JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 57

small coupons to large composite structures runs into practical issues.
We introduced criteria for the determination of the optimal CNT
quantity required to ensure damage detectability at any region of
large composite structures. One of them was the uniformity of CNT
distribution, which gives rise to uniformity in electrical conductivity,
and another one was sensitivity to change in electrical resistance [4,
6]. The SHM technique offers a number of original aspects described
below.
Producing intelligent fibre/epoxy/CNT composite structures
First, the epoxy resin (Epon 862) and curing agent (EPIKURE
W, 26.4 wt%) were mixed. Then, 0.30 wt% multiwalled carbon
nanotubes (MWCNT), as the optimal quantity [4, 6], were added
to the epoxy matrix. The mixture was processed on a three-roll mill
(EXAKT 80E, EXAKT Technologies Inc.) to disperse the MWCNT
within the matrix. The modified matrix was dispersed between
non-conductive plain weave glass fibres and conductive carbon fibres
by hand lay-up to produce glass fibre/epoxy/MWCNT composite
plates and carbon fibre/epoxy/MWCNT composite plates. The
plates were cured in an autoclave. The manufacturing process used to
produce the intelligent composite structure is shown in Figure 2.

Fig. 2: Schematic illustration of the fabrication of intelligent composite structures

Electrical property measurement strategy
- Non-conductive fibre/epoxy/CNT composite structures
For non-conductive fibre/epoxy/CNT composites, a grid of forty
conductive contact points made from silver-epoxy paste spaced
3 inches (76 mm) apart was mounted on the surface of non-conductive fibre/epoxy/CNT plates (22×13 in., 560x330 mm2) (see
Figure 3a). Electrical wires were attached to the contact points to
make electrodes. It is very important to have a wide spacing between
the electrodes in order to avoid using a large number of grid points.
Electrical resistance measurement (ERM) was carried out by the
two-probe method. Electrical resistance change (ERC) is defined as
Rf,i,j - RI ,i,j
∆R(%) =
×100, where RI,i,j and Rf,i,j are the
RI,i,j
initial and final resistance values, respectively.
- Conductive fibre/epoxy/CNT composite structures
For conductive carbon fibre/epoxy/CNT composites, a new electric
potential measurement (EPM) strategy was proposed, as shown in
Figure 3b. Two sets of grid points were mounted on the surface of the
plate. Each set consisted of forty contact points. Each contact point
was made from silver-epoxy paste. Electrodes were made by attaching
wires to the grid points. The first set of grid electrodes, labelled from
1I to 40I and spaced 3 inches (76 mm) apart, was used to apply a
constant electric current. The second set of grid electrodes, labelled
from 1V to 40V and spaced 3 inches (76 mm) apart, was diagonally
shifted by 0.2 inches (5 mm) with respect to the first set to measure
electric potentials. EPM was performed by the four-probe method,
where a constant current was directly applied to first grid electrodes
and then the potential across the second grid electrodes was measured. Electric potential change (EPC) is expressed by:

Fig. 3: Schematic illustration of a) ERM strategy for non-conductive fibre/epoxy/
CNT composite plates, b) EPM strategy for conductive fibre/epoxy/CNT plates

No96 April 2015 /

jec composites magazine 57



JEC COMPOSITES MAGAZINE - Issue #96 - April 2015

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #96 - April 2015

Cover
Edito
Point of view : composites integration
Contents
COMPANY & BUSINESS
China
In brief
JEC Americas
Agenda of Events
APPLICATIONS
Catamaran
RIB
Trimaran
MARKET
Carbon fibre
FEATURE AERONAUTICS
Simulation
Cost-effectiveness
Low cost manufacturing
Thin-ply
High temperature
LFT
Thermoplastics
Laser projection
Release agent
Manufacturing
RESEARCH & DEVELOPMENT
Health Monitoring
Health monitoring techique for large composite structures
TECHNOLOGY & INNOVATIONS
IOT
Braiding
Resin
Vacuum infusion
Machining center
PBT
Index
In the world
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Cover
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 2
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Edito
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Point of view : composites integration
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 5
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Contents
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 7
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - China
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - In brief
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - JEC Americas
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 11
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 12
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 13
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Agenda of Events
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 15
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Catamaran
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 17
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - RIB
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Trimaran
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 20
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Carbon fibre
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 22
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 23
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 24
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 25
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Simulation
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 27
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Cost-effectiveness
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 29
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Low cost manufacturing
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 31
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 32
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Thin-ply
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 34
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 35
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - High temperature
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 37
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - LFT
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 39
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 40
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Thermoplastics
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 42
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 43
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 44
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Laser projection
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 46
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Release agent
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Manufacturing
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 49
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 50
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 51
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Health Monitoring
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 53
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 54
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 55
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Health monitoring techique for large composite structures
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 57
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 58
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 59
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - IOT
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 61
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Braiding
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 63
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 64
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Resin
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 66
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Vacuum infusion
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 68
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Machining center
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 70
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 71
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - PBT
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - Index
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - In the world
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 75
JEC COMPOSITES MAGAZINE - Issue #96 - April 2015 - 76
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