JEC COMPOSITES MAGAZINE - Issue #81 - May/June 2013 - 5

Fig. 1: Employment repartition

JCM: GKN is a wing specialist.
Can you summarize the advantages of composites for wings?

C.G.: The big benefit of

carbon is obviously its weight
and stiffness compared to
aluminium. Typically, you
can save 15 to 20% of the airframe weight if you can turn
it into composites. One of the
challenge we struggle with for
carbon fibre wings is the fuel
tank. Managing the lightningstrike protection of the fuel
tanks is one of the aircraft
industry’s biggest challenges.
We come up with lots of very
expensive and novel fastening techniques to protect for
lighting strike and make sure
that the high voltage in the
lightning can actually dissipate back to the other part
of the sub-frame and back to
the atmosphere. Our biggest
technological challenge is
actually the fastening technique between what is “black
aluminium”, i.e. the front and
rear spars and the top and
bottom skin made of carbon
fibre. Due to cost reasons, we
still use aluminium ribs to
make up the final bit of the
framework. So, there is still

a lot of use of metal at the
joints and junctions. I think
for next-generation aircraft,
we should be looking at greater integration in terms of the
spars, the covers, etc., to start
taking full advantage of the
carbon fibre material properties. Another challenge is the
elimination of fasteners. This
can be achieved by co-curin
parts together. The difficulty
is validating the structural
bond. This means we have to
use non-destructive testing,

and NDT becomes the weak
link in the process. We’ve
got an automated process
for making a part, and very
complicated parts now. But
now, with NDT, we need to
prove that we made a part
that is good. Sometimes the
industry knocks back the
material factors to cater for
our NDT limitations. So,
that’s one of our challenges
in the aerospace industry. As
we make bigger and more
complex parts, we can’t afford
to scrap them, so we need
repeatable manufacturing
processes that produce robust
product. Sometimes with
composites, this takes quite a
bit of development.
JCM: What about continuous
health monitoring?

C.G.: We have actually

done some work at GKN on
techniques for fibre optic
cables embedded in carbon,
but none of our customers
have yet to say they want
to see that, there is still not
enough demand from the
industry. But as we get more

and more products in service,
we have to know how good
the structure is and if it has
any damage, and you cannot see damage on carbon.
So, I can see a demand and a
desire for that. The aerospace
industry has to learn from the
B787, the A350XWB and the
C series. The next generation
of single-aisle aircraft could
benefit from some of those
things.
JCM: What are your main differences compared with your
competitors?

C.G.: GKN’s real strength is

its processing knowledge in
composites, but also in metals. We have a real strength
in terms of a broad range of
composite processes. We
have a lot of knowledge in
resin transfer moulding,
prepregs and different ways
of laying something up using
an ATL or an AFP machine.
So, we have a wide variety
of products. It allows us to
think differently when we
approach a new programme.
We have the knowledge to

Fig.2: GKN Aerospace global footprint

No81 May-June 2013 /

jec composites magazine 5
JEC COMPOSITES MAGAZINE - Issue #81 - May/June 2013

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #81 - May/June 2013
