JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017 - 42

AERONAUTlCS self healing

Fig. 3: a) Anvil schematic,
b) air gun during the impact
event, and c) compression after
impact test

Fig. 4: C-Scan figures from skin-stringer composite component integrated with a) capsules and b)
supramolecular prepreg

onto the component at the bond line.
Immediately after the impact test, all
the demonstrators were examined
using the C-scan method.
Monitoring
After the impact and once the healing
materials were activated, the C-scan
method was used again to monitor the
damaged area and then its reduction
due to the healing system.
The demonstrator design was selected
to investigate mechanical performance
in terms of the compression after im-

pact load level for all cases. The failure
load under compression after impact
(CAI) conditions was the key parameter to i) define how the integrated
self-healing material affects the modified demonstrator, and ii) compare
the different technologies in the same
conditions.
In both cases, the damaged area was
significantly reduced after the healing
process. This reduction was directly
related to the compression after impact
load level, as shown in Figure 5. In the
case of the capsules, their integration
did not disrupt the structural integra-

tion of the component but also proved
efficient by increasing the compressive
load. The self-healing efficiency observed was 8% higher than the sample
without self-healing functionality,
with a total recovery of 108%.
The supramolecular strategy reached
105% recovery regarding compressive
load after the healing process. A 17%
decrease due to the supramolecular
prepreg integration was expected and
was considered acceptable as the process is not optimized yet.
Conclusions
Skin-stringer composite components
were successfully implemented with
two different self-healing materials
(capsules and supramolecular prepreg)
in order to provide a self-healing functionality. Non-destructive techniques
were used to inspect the quality of the
manufactured components and visualize the impacted damaged area before
and after the healing process. C-scan
results confirmed the damage occurred
due to impact and the reduction of
this area due to the activation of the
healing process.
A knock-down effect was only observed
in the case of the supramolecular strategy and efforts are currently on-going
to eliminate this effect. Concerning
the property recovery, both strategies
proved efficient by increasing the
post-healing compressive load by
108% in the case of the capsules and
105% in the case of the supramolecular
prepreg.
Acknowledgments
The present work was supported
by the 7th Framework Program of
the European Commission under the
project: "Self-healing polymers for
concepts on self-repair aeronautical
composites" (Hipocrates project,
ACP3-GA-2013-605412).

Fig. 5: a) Compressive load values due to capsules integration or c) supra prepreg and the respective healing efficiencies b), d)

jec composites magazine / No112 April - May 2017

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Contact:
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Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #112 - April/May 2017