JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 58

TECHNOLOGY bonding

Fig. 5: Fracture surfaces at the rigid adherend of the FM 73 specimens when peeling off (a) the composite from the aluminium (A-c) and (b) the composite from the
composite (C-c): 1-CF, 2- ILFC and 3-AF

peel load increased by approximately 60%, from 52 N/25
mm (A-a) to 83 N/25 mm (C-a), most probably due to an
increase of the CF area from 55% to 90%. The results of the
EA 9695 C-a are actually closer to what was expected for this
adhesive, according to the TDS (90 N/25 mm), most probably because the CF percentage is closer to 100% (90% CF).
The scenario changes significantly when peeling off a CFRP
flexible sheet (C-c and A-c) instead of an aluminium flexible
sheet (A-a and C-a). In both adhesives, there is a very significant decrease of the peel load when peeling off the CFRP
(C-c and A-c) instead of the aluminium sheet (A-a and C-a).
The peel load decreases by about 93% in the FM 73 specimens and about 80% in the EA 9695 specimens. The change
in the order of magnitude of the peel load from A-a or C-a
specimens to C-c or A-c specimens can be clearly seen in the
graphs of Figure 3.
The difference between peeling off flexible CFRP from aluminium or from rigid CFRP is almost negligible. For the FM
73 adhesive, the peel load is 15% lower on the A-c specimens
when compared to the C-c specimens. For the EA 9695 adhesive, the difference in the peel load is actually none (14
N/25 mm on both specimen types).

Discussion
To better understand the results of the peel tests, four different parameters are discussed: fracture surfaces, flexible adherend, rigid adherend and adhesives. The aim is to understand their influence on the test results in order to correctly
evaluate the adhesives peel performance to both materials,
aluminium and CFRP.
Peel loads versus fracture surfaces
In order to better understand the influence of the failure
mechanism on the peel loads, Figure 4 shows an example of
load-displacement curves for the FM 73 specimens and their
corresponding fracture surfaces. All the fracture surfaces
shown in Figure 4 are from the rigid adherend.
Figure 4(a) compares the results of the FM 73 specimens
when peeling off an aluminium adherend from aluminium
(A-a) and from CFRP (C-a).
The peel loads are significantly high, between 200 N/25
mm and 300 N/25 mm, and within a comparable order of
magnitude. For both, the major failure mechanism is cohesive along the complete debonding length. There are no

58

Fig. 6: Fracture surface of both sides of the FM 73 C-c specimen, flexible member
(Fm) and rigid member (Rm) (a) close to an AF ''stripe'' and (b) zoom on both sides:
1-CF, 2-ILFC and 3-AF

significant changes neither of the failure mechanism along
the debonding length of the specimens nor of the peel load
along the displacement.
The results when peeling off the CFRP adherend (flexible)
are significantly different (Fig. 4(b)). The peel loads are between 10 N/25 mm and 30 N/25 mm, i.e. 10 times lower
than when peeling off aluminium (A-a or C-a). In the fracture surfaces of Figure 4(b), three failure mechanisms can
be observed: CF, ILFC and AF. A close-up view of the three
fracture surfaces is shown in Figure 5. When AF occurs, it
is spread along the complete cross-section width (adhesive
failure ''stripes'').
Figure 6 shows the fracture surfaces of both adherends (flexible and rigid) of the FM 73 C-c specimen close to the AF
''stripe''. As can be observed in Figure 6(a), there is no adhesive attached to the flexible member at the AF ''stripe'', and
the complete adhesive layer is attached to the rigid member
(zone 3), which proves that this is indeed AF. Conversely,
in the CF zone (zone 1), the adhesive is attached to both
surfaces, on the flexible adherend and on the rigid adherend. A close-up view of the AF (zone 3) and CF (zone 1)
on both adherends is shown in Figure 6(b). Furthermore,
looking at the load-displacement curves, the peel load drops
suddenly at the AF ''stripes''. One can directly correlate the
load drops with the AF ''stripes'', as indicated in the graph
by the arrows. The distance between the AF ''stripes'' along
the debonding length is the same as the displacement difference between the peel load drops. There is a direct relation
between the debonding length and the crosshead displacement. The sudden drops of the peel load show that AF corresponds to the lowest peel load, as expected. In the areas
where there is a combination of CF and ILFC, these sudden
peel drops do not occur. However, even in the areas where
AF does not occur, the peel load remains below 30 N/25
mm. In the areas where CF is the major failure mechanism,
for example in specimens C-c between 20 mm and 40 mm of
debonding length, the peel load remains 10 times lower than
the A-a peel load with 100% CF. This shows that the signif-

