Three-dimensional fully interlaced woven preforms for composites

Abstract

The aim of this study was to develop three-dimensional (3D) fully interlaced and semi-interlaced representative woven preform structures and to understand the effects of weave pattern and number of layers on 3D woven structures. Various 3D woven preforms were developed. Data generated from these structures included yarn angle, yarn-to-yarn space and density, yarn length and crimp. It was shown that the weave patterns affected the 3D woven preform structures. The yarn-to-yarn spaces of the 3D fully interlaced and semi-interlaced structures were high compared to the traditional 3D woven structures (orthogonal, through-the-thickness and angle interlock) in fabric width due to the interlacement. The 3D plain, twill and satin structures resulted in warp angle (θw) in fabric length and filling angle (θf), and interlaced z-yarn angle (θzi) in fabric width due to the warp–filling and warp–z-yarn interlacements. The weave patterns slightly affected the yarn angles. On the other hand, it was observed that the number of layers considerably affected the z-yarn arc length and the z-yarn length in thickness in the 3D woven structure. The interlacement on 3D plain, twill and satin woven structures resulted in warp crimp, filling crimp and z-yarn crimp. The crimps in the 3D structure fully interlaced and semi-interlaced woven structures slightly depended on the types of weave pattern and the number of layers.

Keywords

three-dimensional representative fully interlaced woven preform three-dimensional plain woven preform three-dimensional twill woven preform three-dimensional satin woven preform z-yarn crimp textile composites

Three-dimensional (3D) textile structural composites are used in various civil and defense areas as they have some improved specific properties compared to basic materials, such as metal and ceramics.^1–6 It was shown that 3D reinforced structures can be considered as alternative materials since they are delamination-free and damage tolerant.^3,7–9 However, they have low in-plane properties due to Z-fiber.^1,2,10 Textile preforms are made by weaving, braiding, knitting, stitching, and nonwoven techniques, and can be chosen, generally, based on the end-use requirements.^2,11–13 Generally, 3D preforms are fabricated by a modified weaving loom, or in some cases by specially designed automated looms, and manufactured to near-net shape to reduce scrap.^12–17

Greenwood¹⁸ modified the traditional weaving loom to make a 3D orthogonal block structure. This arrangement is such that the yarns are firmly bound into the fabric at the upper, lower and two side surfaces. This loom consists of binder and warp beams, a single heald frame and shedding, beat-up, single shuttle and take-up units. Each warp layer is opened by separating bars, allowing weft yarns to be inserted into the structure by the single shuttle, by means of the vertical movement of the single heald frame. Longitudinal binder yarns (z-yarns) are wound through the structure from the top to the bottom and back. Beat-up is achieved by using the traditional reed.¹⁸ Another 3D block structure is formed by repeating a cycle of operations that comprises the following steps: (1) inserting weft yarns that are looped at their fore-ends into spaces between the warp yarns which are aligned parallel in vertical and horizontal directions to provide a number of warp layers and rows; (2) securing the weft yarns by inserting a selvage binder yarn into the weft loops; (3) introducing vertical yarns (z-yarns) into the spaces between the vertical rows of the warp yarns.^19,20 King²¹ developed a 3D orthogonal woven fabric where warp yarns are vertically placed, whereas the weft and z-yarn were inserted simultaneously into each warp layer. This is done by extending the weft needles through the warp layers, and then extending and retracting the z-yarn needles to weave an overlapped double layer of yarns on top of previously inserted weft yarns. A pin is inserted for each insertion of the weft and z-yarn into the warp layers to secure the weft and z-yarn loops. As the yarn layers build up, the pins may be removed and inserted in the higher newly formed fabric structure.²¹ New looms were also developed to make 3D orthogonal woven preforms for high quality, low cost and various sectional fabrics.^22,23

Three-dimensional woven lattice structures were developed by Fukuta et al.^24,25 They have three sets of yarns. These are the warp, weft and z-yarn (binder). These are interlaced with each other based on a plain weave pattern. The weft yarns in the lateral direction interlace around each warp yarn, which occupies the longitudinal direction, and the binder yarns in the vertical direction also interlace around each warp yarn. However, twill or satin or any derived interlace pattern other than plain cannot be produced.^24,25

Three-dimensional woven preforms are classified based on various parameters. These parameters depend on fiber type and formation, fiber orientation and interlacements and micro and macro unit cells.^12,13,16 Various studies have been published on the geometrical and mechanical properties of 3D orthogonal^26–30 and a few interlaced woven fabric preforms.^11,12,31 Gu²⁷ reported that the take-up rate of the 3D weaving affected the yarn-to-yarn distance in the dry preform, which eventually influenced the directional and total volume fraction as well as the z-yarn angle of 3D woven fabrics. Dickinson²⁶ claimed that the density and the placement of z-yarn in the 3D woven preform influenced the in-plane properties of the 3D woven structure. When the z-yarn volume ratio increased, the in-plane properties of the 3D woven structure decreased, whereas when the Z-yarn volume fraction ratio in the 3D woven composite decreased, a local delamination type failure mode on a 3D woven composite occurred. Bilisik⁹ showed that the increasing of the fiber density in the warp or ±bias and filling fiber sets resulted in a high total preform volume fraction and that porosity in the crossing points of fiber sets in the preform was reduced. It was found that the bending strength and modulus of the 3D orthogonal woven composites were higher than those of multiaxis 3D woven composites. This indicated that the ±bias yarn orientations on both surfaces of the multiaxis 3D woven composites caused a reduction in bending properties.⁸ The in-plane shear strength and modulus of the multiaxis and orthogonal woven composites were investigated. It was shown that the in-plane shear strength and modulus of the multiaxis 3D woven composites were higher than those of multiaxis 3D woven composites by almost 25% for in-plane shear strength and 170% for in-plane shear modulus due to the addition of the ±bias yarns on the surface of the multiaxis 3D woven composites.¹³ Cox et al.⁷ stated that a low volume fraction 3D woven preform may perform well under impact load compare to a tight volume fraction 3D woven perform. On the other hand, Babcock and Rose²⁹ explained that under the impact load, 3D woven or two-dimensional (2D) fabric/stitched composites confined the impact energy around the local region due to the z-yarn. Recently, it was claimed that the 3D twill woven composite structure introduced a new failure mode in compression, which was the compressive fiber failure that occurs at an angle with respect to the other two axes due to in-plane crimp.³²

As seen in the literature, a few studies have been carried out on 3D fully interlaced and semi-interlaced woven preform structures. Therefore, the aim of this study was to develop 3D fully interlaced fabrics, and to examine some of their geometrical base structural features for possible soft and rigid material applications.

