Page 18 - 3D Fibre Reinforced Polymer Composites

Introduction 7
It is worth noting that these early 3D composites were made of carbon-carbon materials
and not fibre reinforced polymers. The need for 3D FRP composites was not fully
appreciated in the 1960s, and it was not until the mid-1980s that development
commenced on these materials. From 1985 to 1997 a NASA-lead study known as the
‘Advanced Composite Technology Program’ (ACTP), that included participants from
aircraft companies, composite suppliers and the textiles industry, was instrumental in
the research and development of 3D FRP composites (Dow and Dexter, 1997). The
program examined the potential of the textile processes of weaving, braiding, knitting
and stitching to produce advanced 3D composites for aircraft components.
Developmental work from the ACTP, combined with studies performed by other
research institutions, has produced an impressive variety of components and structures
made using 3D composites, and some of these are described below. However, due to
the commercial sensitivity of some components only those reported in the open
literature will be described.

1.2.1 Applications of 3D Woven Composites
Weaving is a process that has been used for over 50 years to produce single-layer,
broad-cloth fabric for use as fibre reinforcement to composites. It is only relatively
recently, however, that weaving techniques have been modified to produce 3D woven
materials that contain through-thickness fibres binding together the in-plane fabrics. A
variety of 3D woven composites have been manufactured using modified weaving
looms with different amounts of x-, y- and z-direction fibres so that the properties can
be tailored to a specific application. The great flexibility of the 3D weaving process
means that a wide variety of composite components have been developed for aerospace,
marine, civil infrastructure and medical applications (Mouritz et al., 1999). However,
only a few 3D woven components are currently used; most of the components have
been manufactured as demonstration items to showcase the potential applications of 3D
woven composites. A list of applications for 3D woven composites is given in Table
1.1 and some woven preform structures are shown in Figure 1.5. It is seen that a range
of intricate shapes can be integrally woven for possible applications as flanges, turbine
rotors, beams and cylinders. In the production of these demonstration items it has been
proven in many cases that it is faster and cheaper to manufacture 3D woven components
than 2D laminates, particularly for complex shapes. Furthermore, 3D woven
components have superior delamination resistance and impact damage tolerance.

Table 1.1 Demonstrator components made with 3D woven composite
Turbine engine thrust reversers, rotors, rotor blades, insulation, structural
reinforcement and heat exchangers
Nose cones and nozzles for rockets
Engine mounts
T-section elements for aircraft fuselage frame structures
Rib, cross-blade and multi-blade stiffened aircraft panels
T- and X-shape elements for filling the gap at the base of stiffeners when
manufacturing stiffened panels
Leading edges and connectors to aircraft wings
I-beams for civil infrastructure
Manhole covers