JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World - o - 64

JEC WORLD 2017

Innovative composite panels, an alternative to steel and concrete,
for high speed railway tunnel construction
When the two 24km-long Pajares highspeed railway tunnels met the problem of
continuous water infiltration on around 30%
of the total tunnel length, few of the available
solutions in the market were able to solve
the issue. The innovative composite panels
developed by Acciona proved to be the best
solution in this demanding construction
work because they managed to meet all the
technical challenges while complying with
the flame-retardant requirements associated
with this type of application.
The challenges of this innovation were diverse because of the many criteria that had to
be met. From a mechanical point of view, the
use of composites made it possible to meet
the structural requirements while being thin
enough not to change the tunnel's diameter
and being compatible with catenary systems.
The design flexibility offered by composites
also allowed Acciona to develop a system
with leak-proof joints and anchorage system.
The 9.2-metre-long panels were also flexible
enough to adapt to the shape of the tunnel
and its irregularities.

CONSTRUCTION

Another concern in this project was to be
able to produce as many as 15,000 panels
within the delivery schedule and to keep the
cost of the composite panels as low as possible. To achieve this, Acciona opted for a pultrusion process and developed a low-cost resin injection system and fibre impregnation
chamber that were adapted to the viscosity of
the flame-retardant resin formulated for this
project. This new system made it possible to
produce one composite panel in 34 minutes
on a continuous basis.
The other advantages of composites in this
application were their low maintenance and
high corrosion resistance compared to traditional construction materials. Finally, the
handling and installation of the panels in the
tunnel were easy and fast thanks to the light
weight nature of composite panels.
To sum up and illustrate the size of the project: more than 15,000 panels were produced, covering about 200,000 square metres of tunnel for a total of 1700 tonnes of
composites.

SPORTS

Recurve bow riser
This innovation is a new generation of
bow risers made of carbon fibre composite materials. Whereas the use of composites in bow risers in now quite common,
this riser was made utilising an unconventional but stress-adapted design, making
it up to 40% lighter than current solutions (carbon or aluminium) while also
improving the mass-specific stiffness by
about 43% compared to a reference riser
made of aluminium.
To be able to manufacture an actual part,
IPF used the Tailored Fibre Placement
(TFP) technology, a process invented at
IPF Dresden, to produce four preforms
with a truss-like structure. With this
highly versatile technology, IPF managed to demonstrate the capability of a
variable-axis composite design. Because

Company: Acciona Construcción SA
(Spain)
Co-Winner: Owens Corning (Spain),
Scott Bader (UK), CELO - APOLO
Construction Systems (Spain), LUM-Industry (France), BYK-Chemie GmbH
(Germany), Nanjing Loyalty Composite Equipment Manufacture Co. Ltd.
(China)

current state-of-the-art composite manufacturing is mainly based on multi-axial
design, the realisation of a stress-adapted
design may be quite hard, if not feasible
at all.
The application of composite materials
according to precalculated variable-axis
directions can therefore lead to superior
part performance, using the anisotropic
nature of fibres in the best possible way,
and can help to use far less resources, thus
allowing for cost savings.
Another important phase of the project
was the development of the manufacturing process. Due to the part's complex
shape, with various holes and inserts,
the development of a closed pressurised
RTM mould was not possible. Instead, a
quasi-closed tool was manufactured with

jec composites magazine / No111 March 2017

Company: Leibniz-Institut für
Polymerforschung Dresden e.V. (IPF)
(Germany)
Partners: Hochschule für Technik und
Wirtschaft, Faculty of Design (Germany)
special inserts for resin inlet and areas for
air pressure evacuation. The final consolidation process is basically a closed-mould
infusion process, which helps to reduce
the manufacturing costs as no RTM pressurisation device is required, without affecting the part quality.

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