Materials and methods

Three-dimensional fully interlaced woven preform and method

An experimental rig was constructed to make a representative 3D fully interlaced woven preform (plain, twill, satin or derivatives) and semi-interlaced woven preforms (warp–filling plain, twill, satin or derivatives, and warp–z-yarn orthogonal) based on the 3D weaving method. This method involves five distinctive steps to weave two to five layer preforms. These are warp let-off, 2D shedding, multiple filling insertions and beat-up. Figure 1 shows the 3D plain weave (a1–a6) and 3D plain–z-yarn orthogonal woven preform (b1–b6). The 3D plain, twill and satin woven preforms can be defined as warp–filling and warp–z-yarns that were interlaced based on plain, twill and satin weave patterns. Using the same analogy, the semi-interlaced woven preform can be defined as warp–filling that was interlaced based on a plain or twill or satin weave pattern, whereas warp–z-yarn was interlaced based on an orthogonal weave pattern.

Figure 1.

Three-dimensional (3D) weaving method to make representative fully interlaced woven preforms; 3D plain woven preform (a1–a6), 3D plain-z-yarn orthogonal woven preform (b1–b6).

In order to make the representative 3D plain woven preform, the warp must be arranged in a matrix of rows and columns, as shown in Figure 1(a1). The first step is the one-step sequential movement of an even number of warp layers in the column direction (a2). This was carried out by using the 2D shedding unit (not shown). The second step is filling insertion between each warp layer in the row direction (a3). The third step is the one-step sequential movement of an even number of warp layers in the row direction (a4). This was again fulfilled by the 2D shedding unit. The fourth step is z-yarn insertion between each warp layer in the column direction (a5). After the steps (a2–a5) were repeated, the 3D plain woven preform structure was achieved (a6). These steps were repeated depending on preform length requirements. The 3D plain-z-yarn orthogonal woven pattern is also shown in Figure 1 in steps b1–b6, where the z-yarn insertion was fulfilled without any interlacement in the preform structure (b4–b6). The number of warp layers can be expanded in the row and column directions depending upon preform dimensions. Representative 3D woven orthogonal, 3D woven through-the-thickness and 3D woven angle interlock preform structures were also made in order to compare the 3D fully and semi-interlaced woven preform structures.

During the formation of the developed 3D fully interlaced woven preform structures, various filling insertion and shedding types were examined. The resulting 3D woven structures from traditional shuttle, multiple needle and individual rapier are shown in Figure 2. The 3D orthogonal woven preform structures produced from in-out and crossing shedding are shown in Figure 3. The 3D woven preform from the filling insertion by traditional shuttle did not require selvage due to continuation of filling. However, the 3D woven preform from the filling insertion by multiple needles resulted in double filling in the structure and it required selvage to hold the filling loops, as shown clearly in Figure 2(b1 and b2). In multiple individual rapier insertion, the 3D woven preform also required selvage for both fabric edges, as shown in Figure 2(c1–c2). On the other hand, the in-out shedding type did not bind all filling during z-yarn insertion, as shown in Figure 3(a1 and a2), whereas the crossing shedding type bound all filling during z-yarn insertion, as shown in Figure 3(b1 and b2). Therefore, it was found that individual rapier insertion and crossing shedding resulted in an almost perfectly aligned structure in the warp, filling and z-yarn directions.

Figure 2.

Types of filling insertions. Three-dimensional (3D) representative woven preform structure by traditional shuttle type insertion (a1) and computer-aided drawing of the woven structure (a2); 3D representative woven preform structure by needle type insertion (b1) and computer-aided drawing of the woven structure (b2); 3D representative woven preform structure by individual rapier type insertion (c1) and computer-aided drawing of the woven structure (c2).

Figure 3.

Type of shedding pattern. Three-dimensional (3D) representative woven preform structure by in-out shedding (a1) and computer-aided drawing of the woven structure (a2); 3D representative woven preform structure by crossing shedding (b1) and computer-aided drawing of the woven structure (b2).

Three-dimensional representative woven preform structures using polyethylene tubes (diameter, 5 mm and wall thickness, 1 mm) using the 3D weaving method are shown in Figure 4. Individual rapier insertion and crossing shedding were utilized to fabricate the 3D representative woven preforms. The 3D representative woven preforms were formed by using the light beat-up in order to have perfect alignment in generally three Cartesian directions.

Figure 4.

Three-dimensional representative fully interlaced, semi-interlaced and traditional orthogonal woven preform structures where a polyethylene tube was used instead of high modulus yarns. General views of five-layer plain (a1) and plain–z-yarn orthogonal woven preform structures (a2); general view of twill (b1) and twill–z-yarn orthogonal woven preform structures (b2); general view of satin (c1) and satin–z-yarn orthogonal woven preform structures (c2); general view of orthogonal (d1), through-the-thickness (d2) and angle interlock (d3) woven preform structures.

The 3D woven structures were designed as plain (3DWP) (a1) and plain–z-yarn orthogonal (3DWP-ZO) (a2); twill (3DWT) (b1) in which warp–filling was interlaced in a 2/2 twill weave pattern, whereas warp–z-yarn was interlaced in a 1/1 plain pattern at two layers and 3/2 ribs at five layers due to the limitation of number of layers in preform thickness and twill–z-yarn orthogonal (3DWT-ZO) (b2); satin (3DWS) (c1) in which warp–filling was interlaced in a 1/4 satin weave pattern, whereas warp–z-yarn was interlaced in a 1/1 plain pattern at two layers and 3/2 ribs at five layers due to the limitation of the number of layers in preform thickness and satin–z-yarn orthogonal (3DWS-ZO) (c2) and traditional orthogonal (3DWO) (d1), through-the-thickness (3DWTT) (d2) and angle interlock (3DWAA) (d3) woven patterns. They were produced in various numbers of layers for the same width. The measurements of the 3D representative woven preform structures were not repeated due to the limited number of samples. On the other hand, the measurements of the 3D representative woven preform structures were repeated five times on the left, right and middle part of each structure. The average values of the various measurements were presented.

Parameters measured in 3D representative woven preform structures

Measurements of the 3D representative fully interlaced and semi-interlaced woven preforms were performed in normal conditions (out-of-loom). The measurements of the representative woven preforms in normal conditions were carried out in force-free environments. The measurements on traditional 3D representative woven preforms were also fulfilled in order to compare them with 3D representative fully interlaced and semi-interlaced woven preforms. The dimensional measurements of the 3D representative woven preform structures were performed using the Newman digital caliper (measurement length: 0–150 mm and precision: 0.01 mm, China). The uncrimped yarn length and arc-length measurements were performed using the flexible ruler (measurement length: 0–300 mm and precision: 0.2 mm). The angle measurements of the 3D representative woven preform structures were performed using the manual angle instrument (measurement angle: 0–180° and precision: 0.2 degree).

