Page 17 - 3D Fibre Reinforced Polymer Composites

6 30 Fibre Reinforced Polymer Composites

1.2 INTRODUCTION TO 3D FRF' COMPOSITES

Since the late-l960s, various types of composite materials with three-dimensional (3D)
fibre structures (incorporating z-direction fibres) have been developed to overcome the
shortcomings of 2D laminates. That is, the development of 3D composites has been
driven by the needs to reduce fabrication cost, increase through-thickness mechanical
properties and improve impact damage tolerance. The development of 3D composites
has been undertaken largely by the aerospace industry due to increasing demands on
FRP materials in load-bearing structures to aircraft, helicopters and space-craft. The
marine, construction and automotive industries have supported the developments. 3D
composites are made using the textile processing techniques of weaving, knitting,
braiding and stitching. 3D composites are also made using a novel process known as z-
pinning.
Braiding was the first textile process used to manufacture 3D fibre preforms for
composite. Braiding was used in the late 1960s to produce 3D carbon-carbon
composites to replace high temperature metallic alloys in rocket motor components in
order to reduce the weight by 30-5096 (Stover et al., 1971). An example of a modern
rocket nozzle fabricated by 3D braiding is shown in Figure 1.4. At the time only a few
motor components were made, although it did demonstrate the capability of the braiding
process to produce intricately shaped components from advanced 3D composites.
Shortly afterwards, weaving was used for the first time to produce 3D carbon-carbon
composites for brake components to jet aircraft (Mullen and Roy, 1972). 3D woven
composites were made to replace high-temperature metal alloys in aircraft brakes to
improve durability and reduce heat distortion.

Figure 1.4 3D braided preform for a rocket nozzle (Courtesy of the Atlantic Research
Corporation)