JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 80

TECHNOLOGY assembly

bly and have received a robust surface treatment. These
tests serve to assess the impact of water diffusion at the
interface so as to validate the surface treatment.

These tests are also carried out at ambient temperature, at the
mini and maxi temperatures stipulated in the specifications,
in the saturated state and in the dried state.
In some cases (insufficient surface treatment), it is shown that
water diffuses more rapidly at the interface (or in the interphase) than in the bulk adhesive - about ten times faster according to Zanni-Deffarges and Shanahan (1995) [5], or twice
as fast according to Popineau [6]) - and can lead to a premature rupture due to a deterioration of the adhesive properties.
Insufficient surface treatment can also cause corrosion of the
oxide layer and a rupture in that layer.
In fact, it is difficult to predict which of these cases will occur.
The behaviour of each system (adhesive/material/surface
treatment) can be different and is impossible to predict.
For metallic materials, however, it is generally acknowledged
that treatments like solvent cleaning and/or mechanical or
chemical descaling usually lead to greater and more rapidly
changes to the adhesive properties (whether due to faster diffusion at the interfaces or in the interphases, or to corrosion
of the oxide films) than those that occur with water-saturated
adhesives.
In these cases, there is no forecasting model for the loss of adhesion or for the loss of cohesion of an oxide film that would
make it possible to predict the bond characteristics after ageing due to water saturation.

EF validation phase
At this stage, all of the adhesive's intrinsic properties are

known, and more specifically its weakest properties (either in
the saturated state or for the extreme temperature stipulated
in the specifications). Both the reversibility of the adhesive to
the effects of sorption/desorption and the choice of surface
treatments have been validated.
A detailed analysis of the bonded structure is then carried
out, applying the real thermomechanical loads and using the
adhesive properties that have been defined based on bonded
specimens.
In the case of the most important load, the maximum VM
stress at the most heavily loaded point in the adhesive line on
the assembly is compared with the adhesive's minimum elastic tensile stress.
If the elastic stress is lower than the VM stress, it is possible
to propose changes (sometimes minor) to the bond geometry
to reduce the maximum VM stress at the most heavily loaded
point in the adhesive line until it becomes < σE for the adhesive.

Conclusions
The methodology proposed by Cetim differs from the conventional approach to the durability of adhesive-bonded
structural assemblies. It is applicable to homogeneous or
heterogeneous metal and/or composite assemblies that are
bonded using structural adhesives.
It is based on an optimized adhesive-bond concept that limits the maximum level of stress in the assembly so that the
adhesive will not be subjected to stresses higher than its reversibility limit, which is around 50% of its tensile strength
(under the conditions of extreme temperature and humidity
stipulated in the specifications). Part of the optimization involves simplified calculation and analitic that enable a rapid
search for the right geometric parameter values for the bond
and for the thermomechanical adhesive properties. This approach cuts down on the number of tests required to validate
the choice of adhesive.
The type of surface treatment is chosen beforehand in order
to slow down - as much as is possible - the appearance of any
ruptures due to a lack of adhesion (degradation of the interface or the oxide film).
The parameters for water diffusion (sorption/desorption) are
determined using gravimetric analysis on the bulk adhesive.
Any chemical reactions that might govern the degradation of
the bulk adhesive are also monitored, using FTIR spectroscopy during the sorption/desorption phases and at the same
temperatures.

Fig. 8: TAST-type specimen

80

jec composites magazine / N°119 March 2018

The kinetics of the diffusion and the chemical reaction as a



Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #119 - March 2018

Cover
Edito
Opinion: Aeronautics
Contents
NEWS
In brief
Agenda
BUSINESS
KPIs - Up-to-date key performance indicators for the fibre-reinforced plastics market
Opportunities - Advanced plastics and composites break through the automotive sector
EV - China: driving the whole car supply chain, electric vehicles are in full swing
MANUFACTURING
Surface - New machine system takes surface finishing to a new level
3D printing - Additive manufacturing of highperformance composite structures
Automotive - Body in black versus body in white
Automotive - Sheet moulding compression of prepreg sheets for a composite subframe
Simulation - High-quality sound-absorbing automotive carpets
Curing - GRP composite manufacturing optimization: opportunities with UV curing
FEATURE Materials: pushing boundaries - Do materials have their limits?
Fastener - High-resistance fastener for structural composite parts
Recycling - Applications of recycled carbon fibre in high volume manufacturing
Resin - High-performance epoxy/carbon fibre SM
Honeycomb - High-performance polypropylene honeycomb boards at minimal cost
CFRTP - Beautiful, lightweight, and tunable
SOLUTIONS
Aeronautics - A demountable composite wing box for private planes
Civil engineering - Repair and replacement of concrete pipes with carbon composites
Sports - Sustainable composite manufacturing kicks into high gear
Medical - lmproving lives with carbon composites
TECHNOLOGY
NDT - NDT in-line inspection using the NIDIT procedure
Assembly - Ensuring the durability of adhesive-bonded assemblies
Index
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JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 84
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JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - In brief
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 9
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 10
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 11
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Agenda
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 13
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 14
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 15
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 16
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - KPIs - Up-to-date key performance indicators for the fibre-reinforced plastics market
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 18
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 19
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Opportunities - Advanced plastics and composites break through the automotive sector
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 21
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 22
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - EV - China: driving the whole car supply chain, electric vehicles are in full swing
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 24
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 25
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Ad4
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Ad5
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Surface - New machine system takes surface finishing to a new level
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 27
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 28
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 3D printing - Additive manufacturing of highperformance composite structures
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 30
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 31
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 32
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 33
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 34
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Automotive - Body in black versus body in white
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 36
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 37
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 38
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Automotive - Sheet moulding compression of prepreg sheets for a composite subframe
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 40
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 41
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Simulation - High-quality sound-absorbing automotive carpets
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 43
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Curing - GRP composite manufacturing optimization: opportunities with UV curing
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 45
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 46
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 47
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Fastener - High-resistance fastener for structural composite parts
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 49
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 50
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Recycling - Applications of recycled carbon fibre in high volume manufacturing
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 52
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Resin - High-performance epoxy/carbon fibre SM
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 54
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 55
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 56
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Honeycomb - High-performance polypropylene honeycomb boards at minimal cost
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 58
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - CFRTP - Beautiful, lightweight, and tunable
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 60
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 61
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 62
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Aeronautics - A demountable composite wing box for private planes
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 64
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 65
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Civil engineering - Repair and replacement of concrete pipes with carbon composites
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 67
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 68
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Sports - Sustainable composite manufacturing kicks into high gear
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 70
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Medical - lmproving lives with carbon composites
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 72
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 73
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - NDT - NDT in-line inspection using the NIDIT procedure
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 75
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 76
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - Assembly - Ensuring the durability of adhesive-bonded assemblies
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 78
JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 79
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