《纺织复合材料》课程参考文献（3-D textile reinforcements in composite materials）01 3-D textile reinforcements in composite materials

14 3-D textile reinforcements in composite materials Eight9-p时elements Basic 9-ply subelement Stiffener AS4/3501 1/2-in.stitch spacing Eight 9-ply segments stitched with 200d Kevlar to form blade Stiffened panel Skin Fold blade web ends open Stitching head Holding pin Six 9-ply segments Stringer flanges stitched to skin Web locating bar Gde bar- Folding frame able top .Stitched flap on skin 1.3 Combination of FTF and YTF processes. WV LE:6Z can be incorporated into a YTF preform by needle or fluid jet entangle- ment to provide through-the-thickness reinforcement.Sewing is another 2102 example that can combine or strategically join FTF and/or YTF fabrics together to create a preform having multidirectional fiber reinforcement [11](Fig.1.3). 个物鸡 1.3 Structural geometry of 3-D textiles The structural geometry of 3-D textiles can be characterized at both the macroscopic and the microscopic levels.At the macroscopic level,the exter- nal shape and the internal cellular structures are the result of a particular textile process and fabric construction employed in the creation of the structure.Similar shape and cellular geometry may be created by different textile processes.For example,a net shape I-beam can be produced by a weaving,braiding or knitting process.However,the microstructure or the fiber architecture produced by these three processes are quite different. This will lead to different levels of translation efficiency of the inherent fiber properties to the composite as well as different levels of damage-resistant characteristics.The efficient translation of fiber properties to the com- posite depends on the judicious selection of fiber architecture which is gov- erned by the directional concentration of fibers.This directional fiber con- centration can be quantified by fiber volume fraction Vr and fiber orientation,0.Depending upon the textile manufacturing process used and the type of fabric construction,families of Vr-0 functions can be gener- ated.These Vr-0 functions can be developed by geometrical modeling as

can be incorporated into a YTF preform by needle or fluid jet entangle￾ment to provide through-the-thickness reinforcement. Sewing is another example that can combine or strategically join FTF and/or YTF fabrics together to create a preform having multidirectional fiber reinforcement [11] (Fig. 1.3). 1.3 Structural geometry of 3-D textiles The structural geometry of 3-D textiles can be characterized at both the macroscopic and the microscopic levels.At the macroscopic level, the exter￾nal shape and the internal cellular structures are the result of a particular textile process and fabric construction employed in the creation of the structure. Similar shape and cellular geometry may be created by different textile processes. For example, a net shape I-beam can be produced by a weaving, braiding or knitting process. However, the microstructure or the fiber architecture produced by these three processes are quite different. This will lead to different levels of translation efficiency of the inherent fiber properties to the composite as well as different levels of damage-resistant characteristics. The efficient translation of fiber properties to the com￾posite depends on the judicious selection of fiber architecture which is gov￾erned by the directional concentration of fibers. This directional fiber con￾centration can be quantified by fiber volume fraction Vf and fiber orientation, q. Depending upon the textile manufacturing process used and the type of fabric construction, families of Vf - q functions can be gener￾ated. These Vf - q functions can be developed by geometrical modeling as 14 3-D textile reinforcements in composite materials Eight 9-ply elements 1/2-in. stitch spacing Basic 9-ply subelement AS4/3501 Stiffener Eight 9-ply segments stitched with 200d Kevlar to form blade Stiffened panel Skin Fold blade web ends open Stitching head Holding pin Web locating bar Glide bar Folding frame Panel Table top Stitched flap on skin Six 9-ply segments Stringer flanges stitched to skin 0° +45° 0° +45° 0° +45° 0° –45° 90° 1.3 Combination of FTF and YTF processes. RIC1 7/10/99 7:15 PM Page 14 Copyrighted Material downloaded from Woodhead Publishing Online Delivered by http://woodhead.metapress.com Hong Kong Polytechnic University (714-57-975) Saturday, January 22, 2011 12:29:37 AM IP Address: 158.132.122.9