Dimensions

Structure width (Sw), length (Sl) and thickness (St) measurements of the representative 3D woven preform structures were carried out. The precision of dimensional measurements was 0.01 mm. On the other hand, width, thickness and length measurements were performed on the best representative part in the 3D woven preform structures. Yarn-to-yarn distance on warp–warp (w-w), filling–filling (f-f) and z-yarn–z-yarn (z-z) in the top, side and cross-sections of the 3D representative woven structures were measured as shown in Figure 5.

Figure 5.

Measured yarn-to-yarn space on three-dimensional representative fully interlaced woven preform structure.

Angles

Measured angles on 3D representative various woven preform structures were defined as follows: ±θw was the warp angle that was between the warp and the filling in the x-direction (fabric length); ±θwz was the trajectory warp angle that was between the warp and the z-yarn in the z-direction (fabric thickness); ±θf was the filling angle that was between the filling and the warp in the y-direction (fabric width); ±θfz was the trajectory filling angle that was between the filling and the z-yarn in the z-direction (fabric thickness); ±θz was the z-yarn angle that was between the z-yarn and the warp in the z-direction (fabric thickness); ±θzw was the trajectory z-yarn angle that was between the z-yarn and the warp in the x-direction (fabric length); ±θzi was the interlaced z-yarn angle that was between the z-yarn and the warp in the z-direction (fabric thickness); ±θzif was the trajectory interlaced z-yarn angle that was between the z-yarn and the filling in the y-direction (fabric width); ±θzb was the interlock z-yarn angle that was between the z-yarn and the warp in the z-direction (fabric thickness) for the angle interlock structure; ±θzbw was the trajectory z-yarn angle that was between the z-yarn and the warp in the x-direction (fabric length) for the angle interlock structures. All angles on 3D representative woven preform structures are shown in Figure 6. It was found that ±θw, ±θf and ±θzi were due to the fully interlaced and semi-interlaced structures. However, ±θz was partly due to light beat-up, as shown in Figure 4(d1). The angles between warp and filling, warp and z-yarn were measured in the in-plane and out-of-plane directions of the 3D representative woven preform structures by means of a 4-mm rod. The precision of angle measurements was 0.2 degrees. The angles between each of the structure types for each of the measured angles were somewhat high, probably due to the use of polyethylene tubes instead of high modulus fibers.

Figure 6.

Measured angles on three-dimensional representative various preform structures: warp angle (±θw) (a); trajectory warp angle (±θwz) (a); filling angle (±θf) (b); trajectory filling angle (±θfz) (b); z-yarn angle (±θz) (a), (c)–(h); trajectory z-yarn angle (±θzw) (a), (c)–(h); interlaced z-yarn angle (±θzi) (b); trajectory interlaced z-yarn angle (±θzif) (b); interlock z-yarn angle (±θzb) (g); and trajectory interlock z-yarn angle (±θzbw) (g).

Density

The densities of the warp, filling and z-yarn were measured on the top, side and cross-section of the 3D representative woven preform structure. The precision of density measurements was 0.2 ends/5 cm. Also, total yarn ends for each woven structure were found in the following relations as

Total warp ends, We = N \times M

(1)

\begin{matrix} Total filling ends, Fe = N + 1 \\ (for traditional 3D woven structure) \end{matrix}

(2)

Fe = N (for 3D fully- and semi-interlaced woven structure)

(3)

Total z-yarn ends, Ze = M + 1

(4)

where N is the number of yarns in the row direction and M is the number of yarns in the column direction.

Yarn lengths

Measured yarn lengths in the 3D representative woven preform structures are shown in Figure 7. These include uncrimped warp length (lw), uncrimped filling length (lf ), z-yarn arc length in the structure surface (lza), z-yarn length in the structure thickness (lz) and uncrimped total z-yarn length (lzt). The precision of yarn length measurements was 0.2 mm. Uncrimped total z-yarn length was calculated in the following relations as

lzt = lza + lz

(5)

Figure 7.

Measured yarn length on the three-dimensional representative fully interlaced woven preform structure: uncrimped warp length (lw) (a); uncrimped filling length (lf) (a); z-yarn arc length in structure surface (lza) (b) and (c); z-yarn length in structure thickness (lz) (b) and (c); structure length (Sl) (a); structure width (Sw) (a); structure thickness (St) (a).

Equation (5) is simple and it provided the relations between each segment length and the total length of the z-yarn in the 3D structures. Therefore, the required z-yarn in the weaving can be easily determined.

Crimp

Crimps in the 3D fully- and semi-interlaced representative woven preform structure were calculated based on the structure dimensions and the uncrimped representative yarn lengths. The following relations could be used as

cw (%) = (lw - Sl) \times 1 00 / Sl

(6)

cf (%) = (lf - Sw) \times 1 00 / Sw

(7)

cz (%) = (lzt - St \times 1 00) / St

(8)

where cw is the warp crimp (%), lw is the uncrimped warp length (cm), Sl is the structure length (cm), cf is the filling crimp (%), lf is the uncrimped filling length (cm), Sw is the structure width (cm), cz is the z-yarn crimp (%), lzt is the uncrimped total z-yarn length (cm) and St is the structure thickness. The precisions of dimensional and yarn length measurements were 0.01 and 0.2 mm, respectively.

Results and discussion

Preform structure results

Three-dimensional fully interlaced and semi-interlaced woven structures were developed for two and five layers. Three-dimensional fully interlaced woven structures can be defined if all three yarn sets (warp, filling and z-yarn) were interlaced with each other based on any specific weave pattern, for instance, plain or twill or satin. The resulting structure was considered as a 3D fully interlaced woven structure. The 3D fully interlaced woven structures were divided into three basic patterns by analogy with traditional 2D woven fabrics as 3D plain (3DWP), 3D twill (3DWT) and 3D satin (3DWS), as shown in Figure 8.

Figure 8.

Developed representative three-dimensional (3D) fully interlaced woven preform structures. General view of five-layer actual and computer-aided drawing of 3D plain (a1 and a2), 3D twill (a3 and a4) and 3D satin (a5 and a6) woven preform structures.

In the 3D plain woven structure, the warp and filling were interlaced as a 1/1 plain pattern in the in-plane direction (XY), whereas the warp and z-yarn were interlaced as a 1/1 plain pattern in the out-of-plane direction (YZ) for two and five layers. The 3D plain representative woven structure and computer-aided drawings using Unigraphics NX6 are shown in Figure 8 (a1 and a2), respectively. In the 3D twill woven structure, the warp and filling were interlaced as a 2/2 (skipping step is 1) twill pattern in the in-plane direction (XY), whereas the warp and z-yarn were interlaced as a 1/1 plain pattern in the out-of-plane direction (YZ) for two layers and 3/2 ribs (skipping step is 1, plain derivatives) for five layers due to the limitation of the number of warp layers of the rig. The 3D twill (2/2 twill in warp–filling and 3/2 ribs in warp–z-yarn) representative woven structure and computer-aided drawings are shown in Figure 8 (a3 and a4), respectively. In the 3D satin woven structure, the warp and filling were interlaced as a 1/4 (skipping step is 2) satin pattern in the in-plane direction (XY), whereas the warp and z-yarn were interlaced as a 1/1 plain pattern in the out-of-plane direction (YZ) for two layers and 3/2 ribs (skipping step is 1, plain derivatives) for five layers due to the limitation of the number of warp layers of the rig. The 3D satin (1/4 satin in warp–filling and 3/2 ribs in warp–z-yarn) representative woven structure and computer-aided drawings are shown in Figure 8 (a5 and a6), respectively.

