OVERVIEW OF TEXTILES
2.3.1.7 3D Braids
An extension of braiding technology is the 3D braid, in which the braiding yarns
interlock through a volume of material. There are no distinct layers in a 3D braid. A 3D
a) Through-Thickness Angle Interlock
b) Layer-Layer Angle Interlock
Straight-Interlacing Structure
c) Layer-to-Layer Angle Interlock
Wavy-Interlacing Structure
Filler (Weft)
Stuffer (Straight Warp)
Warp Weaver
Figure 2-14. Three-dimensional weave patterns.
braid is also generally nonlaminar, although, as with a 2D braid, nominally straight axial
yarns may be introduced to improve the stiffness and strength in one direction.
A 3D braiding machine can be set up to produce near net-shape matching to the
cross-section of the final part. Typical stiffener cross-sections, such as "I" and "T" shapes
can be produced.
2.3.1.8 Orthogonal Nonwoven Composites
There is a long history of 3D, non-woven reinforcements, primarily in carbon-
carbon composites. Orthogonal 3D materials are fabricated by fixing a series of yarns in
one direction (or rods which will later be withdrawn and replaced by yarns), and then
inserting planar yarns in the two orthogonal directions around the fixed yarns. Figure 2-15
shows a typical arrangement of fiber bundles that might be obtained in this process. Unlike
other textile forms, the reinforcement remains relatively straight throughout the preform in
