JEC COMPOSITES MAGAZINE - Issue #117 - November/December 2017 - 31

fibre placement MANUFACTURING

Automated manufacturing of stiffened
com osite shells using dr fibre material
ANDREAS KOLBE, Research Scientist,
CHRISTIAN KROMBHOLZ, Research Scientist,
German Aerospace Center
SVEN KARRAS, Project Leader,
OLAF ROCKER, Senior Technology
Manager,
CTC GmbH
ANJA HAEBERLE, Research Assistant,
JOHANNES STOLZ, Research Assistant,
Faserinstitut Bremen e.V.

D

LR mainly focused on the automated layup of DFP material. In
a first step, material-dependent
process parameters such as activation
temperature, compaction pressure and
layup speeds were evaluated in vertical
layup trials. Additionally, material
effects like bulking, fuzz balls and tack
behaviour were analysed and considered for process and design modifications. The challenge was the different
behaviour of dry fibre compared to prepreg material with different defects like
fuzz balls. Afterwards, CTC focused
on how to ensure a complete infusion
of the panels. Therefore, a setup was
developed that was, on one hand, as
robust as possible and, on the other,
feasible for later industrialization.
During the first trials, a direct correlation between the layup parameters and
infusion behaviour was detected and
investigated. This article describes the
trial programme, which started with a
parameter study, followed by small- and
medium-scale trials and resulting in the
large-scale part. It shows how CTC and
DLR cooperated to lay up and infuse a
large-scale part with high thickness in
an R&T environment.

Appropriate manufacturing concepts need to be developed to meet the
growing demand for CFRP parts and the increasing production rates
in the aviation sector. Therefore, a development stream is ongoing to
evaluate the otential of dr fibre lacement
rocesses in large
scale shell manufacturing research ro ect funded b the an of
Lower Saxony concentrated on layup, infusion and curing processes
for a full scale dr fibre material shell as art of a close collaboration
between
mb and the erman eros ace enter
in tade

Background
To stay competitive in the growing
aircraft market, future aircraft need
further structural weight reductions
that can be achieved through the use of
new materials and new manufacturing
methods. Actual R&T developments
have to focus on the reduction of recurring and non-recurring costs, especially
for a new generation of short- and medium-range aircraft with an estimated
production rate over 60 AC/month [1].
Therefore, manufacturing processes
with less expensive composite and
auxiliary materials, automated and
flexible plant concepts as well as robust
manufacturing methods are needed
to achieve cost benefits and a stable,
appropriate production.
As part of a large project funded by the
NBank of Lower Saxony, the major aim
was to develop and demonstrate a complete process chain for the production
of carbon fibre-reinforced plastic shells,
focusing on vertical layup, stringer preforming and infusion process. A fullscale generic shell design was chosen as
a validator and demonstrator structure
to determine the potential, benefits and
challenges of a dry fibre process chain
for large-scale aircraft parts with high
thickness.

State of the art
Over the past decade, production
technologies such as Automated Tape
Laying (ATL) and Automated Fibre
Placement (AFP), in combination with
preimpregnated unidirectional fibres
and autoclave curing, were established
as the standard in commercial aircraft
production. Airbus and Boeing are currently manufacturing their composite
wings for the A350 and 777X by ATL
and AFP on huge gantry machinery
with a single layup head [2,3]. The new
competitors in the short-range sector,
like the Bombardiers C-Series or
Irkut MS21, are using dry fibre. While
Bombardier is manufacturing the wing
shells in a semi-automated process with
dry fibre fabrics in combination with a
resin transfer injection process (RTI)
in an autoclave, the Russian supplier
AeroComposit uses fully-automated
Dry Fibre Placement (DFP) machinery
in combination with a membrane-assisted resin infusion process (MARI) in
an oven [4, 5, 6, 7, 8] . Compared to the
prepreg process chain, dry fibre components offer significant potential for cost
and time savings. Direct cost savings
can be expected based on less costly
processes at the material production
stage. Due to the almost unrestricted
processing time of DFP materials, the

N°117 November - December 2017

/ jec composites magazine

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Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #117 - November/December 2017
