JEC COMPOSITES MAGAZINE - Issue #137 - November/December 2020 - 65

Weight and cost reduction with double-double laminates

Fig. 2: Finite element model used in the adapter evaluation. Note the region of
interest and generic load introduction structure considered

structure (see the "top hat" structure attached to the forward end of
the adapter in Figure 2). The baseline configuration was a sandwich
construction with 8-ply quasi-isotropic face sheets (uniform layup
throughout the entire adapter) and an aluminium honeycomb core.
A widely used carbon/epoxy material system - IM7/8552 - was
considered for the face sheets. Following an initial iteration, the baseline quad layup was converted to a double-double layup - [+15°/15°] - using Lam Search. Further model runs were then carried out
to optimize the double-double layup with respect to strength. With
ease of manufacturing in mind, plies were dropped over seven regions from the highly-loaded forward end to the lightly-loaded aft
end. The optimization process was concluded once the face sheet ply
count near the aft end of the adapter reached a practical minimum of
two plies. Compared to the baseline 8-ply quasi-isotropic layup, the
optimized double-double layup showed an estimated 50% weight reduction - all the while maintaining a practical, straightforward route
to manufacturing.

University of Campania/CIRA example
A further application of the double-double conversion process to
a regional aircraft fuselage barrel was performed. Indeed, a portion
of the skin, including window cut-outs, was split in 42 regions characterized by different geometries, lay-ups and averaged stress (see
Figure 3). Starting from a standard baseline [0/45/-45/90]s quad
configuration of 16 plies, the conversion to double-double design
made it possible to reach, in five iterations, a 65% weight reduction
without compromising safety (for the skin). As a matter of fact, the
final double-double configuration, characterized by a double-double
layup of Φ ±37.5, Ψ ±45 and variable thickness in the 42 regions, was
smoothed according to ply thickness obtaining areas with 2,3,4 plies
(see Figure 3). The resulting configuration, which can still guarantee
a weight reduction of about 56.7%, was finally verified by standard
FEM procedures. Additional considerations about the application of
low-cost production processes have led to further modifications to
the thickness profile of the smoothed double-double design. Hence,
two additional optimum configurations were obtained, characterized, respectively, by one thickness variation across the hoop direction (with 52% weight reduction) and by a uniform thickness (with
48% weight reduction). These preliminary results showed the amazing potential of the double-double design approach. Actually, even
a configuration with uniform thickness, characterized by very low
production times and costs, can still guarantee a weight reduction of
about 50% compared to the standard quad design approach.

Fig. 3: a) Fuselage model and the considered 42 regions; b) DD optimized configuration

Conclusion
The conversion to double-double is an instantaneous process with
Lam Search. The same optimization can be applied to quad but the use
of tapering to save weight is not as direct as for double-double. Doubledouble makes preliminary design fast, efficient, and can overcome
many of the barriers that have made composites more complex than
necessary. Hopefully, the examples given here will give engineers confidence to discover if their structure can be improved with very little
effort. One only needs to have the stress and thickness formatted and
enter them into Lam Search. The best double-double and weight will
be right in front their eyes may be after one blink. A recalculation to
validate the weight reduction will make it believable. Many engineers
are afraid to try something new. There is no risk just to find out what
double-double can do.
More information:
Lam Search is available for free on request from stsai@stanford.edu
or thierry.massard@free.fr. A patent by Stanford is pending for double-double. Licensing will be required when it is used for production.
Please contact: luis.mejia@stanford.edu.
Online training: https://web.stanford.edu/group/composites/

N°137 November - December 2020

/ jec composites magazine

65


https://web.stanford.edu/group/composites/

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
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