JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World - o - 34

MANUFACTURlNG automated process

Robotic repair process for composite parts

ROZENN POEZEVARA
R&D Project Manager
AIC Europe Technologies
&
ELODIE PAQUET
Research Engineer
University of Nantes (IRCCyN laboratory)

omposite materials are now used
in a wide range of applications in
the aerospace, marine, automotive, ground transportation, energy and
sports equipment markets. All composite parts can encounter potential damage
and therefore require repairs. Such damage can impact the mechanical behaviour of the structure in different ways:
adversely, irretrievably and, in some cases, in a scalable manner. It is therefore
essential to act quickly and to achieve
the appropriate repairs without immobilizing the composite parts too long.
Scarfing repair involves removing successive plies from the skin to create a tapered
or stepped dish scarf profile around the
damaged area. After the scarf profile is machined, the composite part is restored by
applying multiple plies with the correct
thickness and orientation to replace the
damaged area. Once all the plies have been
replaced, the surface is heated to bond the
new material. The final skin is ground and
smoothed to restore the original design of
the part. Most scarfing operations are currently performed manually. They involve
high costs due to their precision, the as-

Europe Technologies, in association with the University of Nantes
(IRCCyN laboratory), develops robotic milling solutions for composite structure repairs. The first results have demonstrated that
repairs achieved with robotic scarfing reached the same level of
performance as the current manual repair process with enhanced
cycle times and reproducibility.

sociated health precautions and a lack of
repeatability. In these circumstances, the
use of automated solutions could bring accuracy, repeatability and reduce the length
of repair processes.
To perform and automate this repair operation on composite components, a lightweight, portable manipulator with a collaborative robot (Figure 1) was designed
and developed as part of the COPERBOT
project (co-financed by BPI France and labelled by the EMC2 cluster).
The main goal of this project is to develop
a fast, low-cost, automated and reproducible integrated process chain for structural
composite part repairs. This platform will
be installed directly on composite structures, even in the field, avoiding having
to disassemble the part from the repaired
structure. Consequently, a faster, more
reliable and partly automated composite
repair method is possible for the aeronautical, marine or wind industries (Figure 2).
The following detailed operations were
tested on monolithic CFRP laminate
plates representative of primary aircraft
structures. During the process development, the scarf quality and the repair solution were studied, and a first evaluation of
mechanical properties was conducted.

jec composites magazine / No111 March 2017

Fig. 1: Robotic solution developed for composite repairs
as part of the COPERBOT project

Stepped lap milling
To evaluate the optimum conditions for
different repair materials, two types of
cutting tools and three types of materials were used. The repairs were made by
steps. Test results recommend the use of
polycrystalline diamond tools (PCD) to
machine a stepped lap. These tools are
designed to withstand the abrasiveness of
composite materials.
To limit potential defects generated by
the applied machining forces, two types

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #111 - March 2017 - Special JEC World - o