3-D textile reinforcements in composite materials 15 a b 1.4 3-D woven fabrics. detailed by Ko and Du [12].Accordingly,the structure-property relation- ship of 3-D textile composites is a result of the dynamic interaction of microstructural and macrostructural geometries.In this section,the struc- tural shapes,cellular structures and fiber architectures expressed in terms 2-10 of the Vr-0 functions are presented for the four basic classes of 3-D textile reinforcements. 1.3.1 3-D woven fabrics 3-D woven fabrics are produced principally by the multiple-warp weaving method which has long been used for the manufacturing of double and triple cloths for bags,webbings and carpets.By the weaving method,various fiber architectures can be produced including solid orthogonal panels (Fig.1.4a),variable thickness solid panels(Fig.1.4b,c),and core structures simulating a box beam (Fig.1.4d)or a truss-like structure (Fig.1.4e). Furthermore,by proper manipulation of the warp yarns,as exemplified by the angle interlock structure (Fig.1.4f),the through-thickness yarns can be organized into a diagonal pattern.To address the inherent lack of in- plane reinforcement in the bias direction,Dow [13]modified the triaxial weaving technology to produce multilayer triaxial fabrics as shown in Fig.1.4(g). Through unit cell geometric modeling the Vr-0 functions can be gener- ated for various woven fabrics.Figure 1.5 plots total fiber volume fraction versus web interlock angle for an angle interlock 3-D woven fabric,with three levels of linear density ratio.For purposes of calculation,the fiber packing fraction is assumed to be 0.8,which provides the upper limit for possible fiber volume fraction.The fabric tightness factor(n)used is 0.2

detailed by Ko and Du [12]. Accordingly, the structure–property relation￾ship of 3-D textile composites is a result of the dynamic interaction of microstructural and macrostructural geometries. In this section, the struc￾tural shapes, cellular structures and fiber architectures expressed in terms of the Vf - q functions are presented for the four basic classes of 3-D textile reinforcements. 1.3.1 3-D woven fabrics 3-D woven fabrics are produced principally by the multiple-warp weaving method which has long been used for the manufacturing of double and triple cloths for bags, webbings and carpets. By the weaving method, various fiber architectures can be produced including solid orthogonal panels (Fig. 1.4a), variable thickness solid panels (Fig. 1.4b, c), and core structures simulating a box beam (Fig. 1.4d) or a truss-like structure (Fig. 1.4e). Furthermore, by proper manipulation of the warp yarns, as exemplified by the angle interlock structure (Fig. 1.4f), the through-thickness yarns can be organized into a diagonal pattern. To address the inherent lack of in￾plane reinforcement in the bias direction, Dow [13] modified the triaxial weaving technology to produce multilayer triaxial fabrics as shown in Fig. 1.4(g). Through unit cell geometric modeling the Vf - q functions can be gener￾ated for various woven fabrics. Figure 1.5 plots total fiber volume fraction versus web interlock angle for an angle interlock 3-D woven fabric, with three levels of linear density ratio. For purposes of calculation, the fiber packing fraction is assumed to be 0.8, which provides the upper limit for possible fiber volume fraction. The fabric tightness factor (h) used is 0.2. 3-D textile reinforcements in composite materials 15 1.4 3-D woven fabrics. RIC1 7/10/99 7:15 PM Page 15 Copyrighted Material downloaded from Woodhead Publishing Online Delivered by http://woodhead.metapress.com Hong Kong Polytechnic University (714-57-975) Saturday, January 22, 2011 12:29:37 AM IP Address: 158.132.122.9

