pins 2 are removed from the base and are replaced by vertical warp yarns y through a needle Figure 25(f and g) (Anahara et al., 1993).

Fig. 25. Multiaxial 3D woven fabric manufacturing method (Anahara et al., 1993).

(Anahara et al., 1993).

In the production of such a fabric F, a flat base 1 is used as shown in Figure 25 (a). There are a number of pins 2 that can be unfastened which allows the yarns to be arranged in different axes. The support bar 3 can be disposed between the pins 2 on the base 1. The lines of the weft x, warp z and first and second bias B1 and B2 are arranged in a way that these yarns run between the pins 2 and to be looped back, in engagement with those pins 2 which are located along the peripheral portion of the base 1. The weft layer, warp layer and bias yarn layers are inter-laminated in order. Firstly, the lines of warp yarns z are arranged in parallel in the length wise direction of the fabric in a way that they are being repeatedly looped back and forth around the pins 2 as shown in Figure 25 (b). Similarly, the lines of weft yarns x are arranged in parallel in the width direction of the fabric in such a way that they are being looped back and forth around pins 2 located at the right and left sides of the base 1 shown in Figure 25 (c). as shown in Figure 25(d), the lines of bias yarns B1 are inserted at an angle of +45° with respect to the lengthwise direction of the fabric while being repeatedly looped back and forth around the pins 2. Similarly, the lines of bias yarns B2 are inserted again in the length wise direction of the fabric that are being repeatedly looped back and forth around pins 2 however at the angle of -45° as shown in Figure 25(e). After the individual layers are completed one on another in a predetermined order, the pins 2 are removed from the base and are replaced by vertical warp yarns y through a needle Figure 25(f and g)

Fig. 26. Multiaxial 3D orthogonal woven fabric (Mohamed et al., 1995).

In the invention of Mohamed et al., the woven preform consists of multiple warp layers 12, multiple weft yarns 14, multiple z yarns 16 that are positioned in the fabric thickness and ±bias yarns as shown in Figure 26. The ±bias yarns 18 are located at the back and front of the fabric which are connected with the other sets of z yarns. In the manufacturing of this preform, warp yarns 12 are arranged in a matrix of columns and rows based on the required cross-sectional shape. After bias yarns oriented at ±45° to each other on the surface of the preform, weft yarns 14 are inserted between the rows of warp yarns and loops of weft yarns are locked with the help of two selvages at both edges of the fabric. Z yarns 16 are then inserted and passed across each other between the columns of warp yarns 12 to cross weft yarns 14 in place. The weft insertion takes place again as mentioned before and the yarns are returned to their initial positions. Z yarns 16 are now returned to their starting positions passing between the columns of warp yarn 12 by locking ±45° bias yarns 18 and weft yarns in their place. The inserted yarns are beaten up against the fabric formation line and a take up system removes the fabric frm the weaving zone. This is only a one cycle of the machine. By repeating this cycle, 3D multiaxial orthogonal woven fabric can be produced within the desired fabric length (Mohamed et al., 1995).

A three-dimensional multiaxial cylindrical woven fabric (Figure 27) having a core, comprises five sets of yarns: axial (14), circumferential (16), radial (18) and two sets of bias yarns (12) that are orientated ±45° with reference to the longitudinal axis of the cylindrical fabric. The bias yarns (12) occur at the outer and inner surfaces. The fabric is produced using a multiaxial circular weaving apparatus (100) that comprises mainly four units: feeding unit (110), machine bed (130), beat-up unit (180) and take-up unit (190). The steps in the operation of the weaving machine are: rotation of positive and negative bias yarn carriers by

weft yarns Y and grid-like warp yarns Z. Then the warp yarns Z are subjected to form a shed in the row-wise direction (Figure 29 (f)) into which horizontal weft yarns X are to be inserted (Figure 29(g)). The result of interlacing horizontal weft yarns X and grid-like warp yarns Z are shown in Figure 29(h). When the operations of column-wise and row-wise shedding are performed sequentially, and the corresponding wefts are inserted backward and forward in the aforementioned sheddings, the structure of plain-weave 3D fabric is

Fig. 28. Fully interlaced 3D woven fabric structure isometric view (a) and orthogonal view

However, these fabrics suffer from the crimp and fibre damage problems (Mohamed & Bogdanovich, 2009). As the shedding operation alternately displaces the grid-like arranged warp yarns Z in the thickness and width directions, two mutually perpendicular sets of corresponding vertical wefts Y and horizontal wefts X are inserted into the created sheds. The warps Z, therefore, interlace with the sets of vertical Y and horizontal X wefts, thus creating a fully interlaced 3D woven fabric. Due to the interlacing, the resulting structure has crimped fibres in all three directions, which would be detrimental for

Fig. 29. Dual-directional shedding and corresponding picking for weaving fully interlaced

potential applications of this type of fabric as a composite reinforcement

formed that is shown in Figure 29(i).

(b) (Fukuta et al., 1982).

3D fabric (Khokar, 2001).

one carrier distance; rotation of circumferential yarn carriers by one carrier distance; moving radial yarn carriers between outer and inner edges of the machine bed; beating-up the inserted yarns; and taking-up the woven preform from the weaving zone (Bilisik, 2000 as cited in Khokar, 2002).

Fig. 27. Multiaxial 3D circular woven fabric structure and apparatus (Bilisik, 2000).