Three-dimensional semi-interlaced woven structures can be defined if two yarn sets in the in-plane direction (warp, filling) were interlaced with each other based on any specific weave pattern, for instance, plain or twill or satin, whereas z-yarns were laid down between each adjacent warp in the out-of-plane direction. Three-dimensional semi-interlaced representative woven structures were also divided into three basic patterns by analogy with traditional 2D woven fabrics as 3D plain–z-yarn orthogonal (3DWP-ZO), 3D twill–z-yarn orthogonal (3DWT-ZO) and 3D satin–z-yarn orthogonal (3DWS-ZO), as shown in Figure 9. In the 3D plain–z-yarn orthogonal woven structure, the warp and filling were interlaced as a 1/1 plain pattern in the in-plane direction (XY), whereas z-yarns were laid down between each adjacent warp in the out-of-plane direction (YZ) for two and five layers. The 3D plain–z-yarn orthogonal representative woven structure and computer-aided drawings are shown in Figure 9 (b1and b2, respectively). In the 3D twill–z-yarn orthogonal woven structure, the warp and filling were interlaced as a 2/2 (skipping step is 1) twill pattern in the in-plane direction (XY), whereas z-yarns were laid down between each adjacent warp in the out-of-plane direction (YZ) for two and five layers. The 3D twill–z-yarn orthogonal representative woven structure and computer-aided drawings are shown in Figure 9 (b3 and b4, respectively). In the 3D satin woven structure, the warp and filling were interlaced as a 1/4 (skipping step is 2) satin pattern in the in-plane direction (XY), whereas z-yarns were laid down between each adjacent warp in the out-of-plane direction (YZ) for two and five layers. The 3D satin–z-yarn orthogonal representative woven structure and computer-aided drawings are shown in Figure 9 (b5 and b6, respectively).

Figure 9.

Developed representative three-dimensional (3D) semi-interlaced woven preform structures. General view of five-layer actual and computer-aided drawing of 3D plain–z-yarn orthogonal (a1 and a2), 3D twill–z-yarn orthogonal (a3 and a4) and 3D satin–z-yarn orthogonal (a5 and a6) woven preform structures.

On the other hand, traditional 3D orthogonal, 3D through-the-thickness and 3D angle interlock representative structures were made for comparison purposes with the 3D fully interlaced and the 3D semi-interlaced woven structures. The 3D orthogonal, 3D through-the-thickness and 3D angle interlock representative woven structures and computer-aided drawings are shown in Figure 10 (c1 and c2, c3 and c4 and c5 and c6, respectively).

Figure 10.

General view of five-layer actual and computer-aided drawing of traditional three-dimensional (3D) orthogonal (c1 and c2), 3D through-the-thickness (c3 and c4) and 3D angle interlock (c5 and c6) woven preform structures.

Preform yarn-to-yarn space results

The yarn-to-yarn space and dimensional specifications of various 3D representative woven preform structures are presented in Table 1. Figure 11(a) and (b) show the relationship between yarn-to-yarn distance and the 3D woven preform structures in the xz-plane (fabric length) for two and five layers, respectively. Figure 11(c) and (d) show the relationship between the yarn-to-yarn distance and the 3D woven preform structures in the yz-plane (fabric width) for two and five layers, respectively.

Figure 11.

(a) Relationship between the yarn-to-yarn distance and the various two-layer three-dimensional (3D) woven preform structures in the xz-plane (fabric length). (b) Relationship between the yarn-to-yarn distance and the various five-layer 3D woven preform structures in the xz-plane (fabric length). (c) Relationship between the yarn-to-yarn distance and the various two-layer 3D woven preform structures in the yz-plane (fabric width). (d) Relationship between the yarn-to-yarn distance and the various five-layer 3D woven preform structures in the yz-plane (fabric width).

Table 1.

Yarn-to-yarn space and the dimensional specifications of various three-dimensional (3D) representative woven preform structures

Fabric structure	Number of layers	Total yarns			Structure	Yarn-to-yarn distance (Top × Side × Cross-section, cm)
Fabric structure	Number of layers	Warp	Filling	z-yarn	Width × Thickness (Sw × St, cm)	Warp–warp (w-w)	Filling–filling (f-f)	z-yarn–z-yarn (z-z)
3DWP	2	2 × 15	2 × 15	1 × 16	13.0 × 3.2	1.0 × 1.2 × 1.0	2.5 × 2.5 × 0.7	0.8 × 2.5 × 0.8
3DWP	5	5 × 15	5 × 15	1 × 16	15.0 × 5.0	1.0 × 1.0 × 1.0	2.5 × 2.5 × 0.7	1.0 × 2.5 × 1.0
3DWT	2	2 × 15	2 × 15	1 × 16	13.5 × 3.1	1.0 × 1.5 × 1.0	2.2 × 2.2 × 1.0	1.0 × 2.5 × 1.0
3DWT	5	5 × 15	5 × 15	1 × 16	17.5 × 5.7	1.0 × 0.8 × 1.0	2.2 × 2.2 × 0.8	1.0 × 2.2 × 1.0
3DWS	2	2 × 15	2 × 15	1 × 15	14.5 × 3.0	1.0 × 1.0 × 1.0	2.2 × 2.2 × 0.8	0.9 × 2.5 × 0.9
3DWS	5	5 × 15	5 × 15	1 × 15	16.5 × 5.5	1.2 × 0.8 × 1.2	1.8 × 1.8 × 0.8	1.0 × 2.0 × 1.0
3DWP-ZO	2	2 × 15	2 × 15	1 × 16	13.5 × 1.7	1.0 × 0.7 × 1.0	2.2 × 2.2 × 0.7	0.8 × 2.0 × 0.8
3DWP-ZO	5	5 × 15	5 × 15	1 × 16	15.5 × 4.3	1.0 × 0.7 × 1.0	2.2 × 2.2 × 0.7	1.0 × 2.0 × 1.0
3DWT-ZO	2	2 × 15	2 × 15	1 × 16	13.5 × 2.3	0.7 × 0.8 × 0.7	1.8 × 1.8 × 0.7	0.8 × 1.8 × 0.8
3DWT-ZO	5	5 × 15	5 × 15	1 × 16	17.0 × 4.6	1.0 × 0.8 × 1.0	1.8 × 1.8 × 0.7	0.9 × 2.0 × 0.9
3DWS-ZO	2	2 × 15	2 × 15	1 × 15	14.0 × 2.0	0.7 × 0.7 × 0.7	2.0 × 2.0 × 0.7	0.9 × 2.0 × 0.9
3DWS-ZO	5	5 × 15	5 × 15	1 × 15	18.0 × 4.2	1.2 × 0.8 × 1.2	1.8 × 1.8 × 0.8	1.2 × 1.8 × 1.2
3DWO	2	2 × 15	3 × 15	1 × 16	13.0 × 2.6	1.0 × 0.7 × 1.0	2.0 × 2.0 × 0.7	0.8 × 2.0 × 0.8
	4	4 × 15	5 × 15	1 × 16	13.8 × 4.6	0.9 × 0.7 × 0.9	2.0 × 2.0 × 0.8	0.9 × 2.0 × 0.9
	5	5 × 15	6 × 15	1 × 16	13.8 × 5.2	0.9 × 0.8 × 0.9	2.0 × 2.0 × 0.8	0.9 × 2.0 × 0.9
3DWTT	2	2 × 15	3 × 15	1 × 16	15.5 × 3.1	1.2 × 0.8 × 1.2	2.0 × 2.0 × 1.0	1.0 × 2.0 × 1.0
	4	4 × 15	5 × 15	1 × 16	16.0 × 4.5	1.5 × 0.8 × 1.5	2.0 × 2.0 × 1.0	0.9 × 2.0 × 0.9
	5	5 × 15	6 × 15	1 × 16	15.6 × 6.0	1.5 × 0.7 × 1.5	2.0 × 2.0 × 1.0	0.9 × 2.0 × 0.9
3DWAI	2	2 × 15	3 × 15	1 × 16	16.0 × 2.7	1.2 × 1.0 × 1.2	1.8 × 1.8 × 1.0	1.1 × 1.8 × 1.1
	4	4 × 15	5 × 15	1 × 16	16.0 × 4.6	1.0 × 0.9 × 1.0	2.0 × 2.0 × 1.2	0.9 × 2.0 × 0.9
	5	5 × 15	6 × 15	1 × 16	16.5 × 5.6	1.0 × 0.7 × 1.0	2.0 × 2.0 × 1.2	0.9 × 2.0 × 0.9