16 3-D textile reinforcements in composite materials 1.0 0.9 Fiber packing in yarn 0.8 0.7 1.0 0.6 0.5 0.5 0.4 0.3 入we/0M=0.1 0.2 0.1 0.0 10 20 30 405060 7080 90 6() 1.5 Process window of fiber volume fraction for 3-D woven (%whe wo'ssaidmau'peaypoo/:dny WV LE:6Z is linear density of warp or web yarn,Ar is linear density of filled yarn). 210e 1.3.2 Orthogonal non-woven fabrics Pioneered by aerospace companies such as General Electric [14],the non- woven 3-D fabric technology was developed further by Fiber Materials Incorporated [15].Recent progress in automation of the non-woven 3-D fabric manufacturing process was made in France by Aerospatiale [16],SEP [9]and Brochier [17,18]and in Japan by Fukuta and Coworkers [19,20]. The structural geometries resulting from the various processing tech- niques are shown in Fig.1.6.Figure 1.6(a)and (b)show the single bundle XYZ fabrics in a rectangular and cylindrical shape.In Fig.1.6(b),the mul- tidirectional reinforcement in the plane of the 3-D structure is shown. Although most of the orthogonal non-woven 3-D structures consist of linear yarn reinforcements in all of the directions,introduction of the planar yarns in a non-linear manner,as shown in Fig.1.6(c),(d)and (e)can result in an open lattice or a flexible and conformable structure. Based on the unit cell geometry shown in Fig.1.7,assuming an orthogo- nal placement of yarns in all three directions,the Vr-0 function was con- structed for an orthogonal woven fabric.Figure 1.8 plots the fiber volume fraction versus d,/d,(fiber diameter)ratios,assuming a fiber packing frac- tion of 0.8.For all three levels of d,/d,ratios,the fiber volume fraction first decreases with the increase in d/d,ratio,reaches a minimum,and then increases.As can be seen in the figure,the maximum fiber volume fraction is about 0.63 at either high or low d/d ratios,whereas the minimum fiber

1.3.2 Orthogonal non-woven fabrics Pioneered by aerospace companies such as General Electric [14], the non￾woven 3-D fabric technology was developed further by Fiber Materials Incorporated [15]. Recent progress in automation of the non-woven 3-D fabric manufacturing process was made in France by Aérospatiale [16], SEP [9] and Brochier [17,18] and in Japan by Fukuta and Coworkers [19,20]. The structural geometries resulting from the various processing tech￾niques are shown in Fig. 1.6. Figure 1.6(a) and (b) show the single bundle XYZ fabrics in a rectangular and cylindrical shape. In Fig. 1.6(b), the mul￾tidirectional reinforcement in the plane of the 3-D structure is shown. Although most of the orthogonal non-woven 3-D structures consist of linear yarn reinforcements in all of the directions, introduction of the planar yarns in a non-linear manner, as shown in Fig. 1.6(c), (d) and (e) can result in an open lattice or a flexible and conformable structure. Based on the unit cell geometry shown in Fig. 1.7, assuming an orthogo￾nal placement of yarns in all three directions, the Vf - q function was con￾structed for an orthogonal woven fabric. Figure 1.8 plots the fiber volume fraction versus dy/dx (fiber diameter) ratios, assuming a fiber packing frac￾tion of 0.8. For all three levels of dz/dx ratios, the fiber volume fraction first decreases with the increase in dy/dx ratio, reaches a minimum, and then increases. As can be seen in the figure, the maximum fiber volume fraction is about 0.63 at either high or low dy/dx ratios, whereas the minimum fiber 16 3-D textile reinforcements in composite materials 1.5 Process window of fiber volume fraction for 3-D woven (l w/q is linear density of warp or web yarn, lf is linear density of filled yarn). RIC1 7/10/99 7:15 PM Page 16 Copyrighted Material downloaded from Woodhead Publishing Online Delivered by http://woodhead.metapress.com Hong Kong Polytechnic University (714-57-975) Saturday, January 22, 2011 12:29:37 AM IP Address: 158.132.122.9

3-D textile reinforcements in composite materials 17 wo'ssaudmau 'peaypoom//:dny Aq d 1.6 Orthogonal woven fabrics. 'I'EI'85I :ssappy dl 1.7 Unit cell for orthogonal non-woven fabrics. volume fraction of about 0.47 is achieved when both d/d,and d/d ratios are equal to 1. 1.3.3 Knitted 3-D fabrics The knitted 3-D fabrics are produced by either the weft knitting or warp knitting process.An example of a weft knit is the near net shape structure

volume fraction of about 0.47 is achieved when both dy/dx and dy/dx ratios are equal to 1. 1.3.3 Knitted 3-D fabrics The knitted 3-D fabrics are produced by either the weft knitting or warp knitting process. An example of a weft knit is the near net shape structure 3-D textile reinforcements in composite materials 17 1.6 Orthogonal woven fabrics. 1.7 Unit cell for orthogonal non-woven fabrics. RIC1 7/10/99 7:15 PM Page 17 Copyrighted Material downloaded from Woodhead Publishing Online Delivered by http://woodhead.metapress.com Hong Kong Polytechnic University (714-57-975) Saturday, January 22, 2011 12:29:37 AM IP Address: 158.132.122.9

