**3.2. Comparison of woven and nonwoven fabric draping**

shear angle based either on an experimentally determined locking angle, or the maximum orientation that the designer is prepared to tolerate. When defining cutoff angle of 38°, which equals the experimentally determined locking angle, one can, in this case, drape the mould,

Excess fabric

*(a) [0°/90°] ply orientation (b) [-45°/+45°] ply orientation*  **Figure 3.** *Drape results on shear angles of 0° and 45° ply orientations* 

*(a) [0°/90°] ply orientation (b) [-45°/+45°] ply orientation* **Figure 4.** *2D flat pattern results of 0° and 45° ply orientations*

(a) [0°/90°] ply orientation (b) [-45°/+45°] ply orientation Figure 5. Optimized drape results on shear angles of 0° and 45° ply orientations

Fiber stretching

Fiber stretching

(a) [0°/90°] ply orientation (b) [-45°/+45°] ply orientation

Figure 5. Optimized drape results on shear angles of 0° and 45° ply orientations

Shear angle (°)

Shear angle (°)

Figure 6. Shear angles along (a) the line L1 of 45° orientation and (b) along L2 of 0° orientation

The second example concerns the draping of woven and nonwoven carbon fabric on complex plastic mold. The initial rectangular taffeta fabric dimensions are: length = 700 mm and width = 350 mm (Fig. 7). The start point P in the simulation was the center of mass and the initial fiber direction is 45° with the geodesic mold directions (see Fig. 8). Figure 9 shows the resulting 3D draping for the woven and nonwoven fabric. We can note that all part surfaces are completely draped with woven and nonwoven fabric but with defect, the outline shapes of flat pattern are different, and the location of the maximum shear angles is the same as in the draped surface. Figure 10 presents shaded contours interpolated from the map of the fiber shear angles. For the draping of the surface with nonwoven fabric, we note that also all part of surface is completely draped with large shear angle (θ> ° 85 ) with fiber disentanglement and junction unraveling. For drape orientation, the results from geometrical model agree with the experimental results. One can conclude, in the considered cases, the draped surface of the product with 45° fiber orientation with woven or nonwoven fabric is impossible without cutting chisel operation. The

Figure 6. Shear angles along (a) the line L1 of 45° orientation and (b) along L2 of 0° orientation

The second example concerns the draping of woven and nonwoven carbon fabric on complex plastic mold. The initial rectangular taffeta fabric dimensions are: length = 700 mm and width = 350 mm (Fig. 7). The start point P in the simulation was the center of mass and the initial fiber direction is 45° with the geodesic mold directions (see Fig. 8). Figure 9 shows the resulting 3D draping for the woven and nonwoven fabric. We can note that all part surfaces are completely draped with woven and nonwoven fabric but with defect, the outline shapes of flat pattern are different, and the location of the maximum shear angles is the same as in the draped surface. Figure 10 presents shaded contours interpolated from the map of the fiber shear angles. For the draping of the surface with nonwoven fabric, we note that also all part of surface is completely draped with large shear angle (θ> ° 85 ) with fiber disentanglement and junction unraveling. For drape orientation, the results from geometrical model agree with the experimental results. One can conclude, in the considered cases, the draped surface of the product with 45° fiber orientation with woven or nonwoven fabric is impossible without cutting chisel operation. The

0 10 20 30 40 50 60

0 10 20 30 40 50 60

Experimental (Vanclooster et al. (2009))

Distance along L1 (mm)

Experimental (Vanclooster et al. (2009)) Geometrical draping

Geometrical draping

Distance along L1 (mm)

C1

Cutting fabric direction

concluded that for the [0°/90°] ply orientation along the diagonal line L2, the agreement between the experimental shear angles and the predicted draping results is good. On the other side, for [-45°/+45°] ply orientation along the symmetrical line L1, the predicted results do not agree at all with the experimental values. The oversimplification of the fabric deformation in the geometrical model gives shear angles up to 89° in case of the 45° ply orientation, which is impossible for woven fabric. The geometrical model is used with a cutoff shear angle based either on an experimentally determined locking angle, or the maximum orientation that the designer is prepared to tolerate. When defining cutoff angle of 38°, which equals the experimentally determined locking angle, one can, in this case,

7

8

8

which has high shear angles, with nonwoven fabric.

**Figure 4.** flat pattern results of 0° and 45° ply orientations

C2

150 Non-woven Fabrics

Shear angle (°)

Shear angle (°)

0 10 20 30 40 50 60

Experimental (Vanclooster et al. (2009))

**Figure 5.** Optimized drape results on shear angles of 0° and 45° ply orientations

Geometrical draping

Geometrical draping

Experimental (Vanclooster et al. (2009))

Distance along L2 (mm)

3.2. Comparison of woven and nonwoven fabric draping

0 10 20 30 40 50 60

Distance along L2 (mm)

3.2. Comparison of woven and nonwoven fabric draping

**Figure 6.** Shear angles along (a) the line L1 of 45° orientation and (b) along L2 of 0° orientation

drape the mould, which has high shear angles, with nonwoven fabric.