In the yarn-to-yarn space of two and five layer structures to fabric length, as shown in Figure 11(a) and (b), and Table 1, the filling-to-filling and the z-yarn-to-z-yarn spaces in all 3D woven preform structures were almost equal but they were higher than the warp-to-warp spaces. This was because of the processing parameters. For instance, light beat-up was used during weaving under constant take-up rate. Three-dimensional fully interlaced structures have high yarn-to-yarn spaces compared to the semi-interlaced and traditional 3D representative woven structures. In addition, the yarn-to-yarn spaces in 3D semi-interlaced structures were higher than the 3D traditional woven structure due to interlacement. It seemed that the yarn-to-yarn spaces were proportional to the interlacement that occurred between the warp–filling and the warp–z-yarn. On the other hand, the increasing of the number of layers from two to five did not significantly affect the yarn-to-yarn spaces in all 3D preform structures.

In the yarn-to-yarn spaces of all 3D woven preform structures to fabric width, as shown in Figure 11(c) and (d), and Table 1, the warp-to-warp space varied from 0.7 to 1.2 cm in two-layer and from 0.7 to 1.5 cm in five-layer structures. The z-yarn-to-z-yarn space varied from 0.8 to 1.1 cm in two-layer and from 0.8 to 1.2 cm in five-layer structures. The filling-to-filling space varied from 0.7 to 1.0 cm in two-layer and from 0.7 to 1.2 cm in five-layer structures. It was considered that the value of all yarn-to-yarn spaces in all 3D woven preform structures became close to each other, and the yarn-to-yarn spaces for each yarn set were uniform.

Preform structure angle results

The measured angles of the various 3D representative woven preform structures are presented in Table 2. Figure 12(a) and (b) show the relationship between the yarn angle and the 3D woven preform structures in the xz-plane (fabric length) for two and five layers, respectively. Figure 12(c) and (d) show the relationship between the yarn angle and the 3D woven preform structures in the yz-plane (fabric width) for two and five layers, respectively.

Figure 12.

(a) Relationship between the yarn angle and the various two-layer three-dimensional (3D) woven preform structures in the xz-plane (fabric length). (b) Relationship between the yarn angle and the various five-layer 3D woven preform structures in the xz-plane (fabric length). (c) Relationship between the yarn angle and the various two-layer 3D woven preform structures in the yz-plane (fabric width). (d) Relationship between the yarn angle and the various five-layer 3D woven preform structures in the yz-plane (fabric width).

Table 2.

Measured angles of the various three-dimensional (3D) representative woven preform structures

Fabric structure	Number of layers	Total yarns			Warp angle		Filling angle		±z-yarn angle
Fabric structure	Number of layers	Warp	Filling	z-yarn	(θ _w °)	(θ _wz °)	(θ _f °)	(θ _fz °)	(±θ _z °)	(±θ _zw °)	(±θ _zi °)	(±θ _zif °)	(±θ _zb °)	(±θ _zbw °)
3DWP	2	2 × 15	2 × 15	1 × 16	16	74	3	87	40	50	3	87	–	–
3DWP	5	5 × 15	5 × 15	1 × 16	12	78	5	85	28	62	3	87	–	–
3DWT	2	2 × 15	2 × 15	1 × 16	8	82	8	82	29	61	3	87	–	–
3DWT	5	5 × 15	5 × 15	1 × 16	5	85	8	82	23	67	8	82	–	–
3DWS	2	2 × 15	2 × 15	1 × 15	8	82	4	86	44	46	3	87	–	–
3DWS	5	5 × 15	5 × 15	1 × 15	10	80	4	86	10	80	8	82	–	–
3DWP-ZO	2	2 × 15	2 × 15	1 × 16	17	73	5	85	40	50	0	90	–	–
3DWP-ZO	5	5 × 15	5 × 15	1 × 16	10	80	8	82	25	65	0	90	–	–
3DWT-ZO	2	2 × 15	2 × 15	1 × 16	18	72	5	85	35	55	0	90	–	–
3DWT-ZO	5	5 × 15	5 × 15	1 × 16	11	79	8	82	23	67	0	90	–	–
3DWS-ZO	2	2 × 15	2 × 15	1 × 15	13	77	4	86	35	55	0	90	–	–
3DWS-ZO	5	5 × 15	5 × 15	1 × 15	17	73	4	86	25	65	0	90	–	–
3DWO	2	2 × 15	3 × 15	1 × 16	0	90	0	90	40	50	–	–	–	–
	4	4 × 15	5 × 15	1 × 16	0	90	0	90	22	68	–	–	–	–
	5	5 × 15	6 × 15	1 × 16	0	90	0	90	12	78	–	–	–	–
3DWTT	2	2 × 15	3 × 15	1 × 16	0	90	0	90	67	23	–	–	–	–
	4	4 × 15	5 × 15	1 × 16	0	90	0	90	67	23	–	–	–	–
	5	5 × 15	6 × 15	1 × 16	0	90	0	90	63	27	–	–	–	–
3DWAI	2	2 × 15	3 × 15	1 × 16	0	90	0	90	58	32	–	–	79	11
	4	4 × 15	5 × 15	1 × 16	0	90	0	90	58	32	–	–	79	11
	5	5 × 15	6 × 15	1 × 16	0	90	0	90	61	29	–	–	79	11