jec composites magazine / N°137 November - December 2020



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

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020

Cover
Edito
“We can change the way we envision global shipping overall”
Contents
NEWS
In brief
Agenda
BUSINESS
Human ressources - Skills requirements in the composite materials sector – the French example
Startup - Make lightness and performance affordable without compromising the environment
Offshore - GWEC: Asia Pacific to become the largest offshore wind market by 2030
MANUFACTURING
Additive manufacturing - The METHOD platform expands to support more materials,applications, and markets
Automation - One-shot manufacturing of cylindrical lattice structures for satellite applications
Recycling - World’s first fully-recycled thermoplastic composite application in aerospace
Additive molding - From large-scale continuous thermoplastic composites to mass production
FEATURE AUTOMOTIVE - Is it possible to do better?
FRP - Fully coupled processstructure analysis for automotive center floor panel
Honeycomb - Composite materials for lighter vehicles
Additive manufacturing - Transforming composite production processes with FDM additive manufacturing
EV - All-composite EV wheel moves to next development phase with pilot production
Security - The world’s fastest armoured car
Natural fibre - Sustainable composite solution for new Toyota LQ concept car
SOLUTIONS
Defence - Drones as wingmen
City - Composites for tomorrow’s cities
Maintenance - Degradation mechanism and maintenance of GFRP hydrochloric acid storage tanks
TECHNOLOGY
Bonding - Adhesion properties of bonded composite-to-aluminium joints using peel tests
Inside the lab - The University of Southern Queensland - Centre for Future Materials
Method - Weight and cost reduction with double-double laminates
Index
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JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Cover
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 2
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Edito
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - “We can change the way we envision global shipping overall”
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 5
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Contents
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 7
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - In brief
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 9
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Agenda
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Human ressources - Skills requirements in the composite materials sector – the French example
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 12
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 13
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Startup - Make lightness and performance affordable without compromising the environment
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 15
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 16
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Offshore - GWEC: Asia Pacific to become the largest offshore wind market by 2030
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 18
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Additive manufacturing - The METHOD platform expands to support more materials,applications, and markets
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 20
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Automation - One-shot manufacturing of cylindrical lattice structures for satellite applications
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 22
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 23
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Recycling - World’s first fully-recycled thermoplastic composite application in aerospace
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 25
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 26
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Additive molding - From large-scale continuous thermoplastic composites to mass production
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 28
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 29
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - FRP - Fully coupled processstructure analysis for automotive center floor panel
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 31
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 32
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 33
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Honeycomb - Composite materials for lighter vehicles
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 35
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 36
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Additive manufacturing - Transforming composite production processes with FDM additive manufacturing
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 38
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - EV - All-composite EV wheel moves to next development phase with pilot production
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 40
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Security - The world’s fastest armoured car
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 42
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 43
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Natural fibre - Sustainable composite solution for new Toyota LQ concept car
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 45
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 46
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Defence - Drones as wingmen
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 48
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 49
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - City - Composites for tomorrow’s cities
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 51
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Maintenance - Degradation mechanism and maintenance of GFRP hydrochloric acid storage tanks
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 53
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Bonding - Adhesion properties of bonded composite-to-aluminium joints using peel tests
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 55
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 56
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 57
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 58
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 59
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 60
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 61
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Inside the lab - The University of Southern Queensland - Centre for Future Materials
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 63
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Method - Weight and cost reduction with double-double laminates
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 65
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - Advertisers
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 67
JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 68
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