JEC COMPOSITES MAGAZINE - Issue #122 - July 2018 - 46

FEATURE AEROSPACE research
netic induction to induce localized stress.
A reference numerical model was used for
a comparison with the measurements related to the particle displacements observed
by X-ray associated with the altered areas
in the adhesive. It was established that the
perimeter of a mechanical weakening zone
and its abatement factors with respect to a
reference value can be detected.
Another work focuses on the continuous
monitoring of composite structures at different scales throughout their life cycle.
The structures and, when possible, their
tools and means of production, are instrumented to determine the influence of the
various process parameters and materials
and the associated variabilities. Bragg optical fibre was used to study residual curing
stresses in the current or singular zone of
composite parts and to investigate toolpart interactions through work for several
PhD theses considering different manufacturing (autoclave, filament winding, etc.)
and machining (drilling) processes.
An infrared thermography analysis method was developed to measure energy restitution rates during compression of the
carbon plies, among other things. This
method was patented and is the subject of
a dissemination action via TTT (Toulouse
Tech Transfer).
Many tests were developed as part of recent research work, including an experimental delamination propagation method
in Mode I and II under gigacyclic fatigue
that is based on the structural resonance
of the specimen and allows the use of frequencies up to 400 Hz. An original Mode
III measurement method (edge ring crack
torsion test, ERCT) was proposed and extended to the study of mixed modes I + II
+ III.
For staircase repairs of carbon/epoxy
composite primary structures by structural bonding, the conditions of use of the
infrared thermography technique were
evaluated. This situation is not usual given
the subtle nature of the thermal behaviour
difference between the constituent parts
of the assembly zone (parent part and
carbon-epoxy patch), which constitutes
the main problem when capturing the
response. As part of a collaboration with
ENI Tarbes' industrial engineering labo-

Fig. 12: The Vertex test rig

Fig. 13: Edge ring crack torsion test (ERCT)

Fig. 14: STIMPACT platform gas guns

ratory, an original experimental procedure
was developed, allowing numerical modelling physically consistent with the thermal
problem and demonstrating good agreement between the measured and calculated temperature fields. This work proposes
and opens up ways to modify the intrinsic
thermal properties of a joint using addi-

jec composites magazine / N°122 July 2018

tives with an infrared signature that makes
it possible to identify the staircase area and
its geometrical defects more clearly.
Dynamic testing
The Clement Ader Institute, in partnership with Airbus and IRT Saint Exupéry,
developed the STIMPACT dynamic test-

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #122 - July 2018