JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 63
A step toward all-thermoplastic wind blades
weight of the structures.
The demonstrator parts were consolidated in an oven, although the end goal is to eliminate the need for it. Various
surface preparations and erosion protection TP films were
tested. And many experiments have been carried out to find
out the optimum for production parameters such as speed,
laser power and compaction pressure. During the trials, the
Fraunhofer Institute for Chemical Technology and Smithers
Rapra analysed test plates to determine the composite's mechanical properties and quality.
Fig. 2: Fibre placement testing by Coriolis Composites
at CompositAdour's facilities
The work under WALiD also focuses on the spar cap and
shear webs, which support most of the bending load along
the length of the blade and on the coating. The surface coating on very large wind turbines is crucial for stability over
time, as the air is filled with particles that can be very abrasive on the blades, especially at the leading edge. The surface treatment must also prevent frost from sticking to the
blade (Editor's note: The coating is a strong focus within
the project, even if it is not detailed here; composites are
obviously our focus).
Some of the solutions
Coriolis Composites tested fibre placement using laser
heating at the CompositAdour/ESTIA technical platform
in Biarritz, France, on a heating mould made by LoireTech
(Figure 2). The UD tapes used were made by Comfil to the
specifications of the WALiD consortium. Due to cost issues,
polyamide and polybutylene terephthalate (PBT) resins
were studied. PBT was chosen for the demonstrator (Figure
3), together with PPG's Innofiber® XM glass fibre, which is
formulated with a higher modulus than E-glass to lower the
Fig. 3: The WALiD demonstrator using AFP
The Fraunhofer Fraunhofer Institute for Chemical
Technology took care of developing the foaming process
and characterizing the foam and the shell-core and shearweb structures. Because bonding thermoplastics is not easy,
the bonding of various parts was also studied and benchmarked against existing solutions.
Coordinated by the Fraunhofer Institute for Chemical
Technology, this project is a first step with a technological
readiness level (TRL) of 2-3.
Much work remains to be done to reach the actual industrial
phase. According to the WALiD project's sponsors, the wind
energy sector should represent a third of global energy demand by 2050 (compared to 1% in 2013); jobs in that sector
should double within 10 years, and the sector's sales should
climb to US$3.4 billion by 2025. So there is every cause for
optimism, keeping in mind that the sector is highly competitive and always dependent on political decisions that can
sometimes be inconsistent.
The type of disruptive innovation that is occurring within
the WALiD project could perhaps make it possible to win
some market share - for those who dare to take the plunge.
Fig. 4: Loiretech's heating mould
No112 April - May 2017
/ jec composites magazine