In the θz and θw angles of the two- and five-layer structures to fabric length, as seen in Figure 12(a) and (b) and Table 2, the θz angle in traditional 3D woven preform structures was higher than those of 3D fully and semi-interlaced woven structures due to z-yarn orientation in the through-the-thickness directions of the preform structure. On the other hand, the θz and θw angles in the 3D semi-interlaced woven structures were slightly higher than those of the 3D fully interlaced woven structures. In addition, the θz and θw angles of all 3D woven preform structures in five layers were lower than those of two layers except for the angle interlocked structure. The reason was that the z-yarn became steep when the number of layers increased.

In the θzi and θf angles of all 3D woven preform structures to fabric width, as shown in Figure 12 (c) and (d), and Table 2, the θzi angle was unvaried (3 degrees) in two-layer but it varied from 3 to 8 degrees in five-layer structures. The θf angle varied from 3 to 8 degrees in two-layer and from 5 to 8 degrees in five-layer structures. It was also found that the θw angle in all the 3D woven structures was slightly higher than those of the θf and θzi. On the other hand, the values of θf and θzi became close to each other for all 3D woven fully interlaced and semi-interlaced structures. It was found that the θw, θf and θzi angles mainly depended on weave pattern, whereas the θz angle depended on the weaving processing parameters, such as the beat-up and take-up rate. Also, increasing the number of layers tended to decrease the θz angle.

Preform structure density results

The density results of the 3D representative various woven preform structures are presented in Table 3. Figure 13(a) and (b) show the relationship between the density and the 3D woven preform structures in the xz-plane (fabric length) for two and five layers, respectively. Figure 13(c) and (d) show the relationship between the density and the 3D woven preform structures in the yz-plane (fabric width) for two and five layers, respectively.

Figure 13.

(a) Relationship between the density and the various two-layer three-dimensional (3D) woven preform structures in the xz-plane (fabric length). (b) Relationship between the density and the various five-layer 3D woven preform structures in the xz-plane (fabric length). (c) Relationship between the density and the various two-layer 3D woven preform structures in the yz-plane (fabric width). (d) Relationship between the density and the various five-layer 3D woven preform structures in the yz-plane (fabric width).

Table 3.

Measured density of the various three-dimensional (3D) representative woven preform structures

Fabric structure	Number of layers	Total yarns			Structure Length × Width × Thickness (Sl × Sw × St, cm)	Fabric density (Top × Side × Cross-section, ends/5 cm)
Fabric structure	Number of layers	Warp	Filling	z-yarn	Structure Length × Width × Thickness (Sl × Sw × St, cm)	Warp	Filling	z-yarn
3DWP	2	2 × 15	2 × 15	1 × 16	20 × 13.0 × 3.2	7 × − × 7	3 × 3 × −	6 × 3 × 6
3DWP	5	5 × 15	5 × 15	1 × 16	20 × 15.0 × 5.0	6 × − × 6	3 × 3 × −	5 × 3 × 5
3DWT	2	2 × 15	2 × 15	1 × 16	20 × 13.5 × 3.1	6 × − × 6	3 × 3 × −	5 × 3 × 5
3DWT	5	5 × 15	5 × 15	1 × 16	20 × 17.5 × 5.7	6 × − × 6	3 × 3 × −	5 × 3 × 5
3DWS	2	2 × 15	2 × 15	1 × 15	20 × 14.5 × 3.0	5 × − × 5	2 × 2 × −	5 × 3 × 5
3DWS	5	5 × 15	5 × 15	1 × 15	20 × 16.5 × 5.5	5 × − × 5	3 × 3 × −	5 × 3 × 5
3DWP-ZO	2	2 × 15	2 × 15	1 × 16	20 × 13.5 × 1.7	6 × − × 6	3 × 3 × −	6 × 3 × 6
3DWP-ZO	5	5 × 15	5 × 15	1 × 16	20 × 15.5 × 4.3	6 × − × 6	3 × 3 × −	6 × 3 × 6
3DWT-ZO	2	2 × 15	2 × 15	1 × 16	20 × 13.5 × 2.3	6 × − × 6	3 × 3 × −	6 × 3 × 6
3DWT-ZO	5	5 × 15	5 × 15	1 × 16	20 × 17.0 × 4.6	6 × − × 6	3 × 3 × −	6 × 3 × 6
3DWS-ZO	2	2 × 15	2 × 15	1 × 15	20 × 14.0 × 2.0	6 × − × 6	3 × 3 × −	6 × 3 × 6
3DWS-ZO	5	5 × 15	5 × 15	1 × 15	20 × 18.0 × 4.2	4 × − × 4	3 × 3 × −	4 × 3 × 4
3DWO	2	2 × 15	3 × 15	1 × 16	20 × 13.0 × 2.6	6 × − × 6	3 × 3 × −	6 × 3 × 6
	4	4 × 15	5 × 15	1 × 16	20 × 13.8 × 4.6	6 × − × 6	3 × 3 × −	6 × 3 × 6
	5	5 × 15	6 × 15	1 × 16	20 × 13.8 × 5.2	6 × − × 6	3 × 3 × −	6 × 3 × 6
3DWTT	2	2 × 15	3 × 15	1 × 16	20 × 15.5 × 3.1	6 × − × 6	3 × 3 × −	6 × 3 × 6
	4	4 × 15	5 × 15	1 × 16	20 × 16.0 × 4.5	6 × − × 6	3 × 3 × −	6 × 3 × 6
	5	5 × 15	6 × 15	1 × 16	20 × 15.6 × 6.0	6 × − × 6	3 × 3 × −	6 × 3 × 6
3DWAI	2	2 × 15	3 × 15	1 × 16	20 × 16.0 × 2.7	5 × − × 5	3 × 3 × −	6 × 3 × 6
	4	4 × 15	5 × 15	1 × 16	20 × 16.0 × 4.6	5 × − × 5	3 × 3 × −	6 × 3 × 6
	5	5 × 15	6 × 15	1 × 16	20 × 16.5 × 5.6	5 × − × 5	3 × 3 × −	6 × 3 × 6

As seen in Figure 13(a) and (b) and Table 3, the filling and z-yarn densities (ends per 5 cm) of all 3D preform woven structures in two and five layers to fabric length were almost equal to each other. This indicated that all 3D structures were uniformly and consistently fabricated. This is of paramount importance to achieve directional regular properties from the 3D woven structure for either soft or rigid applications.

