JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 44

bi-angle NCF

other layer. This is shown in the figure
2. On the top is the case where all
seams are stacked, and on the bottom,
the case where seams are staggered or
offset.
Uniaxial tensile tests for the three cases

are shown in Fig.3: seamless, stacked
seams and offset seams for the 0 degree
orientations.
Fig. 4: Same data as in Figure 3, except
coupons are oriented at 22.5 degrees
Figure 4 shows a reduction in all coupons, with and without
seams. The stacked seam
coupon (in the middle)
has the lowest values,
while the staggered or
offset coupons are competitive with the seamless
coupons. With the stacked
seams, the effective stress
concentration due to discontinuity is higher than
that with an open hole.

Fig. 3: Uniaxial tensile strength of 0-degree C-PlyTM for seamless,
stacked seam and offset seam coupons, with or without hole. Note all
data are comparable, with no noticeable variation due to the presence
of seams.

Note that along the
0-degree coupon, the
tensile strengths are not
sensitive to the presence of
seams. But for 22.5-degree
coupons, all strengths are
lower (strength is not isotropic like stiffness), and
those with stacked seams
(the middle ones) are the
worst. The offset seams
(on the right) are comparable to those of seamless
panels.

A new 50% offset
Fig. 4: Same data as in Figure 3, except coupons are oriented at 22.5
degrees

Fig. 5: Uniaxial tensile strength comparisons

44 jec composites magazine / No80 April 2013

A proprietary offset can
further reduce the effect of
seams. This is done with
50% offset, one half of the
width of the tape. One
advantage of this offset is
that the thickness of the
finished panel remains
uniform. Offsets larger or
smaller than 50% width
will result in bumps in
the panel thickness. Such
bumps may be tolerable,
but not in all cases.
Panels with a 2-axis layup
of [0/45] with 50% overlap

were produced and tested. The results
are shown in Fig.5.
This chart shows a comparison between
the uniaxial tensile strength of an autoclaved T800 unitape panel and vacuumbagged T700 C-PlyTM, for 0- and
22.5-degree coupons with and without
hole. All data are for the seamless case.
Test data from an ATL panel with 6”
wide tape and 50% overlap are shown
in solid blue lines for both 0- and
22.5-degree coupons, with and without
hole. It can be seen that these coupons
have a strength comparable to both the
seamless C-PlyTM and T800 unitape
coupons.

Conclusions
While more tests are being performed,
it can be seen that 2-axis layup of
[0/45] tape to form [π/4] using ATL
delivered competitive strength properties. This 2-axis layup process is more
than double the speed of layup and the
finished surface was smooth and no different from conventional unitape layup.
The thickness of C-PlyTM tape used was
0.125 mm and was found to be pliable,
and the 50% offset did not present any
problem in the compaction of layers
during the layup.
Other studies including the 1-axis layup
of [0/±45/0] are in progress. Again,
strength data were found to be highly
competitive with even greater gain in
speed (by a factor of 5 to 10 over the
conventional layup). These findings will
be reported in the future.
C-PlyTM can be used with ATL without
any unexpected difficulty. Additional
tests are being done to see that automated manufacturing can be utilized with
C-PlyTM. n
Acknowledgement
Support of this work by Michel Cognet,
Philippe Sanial, Brian Laufenberg of
Chomarat is hereby acknowledged.
More information:
stsai@stanford.edu.



JEC COMPOSITES MAGAZINE - Issue #80 - April 2013

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #80 - April 2013

Cover
Edito
Point of view: hig-end solutuions
Contents
Agenda of Events
COMPANY & BUSINESS In Brief
APPLICATIONS
- Sports & leisure
- Renovation
MARKET
- Singapore
- Education
- Natural fibres
- Biocomposites
FEATURE AERONAUTICS
- Carbon
- Process
- Reinforcement
- Structure
- Bi-angle NCF
- RTM
- Sandwich
- Energy
RESEARCH & DEVELOPMENT
- CAE tools
- CFRP
TECHNOLOGY & INNOVATIONS
- Prepreg
- Material
Index
In the world
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Cover
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 2
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Edito
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Point of view: hig-end solutuions
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 5
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Contents
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 7
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Agenda of Events
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 9
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - COMPANY & BUSINESS In Brief
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Sports & leisure
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 12
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 13
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Renovation
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Singapore
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 16
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 17
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 18
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Education
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 20
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 21
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 22
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 23
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 24
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 25
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Natural fibres
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 27
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Biocomposites
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 29
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 30
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 31
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 32
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Carbon
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 34
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Process
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 36
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 37
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Reinforcement
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 39
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 40
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Structure
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 42
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Bi-angle NCF
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 44
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - RTM
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 46
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Sandwich
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 48
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 49
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Energy
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 51
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - CAE tools
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 53
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 54
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - CFRP
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 56
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 57
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 58
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Prepreg
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 60
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 61
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - - Material
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 63
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 64
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - Index
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - In the world
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 67
JEC COMPOSITES MAGAZINE - Issue #80 - April 2013 - 68
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