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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 fiber1.3.2 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
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