As seen in Figure 13(c) and (d), and Table 3, the warp and z-yarn densities (ends per 5 cm) of all 3D fully interlaced preform woven structures in two and five layers to fabric width were slightly irregular due to the interlacement between the warp–filling and the warp–z-yarn; however, the densities of the others were almost equal to each other. Interestingly, the filling and the z-yarn densities of all 3D preform woven structures in two and five layers to fabric length were half compared to the warp and z-yarn densities of all 3D fully interlaced preform woven structures in two and five layers to fabric width.

Preform structure yarn length results

The z-yarn length and the uncrimped warp and filling yarn length values of the various 3D representative woven preform structures are presented in Table 4. The results of the z-yarn length included z-yarn arc length, which appeared on both surfaces of the 3D woven preform structures, and z-yarn length in thickness, which was placed in the out-of-plane direction of the 3D structures and total z-yarn length. Figure 14(a) and (b) show the relationship between the z-yarn length and the 3D woven preform structures for two and five layers, respectively.

Figure 14.

(a) Relationship between the z-yarn length and the various two-layer three-dimensional (3D) woven preform structures. (b) Relationship between the z-yarn length and the various five-layer 3D woven preform structures.

Table 4.

Measured yarn lengths of the various three-dimensional (3D) representative woven preform structures

Fabric structure	Number of layers	Total yarns			Uncrimped warp yarn ength (lw/20 cm)	Uncrimped filling yarn length (lf/13 cm)	Uncrimped ±z-yarn length
Fabric structure	Number of layers	Warp	Filling	z-yarn	Uncrimped warp yarn ength (lw/20 cm)	Uncrimped filling yarn length (lf/13 cm)	z-yarn arc length in surface (lza, cm)	z-yarn length in thickness (lz, cm)	Total z-yarn length (lzt, cm)
3DWP	2	2 × 15	2 × 15	1 × 16	21.3	14.5	2.5	1.5	4.0
3DWP	5	5 × 15	5 × 15	1 × 16	21.0	13.7	2.5	3.0	5.5
3DWT	2	2 × 15	2 × 15	1 × 16	21.5	13.5	3.0	1.0	4.0
3DWT	5	5 × 15	5 × 15	1 × 16	21.2	13.5	2.8	3.5	6.3
3DWS	2	2 × 15	2 × 15	1 × 15	22.0	13.8	2.4	1.2	3.6
3DWS	5	5 × 15	5 × 15	1 × 15	22.0	13.8	2.3	3.8	6.1
3DWP-ZO	2	2 × 15	2 × 15	1 × 16	22.0	13.8	1.5	1.5	3.0
3DWP-ZO	5	5 × 15	5 × 15	1 × 16	22.6	13.7	2.0	2.8	4.8
3DWT-ZO	2	2 × 15	2 × 15	1 × 16	21.4	14.4	2.1	1.2	3.3
3DWT-ZO	5	5 × 15	5 × 15	1 × 16	21.5	14.2	2.2	2.5	4.7
3DWS-ZO	2	2 × 15	2 × 15	1 × 15	20.5	14.0	2.0	1.1	3.1
3DWS-ZO	5	5 × 15	5 × 15	1 × 15	21.0	14.0	2.0	2.6	4.6
3DWO	2	2 × 15	3 × 15	1 × 16	20.0	13.0	1.2	1.8	3.0
	4	4 × 15	5 × 15	1 × 16	20.0	13.0	1.5	3.3	4.8
	5	5 × 15	6 × 15	1 × 16	20.0	13.0	1.7	4.0	5.7
3DWTT	2	2 × 15	3 × 15	1 × 16	20.0	13.0	1.5	5.2	6.7
	4	4 × 15	5 × 15	1 × 16	20.0	13.0	1.5	9.9	11.4
	5	5 × 15	6 × 15	1 × 16	20.0	13.0	1.5	12.5	14.0
3DWAI	2	2 × 15	3 × 15	1 × 16	20.0	13.0	2.0	2.0	4.0
	4	4 × 15	5 × 15	1 × 16	20.0	13.0	1.7	2.8	4.5
	5	5 × 15	6 × 15	1 × 16	20.0	13.0	1.5	2.9	4.4

As seen in Figure 14(a) and (b) and Table 4, the z-yarn arc lengths of the 3D fully interlaced woven structure in two layers were slightly higher than those of the 3D semi-interlaced and the traditional 3D woven structures. The z-yarn lengths in thickness of the 3D traditional woven structures in two and five layers were higher than those of the 3D fully interlaced and semi-interlaced woven preform structures. In addition, the z-yarn length in thickness of the traditional 3D through-the-thickness woven structure in two and five layers was the highest amongst the others due to the z-yarn orientation in the thickness direction of the 3D woven structure. We did not find any significant differences in the z-yarn arc length of two- and five-layer structures but, the z-yarn lengths in thickness of all 3D woven structures in five layers were higher than those of two layers. It was found that when the number of layers increased, the z-yarn length in thickness of the 3D woven structure increased. However, the z-yarn arc length remained unchanged.

Preform structure crimp results

The warp crimp, filling crimp and z-yarn crimp values of the various 3D representative woven preform structures, especially for the fully interlaced and semi-interlaced woven structures, are presented in Table 5. Figure 15(a) and (b) show the relationship between the yarn crimp and the 3D woven preform structures for two and five layers, respectively.

Figure 15.

(a) Relationship between the yarn crimps and the various two-layer three-dimensional (3D) woven preform structures. (b) Relationship between the yarn crimps and the various five layer 3D woven preform structures.

Table 5.