18 3-D textile reinforcements in composite materials 0.65 100 0.01 0.60 0.55 0.50 Minimum fiber volume fraction 0.45 1010102101001010210310 dyd. 1.8 Process window of fiber volume fraction for orthogonal non- woven fabrics. knitted by the Pressure Foot process [21](Fig.1.9a).In a collapsed form this preform has been used for carbon-carbon aircraft brakes.The unique feature of the weft knit structures is their conformability [22].By strategic introduction of linear reinforcement yarns,weft knitted structures can be used effectively for forming very complex shape structures.While the suit- ability of weft knit for structural applications is still being evaluated,much A progress has been made in the multiaxial warp knit(MWK)technology in recent years [23,24].From the structural geometry point of view,the MWK fabric systems consist of warp (0),weft (90)and bias (t0)yarns held together by a chain or tricot stitch through the thickness of the fabric,as illustrated in Fig.1.10(b).The logical extension of the MWK technology is the formation of circular multiaxial structures by the warp knitting process. This technology (Fig.1.9d)has been demonstrated in the Institute of Tex- tiles of the University of Aachen [25]. An example of MWK is the LIBA system,as shown in Fig.1.9(c)and(d). Six layers of linear yarns can be assembled in various stacking sequences along with a fiber mat and can be integrated together by knitting needles piercing through the yarn layers. The unit cell geometric analysis of a four-layer system is used as an example to generate the Vr-0 functions for the MWK fabric [26].This analysis can be generalized to include other MWK systems with six or more layers of insertion yarns.The fiber volume fraction relation in Fig.1.10 shows that for the fixed parameters selected,only a limited window exists for the MWK fabric construction.The window is bounded by two factors: yarn jamming and the point of 90 bias yarn angle.Fabric constructions cor- responding to the curve marked'jamming'are at their tightest allowable point,and constructions at the 0->90 curve have the most open structure

knitted by the Pressure Foot® process [21] (Fig. 1.9a). In a collapsed form this preform has been used for carbon–carbon aircraft brakes. The unique feature of the weft knit structures is their conformability [22]. By strategic introduction of linear reinforcement yarns, weft knitted structures can be used effectively for forming very complex shape structures. While the suit￾ability of weft knit for structural applications is still being evaluated, much progress has been made in the multiaxial warp knit (MWK) technology in recent years [23,24]. From the structural geometry point of view, the MWK fabric systems consist of warp (0°), weft (90°) and bias (±q) yarns held together by a chain or tricot stitch through the thickness of the fabric, as illustrated in Fig. 1.10(b). The logical extension of the MWK technology is the formation of circular multiaxial structures by the warp knitting process. This technology (Fig. 1.9d) has been demonstrated in the Institute of Tex￾tiles of the University of Aachen [25]. An example of MWK is the LIBA system, as shown in Fig. 1.9(c) and (d). Six layers of linear yarns can be assembled in various stacking sequences along with a fiber mat and can be integrated together by knitting needles piercing through the yarn layers. The unit cell geometric analysis of a four-layer system is used as an example to generate the Vf - q functions for the MWK fabric [26]. This analysis can be generalized to include other MWK systems with six or more layers of insertion yarns. The fiber volume fraction relation in Fig. 1.10 shows that for the fixed parameters selected, only a limited window exists for the MWK fabric construction. The window is bounded by two factors: yarn jamming and the point of 90° bias yarn angle. Fabric constructions cor￾responding to the curve marked ‘jamming’ are at their tightest allowable point, and constructions at the q Æ90° curve have the most open structure. 18 3-D textile reinforcements in composite materials 1.8 Process window of fiber volume fraction for orthogonal non￾woven fabrics. RIC1 7/10/99 7:15 PM Page 18 Copyrighted Material downloaded from Woodhead Publishing Online Delivered by http://woodhead.metapress.com Hong Kong Polytechnic University (714-57-975) Saturday, January 22, 2011 12:29:37 AM IP Address: 158.132.122.9