JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 24

MANUFACTURlNG recycling

World's first fully-recycled thermoplastic
composite application in aerospace
A rotorcraft access panel made of recycled thermoplastic composites was developed and successfully flight tested. Utilizing a novel
recycling route, the panel is lighter and more cost-effective.
Dr. ir. Ferrie W.J. van Hattum,
Professor Lightweight Structures
TPAC

o demonstrate a novel recycling
route for thermoplastic composites
(TPC), an integrally-stiffened access
panel door for a rotorcraft was selected for
detail design and testing, and actually flight
tested.
Access panel
The design, development and validation
followed the traditional building-block
approach. The material used is carbon
fibre-reinforced PPS from post-industrial
waste. This material originates from offcuts generated in the production of components for the same rotorcraft as the access
panel door will be mounted on. This scenario helps to control the traceability of the
recycled access panel door/scrap material.
The development of such an application
improves the logistics as well as the supply
and demand for recycled TPC. Material
data was gathered from mechanical tests
and used to predict the panel's strength and
stiffness. The stringer design was optimised
with regards to part stiffness and internal
stress distribution, using FEM simulations.
A critical design detail was selected and
tested for validation, i.e. flexural tests on
bolted joints. This section was included in a
preliminary manufacturing demonstrator,
along with other integrated design features
such as thickness transitions and various
types of stiffeners. The manufacturing
demonstrator enabled testing of the man-

ufacturing limits regarding design and
processability. The final panel door design
was successfully produced and tested on
the component level.
The proprietary remanufacturing process
includes three steps:
- shredding of waste to centimetre-long
flakes;
- simultaneous heating and low-shear
mixing;
- compression moulding in an isothermal
mould.
This offers the opportunity of retaining
long fibres and therefore reaching high
mechanical properties at the characteristic
short cycle times of isothermal compression moulding. In comparison to the cur-

Fig. 1: Access panel demonstrator

jec composites magazine / N°137 November - December 2020

rent carbon/epoxy hand lay-up solution,
the new product is lighter, significantly
more cost-effective and made of recycled
material (fibre and matrix). Figure 1 shows
the recycled thermoplastic access panels
that have been successfully flight tested.
TPC-Cycle recycling project
The innovation is part of the TPC-Cycle
recycling project, which started 3½ years
ago. With the growth of thermoplastic
composite applications and production, the
amount of generated waste increases and
reaches considerable volumes. Although
the recycling of thermoplastic composites
is theoretically viewed as feasible, it is not
observed in practice.

JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020

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