Measured crimp of the various three-dimensional (3D) representative woven preform structures

Fabric structure	Number of layers	Uncrimped yarn length			Structure			Crimp
Fabric structure	Number of layers	Warp (lw, cm)	Filling (lf, cm)	z-yarn (lzt, cm)	Length (Sl, cm)	Width (Sw, cm)	Thickness (St, cm)	Warp (cw, %)	Filling (cf, %)	z-yarn (cz, %)
3DWP	2	21.3	14.5	4.0	20	13	3.2	6.5	11.54	25.00
3DWP	5	21.0	13.7	5.5	20	13	5.0	5.0	5.39	10.00
3DWT	2	21.5	13.5	4.0	20	13	3.1	7.5	3.85	21.21
3DWT	5	21.2	13.5	6.3	20	13	5.7	6.0	3.85	10.53
3DWS	2	22.0	13.8	3.6	20	13	3.0	10.0	6.15	20.00
3DWS	5	22.0	13.8	6.1	20	13	5.5	10.0	6.15	10.90
3DWP-ZO	2	22.0	13.8	3.0	20	13	1.7	10.0	6.15	0
3DWP-ZO	5	22.6	13.7	4.8	20	13	4.3	13.0	5.39	0
3DWT-ZO	2	21.4	14.4	3.3	20	13	2.3	7.0	10.77	0
3DWT-ZO	5	21.5	14.2	4.7	20	13	4.6	7.5	9.23	0
3DWS-ZO	2	20.5	14.0	3.1	20	13	2.0	2.5	7.69	0
3DWS-ZO	5	21.0	14.0	4.6	20	13	4.2	5.0	7.69	0
3DWO	2	20.0	13.0	3.0	20	13	2.6	0	0	0
	4	20.0	13.0	4.8	20	13	4.6	0	0	0
	5	20.0	13.0	5.7	20	13	5.2	0	0	0
3DWTT	2	20.0	13.0	6.7	20	13	3.1	0	0	0
	4	20.0	13.0	11.4	20	13	4.5	0	0	0
	5	20.0	13.0	14.0	20	13	6.0	0	0	0
3DWAI	2	20.0	13.0	4.0	20	13	2.7	0	0	0
	4	20.0	13.0	4.5	20	13	4.6	0	0	0
	5	20.0	13.0	4.4	20	13	5.6	0	0	0

As seen in Figure 15(a) and (b), and Table 5, the z-yarn crimps (cz) of the 3D fully interlaced structures in two layers were higher than those in five layers due to the large amount of z-arc length. On the other hand, the z-yarn crimps of the 3D fully interlaced structures in five layers were almost equal, whereas they varied from 20 to 25 (%) in two layers. Also, it was noted that the cz of the 3D plain woven structure was slightly higher than those of the 3D twill and satin structures. The warp (cw) and the filling crimp (cf) of the 3D fully interlaced and semi-interlaced woven structures varied from 2.5 to 10 (%) and from 3.85 to 11.54 (%) in two-layer structures, respectively. However, the warp and filling crimp of 3D fully interlaced and semi-interlaced woven structures varied from 5 to 13 (%) and from 3.85 to 9.23 (%) in five-layer structures, respectively. It was found that the z-yarn crimp of the 3D fully interlaced preform structures was higher than those of the warp crimp and the filling crimp in two and five layers.

General results

Preform space

Yarn-to-yarn spaces in all the 3D developed woven preform structures will affect the directional fiber volume fraction and they eventually affect the total volume fraction of the 3D woven preforms. The basic processing parameters for the yarn-to-yarn spaces were beat-up and take-up rate, which mainly affect the filling-to-filling and the z-yarn-to-z-yarn spaces. These spaces in the preform could also affect matrix infiltration during composite fabrication, for instance, directional porosity distribution in the preform, infiltration time and fiber alignment during consolidation.^13,26–28

Preform angle

Generally, the θw, θf and θzi angles can be affected by weave pattern, whereas the θz angle can be affected by the weaving processing parameters, such as beat-up and take-up rate and the number of layers.

Preform density

The filling and z-yarn densities of all the 3D woven preforms in the xz-plane mainly depended on take-up rate, which influenced the directional volume fraction of the 3D woven preform. When the yarn sets in the 3D structure were interlaced, the warp and z-yarn densities in the yz-plane were slightly irregular, which eventually affected the local properties of the 3D preform structures. However, depending on soft or rigid requirements, the warp and filling, and the z-yarn densities in both the xz-plane and the yz-plane could be tailored based on the processing parameters.

Preform yarn length

The z-yarn length in all the 3D woven preform structures was identified as the most critical yarn length due to the placement of the 3D woven preform thickness. When all the yarn sets in the 3D woven preform were interlaced fully, the z-yarn arc length increased. On the other hand, weave pattern types slightly affected the z-yarn arc length. In addition, when the number of layers increased, the z-yarn arc length remained the same. The z-yarn length in thickness depended on the number of layers and the yarn interlacements. In general, yarn interlacement and the number of layers influence all the yarn lengths in 3D woven preform structures.

Preform crimp

The 3D fully interlaced woven structures had warp crimp, filling crimp and z-yarn crimp, whereas the 3D semi-interlaced woven structure had warp crimp and filling crimp. On the other hand, the traditional 3D woven structures had no directional crimps. It was found that the directional crimps of the 3D woven structures slightly depended on the types of weave pattern. The z-yarn crimp was also reversely affected by the number of layers.

Relevance of possible results of three-dimensional fully interlaced woven preform

Yarn interlacements between the warp–filling and warp–z-yarn or warp–z-yarn orthogonal in 3D fully interlaced and semi-interlaced woven structures could improve the energy absorption capabilities of 3D soft woven preform structures for soft ballistic applications. Also, the warp–filling and warp–z-yarn interlacement or the warp–z-yarn orthogonal in 3D fully interlaced and semi-interlaced woven preform structures could also result in better damping properties for semi-rigid^4,19 (flexible) and rigid composite^7,29 structural applications.

Conclusions

Three-dimensional fully interlaced and semi-interlaced woven preform structures were developed. Basically, weave pattern and number of layers were considered as processing parameters. Three-dimensional plain, twill and satin representative woven preform structures were made under these parameters. The generated data included the yarn-to-yarn spaces, yarn angles, yarn length and crimps in the 3D woven representative preform structures.

We found that the yarn-to-yarn spaces in 3D fully interlaced and semi-interlaced structures were high compared to those of the traditional 3D woven structures due to the directional interlacement where the directional fiber volume fraction can be affected. It was found that the warp angle (θw) in fabric length, the filling angle (θf) and the interlaced z-yarn angle (θzi) in fabric width were due to the warp–filling and warp–z-yarn interlacements. These angles depended on the type of weave pattern, whereas the z-yarn angle (θz) in fabric length mainly depended on take-up rate. It was also observed that the interlacement in 3D woven structure caused slight irregular warp and z-yarn densities in fabric width. All yarn lengths in the 3D woven preform structures depended on the weave pattern and the number of layers.

The interlacement on three yarn sets results in warp crimp, filling crimp and z-yarn crimp. Probably, the unique feature of this research was the z-yarn crimp in the 3D woven preform. In addition, it was found that the directional crimps of the 3D fully interlaced and semi-interlaced woven structures slightly depended on the types of weave pattern and the number of layers.

In light of these findings we plan to conduct future research on 3D fully interlaced and semi-interlaced woven preform structures using high modulus fibers for use in possible soft ballistic applications.

Footnotes

Funding

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Acknowledgments

This work is the product of the principle author’s continued research efforts at the various textile material research centers and labs at the University of Leeds, North Carolina State University at Raleigh and Erciyes University since 1988.

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