3-D woven, stitched fibrous
assemblies are textile architectures having fibres oriented so that both the
in-plane and transverse yarns are interlocked to form an integrated structure
that has a unit cell with comparable dimensions in all three orthogonal
directions, i.e., the 3-D structure basically consists of in-plane yarns for
stiffness and strength and z-binder yarns for through-thickness reinforcement.In
other words, 3-D textiles are those materials that have a system or systems in
all three orthogonal planes.These materials offer particular properties, such
as interlaminar shear force, mechanical and thermal stability along all three
spatial axes, that are not achievable with other reinforcements. This
integrated architecture provides improved stiffness and strength in the
transverse direction and impedes the separation of in-plane layers in
comparison to traditional 2-D fabrics. Because of their high transverse
strength, high shear stiffness, low delamination tendency and near-net-shape
manufacture, textile composites from weaving, knitting and braiding have
received tremendous attention recently. Optimal orientations, fibre
combinations and distributions of yarns have yet to be fully developed and
perfected for 3-D fabrics subjected to impact loading conditions. For example,
current body armour relies on ceramic plates to defeat penetrators. The
rigidity and brittleness of these materials limit their use to military
fighting applications. In addition, over time, environmental degradation and
accidental mechanical impact damage the ceramic and render it ineffective.
Hence, there are ample opportunities for substitute materials, and innovative
concepts that combine hybrid 3-D fabrics with other materials such as ceramic
and possibly new nano scale materials are needed. The optimal combinations of
these materials need to be determined along with new methodologies to ascertain
how to utilize the inherent mechanisms of these systems for energy dissipation
and strengthening.