JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 43

vibration/noise and manufacturing cost.
Thermoplastic composites were selected
for this application because they offer
high vibration damping and excellent
thermal insulation, have excellent impact
resistance, are recyclable and can be produced cost-effectively at fast cycle times.
The component is subjected to velocities
of up to 823 m per second and high rotational speeds. Aerodynamic heating of up
to 177°C on the component's outer surface had to be accounted for. The parts
were taken from concept to prototype
and processed via extrusion-compression
and fibre injection moulding. The postprocess machinability of holes, notches
and cut-outs can be seen in Figure 3. This
thermoplastic composite solution met
the required design constraints.

Fig.3: Machinability of holes, cut-outs and
notches in the carbon LFT moulded composite

Case 2: Carbon LFT materials and the
extrusion-compression moulding process
were used to manufacture parts with
complex draws for an aviation electronics

application. Partial views of two components are shown in Figures 5a and 5b to
illustrate the draw and complex features
moulding in cycle times of 90 seconds
per part. Figure 5a features stiffening ribs
of 5 mm in height and Figure 5b shows
ribs of 7 mm in height. The intricate
post-machining of the part segment is
illustrated in Figure 5b. The rectangular
pockets and high-tolerance holes in close
proximity were post-machined. The
flatness tolerance of these components
is +/- 0.0001" (0.0025 mm). Weight
savings of 33% were achieved by conversion of the aluminium part to a carbon
thermoplastic part.
Case 3: Millions of kilos of carbon
fibres waste are generated from decommissioned aircraft, parts/components,
discarded sporting equipment such as
hockey sticks, out-of-date prepregs, edge
trimmings from fabrics, etc. The added
value of carbon fibre thermoplastic
materials for aircraft components is in
applications such as stowage doors, floor
accessories, cargo containers, etc. The
UAB team collaborated with Materials
Innovation Technologies (MIT) Recycled Carbon Fibers (Florence, North
Carolina, USA) to source carbon fibre
thermoplastic polyphenylene sulphide
(C/PPS) from rejected aircraft seat
backs, shown in Figure 6a. These were
shredded and sieved through a screen
to maintain a fibre length of 12 mm in
the shredded material (Figure 6b). The
shredded material was subjected to an
extrusion-compression moulding process
(Figure 6c) similar to that of the virgin

Fig. 5: (a): Deep draw and complex rib features
in a carbon fibre thermoplastic component; (b):
post-machining of rectangular pockets, proximity holes, and flatness tolerance in an aviation
electronics component

LFT materials to produce a representative stowage door. The resulting part has
deep ribs (12 mm) for load bearing and a
flat front surface. The part has high stiffness and strength and represents a valueadded, cost-effective secondary/tertiary
component for an aerospace application.
The tensile, flexural, impact and thermal
properties of the door produced from
recycled sources was compared to that of
the virgin material. The C/PPS material
had equivalent performance at the virgin

No96 April 2015 / jec

Feature Aeronautics

Microstructural studies were carried out
to investigate the consolidation of the
thin-walled shell (see Figure 4). Matrix
burn-off testing indicated that all of the
locations, including the sharp corners,
steps and flanges, show relatively uniform
fibre distribution (Wf 32-37%). No noticeable voids and defects were observed,
indicating adequate consolidation and
material flow. The microstructure of the
locations of the curvature, corner, flange
and step shown in Figure 4 indicates
that material flow and consolidation are
optimized at all locations [9-11].

Fig. 4: Microstructure and weight fraction at different locations in the carbon LFT shell; (a) at location A,
(b) at location B, (c) at location C and (d) at location D (the locations are shown in inset Z)

composites magazine 43

JEC COMPOSITES MAGAZINE - Issue #96 - April 2015

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #96 - April 2015