The second example concerns the draping of woven and nonwoven carbon fabric on complex plastic mold. The initial rectangular taffeta fabric dimensions are: length = 700 mm and width = 350 mm (Fig. 7). The start point P in the simulation was the center of mass and the initial fiber direction is 45° with the geodesic mold directions (see Fig. 8). Figure 9 shows the resulting 3D draping for the woven and nonwoven fabric. We can note that all part surfaces are completely draped with woven and nonwoven fabric but with defect, the outline shapes of flat pattern are different, and the location of the maximum shear angles is the same as in the draped surface. Figure 10 presents shaded contours interpolated from the map of the fiber shear angles. For the draping of the surface with nonwoven fabric, we note that also all part of surface is completely draped with large shear angle (*θ* >85° ) with fiber disentanglement and junction unraveling. For drape orientation, the results from geometrical model agree with the experi‐ mental results. One can conclude, in the considered cases, the draped surface of the product with 45° fiber orientation with woven or nonwoven fabric is impossible without cutting chisel operation. The very excessive shear angles induce defects and superposition of the cross-ply in the composite part after resin injection or polymerization. very excessive shear angles induce defects and superposition of the cross-ply in the composite part after very excessive shear angles induce defects and superposition of the cross-ply in the composite part after

Figure 7. Mold design and experimental nonwoven draping result **Figure 7.** Mold design and experimental nonwoven draping result Figure 7. Mold design and experimental nonwoven draping result

 (a) Nonwoven fabric (b) Woven fabric Figure 9. 3D geometrical draping using UD fabric and woven carbon fabric

Junction unraveling

Junction unraveling P

P

Fiber disentanglement

Fiber disentanglement

0°

0°

 (a) Nonwoven fabric (b) Woven fabric Figure 9. 3D geometrical draping using UD fabric and woven carbon fabric

Figure 8. CAD and mesh of the mold **Figure 8.** CAD and mesh of the mold

P

P

Junction unraveling

Junction unraveling

resin injection or polymerization.

resin injection or polymerization.

resin injection or polymerization.

**Figure 8.** *CAD and mesh of the mold* 

very excessive shear angles induce defects and superposition of the cross-ply in the composite part after

**Figure 7.** *Mold design and experimental nonwoven draping result* 

Fiber disentanglement

**Figure 9.** *3D geometrical draping using UD fabric and woven carbon fabric* **0° Figure 9.** 3D geometrical draping using UD fabric and woven carbon fabric

**Figure 10.** *Shear angle of draped UD fabric and woven carbon fabric* 

9

10

45° 90°

Defect

**Figure 10.** Shear angle of draped UD fabric and woven carbon fabric

#### **3.3. Effect of nonwoven fabric orientation 3.3. Effect of nonwoven fabric orientation**

The mechanical response of nonwoven fabrics exhibits an anisotropic response biased toward the direction of preferential alignment of constituent fibers. The deformation mechanisms governing the fabric response under bias-loads include textural evolution by means of reorientation of constituent fibers, fiber stretch, relative fiber slip, as well as fiber disentanglement and junction unraveling. The proposed mold shape is now draped geometrically using three fiber orientations. Here, only the predicted fiber orientations on the mold shape are compared. Figures 11, 12, and 13 show the resulting 3D nonwoven fabric draping for the 0°, 90°, and 45° drape orientations, respectively, and the The mechanical response of nonwoven fabrics exhibits an anisotropic response biased toward the direction of preferential alignment of constituent fibers. The deformation mechanisms governing the fabric response under bias-loads include textural evolution by means of reorientation of constituent fibers, fiber stretch, relative fiber slip, as well as fiber disentangle‐ ment and junction unraveling.

corresponding shaded contours interpolated from the map of the fiber orientation. From these figures it can be concluded that for the same initial contact point, the shear angle 80 localization is different and level is highly dependent on the mold geometry and the boundary conditions. Various The proposed mold shape is now draped geometrically using three fiber orientations. Here, only the predicted fiber orientations on the mold shape are compared. Figures 11, 12, and 13

defects such as unraveling of weaving and disentanglement of the fibers produced during the layup and may have effects on the quality of the final composite part after the injection of resin or polymerization.

**Draping direction** Fiber disentanglement

Fibre interlacing **90°**

Junction unraveling

**Figure 11.** *3D draping and iso-values of fiber angles of the 0° nonwoven draping*

**0°**

**55°**

**10° 15°**

**0° 6°**

20°

23°

0°

25°

10

11

show the resulting 3D nonwoven fabric draping for the 0°, 90°, and 45° drape orientations, respectively, and the corresponding shaded contours interpolated from the map of the fiber orientation. From these figures it can be concluded that for the same initial contact point, the shear angle (*θ* >80° ) localization is different and level is highly dependent on the mold geometry and the boundary conditions. Various defects such as unraveling of weaving and disentanglement of the fibers produced during the layup and may have effects on the quality of the final composite part after the injection of resin or polymerization. predicted fiber orientations on the mold shape are compared. Figures 11, 12, and 13 show the resulting 3D nonwoven fabric draping for the 0°, 90°, and 45° drape orientations, respectively, and the corresponding shaded contours interpolated from the map of the fiber orientation. From these figures it can be concluded that for the same initial contact point, the shear angle (θ> ° 80 ) localization is different and level is highly dependent on the mold geometry and the boundary conditions. Various defects such as unraveling of weaving and disentanglement of the fibers produced during the layup and may have effects on the quality of the final composite part after the injection of resin or polymerization.

Figure 10. Shear angle of draped UD fabric and woven carbon fabric

90°

70°

The mechanical response of nonwoven fabrics exhibits an anisotropic response biased toward the

The proposed mold shape is now draped geometrically using three fiber orientations. Here, only the

Figure 11. 3D draping and iso-values of fiber angles of the 0° nonwoven draping **Figure 11.** 3D draping and iso-values of fiber angles of the 0° nonwoven draping

Figure 12. 3D draping and iso-values of fiber angles of the 90° nonwoven draping **Figure 12.** 3D draping and iso-values of fiber angles of the 90° nonwoven draping
